Insensitive Munitions (Les Munitions a Risque Attgnu6)

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AGARD CONFERENCE PROCEEDINGS 511 Insensitive Munitions (Les Munitions a Risque AttGnu6)

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...... signed...... date * NOT FOR DESTRUCTION Papers presented at the Propulsion and Energetics Panel *. 78th A Spectalists’ Meeting held in Bonn, Germany, 21st-23rd October 1991.

- <*> - NORTH ATLANTIC TREATY ORGANlZAnON 1

Published July 1992 Distribution and Availability on Back Cover

. c ADVISORY GROUP FOR AEROSPACE RESEARCH & DEVELOPMENT 7 RUE ANCELLE 92200 NEUILLY SUR SEINE FRANCE

AGARD CONFERENCE PROCEEDINGS 511

Insensitive Munitions (Les Munitions B Risque Attknue)

Papers presented at the Propulsion and Energetics Panel . 78th A Specialists’ Meeting held in Bonn, Germany, 21st-23rd October 1991.

- North Atlantic Treaty Organization \/- Organisation du Traite de I’Atlantique Nord I The Mission of AGARD . According to its Chartcr, thc mission of AGARD is to bring togethcr thc leading personalities of the NATO nations in t le fields of science and technology relating to aerospace for the following purposes: -Recommending effective ways for the member nations to use their research and development capabilities for the .. common benefit of the h'AT0 community;

- Providing scientific and technical advice and assistancc to the Military Committee in the field of aerospace research and development (with particular regard to its military application);

- Continuously stimulating advances in the aerospace sciences relevant to strengthening the common defence posture;

- Improving the co-operation among member nations in aerospace research and development;

-Exchange of scientific and technical information;

- Providing assistance to member nations for the purpose of increasing their scientific and technical potential;

- Rendering scientific and technical assistance, as requested, to other NATO bodies and to member nations in comiection with research and development problems in the aerospace field. e Thc highest authority within AGARD is the National Delegates Board consisting of olficially appointed senior representatives from each member nation. The mission of AGARD is carried out through the Panels which are composed of experts appointed by the National Delegates, the Consultant and Exchange Programme and the Aerospace Applications Studies Prograinn e. The results of AGARD work are reported to the member nations and the NATO Authorities through the AGARD series of publications of which this is one.

Participetion in AGARD activities is by invitation only and is normally limited to citizens of the NATO nations,

The content of this publication has bcen reproduced directly from material supplied by AGARD or the authors

ISBN 92-835-0679-0

Printed by Speriulised Printing Services Limited 40 Chigwell Lune, Loughton, Essex IGI0 3TZ Recent Publications of the Propulsion and Energetics Panel - CONFERENCE PROCEEDINGS (CP) Combustion Problems in Turbine Engines ’+. AGARD CP 353, January 1984 Hazard Studies for Solid Propellant Rocket Motors AGARD CP 367, September 1984 Engine Cyclic Durability by Analysis and Testing AGARD CP 368, September 1984 Gears and Power Transmission Systems for Helicopters and Turboprops AGARD CP 369, January 1985 Heat Transfer and Cooling in Gas Turbines AGARD CP 390, September 1985 Smokeless Propellants AGARD CP 391, January 1986 Interior Ballistics of Guns AGARD CP 392, January 1986 Advanced Instrumentation for Aero Engine Components AGARD CP 399, November 1986 Engine Response to Distorted Inflow Conditions AGARD CP 400, March 1987 Transonic and Supersonic Phenomena in Turbomachines AGARDCP401,March 1987 Advanced Technology for Aero Engine Components AGARD CP 421, September 1987 Combustion and Fuels in Gas Turbine Engines AGARD CP 422, June 1988

Engine Condition Monitoring - Technology and Experience AGARD CP 448, October 1988 Application of Advanced Material for Turbomachinery and Rocket Propulsion AGARDCP449,March 1989 Combustion Instabilities in Liquid-Fuelled Propulsion Systems AGARD CP 450, April 1989

.I Aircraft Fire Safety AGARD CP 467, October 1989 * Unsteady Aerodynamic Phenomena in Turbomachines AGARD CP 468, February 1990 Secondary Flows in Turbomachines AGARD CP 469, February 1990 Hypersonic Combined Cycle Propulsion AGARD CP 479, December 1990 Low Temperature Environment Operations of Turboengines (Design and User’s Problems) AGARDCP480,May 1991 CFD Techniques for Propulsion Applications AGARD CP 510,February 1992 Combat Aircraft Noise AGARDCP512,ApriIlYY2

iii ADVISORY REPORTS (AR) Through Flow Calculations in Axial Turbomachines (Results of Working Group 12) AGARDAR 175,October 1981

Alternative Jet Engine Fuels (Results of Working Group IS) AGARDAR 181,Vol.l andVo1.2,July 1982 Suitable Averaging Techniques in Non-Uniform Internal Flows (Results of Working Group 14) AGARD AR 182 (in English and French), June/August 1983

Producibility and Cost Studies of Aviation Kerosines (Results of Working Group 16) AGARDAR227,June 1985

Performance of Rocket Motors with Metallized Propellants (Resultr of Working Group 17) AGARD AR 230, September 1986 Recommended Practices for Measurement of Gas Path Pressures and Temperatures for Performance Assessment of Aircraft Turbine Engines and Components (Results of Working Group 19) AGARD AR 245, June 1990 The Uniform Engine Test Programme (Results of Working Group IS) AGARD AR248,Febmary 1990

Test Cases for Computation oflnternal Flows in Aero Engine Components (Results of Working Group 18) AGARD AR 275, July 1990

LECTURE SERIES (LS) 3-D Computation Techniques Apptied to Internal Flows in Propulsion Systems AGARD LS 140, June 1985 Engine Airframe Integration for Rotorcraft AGARDLS 148, June 1986

Design Methods Used in Solid Rocket Motors AGARD LS 150, April 1987 AGARD LS 150 (Revised), April 1988 Blading Design for Axial Turbomachines AGARD LS 167, June 1989 Comparative Engine Performance Measurements AGARDLS 169,May 1990 Combustion of Solid Propellants AGARDLS 180,June 1991 Steady and Transient Performance Prediction of Gas Turbine Engines AGARD LS 183, May 1992

AGARDOGRAPHS (AG) Manual for Aeroelasticity in Turbomachines AGARD AG 298/1, March 1987 AGARD AG 298/2, June 1988 Measurement Uncertainty within the Uniform Engine Test Programme AGARD AG 307, May 1989 Hazard Studies for Solid Propellant Rocket Motors AGARDAG316,September 1990 REPORTS (R)

Application of Modified Loss and Deviation Correlations to Transonic Axial Compressors AGARD R 745, November 1987 Rotorcraft Drivetrain Life Safety and Reliability AGARD R 775, June 1990 Theme

“Insensitive Munitions” is an important area to NATO in light of the recent initiative by CNAD to develop a NATO Insensitive Munitions Information Centre (NIMIC) in Brussels in 1991. Insensitive munition requirements, evolving in NATO and many individual nations, are aimed at reducing the potential for and effects of unintended activation of munitions caused by their exposure to environmental forces. Such forces can occur either normally in situations such as transport and storage, in accidents such as fire, or combat circumstances through impact from bullets and fragments. The scope of the meeting focused on hazard technologies associated with rocket propulsion but also included other munition components that would be included in an overall safety assessment of a missile system. The scope was: - requirements in NATO Nations - approaches for hazard assessment - studies on hazard threat areas - studies on hazard technology areas - development of new energetic material and - development of devices to reduce destructive response to stimuli.

Theme

“Les Munitions B Risque Att6nui”est un domaine dbormais important pour I’OTAN, suite a I’initiative prise par le CNAD visant a la criation d’un centre de renseignements OTAN sur les munitions a risque attinu6 (NIMIC) i BNxelles pour l’annee 1991. Les spicifications des munitions i risque attinu4 qui sont en cours dilaboration au sein de I’OTAN, ainsi que dans de nombreux pays, ont pour objet la reduction du potentiel et des effets de l‘amorcage involontaire des munitions suite a leur exposition aux forces externes. De telles forces se manifestent soit en temps normal, 101s des operations de transport et de stockage par exemple, soit en cas daccident tel qu’une incendie, soit en situation de combat lors de I‘impact de balles et declats.

La rimion a mis l’accent sur les technologies du risque associees a la propulsion par fusee, tout en incluant les autres i16ments constitutifs du systime qui itaient prendre en compte lors de l‘kvaluation des risques present6 par un systime de missiles.

La r&nion a examine les sujets suivants: - les besoins exprimes par les pays memhres de l’OTAN - les approches possibles de I‘evaluation du risque - les itudes sur les domaines a grand risque - les &tudessur les technologies du risque - le developpement de nouvelles matieres energetiques - le d6veloppement d‘appareils destines a reduire la riponse destructive aux stimuli

Y Propulsion and Energetics Panel

Chairman: Prof. Dr A.U$er Deputy Chairman: Mr R.E. Henderson Middle East Technical University Deputy for Technology ODTU Aero Propulsion & Power Laborawry Makina Miih. Boliimu WL/POT .. Ankara Wright Patterson Air Force Base Turkey OHIO 45433-6.563 United States

PROGRAMME COMMITTEE

Dr R.L.Derr, Chairman Professor D. Dini Head, Research Department Dipartimento di Macchine Code 38 Universita di Pisa Naval Weapons Center via Diotisalvi 3 China Lake, California 935556001 56100 Pisa United States Italy

Dip.-Ing. B.Crispin Mr A. Whitehouse Messerschmitt-Bolkow-Blohm GmbH Manager, Design Assessment Section Kommunikationssysteme und Antriebe Royal Ordnance plc Abteilung AY75 Rocket Motors Division Postfach 80 11 49 Summefield, Kidderminster W-8000 Miinchen R0 Worcestershire DYll 7RZ Germany United Kingdom

Dr B.Zeller Directeur Strategie & Marketing Departement Defense Espace SNPE 12, Quai Henri IV 75181 Paris Cedex04 France

HOST NATION COORDINATOR Regierungsdirektor E Gunther a PANEL EXECUTIVE Dr Ing. E.Riester

Mail from Europe: Mail from US and Canada: AGARI-OTAN AGARD-NATO Attn: PEP Executive Attn: PEP Executive 7, rue Ancelle Unit 21551 F-92200 Neuilly-sur-Seine APO AE 09777 France

Tcl: 33 (I) 47 38 57 85 Tclex610176F Telefax:33(1)47385799

ACKNOWLEDGEMENT

The Propulsion and Energetics Panel wishes to express its thanks to the National Authorities from Germany for the invit;ition to hold this meeting in Bonn, Germany, and for the facilities and personnel which make this meeting possible.

vi Contents

. Page

Recent Publications of PEP iii * ThemeITheme V

Propulsion and Energetics Panel vi

Reference

Technical Evaluation Report T by L. Gilbert SESSION I - INSENSITIVE MUNITIONS POLICY

NATO Insensitive Munitions Information Center (NIMIC) 1 by E.A.Daugherty and M.D.6fourneaux

Progress and Initiatives towards a UK Insensitive Munitions Policy 2 by R.G.Shephard

Specifications et Criteres de Securite des Munitions Destinees a la Marine Franpise 3F par A.Artaud et 0.Saliou

Safety Specifications and Criteria Concerning Munitions Intended for the French Navy 3E by A.Artaud and 0.Saliou

Les Travaux Francais sur les Substances Explosives pour Munitions a Risques Attenues 4 (MURAT) +~~,u~6j~cL~~a s&- 5 ij, 't- .i) (French Policv of Providing Industry with Gun Propellants, Rocket Propellants and High Explosives fo; Reduced Sensitivity Ammunitions) . par J.M.Decore, B.Sainjon et P.Lamy

SESSION I1 - EXPLOSIVES AND GUN PROPULSION The United States Air Force Explosives Hazards Reduction Program 0 by J.Jenus, Jr Advanced Gun Propulsion Concepts and Insensitive Munitions Requirements: An Overview of US Efforts .. .. by LMay, et al. MBB-Development of Insensitive PBX-Charges 7 by M. Held c Methodologie de Conception de Charges Militaires a Immunite Renforcee 8 par G. Couturier et J.Ferron

Less Sensitive Explosives 9 by N.H.A.van Ham, A.C.van der Steen and J.J.Meulenbrugge

Low Vulnerability Characteristics of an HMX-Based Explosive 10 by LHooton

SESSION Ill - ROCKET PROPULSION

ESD Traits of Bulk Propellant under Pressure 11 by C.I.Merril1 and J.A. Askins

vii Reference

Development of a Minimum Smoke Propellant Based on Glycidyl Azide Polymer n:! and Ammonium Nitrate by P. Lessard, et al.

Paper 13 withdrawn

The Design Features of Rocket Motors Relating to Insensitive Munition Response to 1.4 Thermo-Mechanical Stimuli by A.C.MdSon

Hazards Reduction for Tactical Missiles 1 !i by K.O. Hartman

SESSION IV - PHYSICAL PHENOMENA ASSOCIATED WITH INSENSITIVE MUNITIONS

Hazards of Energetic Materials and their Relation to Munitions Survivability ltl by T.L.Boggs, C.W.Dickinson, L.M.Barrington, C.Belanger and P.J.Haskins

Comportement des Chargements de Propergols a I'Impact de Balles 1; (Bullet Impact Behavior of Solid Propellant Grains) par J.Brunet, SHamaide, B. Nouguez et I;'.Pitiot

Effect of Case Thickness and Projectile Geometry on the Shock Initiation Threshold for 18' a Given Explosive by H.R.James, P.J.Hdskins and M.D. Cook

Fuel Fire and Bullet Impact Tests with Warheads 14 by P. Wanninger

Three Efforts Concerning Fragment and Shock Hazards to Cased Munitions 20 by M.R. Wagenhals, et al.

The Effect of Heating Rate in Cook-off Testing of Energetic Materials 21 by R.Farinaccio

PhPnomknes Thermiques Induits par un Accident de Munition a Bord d'un Wavire 22 (Thermal Phenomena Induced by an Ammunition Accident on Board Ships) par A.Fournier et C.Lallemand

Numerical Modelling of the Shock Initiation of High Explosives by G. Pezzica

Phenomene de Detonation par Influence: Approehe Numerique et Experimentale 24 (Sympathetic Detonation Phenomenon: Numerical and Experimental Approach) par B. Nouguez, M.Quidot, P. Gimenez et J.C.Derrien

Paper 25 withdrawn

... "lll T- I

. TECHNICAL EVALUATION REPORT

Lee N. Gilbert Associate Depamnent Head AmkWeapons Depamnent Naval Air Warfare Center-Weapns Division China Lake, Caliiomia USA

1.0 SUMMARY

This meeting provided a forum for technical interchange between insensitive munitions policy e makers from the North American Treaty Organization (NATO) countries and the research and development technologists of the Advisory Group for Aerospace Rasearch and Development (AGARD). The objectives of the meeting, which are described below, were achieved. It was also concluded that, although not all countries have insensitive munitions policies, they all support insensitive munitions, at least in principle, and that a great deal of additional work needs to be conducted to accurately predict from small-scale tests the response of full-scale munition to hazard stimuli.

2.0 INTRODUCTION

The objectives of this specialist meeting were as follows: (a) review the insensitive munitions policies of the NATO member nations, (b) discuss the sratus and results of research and development programs in the member nations that address insensitive munitions, (c) identify new ideas for research, and (d) stimulate interchange and communication between research and development scientists within member countries who are addressing insensitive munitions. This meeting was very timely and addressed an important NATO issue, in light of the recent initiative by the Conference of National Armaments Directors 0 (CNAD) to develop a NATO Insensitive Munitions Information Center WMC) in Brussels in 1991. NATO policy and technical specialists in the following areas were represented: (a) insensitive munitions requirements and policy, (b) high explosives, (c) gun propulsion, (d) rocket propulsion, and (e) . energetic materials and physical phenomena research. The meeting involved twenty four papers, plus a keynote address, and was organized in the following categorier

LI Insensitive munitions policy . Explosives and gun propulsion * Rocket propulsion Physical phenomena associated with insensitive munitions.

3.0 BACKGROUND

More than 6000 people have been killed during this century as a result of hazards created by munitions responding to unplanned stimuli such as heat or shock. The largest of such events was the collision of a Belgium boat with a French cargo ship loaded with ammunition in the harbor of Halifax, Nova Scotia, Canada, on 12 December 1917, which resulted in approximately 5000 deaths (Reference 1). In response to these accidents, several NATO countries initiated the definition of requirements and policies T-2

addressing insensitive munitions. The NATO Group ACBlO, one of six cadre groups under CNAD, Wac formed in 1979 to address the need for standardization of weapons systems, with emphasis on energetic materials. Specifically, NATO Group ACDlO was tasked to establish a common international termino1og:r and develop design principles, criteria, procedures, and tests to cover all aspects of the process by which . weapons systems are assessed to be safe and suitable for service. Propulsion and ordnance systems, therefore, are only one of the NATO Group ACBlO's responsibilities (Reference 2). I NATO Group AC/310 envisioned the need for a mechanism to disseminate information withui NATO member countries and hosted a workshop, entitled "Insensitive Munitions Information Exchange," in 1986 (Reference 3). This workshop confmed the need and justification for an insensitive munition!: information exchange system within NATO. In 1988, NATO Group ACDlO established a Pilot NATCl Insensitive Munitions Information Center (PNIMIC) to validate and justify the need and operational concep: of this information exchange system. The PNIMIC was successful, and the formal NATO Insensitiw: Munitions Information Center (NIMIC) was established in May 1991 in Brussels, Belgium (l).*

At about the same time that NATO Group AC/310 was addressing the insensitive munition$. information exchange mechanism, AGARD became interested in the technology associated with alleviating. the hazards of energetic materials and its application to propulsion systems and warheads. In 1984, AGARD hosted a Conference entitled "Hazards Studies for Solid Propellant Rocket Motors" (Reference 4). During this meeting, technical interactions between AGARD and NATO standardization activities provided the basis for improved hazard methodologies to be used in the design of future solid propellant rockec motors. In addition, a basis was provided for new research and development topics to be addressed by the different NATO countries interested in the development, production, and operation of high-energy, solid propellant rocket motors.

The second conference, in 1986. focused on smokeless propellants (Reference 5). It highlighted the severe problems encountered by propellant formulators in trying to develop insensitive smokeless propellants, while maintaining performance. The need for an "AGARDograph (Reference I) to dxumenl the status of hazard studies within NATO member nations was identified at the conference.

4.0 EVALUATION

Rear Admiral Meinig's (U. S. Naval Sea Systems Command) keynote address reemphasized the need for insensitive munition requirements and international research collaboration which would result in better solutions reached in a shorter time. The U.S. Joint-Service Insensitive Requirements, and desired munition response, were reiterated. Munitions should satisfactorily pass the following hazard tests: fast e cookoff, slow cookoff, fragment attack, bullet impact, sympathetic detonation, spall attack, and shape

charge attack. It was emphasized that the requirement for ammunition to pass these hazard tests must c compete with other system requirements, such as cost and performance; all requirements must interact to optimize the overall system and meet the users' needs. The keynote address focused the attention of

conference attendees to the need for insensitive munitions and the need to share information in order to more 4 rapidly solve problems.

The four major sessions of the conference are discussed and evaluated in the following sections.

* Number in parentheses refers to paper number in the meeting. T-3

4.1 Insensitive Munitions Policy

This session contained four papers which addressed insensitive munitions policies and information . exchange procedures practiced by various member nations. The paper presented by Defoumeaux (1) gave an excellent overview of the history of PNIMIC and NIMIC, as well as informing the attendees on how to add information to NIMIC's database and have NIMIC conduct literature searches on specific insensitive * munition subjects.

Shepard (2) stated that the U.K. has no formal statute on insensitive munitions; however, it has a Joint Insensitive Munitions Working Group that tries to meet performance and readiness requirements with the least sensitive munition. Even without a formal requirement, the U.K. has a policy to analyze and study vulnerability and its eade-off against weapon system cost and effectiveness.

Saliou (3) presented France's requkements, which are quite similar to U.S. requirements, except for spall attack, which France does not have. France's insensitive munition reponse requirements are defied as follows: (a) no reaction except burning for fast cookoff, drop, bullet impact, and light fragment attack; (b) no detonation response for heavy fragment attack and sympathetic detonation: and (c) no specified response for slow cookoff. a- The fial paper, of this session, by Lamy (4) addressed trade-off studies for projectile explosives and propellants. It was found that combustible cases, in place of metallic cases, reduce the sensitivity of shells when exposed to the required hazard tests. Data on high explosives @ressed PBXs) with aiaminotrinieobenzene (TATB) showed reduced sensitivity, bot also markedly reduced performance. Some very interesting data presented indicated that, if the design of a system allows the projectile penetrating energetic material to stay ahead of the shock wave, then a detonation will not result from bullet impact or fragment attack. Lamy also reiterated that a balance between performance, vulnerability, and cost has to be achieved.

4.2 Explosives and Gun Propulsion

The second session addressed explosives and gun propellants and contained six papers. The paper by Jenos (5). presented by Day, described the U.S. Air Force program for techniques to reduce the quantity/distance requirements for bombs in mass storage; this would result in significant increases in combat effectiveness at airfields. By using buffer materials between the stacks of bombs, the packing density of the bombs could be doubled. These buffer materials could even be other types of ammunition, such as boxes of 25-mm ddges. . The paper by May (6) described a novel electromagnetic (EM) gun system that does not require any energetic materials to propel the projectile. However, EM gun power trains (high-density electrical energy . storage and power supplies) may in themselves induce separate hazards unforeseen at thii time. Held (7) provided a review of insensitive munition testing techniques and definitions used throughout NATO member countries. Couturier (8) presented experimental results on an especially designed warhead loaded with cast PBX that passed all of the insensitive munition tests. This particular warhead included an absorbing material between the explosive and warhead case and employed a venting device; this concept proved to be less sensitive to hazard stimuli than a similar design without the absorbing material. The design principles used were as follows: (a) use explosives with high initiation pressures and good thermal and mechanical properties: (b) employ shock absorbing materials at the interface of the explosive and warhead case; and (c) employ venthg devices. T-4

The last two papers (9 and 10) of this session dealt with the sensitivity of cyclotrimethylenetrinimine (RDX)and cyclote~ethyleneteerranihamine(HMX) and the effects of crystal shape and defects. Vander Steen (9) presented data showing the influence of RDX crystal shape and defects on the sensitivity of a RDX/polyurethane formulation, while Hooton (10) @resented by Lessard) presented data showing that identical formulations using HMX in place of RDX were less sensitive, yet provided higher performance.

4.3 Rocket Propulsion

The third session addressed rocket propulsion and propellants and contained five papers. Memll (11) presented an excellent summary of ongoing work in elecmstatic discharge abatement. The paper described a subscale test technique that allows samples to be tested under pressure and at varying temperatures. Data on bddown voltage vs. pressure and sample bulk temperature of hydroxyl-terminated polybutadiene (HTF'B) propellants were presented

The next two papers by Lessard (12) and Menke (13) addressed formulation studies for minimum- smoke and low-sensitivity rocket propellants. Lessard (12) presented data 0x1 a glycidyl azide polymer and ammonium nitrate oxidizer formulation that, to date, has not met the target performance, burning rate, ox mechanical properties of the program. The program is continuing to address these shortfalls by looking at other oxidizers and additives. Menke (13) described a nitroguanidineoxidimi formulation that has reduced sensitivity if it is contained in a motor tube that ruptures easily during hazard testing. Nitroguanidine was used to eliminate HC1 from the exhaust products. However, during questioning, Menke stated that aluminum would have to be added to the formulation to achieve adequate pxformance. The Evaluator nom that this would result in primary smoke (Alz03),and therefore eliminating the concern for HC1 (secondary smoke).

The final two papers of this session by Mason (14) and Hartman (15) addressed various aspects of rocket motor hardware and propellant hazards testing. Mason (14) gave an overview of a very large British database of propellant formulations and rocket motor case designs that have been subjected to llazard testing. Of interest was the apparent lack of correlation between pass/f&l of Class 1.1 and 1.3 propellant formulations when they are subjected to a 0.5-inch-diameter bullet impact. Additional data presented showed that all elastomer-modified. cast double-based (EMCDB) propellant formulations react in approximately 60 seconds. independent of case design, when subjected to a fast cwkoff test. Hartman's paper (15) summarized a great deal of data on the testing of minimum-smoke propellants with ammonium perchlorate (AP)or potassium perchlorate (KP) as oxidizers. The KP formulation has significant potential for high-density propellant applications. A laser safe/arm igniter concept was described that may alleviate some of the sensitivity caused by the igniter components in rocket motors. Data comparing several types of rocket motor case materials and their response to hazard stimuli were also provided.

4.4 Physical Phenomena Associated With Insensitive Munitions

The fourth and final session of the conference covered the physical phenomena associated with energetic materials responding to hazard stimuli, both in terms of testing and modelling. This session contained nine papers. The opening paper of this session, presented by Boggs (16). described a collaborative effort of The Technical Cooperation Program ('ITCP),Panel W,Action Group 11 (WAG11). This effort consists of developing hazard assessment protocols and their uses for each of the hazard heats. These protocols, available through MMIC, will be further discussed in the recommendations section of this report. T-5

Brunet (17) compared some fragment and bullet impact experimental results with modelling results obtained with the LS-DYNA-2D computer code. The two sets of data correlated very well and indicated that tension waves, caused by a projectile or fragment penetrating an undamaged propellant mass, sensitize the . propellant. If this occurs at the right projectile velocity, it will cause an XDT reaction.

The next paper (18). presented by Shepard, described an analytical and experimental program that . evaluated projectiles that transmit a one-dimensional shock into a cased explosive. Some of the variables tested were case thickness, case material, projectile velocity, and projectile shape.

Wanninger (19) covered the results obtained in three different study areas and summarized his conclusions as follows: (a) an explosive material with good mechanical properties is required in order to pass the fuel fue cookoff test: (b) the ammunition caliber and the critical diameter of the explosive have a significant influence in bullet impact safety; and (c) the more brittle the explosive, the more susceptible it will be to shape charge attack.

Lindfors (20) briefed the audience only on the paion of a three-part paper that regarded shock sensitivity of propellants in the wedge test. This study led to insights into the influence of certain components of energetic composite materials in the shock-to-detonation reaction. The other two parts of a the paper dealt with delayed detonations of propellant impacted by a projectile, and munition response predictions using the FRAG-MAP code, which is a development based on the hazard assessment protocols discussed by Boggs.

The degree of confinement of a plastic-bonded explosive significantly influences the degree of reaction to a cookoff hazard stimulus. Farinaccio's (21) results demonstrated this, as well as the influence that the heating rate has on the temperature at which the reaction will occur. Fournier (22) used one- dimensional and three-dimensional computer analysis to model three areas of concem associated with a fue in ship compartments: (a) heat msfer between compartments and containers; (b) hot gadexhaust jet impacting on a flat plate surface; and (c) thermal response of warhead and rocket units in the compartments.

Pessica (23) showed that, by adding extemal user subroutines to the two-dimensional finite difference coupled Lagrangian-Eulerian PISCES code, it is possible to perform a very wide range of useful shock-to-detonation transition predictions under most circumstances.

The final paper of the conference, by Nouguez (24). demonstrated that current cast PBXs, with confinement modifications, can meet all the insensitive munitions tests, except sympathetic detonation. Two new cast PBXs have been formulated using nitmniazolone NO)as the primary energetic ingredient. a DYNA-2D models and experimental tests have shown that these cast PBXs can successfully pass the sympathetic detonation test and can perform fairly satisfactorily in slow cookoff, fast cookoff, bullet c impact, and fragment attack tests.

\ 5.0 CONCLUSIONS

While large-scale go/no go tests are important to demonstrate insensitive munitions compliance, they lack in other areas: (a) they are inadequate by themselves because. they cannot be well instrumented and, therefore, valuable lessons are hard to learn from their final outcome; @) they are too costly for the amount of infomation they provide; moreover, because they are conducted at the end of a weapon's development program, any problems identified during these tests are also very costly to fv;and, finally. (c) they are poor statistically (most hazard requirements demand 1: 106 probabilities). As a result, small-scale tests need to be validated and accepted so that their results can be included in the statistical probability of failure prediction of the all-up system.

6.0 RECOMMENDATIONS

Recommendations based on the outcome of this meeting are as follows:

1. The use of hazard protocols should be supported and encouraged. NATO member countries should use and evaluate the protocols, exchange the results, and, through a coordinating AGARDPEP working group, compare and document the outcome.

2. All AGARDPEP members should be encouraged to support and publicize NIMIC and its capabilities.

3. Fundamental research on the mechanisms that trigger violent responses during cookoff should be supported and encouraged. Of particular importance are the following: (a) the thermochemical and thermomechanical mechanisms that trigger the violent response of energetic materials under confinement during a fast cookoff; (b) the thermochemical and thennomechanical mechanisms that trigger the violent response of energetic materials during slow cookoff; and (c) the elevated temperature chemical mechanisms occuning in bulk propellant during slow cookoff.

7.0 REFERENCES

1. Hazard Studies for Solid Propellant Rocket Motors, edited hy Thomas L. Boggs and Dr. Ronald L. Den; September 1990. AGARDograph No. 316

2. Col. G. G. W. Brace. Aims and Requirements of NATO Group ACl310. presented at AGARD’ Specialist Meeting. 28-30 May 1984. AGARD Conference Proceedings No. 367.

3. Workshop on Insensitive Munitions Infomiion Exchange. 13-15 October 1986, published March 1987. NATO AC/310 Conference proceedings No. 001.

4. Hazardr Studies for Solid Rocket Motors. AGARD Specialists Meeting, 28-30 May 1984. published September 1984. AGARD Conference Proceedings No. 367

5. Smokeless Propellants. AGARD Specialists Meeting, 12-13 September 1985, published January 1986. AGARD Conference Proceedings No. 391 1-1

NATO Insensitive Munitions Information Center (NIMIC)

E.A. Daugherty Marc Dkfourneaux Program Manager Pilot NIMIC Program Manager NIMIC AOT, Inc NATO Headquarters 2001 Jefferson Davis Hwy Brussels 11 10 Arlington, VA 22202 Belgium USA

Presented by Marc Dkfoumeaux Nato Insensitive Munitions Inforination Center

Centre Otaii d’information sur les munitions h risque att6nd SUMMARY the input, content and maintenance of information in the database; the background Having proven its value during a and technical expertise of the staff of three-year Pilot phase, the NATO munitions experts; the analytical capability Insensitive Munitions Information Center of the NIMIC in providing support to the began operations in NATO Headquarters, munition design community in areas of Brussels in May 1991. This paper presents insensitive munitions and safety; and the an overview of the evolution of NIMIC: its procedures by which one may request concept formulation in NATO AC1310, its NIMIC technical assistance. Pilot phase years, and the Center as it exists today. LIST OF ACRONYMS * These introductory comments are followed by an in-depth discussion of the AGARD Advisory Group for Armspace and following: the NIMIC management structure Development including its Steering Committee function; BRS Bibliographic Retrieval Sewices .. .. ,: ,

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These considerations have led to an 2.NIMIC WlTHIN NATO international approach to the problem under the auspices of NATO, and to an 2.1 Position attempt for a joint definition of rules governing the design of safer munitions, To provide a frame of reference in though still efficient, whatever the name understanding NIMIC and its functions, they are given: Chart 1 presents a simplified organizational structure for NATO. Indicated are the two major sides of the house, namely the civil in English, LOVA (LOW and the military organizations. To these Vulnerability Ammunition) or IM must be added the International Staff (IS) (Insensitive Munitions), although -the which provides support to all groups, adjective "&sensitive" is certainly committees and agencies. Only those exaggerated; groups and agencies of prime significance to NIMIC have been listed in this chart, for - in French, MURAT (Munitions 31 clarity. Risque AttBnuB). On the civil side, the main group of interest is the CNAD (Conference of National This international approach has resulted in Armament Directors), to which the NIMIC the creation of NIMIC, i.e. the NATO Steering Committee reports annually. Insensitive Munitions Information Center. Under CNAD are Army, Air Force and The purpose of this paper is to describe Navy Armament Groups, the Industrial how the NIMIC concept came out, what Advisory Group and the Defense Research Pilot NIMIC has achieved, what NIMIC is Group. Also under CNAD are several currently doing and what it expects to do cadre groups which are basically multi- in the future. service (Army, Navy and Air force) in

Chart 1 . . civil organization Military "ittee

+I I

iiiii ember Nations 1-4

nature, among them two groups specifically related with NIMIC is Propulsion aid devoted to munitions: Energetics, the organizer of this meetiq;. Now, NIMIC is also interested in the - AU2.58, involved with safety aspects activity of the 'Technical Information Pm:l of transportation and storage of TIP. Indeed, as an aside, AGARD tasked ammunition and explosives, and TIP to address the need for a centr,ll repository for all NATO scientific and - . AC/310, involved with safety and technical Information. As a result, TIP suitability for service of conventional summarized the problem of NAT9 munitions. information as follows: "Scientific, Technical and other information (ST[) On the military side (Le. under the Military generated by NATO is not fully utilirrd Committee), we find military commands, because it is not readily identifiabli:, and also agencies, among them: retrievable or available to NATO staff asd the nations, thereby causing great waste of - the Military Agency for time and resources" (Ref. 1) Standardization (MAS), and of course This concern of AGARD TIP covered the total spectrum of information available :n - AGARD. NATO, and a study group developed a concept for a NATO Scientific and e 2.2 NIMIC and AGARD Technical Information Service (NSTIC) (Chart 2). The proposed concept (Ref. :.) The relations of NIMIC with MAS are outlines a centralized, automated, essentially devoted to the preparation of information service performing the functio 3 STANAGs, is. standardization agreements. of acquisition, selecting, cataloging, The relations with AGARD are of a more information retrieval and document technical nature. ordering. It has always been intended thai:, should NSTIS become operational, NIMXC Within AGARD, the panel most obviously would be a sub-set group interfacing with it. Chart 2 - Interaction of NIMIC With The AGARD STIS- 0 NIMIC .

5. 4. NATO Organmtlon , NATO HQ - NSTIS* --f NATO HQ 6 NATO Nations I COMMERCIALI NATO NATIONS DATABASES DOCUMENTATION CENTERS

'NATO Scientific and Technical Information Service 2.3 NIMIC and AC/310 - in 1991, the transition from Pilot NIMIC to NIMIC and its transfer Now, the main link for NIMIC within to the NATO Headquarters in NATO is with AC/310, where NIMIC was Brussels. conceived to some extent, although NIMIC itself is a separate and distinct entity. Chart 3

AC1310's full name is "Group on Safety and NIMIC History Suitability for Service of Munitions and Explosives". It was formed in 1979 to 1979 Creation of AC/310 address the problem identified by CNAD as a major impediment to munition 1984 US (initiative) interoperability within the Alliance, FR specifically, the lack of an agreed safety IM Group assessment process. 1986 UK (workshop)

In 1984, AC1310 became aware of the 1988 Creation of Pilot NIMIC (USA) increased concern being voiced by nations 1991 Transition to NIMIC (NATO Ha) regarding the vulnerability of launch (CA, FR, NL, UK, US) platforms and storage sites as a function of the reaction of munitions to combat-induced environmental forces. Due to these concerns, the criteria for acceptance of 3. NIMIC HISTORY munitions as safe and suitable for service, as stated in resulting national insensitive 3.1 steps to Pilot NIMIC munition programs, were being stated in more stringent terms. AC1310 noted that, The initiative for promoting the IM concept without the knowledge and availability of originated in the United States, involving new technology, the task of munition both Departments of Defense @OD) and designers in meeting these criteria while Energy @OE), the main promoter being retaining operational effectiveness - which the US Navy, which paid a heavy tribute to remains the primary goal of munitions - was sensitivity in the last decades. An becoming increasingly more difficult. Insensitive High Explosives and Propellants (IHEP) study was conducted to increase the This is how AC1310 identified the need for safety and survivability of munitions. This a focal point within NATO to exchange program was given additional impetus by a Technical Information on Insensitive Joint Technical Coordination Group to Munitions (IM) to facilitate design efforts in improve munition survivability. meeting the new and evolving IM . requirements. This identified need then led Ideas developed in these studies were to a series of actions initiated in AC1310, presented to international and NATO leading to the formation of NIMIC. audiences by the US., and support in a number of nations was evidenced. Virtually Chart 3 summarizes the main three phases concurrent with the U.S. Program, both of this formation: France and the United Kingdom launched efforts in the area of interest, focusing - from 1984 to 1986, a number of mainly on energetic material development intermediate steps toward the or use. concept of an IM group, The NATO group AC/310 formed several - in 1988, the creation of a Pilot ad-hoc groups to validate the need for a NIMIC in the United States under center for IM technology exchange and to a 5-nation MoU, determine a logical location within NATO. 1-6

This study started under French concept is viable. This report provides the chairmanship, and culminated in a workshop evidence on which is based the conclusion held in 1986 in London, which provided a that implementation of the NIMIC conct:pt forum for potential users to assess the value is capable of achieving the desiied of such a center. The workshop was objective". The result of national staffing attended by 70 representatives of national was a consensus that a permanent NIMC government and industrial agencies, as well should be formed. as various NATO groups from CNAD and MAS, including the Service Armament 4. NIMlC Organization Groups. 4.1 Statu$; The workshop resulted in a consensus that an Insensitive Munitions Information Another MoU was executed on 24 October Center, with an analysis capability, would be 1990 establishing a permanent NIMIC. of vdue. The Center should develop and Original participants are Canada, France, maintain a data base of scientific and Netherlands, IJnited Kingdom and UnitNd technical information, and be staffed by States. Prior to this, a letter of agreemeit technical personnel to interrogate and was signed on 24 September 1990 by tie analyze the data base to respond to Steering Committee and NATO regardi ig technical questionnaires. the provision of services and facilities by e NATO in support of the NIMIC project. Since the need was immediate, the US. proposed a Pilot Center be established to Total funding of NIMIC is provided by the meet the current need and plan for the participating nations on a share basis, establishment of the permanent NIMIC. A wherein large nations pay two shares and Memorandum of Understanding (MoU) was smaller nations one share. NIMIC operatm signed in May 1988 by France, the under a budget approved by the Steeriiig Netherlands, Norway, the United Kingdom Committee, with NATO administering ,AII and the United States. Canada joined by financial matters, including the an Amendment to the MoU in April 1989. establishment of a NIMIC account in a NATO approved commercial bank. The core staff of Program Manager, Systems Administrator, Technical Writer, Security is governed by a NIMIC Proje:t Legal Consultant, and Secretary were Security Instruction which was developed to provided by the Pilot NIMIC host country, provide protection of classified information i.e. the United Sates. Technical staff up to and including "Confidential", in members were provided by secondment accordance with national laws and from the participating nations. Overall regulations provided such are no less e administration was provided by a Steering stringent than the NATO Securiiy Committee composed of a representative of Document C-M(SS)lS(Final) of 31 July - each participating nation, and chaired by 1972. NATO will provide physical securi:y the U.S. Rkpresentative. for the NIMIC facility in accordance wih normal NATO procedures. , The Steering Committee agreed that the efforts of Pilot NIMIC in performing the 4.2 Staff tasks identified in the MoU would be assessed prior to the establishment of the Unlike Pilot NIMIC, the total staff Ifor permanent NIMIC. An assessment report NIMIC is being hired in accordance wiih was written (Xef. 2), which was staffed NATO hiring procedures. While the staff within all participating nations. The report members are NIMIC employees, all states in its synopsis: "In May 1988 a Pilot personnel matters are processed in NIMIC program was established with the accordance with NATO procedures. Stafi' object of determining whether the NIMIC 1-7

NIMIC Operation

I STAFF:

4 Technical officers 1 Technical Mitor 1 systens Analyst I I mum": I T&lS

TASKS:

NATIm aXrATs: prosrans t------FcrAL POINTS t----DaDatahases

Chart 4

performance is assessed by the Steering taken into account. Hence the theoretical Committee. staff of 8 is still far from being completed today, which temporarily reduces NIMIC's This staff is presently defined as shown in efficiency. The transition from Pilot NIMIC Chart 4: to NIMIC certainly was a necessary step, but it is a difficult one, and the full working - a program manager, with a secretary, pace will only be attained in early 1992. NIMIC will then resume and expand the 0 - four technical officers. each one tasks identified in both the Pilot NIMIC specialized in a given field, i.e. and NIMIC MoU documents. Explosives, Explosion effects, * Warheads design and Propulsion 5.NIMIvlIc's tasks design, 5.1 Links with Users . - a technical editor and a systems analyst, more particularly in charge These tasks can be listed under three of the database and the computer headlines (right to left on Chart 4): equipment. - maintaining a specialized database, This amounts to 8 staff members, to he hired among candidates belonging to the responding to questionnaires issued participating nations. Unfortunately, the by member nations, and NATO hiring process is very lengthy, due to the obvious security requirements and to - performing inquiries of its own. the inevitable political considerations to be All these tasks imply the existence of formal function for the selection of relevant links with the users. To this end, each documents, a characteristic whi:h participating nation has provided NIMIC differentiates it from other "information with a contact within the nation, a National centers". Focal Point Officer (NFPO), who assists in efforts to input data and process Collection and selection of information questionnaires. Also each participating can be effected through two different nation has identified national governmental channels: agencies authorized direct contact with NIMIC. Any questionnaire from these - the main one utilizes the NFPO to agencies can be received and responded to conduct searches for relevant directly by NIMIC. Other agencies and information in national agencies, industrial concerns are to forward questionnaires to NIMIC via the - an optional channel is direct appropriate NFPO, whose responsibility it is interrogation of national databasis to validate, from an administrative view, the by means of a MODEM. need for the assistance being sought. NIMIC responses will also be sent via the The main agencies and databases of the NFPO unless stipulated otherwise. member nations are listed in Annex A. Rlt this is not to say that the NIMIC databide Other NATO groups (such as the Service precludes entrance of information from Armament Groups) and other NATO non-participating nations. To the contrary, nations can submit questionnaires to NIMIC a significant amount of data from noli- via the Steering Committee. The participants resides in NIMIC having been authorization of the Steering Committee is either volunteered by such nations or necessary since many NATO groups have accessed from open literature. nations in membership which are not participants in NIMIC. The SC, if in In September 1991, these searches hid unanimous agreement to provide the already resulted in the review of more than service, will forward the questionnaire to 30,000 technical abstracts for relevancy IO NIMIC for response. Assistance provided NIMIC. Of these, about 60 percent were to non-participants will be subject to considered relevant. In addition, over 7,000 payment of a fee for services, based on the hard copies of documents were received and complexity of the effort involved. a review indicated over 95 percent relevalit for entrance into the NIMIC databaw. These searches will be a continuing effo-t 5.2 IM Database of NIMIC to provide input to the database in as timely a manner as possible. As far as the database is concerned, NIMIC's tasks are the following: Information ha!; been received in basicdly two forms: hard copy and floppy discs. All - collect, store and disseminate relevant information is processed for scientific and technical information entrance into the IM database (machin: on IM; searchable). Obviously it is of an advantag: to NIMIC to receive the information in - provide and maintain a floppy disc or magnetic tape form, which comprehensive data collection so as aids not only in timely processing is to facilitate design efforts for IM machine readable, but also in reduction of and minimize the cost of research storage space. and development efforts; Once the information is converted to It is important to note that, even at this machine readable form, it is then placed in level, NIMIC already provides an analysis Bibliographic Retrieval Services (BRS) 1-9

Search format. BRS Search is a text-based for application require consideration at a database system residing on the hard disc of systems level. It is counterproductive to a compaq Deskpro 386 (IBM compatible) prevent a hazardous condition that arises computer with backup onto two magnetic infrequently in a combat situation and tapes. BRS Search is used extensively to create a highly likely hazard in other phases query the databases listed in Annex B. of the logistic cycle. NIMIC was created to provide a source of information for the assessment of &lfactors involved in arriving at a design solution. 5.3 Responses to Technical QUestiOMaireS In the early months of Pilot NIMIC, the majority of questionnaires were factual in The principal objective in establishing nature, not requiring much analysis or NIMIC is to provide a NATO central point presentation of opinions and for the exchange of technical information in recommendations. In recent months, the order to facilitate the design of munitions questionnaires have been more searching in to meet national and future NATO IM nature, and thus more in conformity with requirements. While the term "insensitive the plan for NIMIC. Chart 5 lists the munitions" is defined somewhat differently activity of NIMIC in this area. It is evident a by nations, the general goal of reducing from the number of questionnaires vulnerability of launch platforms and storage submitted that pilot NIMIC was recognized areas while retaining combat effectiveness is in the munitions community, and that this generally accepted by all. The goal is community is now anxious for assistance seldom achievable by a single approach, but from NIMIC. requires the combination of several technologies (e.g. energetic material A comparison of the types of information selection in conjunction with mitigating in the database versus the subjects of devices). questionnaires is presented in Chart 5. Not surprisingly, this chart indicates heavy In all instances, the synergistic effects of the emphasis in data input and questionnaires technology or technologies being proposed related to energetic materials. As time

Chart 5 Subjects of Technical Questions vs. Data (as of 1 October 1991) a 100 90 . 80

P o 70 , 3 860 0 0 0 .-0 .i 9 50 2 6 L( I 0 0 va LI D 40 I) z 30 20

0 0 1 2 3 4 5 Thousands Subject Coverage in Databases (# references) 1-10

progresses and the requirements for IM identifying a deficiency in its database, will (nationally and in NATO) become better contact participants, requesting (and aiding defined, the questionnaires to NIMIC will when possible) in the conduct of an in- reflect the complex nature of design depth search of national databases. Should problems in meeting IM requirements, and the in-depth search of the specific technical will require an expanded database and the area prove fruitless, then the deficiency concerted efforts of the technical staff. obviously is due to a lack of existing dat,i.

5.4 Inquiries and Studies NIMIC, in such a situation, develops a proposal for a program to be undertakcn Last but not least, NIMIC will develop an as a collaborative venture to correct the activity of its own (although obviously along deficiency. Current national budgetary the lines defined by the Steering constraints make collaborative ventures Committee) in order to anticipate the needs more than ever desirable and even of the Member nations prior to future necessary. Some specific area identified by questionnaires. To this end, as its staff of NIMIC as potential for collaborati ,e technical officers is gradually completed, it programs are: will utilize its expertise for the following tasks: analyzing the interest of some novel explosive molecules for 1[M; a - analyze technical requirements for IM, and assess methods and systems - assessing IM insensitivity tests in for improving IM to meet these order to get a better scientiic requirements; understanding of the real phenomena occurring within the - recommend solutions or design munition tested; approaches to meet IM requirements; - developing reliable small scale or math model predictive tools; - identify technology deficiencies that prevent requirements from being - designing means to prevent or achieved, and make proposals for reduce the potential f3r remedial actions; and sympathetic detonation in mass use munition storage configurations. - analyze data provided to NIMIC, and prepare data books and state- of-the-art reports on IM. 6. NIMIC AND THE [M PROCESS a Indeed, through database interrogations to 6.1 Munition Assessment Process respond to questionnaires, NIMIC may . identify technology deficiencies in its AC/310 published AOP-15 "Guidance (in database in a given technology area. Such the Assessment of the Safety and Suitability a deficiency can be indicative: for Service of Munitions for NATO Armed I Forces" (Ref. 2), and summarized Ihe - either simply by a lack of data input assessment process in Chart 6. While not by participating nations; specifically addressing the 1M aspect of munition design, the same philosophy ard - or by lack of data having been methodology applies to assessing a munition developed in that given technology to IM requirements as for safely area. requirements. Therefore, the subsequer t comments will treat the two disciplines ,IS NIMIC, as a first order of business, upon one. 1-11

Chart 6

- advice and assistance in selecting adequate explosive and propellant materials; and

- information from accident and incident data on the past history of designs similar to that proposed, so that known pitfalls can be avoided.

Further down in the process comes Step I. The need for support in this step reflects the basic purpose for establishing NIMIC. In this area of recommending actions to eliminate or control"'.hazards, NIMIC will utilize its database and the expertise of its 0 staff to the fullest extent. NIMIC assistance is also available through this design process in Steps L and K (involving the selection of tests and test parameters to validate that the design does in fact meet IM requirements).

It might be even more necessary in Steps u owlIyyuyW "U P and R, which have an added degree of AC/310 agrees that the achievement of IM complexity in that any remedies suggested program goals can best be accomplished if more than likely will be of a retrospective IM characteristics are designed into the nature to an already existing design. munition, and efforts to accomplish this should be initiated at the beginning of the In order to cope with these tasks, the staff munition development program. In cases of NIMIC, though small in size, is where lack of technology, impact on composed of personnel who, as a group, performance, cost, etc., prohibit have experience in total munition design 0 achievement of IM requirements through Fnergetic Materials, Warheads, Propulsion design, solutions should be sought by Units, Fuzes and Safe-Arm Devices, and providing safeguards or protection to the Explosion effects). Albeit that the NIMIC munitions. data, as with any database, will always be expanding and will lag timewise behind the Within Chart 6, we will now put emphasis most recent technological developments, % on those steps where NIMIC is capable of access to these recent developments is providing assistance to the design agent, as available to NIMIC. Indeed, one of the progress is made through this process. NIMIC sub-databases is the PCDB, or Points of Contact Database. This contains 6.2 NIMIC's Role With the Process a listing of several hundred technologists in participating nations who have indicated a NIMIC's assistance can be sought from the willingness to assist the NIMIC staff. very beginning of the process, i.e. Steps A, B and C, where NIMIC can provide: In instances of lack of information in the NIMIC database and/or lack of experience - input regarding current national and in a given subject by the staff, appropriate NATO IM requirements; points of contact will be solicited to assist in identification of any new unreported technological advances. 1-12

Assistance of this nature, sought from Full national participation will provide many nations by NIMIC, will he solicited to assist advantages such as: in identification of any new unreported technological advances, and will be - improved cost-effectiveness of governed by the NIMIC Security Guidelines operating the Center; established and agreed by the nations. . expansion of the database; and

7. FTJTmE higher potential for achieving muniti.on interoperability in the NIMIC is a project functioning within Alliance. NATO. It is actively solicited for assistance by other NATO entities and even by non- Many lessons have been learned during the NATO nations. At the same time, it is Pilot Phase regarding both administrative actively soliciting participation by all and technical aspects of operating an Alliance nations. information center of this magnitude. NIMIC will continue to learn and grow in NIMIC, in these early months of NATO its ability to cope with future problem both operations (as in its Pilot phase), has placed administrative and technical as they arise. emphasis on IM considerations. However, recognizing the relationship between safety In the near term, NIMIC will be engaged and IM concerns, NIMIC plans to expand in a vigorous campaign to inform he its database to encompass safety as well as technical community of its presence in IM information. This expansion is NATO and its capability to serve their necessary to allow full assessment of the need. You, as members of this technical synergistic effects of proposed remedial community, can assist NIMIC within your actions. influence and also pass to the NIMIC staff suggestions for improvement. Now, NIMIC is also solicited by other NATO entities to expand its database and NIMIC will function as a team member the activity of its technical staff to other with the national and NATO munition areas within the munitions field. If this is developers andl desires that a spirit of accepted, a balance will have to he defined cooperation permeates all of our mutual between: endeavors.

- on the one hand, the interest for References NATO of making the best possible utilization of the role of expertise 1. Advisory Group for Aerospace represented by NIMIC, and Research and Development (AGARD) -Technical Information - on the other hand, the need for Panel (TIP), "Proposal to NIMIC to retain its primary mission Establish a NATO Scientific and in the IM field. Technical Information Service" (NSTIS), AGARD Report No. Even within the field of IM, as previously TIP/WG-Ol/NATO, AGARD HQ, indicated, any assistance from NIMIC to Paris, France, April 1986. NATO as a whole - or to non-participating nations - can only be sporadic in the 2. NATO Insensitive Munitions present situation, where NIMIC is only Information Center (NIMIC) - " funded by the participating nations. This is An Assessment of Pilot NIMIC", why NIMIC advocates the active NIMIC-ESN-371-90 of 20 April participation of other nations. 1990. 1-13

ANNEX A ANNEX B

National apencies and databases contributing Breakdown of the NIMIC IM Database to the NIMIC IM database

Canada - IMDB (IM DATABASE) - Nomenclature for the function allowing simultaneous - Defence Scientific Information search of the major subset databases Service @SIS) - NIDB (NIMIC Informational Database) - France Main database containing bibliographies of technical reports. All documents - CEDOCAR entered are in hard copy NIMIC files.

Netherlands - STANAG - Contains NATO (particularly AC/310) Standardization Agreements. - Prins Maurits Laboratory/TNO - JADB (Journal Articles Database) - Contains articles from technical periodicals. I - Norwegian Defence Research Establishment (NDRE) - PTDB (Patent Database) - Contains - Norwegian Defence Industry Munition Related Patents (Worldwide).

United Kinedom - PCDB (Points of contact Database) - Contains listing of individuals in - DRIC participating nations available to assist the - IRS Dialtech NIMIC Technical Staff. - HSELINE - CPDB (Company Database) - Contains United States information of the capability of industrial agencies for testing, analysis, etc. - National Technical Information Service (NTIS) - AXDB (Accident Database) - Contains - Defense Technical Information information on munition related accidents. Center @TIC) 0 - Local databases such as those - QSUM (Questionnaire Database) - maintained for NASA, Chemical Contains a compilation of questions * Propulsion Information Agency referred to NIMIC. (CPIA), World Patent Index, etc. 0

0 . 2-1

PROGRESS AND INITIATIVES TOWARDS A UK INSENSITIVE MUNITIONS POLICY

R.G. Shephard Superintendent, Explosives and Propellants Group Defence Research Agency, Military Division (RARDE), Fort Halstead, Sevenoaks, Kent, TN 14 7BP United Kingdom

Summary The UK view on the reasons for establishing an Insensitive Munitions policy and the difficulties in doing so are discussed. Recent MOD funded studies which throw light on the benefits of such a policy are considered. The organization being set up in the UK to support such a policy is described together with progress towards this goal.

Remark The full paper is classified NATO confidential and cannot he included in this Conference Proceedings. If a reader is interested in more information on the subject he is asked to contact the author at the above address, or by phone: 619-959 532222 orfax: 619-939 1413

Discussion

QUFSTION BY W EISS. US : Please expand on the benefits part of the cost and benefits modelling. Does it take into account the cost of "unreliability" of the weapon system which would dictate more spares, more platforms, etc.? How about operational consideration whereby incidents due to a specified level of sensitivity less than satisfactory result in decommissioning of a platform or force stand-down while solutions are sought? . ANSWFRr Ideally life costing of platforms using insensitive munitions should include all these effects if they are relevant. .. Indeed such costing would also normally include a period of wartime usage. However, I do not believe that the "unreliability" or "decommissions" aspects are currently being built into UK cost- benefit models.

FURTHER ANSWER BY MAWBEY. UK: The cost benefit analysis concerned with the benefits of introducing less-sensitive munitions on ships and submarines cover both peacetime and wartime scenarios. In the peacetime case the loss due to an accident is based on (a) the repair cost and (b) the potential loss in fighting availability due to the predicted damage. In the wartime case only 2-2

the potential loss in fighting capability resulting from a range of attack weapons is considered. The basic loss due to the accidentlattack alone is compared with the loss clue to: (a) the accidentlattack with current munitions, (b) the accidentlattack with munitions that meet BR8541 requirements, and (c) the accidentlattack with munitions which meet the IMP requirement. Thus the net benefit of introducing less-sensitive munitions can be established. Comparing the benefit factored by the probability of the accidentlattack occurring with the costs of introducing the less-sensitive munition contributes to the judgernent which has to be made on safety policy. In the analysis it is assumed that an uncontrolled fire in a ship’s magazine will lead ,to the effective loss of the munitions it contains.

QUFSTION BY MOUIn any intense conflict where resupply is difficult or too long in time, repairability becomes a very important term in the equation for availability. Explosions and fire almost always render a platform non-repairable and therefore unavailable; but repairable vehicles can often be returned in a few days (e.9. a largely tanks during the 7-day war and the Yon Kipper war). This also has an impact on the maintenance and logistics requirements. Does your modelling take these benefits and costs into account?

ANSWER: Repairability and cost of repair is included in the UK whole life costing models. In a combat situation, a ship may not necessarily become unavailable after a minor fire and even tanks and aircraft might be more able to accomplish their immediate mission if the result of attack on an IM was no more that burning. However, repairability in orcler to ensure reuse of a platform during the same campaign is certa.inly a factor that should be built into combat availability models though it has not yet been taken account of in the UK modelling program. a .

z 3F-1

SPECIFICATIONS ET CRITERES DE SECURITE DES MUNITIONS DESTINEES A LA MARINE FRANCAISE - Alain ARTAUD DGA/STCAN 8. boulevard Victor 75732 PARIS CEDEX 15 FRANCE Olivier SALIOU DGA/GERBAM ~ 5. bd Marechal Joffre BP 41 56998 LORIENT NAVAL FRANCE

RE- RE- : Apres avoir expose la genese des specifications et des essais de securite applicables aux munitions embarqudes sur navires. des criteres d’acceptation sont presentes et compares aux norme8 en vigueur dans d‘autres pays ou organisations.

Des evolutions possibles pour les annees i venir sont ensuite evoquees. Enfin. d‘autres approches compldmentaires a la securisation des munitions sont presentees.

INTRODUCTION Un navire de combat rassemble dans un espace Neanmoins. dans le souci d’eviter les risques de restreint de nombreux risques potentiels. parmi personnalisation i outrance. il est apparu le lesquels ses propres munitions embarquees consti- besoin d’un cadre de rCfdrence : =’est l’objet des tuent un facteur de vulnerabilite particulierement specifications d’essais et des criteres standards important, car elles peuvent initier des accidents de securite. Dans la mesure OG les standards sont ou en amplifier les effets. bien choisis. la personnalisation pourra rester relativement limitee, et rdservee aux cas La Marine Frangaise. come la plupart des autres particuliers. qu’il s’agisse de la munition elle- Marines. a toujours et6 sensible aux problemes de &me ou du navire porteur. securite de stockage et de mise en oeuvre des munitions i bord. Cette priorit4 s’est encore accrue & la lumiere des enseignements tires des engagements navals des dernieres annees. et Les standards ont pour objet : d’accidents survenus a bord de bitiments de combat modernes du monde occidental. - de fixer un corps de doctrine. qui reste i moduler dans les cas particuliers. La methodologie retenue pour garantir un niveau de skurite satisfaisant consiste B realiser pour - de servir de guide aux concepteurs de munitions. les munitions des etudes de securite prenant en . compte les different5 environnements rencontres : - de couvrir le cas des munitions simples 6. usage normal. anormal et accidentel. Pour ce dernier. tr&s general, qui est le seul trait6 ici, les accidents les plus vraisemblables sont identifies. et des objectifs - d’evaluer a posteriori le niveau de &curite des -. de securite leur sont associes. munitions anciennes pour lesquelles il n’avait pas et6 etabli initialement d’objectifs precis I1 est evident que les types d’accidents possibles de securitd. dependent largement du navire porteur et des conditions d’emploi de la munition. C’est ainsi 11s doivent itre suffisamment ambitieux pour par exemple que l’environnement d’un missile apporter un niveau eleve de skurite. mais sans destine 2 un avion embarque sera assez different entrainer de surcoiit excessif. de celui rencontre par une torpille de sous-marin. et qu’un certain degrd de personnalisation des 11s doivent itre egalement compatibles.,autant que environnements accidentels s‘impose. possible. avec ceux retenus par 1’OTAN et par les Marines alliees pour faciliter l’interop6rabilite. De &me. les criteres de securiti varieront Une concertation permanente existe i ce sujet au suivant que le potentiel explosif de la munition sein du groupe AC 310 de 1’OTAN “skurite et apti- est plus ou moins eleve. que le navire est plus tude au service des munitions et explosifs”. Le ou moins prdcieux. et que les consequences d’un NIMIC (Centre d’lnformation OTAN sur les munitions accident sont plus ou moins graves. insensibles) constitue egalement une reference interessante. 3F-2

AGRESSIONS RETENES PRIORITAIREMENT :

Les accidents imagiFables, en temps de paix ou au Cette derniere agression presente un grand int&t combat. sont extremement nombreux. et il est technique, car la mesure de la vitesse limite necessaire de proceder H une analyse prdalable entrainant la detonation est un parametre tres pour retenir ceux qui sont les plus caracte- discriminant. La procedure d’essai d’eclat lourd ristiques des menaces rencontries. est largement utilisee pour caracteriser la vulnerabilite des nouveaux explosifs dans des C’est naturellement l’incendie. susceptible d’gtre maquettes elles-m&es standardisees. Le tableau 1 rencontre en temps de paix ou come consequence presente quelques rdsultats 3‘une agression de combat. qui apparait comme 1.accident a prendre en compte en primite. mais en distinguant deux types principaux dont les scenarios et les effet?. sont assez differents : Tableau 1 - l’incendie de bstiment de surface. et plus particulierement de porte-aeronefs. dans lequel le IMPACT BlLLE LOURDE carburant est un hydrocarbure brGlant en grande quantite avec un important apport d’air. Les temperatures sont elev6es. et les durees peuvent Vi(essebillem/r &re longues. x 0 . - l’incendie de sous-marin. dans lequel le carburant est plut6t une huile ou un fluide hydraulique. et oi~la quantite d’air disponible est limit& Les temperatures sont beaucoup moins elevees. et les durees assez breves.

Ensuite. l’accident de manutention apparait egalement come devant faire l’objet d’une grande 0 attention. I1 est admis que la chute de grande hauteur en est l’exemple le plus representatif. La hauteur de chute est generaleaent fixee H 12 m. le receptacle pouvant &re plat ou dote d’obstacles pour simuler un effet de poinconnement.

Une troisieme categorie comprend les agressions representatives de l’effet direct d‘une agression de combat , sous la forme d’impacts de projectiles 01 ou d’eclats. parmi lesquels on tmwe : 0 Explosion - l’impact de projectile bassement dnergetique. DBtonation modelis6 par une ou plusieurs balles de 12.7 mm perforantes. Une quatrihme categoric1 regroupe les agressions repr8;anratives drs effets ‘secondairis d’un - l‘impact d’eclat Mger tres rapide. accident initial. On y trouve : remesentatif d’un missile antiadrim. modClisP par plusieurs eclats de faible masse atteignant - la detonation par influence. qui permet simultanement la munition. d’evaluer le pauvoir amplificateur des munitions dans un accident. en tenant compte des - l’impact d’eclat lourd. representatif de configurations de stockage et du facteur aggravant missiles antinavires ou de bombes, modelis6 par un apporte par le confinement. seul eclat de masse plus Blevee (par exemple. sphere d’acier de 250 g). - l’gchauffement lent. qui peut representer l’effet a distance d’un incendie majeur de bitiment de surface. avec un faible gradient de temperature et une longue duree. Cette agression presente egalement un grand inter& technique car elle conduit aux reactions les plus violentes de la munition en ambiance thermique. - l‘incendie de munitions, dans lequel la matiere combustible est un propergol ou un explosif. Les temperatures sont alors tres Blevees. et les modes de reaction des munitions agressees sont encore peu connus. Une derniere categorie. qui n’est cite= ici que pour memoire. couvre les agressions d’origine electrique ou electromagnetique, come la foudre, 1‘6lectricit6 statique. les rayonnements electro- magnetiques continus ou impulsionnels. Elle ne sera pas developpee ici

Eclat loud : sphere d.acier de 250 g munie de son sabot de ].ancement 3F-3

Le tableau 2 recapitule les specifications - incendie de sous-marin : l’objectif eat de existantes ou en cours d’achevement. n’avoir aucune reaction compte tenu de l‘environnement particulier.

Tableau 2 - chute de grande hauteur : il ne doit y avoir aucune reaction, avec possibilite de neutra- lisation de la munition pour enlevement.

Liste des specifications d’essais - impact de balla de 12.7 mm : l’objectif est de I n’avoir aucune reaction, ou au maximum une combustion, Reference Titre d’appro- bationDate I - impact d’dclat leger : l’objectif est de ne pas avoir de reaction plus intense que la combustion. IT no 9282-1 Echauffement rapide : . incendie type - impact d’eclat lourd : l’objectif serait de ne Bitiment de Surface pas avoir de reaction plus intense que la (BS) 14-01-88 combustion mais, compte tenu de la violence de l’agression. il pourra &re accepte des reactions . incendie type Sous- 1plus importantes sans toutefois atteindre le Marin (SM) niveau de la detonation. IT no 9282-2 Impact de balle de 28-02-88 - detonation par influence : l’absence de mm --I detonation sera demand&. 12.7

IT nD 9282-3 Chute de grande hauteu 20-07-88 Ces exigences. qui sont si besoin a mcduler, constituent une base significative : elles IT na 9282-4 Impact d‘eclat lourd 28-11-89 apportent un degre de securite suffisant pour qu‘un accident de temps de paix ou une agression IT no 9282-5 Detonation par in- de combat ne soit pas amplifiee de facon 0 fluence excessive. IT nr 9282-6 Echauffement lent 23-10-90 I Bien que non entierement fig&, ces criteres peuvent constituer un guide utile pour les IT no 9282-X Impact d‘eclat leger En cours concepteurs de munitions. leur permettant de Droiet cboisir les options techniques pour un large I&entail d’applications presentes ou B venir. CRITERES D’ACCEPTATION Les munitions recentes font l’objet de specifications de securite, etablies en fonction du risque potentiel present6 par la munition. de son environnement logistique et operationnel. et du type de navire ou d’aeronef qui les portent. I1 apparaft que. pour des munitions d’une m&e generation. la demarche securite et la technologie disponible conduisent en general B des exigences similaires. Cette similarit4 est encore accrue chaque fois que l’on mene une etude d’ensemble pour la totalite de l’allocation en munitions d’un navire : ceci est naturellement le cas pour les grands projets de navire come par exemple le Porte-AvionrNucleaire Charles de Gaulle. Au stade actuel. des criteres standard sont en cours de mise au point. Les grandes orientations sont les suivantes :

- incendie de bitiment de surface : la reaction ne doit pas &,re plus violente qu’une combustion. Une exigence supplementaire est visee pour les Lanceu d’eclat loud de 112.7 mm . munitions d’ahronefs embarquees sur porte-avions, i savoir : aucune reaction ne doit se produire pendant les premieres minutes de l’incendie. 3F-4

COMPARAISON AVEC LES NORMES ONU - OTAN - ETATS-UNIS - GRANDE BRETAGNE La comparaison des normes fransaises avec les normes etranggres et internationales fait l'objet du tableau 3 : il est notamment fait etat des criteres d'acceptation lorsque ceux-ci existent.

Les informations presentees proviennent de : - ONU : division 1.6

- OTAN : STANAG 4325

- ETATS UNIS : MIL STD 2105A

- CRANDE BRETAGNE : BR 8541 La comparaison fait apparaitre une forte convergence pour les principaux essais. et une oarente certaine DOU~les critires associgs.~~~ Le~ groupe AC 310 de l*'OTAN favorise l'emergence d'une DBtonation de bomb soumise B l'gchauffement rapide doctrine commune.

Tableau 3 e

Payslorganisat ETATS UNIS GRANOE BRETAGNE FRANCE

Impact balle (12,7 P) Combustion Combustion Combustion Pas de detonation Combustion (recommandation) Pas d'explosion

Echauffement rapide Combwtion Combustion Cc"b"sti0" Selon sphcificatio 1) Combustion(Bs) (recommandat ion) 2) Non reaction(sr

Detonation par inflve Pas de detonation Pas de ddtonatior Pa5 de detonation (recommandation)

Impact d'dclat Xger Combustion Combustion :ombustion (recommandation)

Impact d'dclat lourd >as de d&tmation

Echauffement lent Combustion ToUte reaction Combustion Yon specifie doit etre notee

Chute de grande haute, -creaction reaction Yon No" ton reaction e EVOLUTION DES AGRESSIONS ET DES CRITERES . Les agressions et lea criteres present& ci-dessus A cet egard les capacites de lutte contre conduisent B concevoir des munitions presentant un l'incendie (passives et actives) d'un bitiment de niveau de risque attenue. Mais paradoxalement, un surface ont une limite : en fonction de cette nouveau type d'agression doit alors &re pris en limite. des environnements thermiques maxima sont compte : l'incendie de munitions. d l'etude. En effet. les munitions B risques atthnues. Ceux-ci s'expriment en pratique par la notion de consues pour brsler et non dBtoner lorsqu'elles quantite maximale de munitions pouvant briiler sans sont soumises a des agressions du domaine mettre en cause la vulndrabilite de la soute. et accidentel. deplacent le probleme de la securi- par la notion de temps de reaction des munitions sation du stackage en soUte ou de la mise en avec ou sans conteneurs soumises B des agressions oeuvre operationnelle des munitions. L'analyse des thermiques de fort gradient de temperature. risques conduit desormais. pour les programmes d'armement futurs. B prendre en compte les La definition des criteres associes B ces exi- incendies de matihres explosives et de propulseurs gences de securite depasse ainsi la formulation pouvant ddgenerer en incendies generalises. des premiers criteres. present& precedemment. 3E-1

SAFETY SPECIFICATIONS AND CRITERIA CONCERNING MUNITIONS INTENDED FOR THE FRENCH NAVY

Alain ARTAUD DCA/STCAN 8, boulevard Victor 75732 PARIS CEDEX 15 FRANCE

Olivier SALIOU DGAKERBAM 1) 5. bd Markha1 Joffre BP 41 56998 LORIENT NAVAL FRANCE -

ABSTRACT : After considering origins of safety specifications and tests applicable to munitions carried on board navy ships. criteria of approval are examined and compared with standards in force within other countries and organizations Next. are considered possible developments in years to come.

Lastly. further approaches concerning safety measures of munitions are discussed

INTRODUCTION

A warship brings together in a limited space Nevertheless. in order to avoid the risk of numerous potential risks, among which its own tayloring things to excess. it has become clear munitions carried on board represent a that a reference framework is needed : this is the particularly large and vulnerable load as they can aim of the test specifications and of the standard initiate accidents or amplify their effects. safety criteria. In so far as the safety standards have been well-selected. the tayloring may remain The French Navy. like many other Navies, ,has relatively limited and reserved for special always been sensitive to the problems of storage cases - be it a question of the munition itself or and carriage of munitions aboard. This priority is of the carrying ship. increased still further in the light of experience drawn from naval engagements of recent years and from accidents which have arisen aboard modern fighting ships of the viestern world. The objective of the standards is :

The methodology retained in order to guarantee a - to establish a general policy which may be satisfactory level of safety involves carrying out adapted to suit the particular case concerned, @ safety studies on munitions and taking into account the different environments encountered : - to serve as a guide to the munitions designer. normal. abnormal and accidental. As far as the last of these is concerned and it is the only one - to cover the case of simple munitions designed dealt with here. the most likely accidents are for general use. identified and some safety objectives are identified with them. - to evaluate, a posteriori, the safety level of old munitions for which no precise safety It is clear that possible types of accident objectives had been established initially. depend largely on the carrying vessel and the conditions under which the munition is used. Thus. They must be ambitious enough so as to provide a for example. the environment applied to a missile high level of safety. yet without entailing . intended for a seaborne aircraft will be rather excessive costs. different from that of a submarine torpedo. so some degree of tayloring of the accident They must be also compatible. as far as is environment becomes essential. possible. with NATO and Allied Navies standards in order to facilitate interoperability. A permanent Similarly. safety criteria will vary according to dialogue exists on this subject within the NATO whether the explosive potential of the munition is group AC 310 "Safety and Suitability for service high or low. whether the ship is particularly of munitions and explosives". NIMIC (NATO valuable or not and to the gravity of the Information Centre on Insensitive Munitions) also accident. represents an interesting point of reference. 3E-2

SELECTED AGRESSIONS :

Conceivable accidents. whether in peacetime or This last agression is of great technical during a conflict. are extremely numerous and interest, as the measuring of the maximum fragment first need to be analysed to identify the most speed leading to detonation is a very characteristic of the threat3 encountered. discriminating parameter. The heavy fragment test procedure is widely used to characterise Fire is the most likely accident to occur both in vulnerability of the new high explosives in model peacetime and during a conflict and so must take which have themselves been standardised. Table priority over the others, not forgetting to shows several results distinguish between its two principal types. each of which has different patterns and whose effects are rather different : Table 1 - fire aboard a surface ship and more particularly aboard aircraft-carriers. in which fuel consists HEAVY FRAGMENT IMPACT of a large quantity of combustible hydrocarbon with a large proportion of air. Temperatures are high and the periods of time concerned can be x long. - . fire aboard a submarine, where fuel is more usually an oil or a hydraulic fluid and where the quantity of available air is Limited. Temperatures are not nearly as high and the periods of time concerned are rather short.

Next are the accidents which occur during handling and these deserve a fair amount of consideration. It is accepted that material falling from a great height is the most representative example here. Height of drop is generally fixed at 12 m. its a landing place may be a flat surface or one equipped with obstacles in order to simulate a perforation effect.

A third cateeorv includes aeressions remesentine the direct Tffict of a coibat agressibn in the form of projectiles impacts or fragments. among which are found : 0 Explosion It Detonation - Low-energy projectiles impacts modelled by one or several shots by 12.7 mm perforating bullets.

- very rapid light fragment impact from an anti- A fourth category covers agressions representing aircraft warhead modelled by one or several shots the secondary effects of an initial accident. from low-mass fragment hitting the munition These include : simultaneously. - sympathetic detonation. which allows for the - heavy fragment impact from anti-ship missiles or eval.uation of the amplifying power of munitions from bombs modelled by a single shot from a higher in an accident. whilst taking into account mass (e.g. 250 g steel sphere). storage layout and the aggravating factor of the confined space.

- slow cook-off, which. with a low temperature gradient and over a long period of time, can model the effect of a major fire on board a a surface ship. This agression is equally of great technical interest as it leads to the most violent munition reactions in thermal environment. munitions fire. in which the combustible material is a propellant or a high explosive. In such cases. temperatures are very high and . the ways in which the affected munitions react are still 1ittl.e known. One last category. only referred to here for the L sake of completeness. covers agressions originating from electrical or electromagnetic Sources ; such as lightning. static electricity, continuous or pulsed electromagnetic radiation. This category will not be developed here.

Heavy Fragment : 250 g. Steel Ball on its Launching Sabot 3F-S

D’autre part, la menace terroriste fait peser et va faire peser pendant le temps de paix et le La definition de barrihres de securite type temps de crise sur l’ensemble des nations et de blindage. protections thermiques. dispositifs leurs Marines en particulier un risque important : d’evacuation des gaz . .. contribue a cette c’est ainsi que l’attaque terroriste type charge securisation. La reflexion est menee au cas par creuse impose que les effets du jet residue1 cas en prenant en compte chaque couple soient fortement attenues et que la tenue des soutelmunition. munitions futures a ce jet residue1 soit etudiee.

Cet exemple illustre les nouvelles preoccupations Ainsi ces trois actions subsidiaires contribuent issues de l’utilisation possible terroriste ou non au durcissement de l’environnement munition. des armes de combat terrestre contre les navires. L’integration des munitions B bord des bitiments de surface B un niveau de securite satisfaisant passe egalement par ces voies d’etude elles-mimes complementaires de l’effort realis6 en matiere de UNE AUTRE APPROCHE : PRISE EN COMPTE DE munitions a risques attenues. L’ENVIRONNEMENT En conclusion. la convergence entre les actions La technologie disponible dans le futur permettra portant sur la skurite intrinshque des munitions la tenue des nouvelles exigences de securite et celles portant sur le durcissement de leur

I assocides aux nouvelles agressions et nouveaux environnement devrait permettre de deboucher sur crithres definis. des solutions techniques de moindre cout pour satisfaire les exigences de skurite de chaque Celles-ci peuvent sembler aujourd’hui tres programme. ambitieuses compte tenu de 1’6tat de l‘art disponible en matiere de munitions B risques attenues pour des coiits acceptables. Pour tenir les objectifs de skurite des programmes, il est donc utile de rechercher des solutions complementaires d’amelioration des conditions de stockage et de mise en Oeuvre operationnelle des munitions : celles-ci passent par le durcissement de l’environnement meme des munitions.

Cet environnement se decline selon trois niveaux :

- les conteneurs de munitions - l’organisation du stockage - la conception et l’amenagement des soutes

Les conditions de stockage en mute de munitions conventionnelles embarqudes sont cansiderdes come critiques si la reaction accidentelle d’une munition peut entrainer la detonation en masse des munitions voisines. mire la perte du bitiment. La definition de conteneurs securisds est susceptible d’ameliorer cette situation. Des rhgles de dimensionnement ont et6 Gtudiees : elks portent sur la recherche d’une configuration de stockage optimisde. sur la definition des d’isolement i respecter entre sur les caracteristiques des ecrans B interposer. Les resultats significatifs obtenus pour des munitions chargees en explosifs coules fondus permettent d’envisager. pour des explosifs moins sensibles. des protections type conteneurs et ecrans d‘un devis de masse notablement allege. D‘autre part, la connaissance des effets des munitions soumises aux agressions accidentelles permet la realisation d’etudes de &curite de stockage afin d’optimiser le plan de stockage des munitions et conteneurs embarques. Enfin. la conception des soutes et leur seeurisation sont des composantes esaentielles de 1 ‘environnement “munition“. . a

I 3E-3

Table 2 summarises existing specifications or - fire on board a submarine : the objective is to those in the process of being completed. have no reaction given the particular environment.

- drop from a great height : there must be no Table 2 reaction. with the capability of neutralizing the munition for removal. List of the test specifications - 12.7 mm bullet impact : the objective is to have Approval no reaction. or at the very most a burning. leference Title date - light fragment impact : the objective is .to have no stronger a reaction than burning. IT Ne 9282-1 Fire : . type of fire - heavy fragment impact : the objective would be surface ship 14th to have no stronger a reaction than burning, but. January taking into account the violent nature of the 1988 agression. stronger reactions may be acceptable as . type of fire long as they do not reach detonation level. submarine - sympathetic detonation : there must be no IT NO 9282-2 12.7 mn Bullet 28th detonation. impact February 1988 Although not entirely finalized, these criteria can from now on act as a useful guide for IT Ne 9282-3 Drop from a great 20th munitions designers. giving the opportunity of height July selecting technical options for a large range of 1988 present or future applications. IT N' 9282-4 Heavy fragment impact 28th November 1989 IT Na 9282-5 Sympathetic detonation 10th October 1989 IT N* 9282-6 Slow cook-off 23rd October 1990 IT Na 9282-X Light fragment impact currently underway

ACCEPTANCE CRITERIA Recent munitions are the subject of SafetE specifications. established in relation to their potential risk. their logistical and operational environment and the type of ship or aircraft carrying them. Gun Launching 112.7 mm Heavy Fragment For munitions from the same generation. safety processes and available technology generally lead to specify similar requirements. This similarity is further increased each time an overall study is carried out on the whole of the munitions allocation of a ship : this is naturally the case for large ship projects such as the Nuclear Aircraft-Carrier Charles de Gaulle. At this moment in time. the standard criteria are in the process of being finalised. The main trends are as follows : - fire on board a surface ship : the reaction must be no more violent than burning. A further requirement is intended for aircraft munition carried on board aircraft-carriers : no reaction must occur during the first minutes of the fire. 3E-4

COMPARISON WITH UN - NATO - UNITED STATES - GREAT BRITAIN STANDARDS

Comparison of French standards with foreign and international standards is the subject of Table 3 : it notably sets out the acceptance criteria where appropriate.

Information presented originates from : - NATO : STANAG 4325

- UN : division 1.6 - UNITED STATES : nm STD 2105~ 1 - GREAT BRITAIN : BR 8541

The comparison reveals a strong convergence for the main tests and a certain parity for the associated criteria. The AC 310 NATO group may . encourage the emergence of a common policy.

Detonation of a Bomb under Fast Cook-off

Table 3 0 countryiorgani- sation 1 NATO 1 UNITE0 STATES 1 GREAT BRITAIN FRANCE

Bullet impact Burning Burning Burning NO detonation Burning (recommendation) NO explosion

Fire Burning Burning Burning According to speci- 1) B"r"ing(S"rf.) (recommendation) fications 2) Non reaction(Sub.:

Sympathetic detonation NO detonation NO detonation NO detonation NO detonation NO detonation (recommendation)

tight fragment impact Burning Burning Burning (recommendation)

Heavy fragment impact NO detonation

Slow Cook-off Burning Every reaction Burning NO specified must be noted

Orop from a great height NO reaction NO reaction NO reaction 0

EVOLUTION OF AGRESSIONS AND CRITERIA The above agressions and criteria have lead to the In this regard. the fire-fighting capabilities concept of less sensitive munitions. However. (passive and active) of the surface ship are paradoxically. a new type of agression must limited : with regards this limitation, maximum therefore now be taken into account : munitions thermal environments are under study. fire. In practice, these are expressed by the idea of In effect. the lower risk munitions. designed to the maximum quantity of munitions which can burn burn and not to detonate when submitted to without jepordising the vulnerability of the agressions of an accidental nature. modify the magazine, and by the notion of reaction time of problem of safe storage in magazines or the munitions. whether containerised or not. and operational applications of the munition. As far submitted to thermal attacks with a strong as concerns future armement programmes. analysis temperature gradient. of the risks from now on leads us to take into account fires of explosive materials and The definition of the criteria associated with propellers which may degenerate in generalised these safety requirements thus goes beyond. the fires. drawing up of those first criteria formerly presented. 3E-5

Moreover. threat of terrorism weighs neavily and Finally, design of the magazines. and making them affects all nations during both war and peacetime. safe. are essential components in the “munitions“ representing a huge risk for navies in environment. Definition of safety barriers in particular : that is why terrorist attacks of the terms of screening. thermal protection. devices shaped charge type imply that effects of the for the evacuation of gases ,. . contributes to residual jet are greatly extenuated and that these safety measures. Careful consideration is behaviour of future munitions in response to this given to each case. taking into account which residual jet has to be studied. munition is put into which magazine each time. This example illustrates the new pre-occupations Thus these three subsiduary actions contribute to arising out of possible terrorist use of weapons hardening of munition’s environment. If munitions designed for land combat against ships. are to be integrated at satisfactory safety-levels on board surface vessels, they have to equally undergo these study-processes. the studies themselves being complimentary to the work put ANOTHER APPROACH : CONSIDERATION OF THE into low-risk munitions. ENVIRONMENT In conclusion. convergence between actions Technology available in the future will allow for relating to intrinsic safety of munitions and respect of new safety requirements associated with those relating to hardening of their environment. the new types of agressians and with the newly should allow technical solutions to be developed defined criteria. at minimum cost. in order to satisfy the safety requirements of each programme. All this may seem very ambitious today when state of the art available. in the matter of low-risk munitions at acceptable costs. is taken into account. In order to fulfill safety objectives of the programmes. it is therefore useful to look for additional solutions to improve storage conditions and operational uses of the munitions : the latter involving a hardening of the environment and even of the munitions. This environment declines at three levels : - Munitions containers - Storage organisation - Magazine design and layout Storage conditions. in the magazines, of conventional munitions taken on board are seen to be critical if accidental detonation of a munition can entail the mass detonation of neighbouring munitions. and even loss of the ship. Definition of securized containers is hoped to improve this situation. Rules for measuring up have been studied : they relate to the search for a configuration of optimised storage. to the definition of minimum isolating distances to respect between munitions and also to the characteristics of screens to be interposed. Significant results obtained for munitions carrying cast high explosives allows for consideration. in the case of less sensitive high explosives, of a container or screen form of protection made of a notably much lighter mass. Morerover. knowledge of effects of munitions subjected to accidental agressions allows for studies ta be carried out on safety of storage in order to optimise storage layout of munitions and containers taken on board. 3E-6

Discussion

QUESTION BY MAWBEY. UK: The Royal Navy reyuirement for the drop test is also that there should be "no reaction"; also the munition must be dropped from a credible drop height representative of service use. The sympathetic detonation pass criteria implies "explosion" is acceptable - should we not be seeking a response no more severe than burning or deflagration?

ANSWFR; As I indicated to you in the presentation, that is not completely defined. However, I gave you a full orientation, concerning the criterion associated with the detonation. The announced objective is to not have a detonation of the receptor munitions: that is the minimum safety requirements; in fact, specifying such non-detonation implies a non-amplification of the initial accident. But as you suggested, 'in other reactions less severe than a detonation there is not less damage for the condition of the munition. In case of a specific naval program, we are bringing more specification of the reactions in which the level of severity is not more than a combustion.

QUESTION BY HELD. FRG: What was the weight and velocity of your light and heavy fragments?

ANSWER; The fragment velocity for the light fragment impact test is defined as follows: 200 mls for three fragments of 4 gm mass each. For the heavy (250 gm) fragment impact tests the velocity specified is 1500 mls. That velocity can evolve in case people criticize the testing conditions in Fin's evaluation of new pyrotechnic products. 4-1

Formulation - CaractCrisation ~ Pr6diction du comportement

par : Jean Marie DECORE

.I Bruno SAINJON Pauick LAMY DGA/DME/Service 'lcchniquc des Paudrcs et Explosifs 2 Boulevard Victor 00460 Armt'es . France

1 - PREAMBULE

En France, les premieres ttudes concernant les MURAT on1 Situt entre les fommlateurs, fab:icants de produits explosifs ttt ianctes et conduites par le Service Technique des Poudres et les inaitres doeuvre concepteurs de munitions et systcmes et Explosifs (STPE) de la DGA. darmes, le STPE est donc en quelques sorte IC point focal fran5ais des prohlkmes liis B I'utilisation des substances La DGA est I'organisme du ministkre franyais de la Dtfense pyrotechniques. a chargt de : - dtvelopper et acqutrir les mat6riels qui correspondent :lux besoins de I'armCe franyaise, MINISTERE DE LA DEFENSE - veiller B la bonne sant6 des industries franpises de I'armement des secteurs ttatiques, nationalist's ou privt's, u - d6velopper les exportations darmement - produire certains Cquipements

Au sein de la DGA, le STPE est le service responsable des Crudes de synthkse, formulation et dtveloppement des mattriaux tnergttiques (poudres, explosifs et propergols). Ces Etudes sont effectuies en grande partie 3. la SNPE, mais aussi dans un certain nomhre dhablissement de la DGA pour ce qui concerne I'tvaluation de leurs performances, skcurite, aptitude au service (GERBAM et GERPY de la Direction des Constructions Navales, ETBS de la Direction des Armements Terrestres, CAEPE et CEL de la Direction des Missiles et de I'Espace) et la comprthension des phtnomknes de dttonique mis en jeu (CEG et lnstitut franco Allemand de Saint-Louis de la Direction des Recherches, a Etudes et Techniques).

2 - INTRODUCTION

La stcurit6 pyrotechnique est un souci permanent des Certaines solutions techniques permettent d'assuier concepteurs, des fabricants et utilisateurs de munitions. Cest aujourdhui une stcuritt satisfaisante : un problkme qui est mitt depuis de nombreuses anntes et qui fait I'objet dune rtglementation Ires prtcise et trks stricte - protections par des matt'riaux qui attt'nuent I'tnergie de (stcurit6 des travailleurs, au stockage, au transport ...) (I). I'agression initiale, L'absence daccident important en France depuis de nombreuses annCes dtmontre I'efficacitt des mesures - cloisonnements qui ralentissent ou arr&tentla propagation rtglementaires ou des solutions techniques utilistes. du sinistre,

Cependant l'amtlioration des performances des munitions se - disposition des munitions les unes par rapport aux autres et traduit souvent par un accroissement des risques qu'elles procedures dutilisation, prksentent ; leurs conditions demploi tvoluent, et les menaces, particulikrement en temps de crise, augmentent. II - dispositifs dintervention, est donc primordial de rester vigilant et d'ttudier toutes les solutions permettant de s'adapter B I'tvolution des risques pyrotechniques. 4-2

Mais toutes ces solutions portent sur l'environnement externe etlou locale de dtgt'ntrer en rtaction violente etlou de la munition. Les progrhs technologiques de ces deux gtntralide (structures bobintes ou mitalliques spiraltes en derniires dtcennies permettent maintenem de concevoir de CAS de surpressions internes, cordeaux dtcoupants ou nouvelles solutions pour diminuer les risques eo agissant Cltments de stnctui-e fusibles en cas dtchauffements), mais directcment sur les niatiriaux explosibles etlou sur les autres c'est principalement en agissant sur la substance composants de la munition, et ont conduit au concept de pyrotechnique elle-m&ne que l'on s'assurcra du respect de Munitions B Risques ATtinuis (MURAT en franpis, IM ces labels dimmunitt, pour lilsensitive Munitions en arntricdin, ou LOVA pour Low Vulnerability Ammunition en anglais (2). La difficult4 consiste alors B rtduire la riactivitt des substances tout en conservant un niveau de performances Ces risques pourrotit encore &irerkduits en paniculier par des compatible avec la mission de la munition. systb" de dtconlinement qui empgchent une rkaction faible . 3 - EAVAUX EN FORMULATIQN

La mise au point de fonnulations mOinS vulntrables passe - B partir dtltments de formulation (liant, huile nitrie, par une analysc des agressions et des mCcanismes charge) que 1'0" estime devoir prt'senrer de bonnes . rCactionnels que celles-ci niettent en jeu. On en diduit caractiristiques de sicuriti, amilioration des autres propriitis alors les paramhres critiques au nivedU de la fomlulation. des propergols obtenus (performances, discrttion, propri6tks et les voies dans Iesquelles la recherche doit s'orienter. micaniques et balistiques, rhCologie, stabilitC, ...).

bm&: II s'agit ici d'utiliser des matiires premikres peu sensibles, notamment le nivate dammonium k la place des nilrdmines et du perchlorate dammonium, associCes ;I un liant bast sur un nouveau prtpolymk iner&que (le PAC) non plastifit par de la nitroglyctrine. Toutes ces t'tudes de formulation se font en ttroite liaison a I I avec des tiavaux de mithodologic visant h comprendre les 1 1 phtnomhes entrant en jeu lorsqu'on soumet les chargemem aux difftrentes agl-essions (analyse des phCnom5nes de trnnsition en dttonation, modtlisation de I'effet des agressions sur les chargements et vdiidation SUI des essais + + instrunientts).

I * extension de la gamme d'explosifs composites a liant 1 polymtrist fortement chargts en oxynitrotriazole (ONTA) grace auxquels la dttonation par influence de munitions (5,35 et 100 kg) est tvitte (5) : augmentation du taux de charges, amtlioration du vieillissement, introduction de nouveaux liants et plastifiants, formulations adapties aux munitions peu sensibles devanr procurer un effet diclat. de souffle, de relhvement ou aux blindages riactifs

Les grands axes defforts pilotts en France par le ministhe * ttude tht'orique de I'enrobage des grains denplosif pour de la Dtfense pour les 3 grandes faniilles de substances compression et influence sur l'objet coniprimt. explosives : explosifs, propergols. poudrcs pour amies sont 0 brihvemcnt indiquts ci-apris :

3~1Pronercols nour autonrondsion hexogbie Les ttudes sont axies sur 2 voies coniplimentaires : Lh encore, les ttudes de formulation utilisent (ou servent 8) des travaux de mtthodologie visanr B comprendre et - amt'lioration des caracttristiques de stcuritt et de ameliorer lcs rimions des munitions (ou t'lt'ments de vulntrabilitt des familles de propergols existantes munirion) ies utilisant. On peut citeer i titre dexemple rttude * en jouant sur le liant (taux, masse molCculaire, ...) et les de I'influence de la granulomt'trie et du taux des diverses charges (taux, granulomCtrie, ...) charges sur la vulnirabilitt aux divcrscs agressions et les * en recherchant des additifs qui diminuent la vitesse de petfonnances combustion des propergols B pression atmosphtrique ou qui diminuent la sensibilitt de ces compositions nux agressions Enfin, du point de vue fonctionnement, la mise au point de thermiques. B rimpact de balle ou B rimpact de fragments. nouveaux systimes ou principes damorGage, dune part h base de compositions elles~mhcspcu sensibles, d'autre part Ces travaux concernem les butargols (propergals composites capables d'amorcer ces nouvelles formulations nioins B liant polybutadikne) et les propergols a liants tnergttiques sensibles RUX chocs, s'est egaienient avirte ntcessaire. Les (plastifiks par de la nitroglyctrine et charfCs en nitramines risultats les plus iotemsants om it6 obtenus avcc la mise au ctlou perchlorate dammonium). point de gtntrateurs d'ondes de Mach. 4-3

3-3 Poudres DOUT armes Les Ctudes concement essentiellement des poudres sans - I'amtlioration de l'allumage au moyen dadditif nitrocellulose comportant une substance explosive, en gCntral I'hexogkne, et un liant. - I'accroissement de la force par augmentation du iaux de charge ou utilisation de liants Cnergttiques. Ces poudres dites composites constituent une transposition aux armes B tube des technologies dtvelopptes pour Pmallklement B ces travaux concernant les substances sont - propergols composites. Deux voies sont explortes effectuts des tvaluations en armes et des essais de simultaniment, compositions avec ou sans solvant, et les vulntrabilitC ainsi qu'une Ctude SUI I'allumage de ce type de travaux concement : poudre. - l'amklioration des proprittis mkcaniques par optimisation du liant

4 -EVALUATION

I 4-1 Essais standards d'Cvaluation de la sensibiliti On retrouve priincipalement les kpreuves prkonides par Les maquettes utilides sont : l'ONU pour le transport des marchandiscs dangereuses (tpreuves des stries 1.2 et 3) et en cours de standardisation * pour les explosifs au sein du goupe OTAN AC 310 : - maquette acier (tpaisseur 10 mm) contenant 5 kg de produit - onde de chcc - maquette aluminium (tpaissetu 1 mm) contenant 5 kg de produit :::En - maquette acier (tpaisseur 15 mm) contenant SO kg de - dkharee tlectrostatiaue produit. - &haufFement * pour les propergols mais aussi des tpreuves plus spkcifiquement destinies aux - maquette acier (0 120 mm) avec chargement B canal substances ayant le label dextrkmement peu sensibles central contenant S kg de produit (Cppreuves de la strie 7 ONU pour MURAT) : (On peut noter la criation prcchaine dune maquette de diamktre extkrieur plus ClevC pour tenir compte du - sensibilitt B l'amorce problkme de I'effet canal (4)) - impact de balk - friabilitk dangereuse * pour les poudres pour mes - tchauffements lents et rapides - douille acier 0 90 mm contenant 2 kg de produit - douille combustible 0 90 mm contenant 2 kg. de Ces tpreuves correspondent gtntralement B des stimuli produit ClCmentaires et permerrrent de classer les produits de fagon relative. et les principales agressions CtudiCes : Avantaees * impact de balle cal 12.7 (vitesses variant de 400 B 1200mls) - ipieuves peu cocteuses et donc possibilitt dune large * impact de fragment Iourd (bille de 250 g - vitesse banque de donnCes. jusqu'2 2400 ds) - rtalisables dks la mise au point des nouvelles formulations * Ccrasement sous faible vitesse par un boulet de 8 kg (peu de produit mis en jeu). * impact de jet de charge creuse 0 62 mm (avec atttnua~ teur acier dtpaisseur variable 10 B 360 mm) Inconvtnients * incendie de kerosene (bac de 2 m x 2 m) * tchauffement lent (3,3'Cih) - ne prennent pas en compte les effets de giomCtrie, masse et confinement. - la pridiction du comportement en munition n'est possible que de faqon relative par comparaison avec les rtsultats Exemales de risultats obtenus sur des produits dune meme famille. GA En OF IYFICAI RESUI TS 001A111En fps WITH TCSTS ON IIIGII FXPLOSIVFS ANALOGUFS 4-2 Eareuves sur maauettes

Afin de prendre en compte I'influence de la gtometne, de la masse et du confinement des chargements sur la dactiviti des substances explosives, la France a lanct depuis un peu plus de 5 ans la rtalisation d'Cpreuves ginCriques sur maquettes standardistes reprtsentatives dobjets rCels. II est B noter que ces essais ne se substituent en aucun cas aux essais sur munition et, s'ils tiennent compte de I'environnement rtel des substances explosives, ne prttendent qu'en donner une rCactivitt relative et comparative. DGA EG. OF TYPICAL RESULTS OBTAINED WIT11 TESTS ON HIGH EXPLOSIVES bNALOGUES. C"mllR1 curmcrr

IGA 3GA EG. OF TYPIC&L RESULTS OBTAINED EG. OF TYPICAL RESULTS OBTdlNEO WE WIT11 TESTS ON GUN PROPELLANT ANnLOGUES. iTPE WITH TESTS ON GUN PROPELLANT ANALOGUES. rhJImcrr am" rnn41

5 - PREDKTION DU COMPOKTEMENT

Un certain nombre de modilisarioris oumt.riques sont en De telles modklisations ont en cours cn Frcince itudc pour prediie, h partir des caractkristiques (principalemem riahies par DRET, DCN et SNPE) sur fondamcntiiles d'une substance explosive (donoies de sensibilitt: milis t:galcrncnr propri6tks chimiques, dttoniqucs - les impacts de balks et mkiiniques) et de la giomktrie de 181 munition dam laquelle - les tctiauffements elk entrc (confinement, diamitre ... ) le comportcment de cette - les impacts &tclats munition soumisc B une agression sptcifique, elle-m&me - les jets de charge creme. modklisie. Si les resultats sont satisfaisants pour lcs phi-nomknes de wansition chocid6tnnalion (pridiction du iype de r&iction) ou &6chauffenients (plhliction des d6lais avant rtaction), les predictions son1 beaucoup plus difsicilcs pour les phinomhnes de type transition dtflagretion/dtton;itio~~OLI transition retardee chccldetonation

I L 4-5

6 - LA PRISE EN COMPTE DES SOLUTIONS "SYSTEME I La rtactivitt dune munition soumise h une agression depend non seulement de Pa nature de la substance explosive mais aussi de la masse, de la gtomktrie et de i'enveloppe du chargement. I1 est donc possible de jouer sur ces diffkrents facteurs pour rkduire les risques potentiels et les reactions obtenues.

- le sctnario dit Ckffet canal sur les propulseurs soumis 8 impacts de balle et pour lesquels les risques ion1 dus 8 la geomktrie du chargement (rapport entre le diametre du chargement et celui du canal central) favorisant les I focalisations dondes de choc (4) Ce probkme est soluble par modification de ce rapport de diamktres, B prendre en compte d& la conception du propulseor.

I - le problhme de dktonation par influence de deux chuges

7 - CONFIRMATION A ECHELLE 1 Mal& le credit ponk par i'utilisateur potentiel de la munition aux travaux d'tvaluation et de prtdiction du comportement, la qualification d'une munition risque en pratique de n'&tre prononcke qu'apres confirmation sur objet reel. En particulier, il semble qu'une demonstration 8 I'kchelle 1 de la non dktonation painfluence d'une munition en confiwration de stockage soit obligatoire

De tels essais ktant coiiteux, ils devront gtnkralement &re rtalisCs en "stverite accrue", par maximisation de I'agression.

CONCLUSION MURAT : un label a la carte Tr&sattentive aux orientations prises tan1 par les pays de YOTAN (particuli&rementpdr les Etats-Unis) que par les instances internationales (ONU) en matiere de label de munition B risques attends (LOVA, IM, objets 1.6 ...), la France a jusqu'i maintenant prefer6 adapter ses criteres d'acceptation au cas par cas, systkme darme par systeme e darme.

A une liste dkpreuves obligatoires minimale, le maitre d'oeuvre ktatique de la munition ajoutera des criteres Gacceptation spkcifique en fonction de son application. II est imponant de souligner qu'au niveau des compositions (propergols, explosifs) utilisies, il n'existera sans doute pas de "formulation miracle" mais que le choix d'une composition pour une munition donnte dkpendra de l'architecture de cette munition ainsi que de ses conditions demploi (mission, mais aussi conditions de stockage, transport ...) et surtout des specifications de performances- vulnerabilitGco0t retenues pile maitre doeuvre.

La munition idCale ne sera en definitive que le compromis optimal entre performances et faible vuln6rabilitk. BIBLIOGRAPHIE

(1) * INSTRUCTION GENERALB CONCERNANT (4) * AN ODD BORE EFFECT ON BULLET INDUCED LEMPLOI DES SUBSTANCES EXPLOSIVES DETONATION OF HIGH ENERGY PROPELLANI DANS LES MUNITIONS DESTINEES AUX GRAINS ARMEES (Con& AMA 1989)

FRANCAISES ET A LA GENDARMERJE B Nouguez - H.Berger - B. Gondouin ~ NATIONALE. J. Brunet (SNPE) - Y. de Larminat - B. Sainjon (STPE) (Instruction DGA no I1500 du 14 mai 1991). . (5) *INSENSITIVE HIGH EXPLOSIVES AND (2) * LES MUNITIONS A RISQUBS A'ITENUES MUNITIONS (MURAT) AT SNPE . J.M. Decare - B. Sainjon

Revue LARMEMENTdu 24.10.90 pages 144-151. (Congrks ADPA " Insensitive munition technology" -

White Oak ~ Mars 1990) B. Nouguez, J. Derrien, M. Andre, G. Donzel.

(expos6 pr6sentt. aim ioumies Sciences et Difense Paris- - 0 Mai 1991). B. Sainjon, A. Becuwe.

Discussion

QUESTION BY MAXEY. UK: In the evaluations, marly pressure burst responses were noted. In France, is this an acceptable response and what parameters (eg pressure level, fragment throw) defines a pressure burst?

ANSWER; The experiments (tests) presented are the evaluation tests and non-acceptance tests associated with the precise criterion. The dummy utilized in these tests include safety plugs. At the time of a "over pressure burst" reaction type the plug is ejected but the rest 0 of the dummy is intact. The question is in the case of a reaction of type 4 or 5 according to the definition of NATO (non-violent) and then by no means comparable to a deflagration.

QUEST ION BY HELD. FRG; Should not the PASS/FAIL criteria correlate with munitions - quantity, confinement, configuration - and iiot on substances alone?

ANSWER: The tests in full-scale are costly and carried out in limited quantity (for example, people only carry out bullet impact tests of a certain caliber, at a certain velocity, etc.). The test of interest on a substance is allowed to extend the results obtained on similar aggression (for example on the behavior of a model generated for bullet impacts). That level of acceptance criterion enable us to look at same substances, by transportation and storage the ONU and NATO AC 258 required, by class object 1.6, such criterion associated with test series 7 ONU. 5- 1

The United States Air Force Explosives Hazards Reduction Program Mr. Joseph Jenus, Jr., Director Insensitive Munitions Directorate Air Base Operability Program Office (ASDIYQI) Eglin Air Force Base, Florida, 32542, USA

SUMMARY AND INTRODUCTION

United States Air Force military operations require large amounts of conventional high- explosive munitions. These materials must be stored in accordance with Air Force, NATO, and host country regulations, and in large part consist of hazard class 1.1 mass- detonating munitions. Because of limited real estate available in manv< theaters and the current Figure 1. F-I 6 in Hardened Aircraft Shelter quantity-distance (Q/D) requirements for safe storage, significant portions of the available EHR Program encompasses more than the munitions inventory are either stored under development of insensitive High Explosives waivers or are malpositioned (Le., stored in and Desensitized High Explosives to provide locations remote to the airbases). chemical solutions to reduce munitions hazards. The immediate goal of the United The major objective of the United States Air States Air Force is to reduce the hazards Force Explosives Hazards Reduction (EHR) presented to inventory munitions by Program is to gain full combat capability by developing and incorporating energy allowing required munitions to be safely suppression devices such as barriers, shields stored at the base of intended use. Reduction and diverters, redesigning munitions of munitions hazards will significantly reduce packaging, and applying innovative storage air base vulnerability as accidents or attacks and handling techniques. These activities will on munitions stocks will not result in permit the reduction of safety imposed catastrophic collateral damage. The long restrictions (Q/D limitations) associated with range goal of the Air Force EHR program is these munitions. This paper presents the to complete transition to insensitive or less progress being made in attaining the Air Force sensitive munitions in all major weapon immediate goal including key initiatives, systems as soon as is practical without ongoing and planned. significant loss of weapon performance or reduction in operational effectiveness. The 52

BACKGROUND

Without munitions war is difficult and ineffective. Munitions support the full spectrum of conflict. Bullets, grenades and rocket launchers permit ground defense to provide security from ground attack. Air defense missiles and anti-aircraft use. Shipments may be made by sea transport guns provide security from air attack. or we may have to rely on host nation civilian Bombs, missiles, and bullets used to carry war transportation resources which are to be to the enemy are the tools with which the war nationalized at the outbreak of hostilities. . is won. Central storage areas are extremely vulnerable to enemy action. The bulk of the stocks are Historically, explosives and propellants have stored in open revetments and not in posed a major challenge to military users. munitions storage igloos. Destruction of these The transportation and storage of large stocks or interdiction of supply lines to the amounts of munitions are necessary to modem bases needing these munitions is likely. A warfare, but present significant hazards to number of mechanisms or stimuli can initiate friendly forces because of the possibility of an explosion of a single round of ammunition, inadvertent explosion and mass destruction of and the inevitable result has been the the munitions and surroundings. Large propagation of sympathetic detonation quantities of munitions are needed to conduct throughout the munitions storage site, with a war. Additionally, storage space is needed for total 10SS of ihe munitions and, more bomb components: fuzes, boosters, fins, etc. importantly, personnel and materiel in the While these are relatively low in explosive local area. Because of the violence of the weight, storage volume i:equired for these reaction to various stimuli, large safety zones items is significant. are required around munitions, The size of these safety zones increases as the number of Large land areas are needed to accommodate munitions which are likely to react the safety clear zones for explosives. This simultaneously increases. The term Maximum land, particularly in Europe, is expensive and Credible Event (MCE) is used to quantify the sometimes not available at any price. The largest simultaneous explosive reaclion amount of explosives for each storage facility possible (in teIms of pounds of TNT must, therefore, be tailored to fit the land equivalent) in any given situation. For available. Storage facilities which can example, the MCE for a single MK82 bomb physically contain 500,000 pounds of is 192 pounds. The MCE of a stack of 312 explosives are limited (on the average) to MK82 bombs is 59,904 pounds. The MCE around 60,000 pounds because of land can be controlled to some extent by the way constraints. This limitation has resulted in the munitions are stored, packaged and situation where munitions in the quantities constructed. required are not at the bases where they are needed. These munitions may be stored at --I another base or at major Air Force central The goal of the Air Force storage areas. Explosives Hazard Heductiorr Program is to reduce MCE Since these munitions are not where they are needed, they must be transported, sometimes - I over great distances, to the base of intended 5-3

GOAL

In order to establish a program to reduce EHR PROGRAM BENEFITS (PAYOFF) munitions hazards, in September 1987 a Memorandum of Agreement (MOA) on a Joint Requirement for Insensitive Munitions OM) was signed by representatives of the US Army, Navy and Air Force. This MOA established a joint service insensitive munitions policy for reducing the threat (to survivability of US ships, aircraft, weapons carriers, tanks, other weapons platforms, and , stockpiles) posed by munitions and their reactions to unplanned stimuli. This policy extends beyond the development of insensitive chemical materials [Insensitive/Desensitized High Explosives (IHE)/DHE)] as the solution to the problem and includes the use of improved mechanical/electrical design concepts to reduce munitions hazards. Each Service was tasked by the MOA to implement a system for planning, funding, and executing its IM efforts.

As defined in the USAF's EHR Master Plan, the immediate goal is to reduce the hazards affordability, inventory, shelf life, and return presented to inventory munitions by on investment. If a munition cannot be developing and incorporating energy designed to be insensitive, it will be made less suppression devices such as barriers and sensitive by incorporation of appropriate and diverters, redesigning munitions packaging, feasible IM design features. Munitions that and applying innovative storage and handling are not made insensitive will be examined techniques. These activities will permit the periodically to determine if emerging reduction of safety imposed restrictions (QD technology or other factors can make the limitations) associated with these munitions. munitions less sensitive. The long-range goal of the program is to complete transition to insensitive or less The Air Force IM policy directives require sensitive munitions in all major weapon that all US munitions will be designed to systems as soon as practical without minimize the effects of unplanned stimuli. significant reduction in operational While the standards for such occurrences effectiveness. IM requirements will be could be satisfied by insensitive energetic . included in all new munition programs materials, these materials are presently not through MIL Standards, Specifications, and available and it would not be feasible to Program Management Directives (PMD). To replace the explosives in all inventory the extent practical, all munitions shall be munitions. Therefore, the long range policy, made to meet the IM criteria (MIL STD 2105 to transition all major weapon systems to "Hazard Assessment Tests for Non-Nuclear insensitive or less sensitive munitions, must Ordnance"). Practical constraints include, but await development of a chemical solution are not limited to, technical feasibility, which is several, if not many, years away. KEY INITIATIVES

Several key initiatives of the IM Program are listed in table 1.

Table I. Key Initiatives 1. Buffered storage prevents propagation between stacks of bombs in storage. Tests have proven that barrier materials placed hetween stacks of bombs can prevent explosive propagation. The concept has been approved by the Department of Defense Explosives Safety Board (DDESB). Barrier materials which have been approved include 20" ammunition and certain CBUs. Since these are not universally available, a generic buffer program using earth, sand, gravel, and manufactured harrier materials has been initiated. The generic buffered storage program will allow increased munitions storage in the same land, area and limit the effect of enemy attack and terrorist actions on a munitions storage area. . 2. Barrierdshields and packaging designed to prevent the propagation of one munitions item to the next will reduce the MCE. Barriers can he placed inside or outside munitions containers or between bombs on parked aircraft. Simple changes to the way munitions are packaged, such as orienting missiles within a container so that the warheads do not align, can also reduce the MCE. Effective barriers can limit the maximum credible event to one munitions item in a magazine full of munitions or one bomb on an aircraft. Barrier and packaging technologies will result in significant reductions in Q-D required. It wi.ll also reduce the effect of enemy or terrorist attack. The use of harriers has already pr0ve.n successful with 40mm grenades, and propagation between two MK-84 bombs on the wing of an F-16 has been prevented. Other munitions being addressed for harrier technology are the MK-20 Rockeye, CBU-87, and CBU-89. All munitions could benefit from this technology. 3. Flight line storage bins will reduce many of the hazards associated with explosives operations on the flightline. Proof of concept testing for a flight line storage bin has been completed. A significant increase in sortie generation is possible.

1. Hardened aircraft shelters (HAS) provide an opportunity to increase sortie generation. When an aircraft load of munitions detonates within a HAS, massive fragments are projected and large safety iistances are required around the HAS. Scale model tests have shown that if the MCE could he reduced to 1000 pounds or less, no significant fragment hazard would exist outside the HAS. Barrier technology could limit the MCE of a loaded aircraft to loo0 pounds or less and reduce or eliminate the Q-D requirement wound HAS.

5. Munitions site surveys will he conducted to determine how both existing criteria and IM initiatives :an he best applied at the air base. EHR initiatives needed to resolve specific problems can also he dentified. This evaluation will include a site plan and storage planning documents. In addition, the site survey team will provide munitions site survey training to those commands desiring this type of service. 0 5. Munitions Storage MLodules (MSM) are less expensive alternatives to concretekttel arch gloos. Large Scale testing on MSM was conducted in 1989. Engineering design changes resulting from the esting are being completed. Small scale tests, to verify these changes, and the final design drawings need to )e completed before MSM can be certified by the DDESB. MSM will provide the same protection as a :onCrete arch igloo, at less cost. MSM can be used cost effectively to provide covered, deep, secure storage or munitions at central depots. . 7. Lightning protection is a key initiative for munitions storage. Lightning protection is now required )y DDESB for all munitions storage facilities, and appears to he a default requirement. However, the Air ?orce has never provided lightning protection for open storage of munitions and there is no evidence of any iccidents resulting from lightning-caused detonation of these munitions. There is good technical evidence hat properly stored munitions do not need lightning protection. Providing this protection for open storage )f munitions in Europe alone would cost at least IO million dollars. A study and, if necessary, testing will )e conducted to determine if the requirement for lightning protection of open storage munitions is valid. - Each of the above key initiatives will be discussed in greater detail in the following paragraphs. BUFFERED STORAGE

Previous Air Force Testing Programs have shown that propagation between stacks of bombs could be prevented by using air and or munitions items as buffer materials between stacks of MK-82 and MK-84 bombs in munitions storage igloos'. Various densities of buffer Figure 2. Buffer Materials can prevent materials were placed between two propagation between stacks of munitions c stacks of bombs in an attempt to prevent propagation from one stack to the tested as buffers are not always available. other (see figure 2.). Each stack contained Since only tested items may be used as about 60,000 pounds net explosives weight buffers, it is imperative that other readily (NEW). The munitions buffers selected were available materials be qualified for use. of sufficient densities to defeat fragment attack. Areal densities of 500 pounds per Several factors must be considered in square foot were successfully tested. designing these buffering systems as shown in Separation distance was found to be important table 2. These include cost and availability of because of overpressure in an enclosed space. the raw materials or final products, the ability An acceptable separation distance proved to be to handle buffer materials with existing 38 feet between bomb stack boundaries. equipment and the labor needed to maintain, While it is convenient to use munitions as emplace and remove the buffer materials as buffers, the munitions items well as the performance of the buffer system.

Table 2. Buffer Material Considerations

COST AND AVAILABILITY: Since large amounts of buffer materials will be required, it is necessary to minimize the cost for these systems. If they can be fabricated from local, readily available materials, significant savings in shipping costs could be achieved.

HANDLING COMPATIBILITY: The final buffer must be compatible with existing handling equipment. Weight and size limitations will be dictated by the capacities of available forklift trucks, door sizes of igloos and magazines, and other logistics considerations of this nature.

LABOR REQUIRED: The labor required to emplace, maintain and remove these buffer materials is a key factor. Materials which need little or no continuing maintenance, such as concrete blocks, are preferred over more labor intensive systems.

BUFFER PERFORMANCE: The buffer must be able to sufficiently mitigate the fragment attack from the detonation of a 60,000 pound NEW stack of bombs to prevent propagation to the next stack of bombs.

' This concept was approved by the Department of Defense Explosives Safety Board IDDESBI. At the 299th DDESB meering, the following subparagraph h was added to DOD 6066.9-STD Chapter 9 paragraph b. 1: "If DDESB approved buffered configurations are provided, the NEW for WDpurposes is the explosive weight of the largest stack plus the explosives weight of the buffer material. " BARRIERS AND PACKAGING

\ Currently fielded munitions containers are designed to meet requirements defined in MIL-STD 648A "Design Criteria for Specialized Shipping Containers" and XWS-32350 "Critical Itern Development Specification for Containers". These documents address specifications for vibration, environment, handling, maintainability, size and weight. The following stimuli which are not currently addressed in container design are of . immediate and critical concem to the Air Force; cookoff (fire hazard), bullet Figure 3. Barriers can prevent impact, fragment impact and sympathetic propagation between munitions detonation. With the application of modem armor technology and advanced materials, a munitions container can be strike the adjacent weapons or their impact a designed to protect the weapons from angles are very low. The effectiveness of this unplanned stimuli; but, should a reaction technique has been demonstrated in a occur, sympathetic detonation from container configuration of four MK-82 bombs in a row, to container will be mitigated. This class of two bombs high, facing a similar physical mitigation or suppression devices is configuration nose to nose. Tests also being investigated to improve safety and to included bombs configured with fuzes and permit reduced MCE and lQ/D. fins. In one case, 15 of 16 bombs in the test were not sympathetically detonated by the Barriers, diverters and packaging with internal donor. Many MK-82 tests were conducted; or extemal shielding provide a low cost some resulted in successes, others failed. opportunity to reduce munitions hazards. It is Diverter technology efforts to date strongly the intent of the Air Force to continue to indicate that diverters can deter sympathetic develop and implement a comprehensive detonation. The reasons for diverter failures barrier technology effort. The Air Force has encountered with MK-82 bombs are being been conducting a technology investigation of investigated. a deformable mechanical diverter which a separates MK-84 general purpose bombs (see Diverters will deter sympathetic detonation in figure 3.). This barrier typically runs the many situations, but it is necessary to acquire length of the weapon and varies from 6 to 12 a thorough understanding of the detonation inches in width and 2 to 4 inches in thickness, products (fragments and blast characteristics, depending on the material used. The etc.) and how these products affect adjacent combination of physical separation with a rounds. Only then can we select materials shock reduction media is intended to reduce and design a diverter that will reliably deter the peak shock experienced by the adjacent sympathetic detonation. One of the major weapons to a level below the initiation objectives of this task is to define and verify threshold for the explosive used. The diverter modeling and testing techniques to assist in also acts as a deflector for the bulk of the developing and implementing divertedbarrier weapon fragments so that either they do not technology. The Air Force has an operational requirement to store 40 MM High Explosive Dual Purpose (HEDP) rifle grenades in Security Police armories. These items are Hazard Classification 1, Division 1 (C/D 1.1) because they mass detonate and they can be stored only in the munitions storage area.

The Air Force has conducted a series of tests using a new packaging configuration for the HEDP rounds I (see figure 4.), and has shown that, the maximum credible event (MCE) can be limited to one round. Also, testing has shown that, when the Figure 4. Prototype Container containers are stacked, initiation of for 40MM (M433) grenades the shaped charge in the upper a container does not propagate to a round submunitions are known; however, detonation directly below in the lower container. This of an intact CBU-87 and CBU-89 has not been means the grenades can be reclassified to CD characterized. This characterization will be 1.2 non-mass detonating, and can be stored in conducted both on single items and on a the armories where they are needed. standard storage configuration (CNU-327E containing two CBU’s). Information derived Cluster Bomb Units (CBU’s) in the current from the munitions characterization test, inventory are being replaced by the CBU-87 coupled with known characteristics of (Combined Effects Munitions) and CBU-89 candidate barrier materials and the sensitivity (Gator Antitank and Antipersonnel Mines). of the submunitions, will determine if redesign The inventory CBUs are assigned C/D 1.2. is feasible. Extemal modifications to the However, the new CBU-87s and CBU-89s are CNU-327E may be required to ensure assigned C/D 1.1. and require large Q/Ds sufficient mitigation of fragment, blast, and because they mass detonate. Storage capacity shaped-charge effects. for C/D 1.1 munitions is already limited. The introduction of CBU-87 and CBU-89 creates a additional storage problems, which can be avoided if modifications can be made to the munitions or munitions containers which allow them to be classified as C/D 1.2. The CBU-87s and CBU-89s are packaged two in a CNU-327E container (see figure 5.). It may be possible to stop propagation by modifying the packing material within the container or by placing external mitigating material shields on the outside of the container. To this end, testing will be done to better understand close-in effects of the detonation of a CBU-87 Figure 5. CBU Container with Barriers and CBU-89. Characteristics of the individual 5-x

Modeling and vali.dation of the exemptions identify hazardous conditions modification/redesign is accomplished in four which threaten both U.S. and other nations’ stages. Small-scale tests using sections of the assets and personnel. Aggressive action must proposed container determine if the design is be taken to eliminate the hazard or protect the feasible and obtain relative measures of the personnel and assets affected. Funds to mitigation/protection afforded to the construct new facilities and/or purchase submunitions. Single-package tests determine additional land are not available. One if propagation can be prevented between two relatively inexpensive solution to many of the CBU’s in the same container (these tests may conditions requiring waivers and exemptions be omitted if munitions characterization tests is the use of munitions storage bins or in- indicate there is little likelihood that ground munitions containers (see figure 6). In propagation between individual items can be addition to reducing required clear zones, prevented). Unconfined container-to-container munitions storage bins will provide for tests determine if propagation can be improved survivability and sustainability at prevented vertically, horizontally, and front to both permanent and bare base facilities. rear. If the foregoing tests are successful, a standard hazard classification test series is accomplished in accordance with Air Force Technical Order 1IA-1-47.

FLIGHT LINE STORAGE BINS

Figure 6. Bins, each containing one sortie of munitions, can be located adjacent to aircraft operating areas. Other munitions can be dispersed in bins HARDENED AIRCRAFT SHELTERS throughout the airbase. Bamer and flightline storage bins or in- Mission requirements and physical constraints ground munitions containers have the potential have created a requirement for waivers and for solving the most serious operational exemptions to explosives safety criteria at limitation problems facing our logisticians. many Air Force Bases. These waivers and For example, hardened aircraft shelters (HIAS) 5-9

are generally sited for the maximum quantities of munitions they are permitted to store (only HAS clear zone 10,000 pounds net explosives weight). This for 10,000 pounds of explosives limits the amount of explosives to Football Field for accommodate multiple sortie generation. The size reference explosives safety clear zone required to store 10,000 pounds of explosives in a hardened aircraft shelter is 1,335 feet. If the munitions are stored on the ground outside of the shelter the required distance is 1,250 feet. If munitions storage bins were used to store the additional sorties required at the aircraft , shelter, the shelter could be sited for 4,000 pounds NEW (enough for one sortie) and the required safety distance could be reduced to 985 feet. Proof of concept testing indicates that the inhabited building distance required around munitions storage bins would be 760 feet. The munitions storage bins could be located within the 985 foot clear zone of the HAS Clear Zone for 4000 pounds of explosives plus 36 munitions HAS and therefore effectively reduce the clear storage bins sited for 2500 zone around hardened aircraft shelters from pounds of explosives each 1335 feet to 985 feet. Bins/below-ground (a total of 94,000 pounds). storage containers make it possible to store a significant number of munitions, increase Figure 7. Expected Clear Zone sortie generation and not exceed Q-D for 4000 Reduction pounds NEW.

Munitions SITE SURVEYS

Airbase munitions site surveys and munitions restrictions limiting the unit’s ability to hazard reduction planning will identify effectively complete its combat mission. problems created by the presence of Surveys will address peacetime operational munitions, and quantify the scope and seventy needs, pre-hostility build-up, and sustained of the problem as it relates to airbase combat operations. The surveys will survivability and operability. These data will particularly address explosives safety waivers be used to quantify benefits gained by and exemptions to determine what actions can application of IM technologies and will help be taken to reduce or eliminate them without prioritize and justify funding for IM degrading the mission capability. Surveys initiatives. These surveys will identify actual will consist of five phases shown in table 3. operational combat limitations and other Table 3. Five Phase Program for Munitions Site Surveys Phase 1: Determine munitions requirements. Review applicable documents to determine the total munitions requirements. Identify explosives capacities for all storage, maintenance, assembly. holding areas. emergency munitions storage sites, hardened aircraft shelters and other areas that ara identified as explosives locations.

Identify USAFIMAJCOM. as well as funded and unfunded MCPINATO munitiolis storageloperating facilities. Determine applicable national and internstionel explosives safstylsurvivability criteria. Review existing approved explosives site plans and Host Nation approval documents if applicable. Obtain waiver, deviation, and exemptions documents if applicable. . Determine the total explosives capacities and Operational limits for all explosiv0s locations (currently approved). Determine the difference between existing storage capability and requirements. Evaluate previously directed Ipre-direct) munitions shipment for quantity and timing of munitions shipments. Review existing munitions pre-direct transportation plans far currency with relevant agencies. Validate pra-direct emergency munitions storage locations and Storage capabilities. Evaluate munitions assembly and delivery capabilities. Determine munitions personnellsquipment requirements & availability to SuStain daily combat operations. Determine munitions personnsliequipment requirements .% availability to receive pre-direct munitions shipments. Phase 2: Quantify survivability, sustainability. operability problems under existing operating conditions. Determine munitions shortfallsioverages and operational restrictions caused by munitions. Determine impact of pre-directed munitions receipt on combat operations.

Determine the hazard posed by U.S. munitions on survivability, operability, and sustainability of the airbase

Develop a base map depicting munitions hazards affecting survivabilityloperability. Prepare documents describing operability and sustainability problems created by munitions shipmentsloperations. Phase 3:

Determine enhancements possible to survivability, sustainability, and operability, through improved application of current safety criteria, re-warehousing munitions. or adding low cost enhancements such as barricades.

Review existing waiversldevistians to determine if they are requiredivalid. Develop munitions storage plans for all munitions storage facilities. holding areas, other operating locations, and hardened aircraft shelters. if applicable.

Prepare B revised EXplOSiVes site plan indicating peacetime and wartime munitions, if applicable.

Phase 4

Quantify survivability, operability. and sustainability gains from application of current or ongoing IM initiatives Develop munitions storage plans which depict storage gains through application of IM technologies. Develop explosives Site plans to quantify gains in base storaga capacities.

Develop a base map to compare explosives hazards using EHR technologies versus current technologies. Document survivability. operability,and sustainability gains made through use of these technologies. 'hase 5:

Identify and quantify new initiativesltechnologies which should be included in the Air Force EHR program. - 5-11

MUNITIONS STORAGE MODULE

Standard munitions storage igloos are designed and certified to store a Net Explosive Weight (NEW) of 500,000 pounds. These igloos cost approximately $450,000 each. Tests conducted under the Air Force Munitions Hazards Reduction Program using a modular igloo have demonstrated the feasibility of this new design approach (see figure 8.), which , would cost about $250,000 each. The igloo concept is based upon the integral connection of single precast concrete panels. Steel beams are cast internally

in the IDanels and are assembled to provide most of the structural integrity. a Figure 8. Munitions Storage Module

The MSM provides an increased explosive siting capability, more effective use of land and a substantial cost savings over standard steel arch and Stradle y explosives storage facilities.

The general procedure for erecting the modular igloo is outlined in table 4:

~~ ~ Table 4. MSM Erection Procedure Prepare the construction site and foundation Place the precast floor slabs a Erect and hold in place the back wall and first section of each side wall (wall sections are joined to the floor slab by inserting the steel members into existing slots in the floor slab) Place the first section of the roof (this stabilizes the first wall sections) Continue wall erection and roof placement of each section until the basic structure is complete (wall and roof sections are attached to previously erected sections by slip joints) Place door frame and doors Place frontal retaining cap and wing walls Cover the structure with soil overburden 5-12

LIGHTNING PROTECTION safety and survivability of munitions stocks will provide significant operational benefits. Currently the DOD requires lightning This program has been fully included in Air protection for open munitions storage pads. Base Operability considerations to improve air The Air Force has not implemented that base operations, survivability, and requirement and is being pressured by the sustainability. The Air Force EHR program Department of Defense Explosives Safety has several key initiatives which directly Board (DDESB) to do so. This is in spite of address the changing needs of the Air Force. an apparent lack of information on the effects of lightning strikes on munitions. In fact, it appears that there have been no Air Force Key initiatives are in the barriers and incidents of munitions exploding because of packaging area. Barriers and packaging which lightning strikes. In addition, the Air Force is can be designed to prevent the propagation of . unaware of any instances in service or one munitions item to the next will reduce the industry where the main charge explosive MCE. Barriers can be placed inside or inside unfuzed, cased munitions has exploded outside munitions containers or between as a result of lightning strikes. Because bombs on parked aircraft. Simple changes to lightning protection for open storage will cost the way munitions are packaged, such as $10-20 M in USAFE, the EHR program orienting missiles within a container so that a office discussed the lightning hazards with Los warheads do not align, may also reduce the Alanos, Sandia National Laboratories MCE. Effective: barriers and packaging can Albuquerque, and the U.S. Army Missile limit the MCE to one munitions item in a Command (MICOM), the latter two having magazine full of munitions or one bomb in a lightning simulation fa.cilities. These mission ready aircraft. This will also result in discussions indicate that the explosives inside significant reductions in quantity-distances unfuzed, cased munitions should not react required, and allow more munitions to be upon attack by generic lightning strikes. This stored in closer proximity to airbases, initiative will validate or try to eliminate flightlines and hardened aircraft shelters explosive safety requirements for lightning (HAS) where they are needed. protection. Because munitions are critical to the war fighting effort, the hazards to friendly forces CONCLUSIONS must be accepted but must also be minimized. The Air Force Explosives Hazard Reduction Program interfaces within the framework of The Air Force Insensitive a the Air Base Operability mission to Mend, Munitions/Explosives Hazard Reduction survive, recover, generate and support. Program is a significant undertaking that has the cooperation and support of the major Under the defend framework, explosives commands. The program serves the changing hazard reduction procedures will incrmse needs of the Air Force. It will facilitate base munitions storage capacity, and ensure that reductions and future operational base defense ammunition and explosives can requirements. Cost savings realized by be stored at the base and locality of intended implementing EHR initiatives will more than retum the cost of this program. Improved 5-13

use. Additionally, techniques which rcduce hazards of munitions can enhance availability ~h~ ,M program is as of munitions to the base defenders. critical to the survival of our Survival can also be greatly enhanced by tactical air forces, and will be storage techniques, containers dcsigned to pursued with vigor and a high mitigate propagation, and facilities which will priority sense Of purpose. lower MCEs and reduce both direct and collateral damage from enemy action. With the advent of the Air Force IM program, L reduced munitions hazards have become a To ensure survival of vital munitions design requirement for all munitions planned resources, innovative storage facilities such as and in development. Improved defense and I flight line munitions storage bins will disperse survival of munitions and user personnel make munitions stocks in the operating areas, it much easier to recover from enemy attack, provide protection from attack and reduce the generate sorties and provide combat support to need for large and vulnerable munitions attack the enemy. storage areas.

Discussion

QUESTION BY FRECHE. FRANCE: You have shown that reduction of risks can bring an important increase of quantities of munitions that can be stored in a given storage area. If you have insensitive munitions will you be able to increase again these quantities?

ANSWER; Yes! The ultimate solution to the Air force's storage problem is truly insensitive munitions using insensitive high explosives (IHE). When IHE is available, there will be no problems with storage. However, we believe that IHE will not be available for many years, and that expedient methods, such as buffered storage and underground bins next to hardened aircraft shelters are needed to improve storage problems in the interim.

QUFSTION BY CH17AI I FT. FRANCE?: The USAF has a strong interest with problems met in storage. This means an interest for NATO 1.6 risk division which mainly solves IM by just utilization of IHE to fill in the munition. This is not necessary with IM policy, where the only important point is result. What is the USAF position regarding this question?

ANSWER: It is our position that the insensitive munitions goal to achieve hazard classification/division 1.6 (C/D 1.6) will not be achieved in the near future. Maybe never! However, there are many ways to make munitions & sensitive, to reduce hazards to a more acceptable level and to thereby improve our storage problems and combat capability. We are actively pursuing methods to reduce munitions hazards to C/D 1.2 and C/D 1.4 using mechanical and physical means while awaiting the ultimate chemical solution. II .

0 6-1

ADVANCED GUN PROPULSION CONCEPTS AND INSENSITIVE MUhTTIOSS REQUIREMEWS AN OVERVIEW OF US EFFORTS

Ingo W. May. loscph 1. Rocchio. Waller F. Monism Albm W. Horst. Joseph M. Heimerl Ballistic Research L.boratory, Aberdm Roving hund MD 21005

David Downs. Thaddeus Core, Anthony BeanieU hamenu Research Development md Engineering Center. Picathny Arsenal. Dover. N107806

T. Craig Smith. Naval Ordnance Slation, Indian Head. MD 20640

1. SUMMARY survivability such as infantry fighting vehicles. lanks and ships, reduced vulnerability of rocket pmpellanu and reduction This survey paper summsrizes current US effons in of synpathetic detonation ard response to cook-off of bombs advanced gun propulsion technologies. The majority of these in stores. Each service has different priorities. The Air Force R&D efforts today focus on dvwced solid popellanu is mncaned with base magazine swage of munitions (including those specifically designed for low vulnerability (survivability and quantiry distance). The Navy w-rn is charet&tics). liquid propellant guns,elecuic guns concepts. ship survivability. The Army’s primary concern is combat and the ramjet Cannon accelerator. While the motivation for vehicle survivability and munitions transpon and storage these efforts is mainly improved ballistic performance. of safety. hostequal con- ue operational vulnerability as well as a hazards associated with the Uansporlation, slorage. and Since the initial efforts teem, a Navy-approved handling of munitions. A major wncem for lshnologisu document. MILSTD-2IOSA (Ref 2) has been developed today is how to rmcile these sppaxent contradictory goals. which defmes the mandatory tests and the passlfail criteria for The goal of buly “insensitive” munitions is probably the assessment of safety md insensitive munitions me&tic. Less-wnsitive munitions are. however, possible chareteristics of 111 non-nuclear weapon systems and and desirable. It is now clear thal ~peretionalsurvivability munitions. munition systems. and explosive devices. Program and vulnerability of puncaxrybg weapon systems are affected managers are now responsible for plwning and exsudng a to a significant degree not only by the sensitivity of munitions hazard assessment test pogram which includes a lest plan stored on-board. but also by the pekaging. storage location based on a realistic life cycle ttueat a hazard environmental degree of wniiiemenl. wmparmentation. and overall extemal profie. and intemal system protection. Munitions sensitivity or vulnerability can no longer be evaluated realistically in In virmally all advanced gun propulsion pograms isolation from the weapon system. This has pofourd the dominwt ballistic goal is to rrhieve substantial increases implications on insensitive munitions design md test in kinetic energy. The necd for higher muzzle velocities may melhodology. be”e clearer as the bmefiu Md system burdens of very high velocities bwme bener defmed. However. it is 2. INTRODUCTION be”ing increasingly more difficult to exuet more kinetic energy from a given conventional gun envelope. While Gun popllsion rewarch and development efforts in conventional wisdom says that we are at the limit of muule the US ue currently focused on improving the ballistic velocities for chemical gun propulsion. velocities on he order performance and nchieving meaningful increases in overall of 3Ws have been demonstrated (Ref 3-4). However, the system effectiveness. Reduction of weapon system thermodynamic efficiency decreases at very high velocities to vulnerability has be”e a major motivation during the last rhe point that such m appoeb is typically not attractive f“ two decades with the growing realization that wmbal a uctical sysmperspective. survivability is as impomnt a factor in effectiveness as system lchlity. With he additional bekgound of c~aroophic The options available to increasc the kinetic energy munitions fires on-board aircraft carriers, massive munition of projectiles are: (1) combine modest incremental dmpfues. vd munition train disastm experienced in the last improvements m pojectile design. gun pressure limits. 25 years. it is not suprising that L wnsensus developed with propellant energy dcnrity. md progressivity; (2) develop a I clcarly slated goal to field only munitions (Ref 1) which are larger. longer gun: (3) explore alternative. non-wnvmtional inrcnSitivc to the maximum CXMI possible. gun propulsion options for imp :‘distic pformance at a system penalty less than the fust two O~~ON. bly mdies showed that the elimination of sympathetic debnation could significanlly mnease The challenge to umvmtional munitions &signers survivability of ships ““ying mixed stores of explosives and is now wo-fold. In addition to the usual requirements of propellants; and that thc use of less-sensitive gun popellmu increased paformance and effectiveness. the requirement for would dramatically reduce the number of M60 ncries tanks reduced vulnerabiliiy and inneased survivability of the killed in battle. munition is alw established by the IM policy, Increased energy and lrsr sensitivity are not wily xhievable in concert bitive Munitions (ul) Programs in the US and novel approaches and tradeoffs are required as described Sewices have focused primarily on wespan plarlom below. While advanced conventional gun popllsion 6-2

app.orhes ue mdced making reminklblc progress. the hope LOVA popcllant WM dcvclaped (md qualified m vmrdance is that m thc long mm elccm'c pm propulsion options will with Ref 5 to rcplscc the single-basc M6+2 propellant (Ref result m more effective gun syslrms than possiblc by IO). This LOVA propellant featured many attributes nought mnvmwnal mum. in 8 popchnl required to meet IM requiremcnu (e.&. higher ignition temperature): yet until the BE"E igniter mltaial 3. US PERSPECTIVES ON INSENSITIVE MUNITIONS was rcpltd with II special LOVA Igniter (W matmal and until the drawn steel cnmidgc cau was r~pl.ccdwith I spiral- Specific IM raquiments and thus the ~6ebsment wap case desigq the cnmidge WM unable to meet the Navy's tests must be pldin the perspective of thc specific weapon IM requirements. Regarding the ipnitcr. in fast andla slow system m which munilions are to function. Weapon systems wok-off the BE" ignita material ignited .I a tanperawe md rhrut mvirments differ grully buwkn the services. well below the LOVA popellant resulting in m igniter wok- Guns sysm on bard ship. .irnafc un*s. mmored off md subsequent aggressive nsponre of the camidge. pmonnel curim. scll-propelled ~illery.towed Ptillery. CLE. Similarly. even when hpecial temperam resistant Ll materials 111 frc considerably diffamt baulcficld threats md may have were incorporated sa that the LOVA propellant avked-off differat levels of acceptable survivability. These diff~mc~s before the igniter (in 1 localizd zone). there was nill m must be munted for m establishing the IM crilcria ud aggressive response of the cnmidge until the drawn stccl cau USCSSmeN lesu for munitions. design was rcplsced with a apiral-wup use (capable of v&g at low pasure). In this seaion we briefly summarize the US Army md Navy pcrspstivcs on lnscnsitive Munitions with respect Finally. despite demonstration of the improved to gun propulsion tachnologies. The views of the US Air camidge to me! LM requirements. a simulated shipboard Force reflect to L significant exlent both Army and Navy magazine test revealed that a characteristic of the fue views. Wethe focus here is gun propulsion, Boggs and protection system pevented realizntion of the full polential of Den. (Ref 5) describe many of the sane issues and poblems thc improved camidges. In testing for confomwce to IM for haznrds of solid popellant rocket moton. requirements (Ref 9). it had been demonstrated that the response of chdges improved, typically. from an aggressive 8 3.1. Navy Perspective propulsive deflagration to a mild burning mponse. Ih the mock magazine simulation test (incldng sprinkla protection The US Navy has led the way towvardr establishing systan). it whs lcarned hat the IM test pamissible huning Insensitive Munitions requirements ud 1~61pomwls largely response can still result in utasmphic response as &-off as a consequence of the imporrance of ship survivability. To propagation of djacmt munitions m 1 wnfirsed sunage I significant exlent the requirements ud potocols served hs arrangement is likely. The simulated systems tests models for the Joint Services Requirements Document. Any demonsuated that application of large quantities of wmf" advanced naval gun systems will be required to meet the existing sprinkler system was effective m omtrolling avk- Insensitive Munition requirements (Ref 1-2.6-9).To that end ONpropagation. However. the raponre characteristics of the thc USN is collaborating with the other Services on some sprinkler sensoshystem needed to be improved to pcvent ldv~ced(non -solid) gun propulsion technologies (e.g.. the wok-off propagation. In summary. thm mnsideration ud clecuo~hermaVchanical (€TC) grm system to mea the complete understanding of thc munition (and all its parts) merging mti-ship missile heat in close-in weapon system in its entire logistiw life cycle is vital to the s-s of heIM (CIWS)application). Becaux resources PC limited, however. initiative. and because there remains a conriderable inventory of solid propellant based gun weapon systems. thae mains n 3.2 Amy Perspective WNinUing focus to meet the goals of IM requirements in these more mnventional systems. While much of the early eNm Rocchio. et al. (Ref 11) dncribe one of the emliest was based upon application of niumnine propellant laanpu m the US to find low vulnerability munition tachlogy. more rdythae has becn added emphasis on (LOVA) nllematives to conventional tank ammunition. Only 0 the munition as a total system. That is. improvements are recently did Insaitive Munitions Requirements (Ref 1) ud sought for the total gun munition package in its entire logistics the rrsociated test protocols (Ref 2) becane Army policy. life cycle. An example is described below. while L standard lest methodology is vny imponant and useful, it has been fotmd to be difficult to apply the Navy For bed chdgcs. subatimtion of PBX explosive standard methodology to Army systems. MILSTD-ZlMA in thc warhud should be mmplished m mcm with apsifies tests that ue of marginal relcvancc to the substitution of LOVA (low vulnerability "ition) environment m which Army munitions may be exposed. popellant in the poprlsion system. Mennore. at the Another isssue. however, is that passing rll the required su-mbly level umsidaation needs to be given all the standard tests summarired below SUI does no, .,asarily mmponmra, n well. The relative roles of the propellam, the result in munitions sarisfactory for an Army threat/hRzaJds ignim dcsigzh the ignitu material. the case design, and even CWirmunelU. thc crimp fmmust be urdcrsrood md lddresrcd s L system. Similarly. packagink stowage mmgmenc fragmmt md/or 'Ihm are hee sc16 of tests wl to asses or qualify Cue prowtion systems nced to be given paper 1nention not mergetic materialdmunitions with respect to hazards. The only m acdiblc evmt malytical sscssmenc but llso m sus of tests me (a) IM Tests (dtacribed m MILSTD 2105A). specific end item lesting. @) system vulnersbility tests (developed to assess system survivability requirements ud (c) the UN Hazard Experimce in developme m improved 76 mm Classification Tests. described in Army TB 7002 used for umidge meto illustrue mmy of thc &vc points. A 6-3

shipping md Uoragc puposrr. Table 1 liau the wen build flexibility into thc test p&~ md to make a smdard IM mu. distinction betwcen bgistic md &tical type tesu.

Table 1. US hitiveMunitions Test Summary The Army is mlly rcmnciling these fat methodologies in I cohumt framework to be published u Test Passing Criirria MILSTD-2105B.

. Fut cookoff burning permined 4.0 CURREhT MAJOR US GUN PROPULSION Slow cookoff burning permid EFFORTS BuUet imprt buming permined Fragment impact buming permitted In this section we nwey many of the gun propllsion Symp. detonation no propagation of &mation technologies cunenlly under mVMdg&m in the USA. The Ju tnprr no detonation discussions include brief technical descriptions. the wderlying Spal1imp.a nobumingpermirtcd motivation for the efforts, a summary of thc current technological status and trchnical challenges. md a brief The law two tesu M only nquircd if the threat hazard review of the insensitive munitions ~6pectsof these p assessment detamines that they me aedible threats. The slow propulsion approaches. I cookoff test is rlso waived for Army system if no realistic scenario cm be described. All tesu are described in MIL STD 2105A. which has recenlly been approved for Navy use and is available for use by the other services 4.1 Advanced SoUd Propulsion

Hazard Classification tests we run in conformity with 4.1.1 Energetic Materials LJN procedures and are described in Army Technical Bulletin TB 7OC-2. The tesu ue intended to assess the response of the The energetic material is often the most critical a munition in iu shipping and storage configuration As paR componm which determines vulnerability of munitions (Ref of the Hazard Classification Praess. all munitions are 11). There are, however, exceptions IO this rule and thus the subjected to a sympatheric detonation test and a bonfire (fast entire munition [projectile, case, ignition systan. dditive cookoff) test. which are very similar (but not identical) to their packages. propellant. storage system ew.1 must be trcnted as IM countqaru. To qualify for Hazard Class 1.6 (Extremely a sysm md the interplay of critical components identified. Insensitive Detonating Subsmce). munitions must be subject While the system aspects of vulnerability rmhction of to a slow -koN test md a hllet impact test. which me also ammunition must be always be kept in mind the disausion similar to. but not identical with their IM coun"pans. here will focus on solid gun propellmu. The goal of US resemch has teen '"low vulnerability" mununition (LOVA). The IM Tau do not necessarily admess Army system not "no vulnuability" munition! vulnerability problem. For inslance. it would be very unusual for mymunition to be hit by a 16 gram fngment at 8300 The mechanism of mpm of munitions IO a threat fps (the IM Frapent Test). LiLewise. it would be very stimulus must be understcod in order IO have a reawnable unusual for an Army munition to be exposed to a heat source chmce to develop improved mergetic materials. The effective which would result in a 6 degree F per how heating rate (the threat stimulus cxperierred by a p-opellmt depends on: the UI Slow Cookoff Test). On the other hand, it is quite possi- initial threaL the mor or other protection that fim this ble that I propulsion charge could pass the IM Shaped Charge threat, ud the local stowage configuration of the rounds Impact Tes& but the buming reaction could be sufficiently themselves. For armored systems there M two fundamental rapid to destroy a lank munition compwmenL heats: fragmeru/spallimpact and hypavelocity impact (HVI) with the latter resulting from either chemical energy jet (CE) a while this technical view is mt an official Army or kin& energy peneoator (KE) threau. Fire md heat are position, cNms are rmdenvay IO develop a unified. coherent secondary heau u they uise from pior initiation of a policy tailored for Army systems. munition by I primary threaL

The Army position is thar if the munition does not m. The principal initiation mechanism usociated with psthe insensitive munition tests using the recommended spall impact of gun propellmu has becn show to be thermal pmdures. iwaivea must be grmted to type clarslfy the item. ignition by mnductive heat transfer from the spall. The An esmtial clment m approval of the waiver is an delailed mechanism is vay complex ud is controlled by the apc"t betw~G.. urvcloper md the user (0 correct the chemical. mechanical. and thermophysicd propaties of the deficimcy. propellant. Figure 1 (Ref 12). ExIcnsive research showed that this threat could be mitigated by propellmts with high thermal Rmtly, this policy was tested only partially for a ignition thresholds. characteristics which unmt be Ichieved kinetic mngy wnk round which conlaina the propellant JAZ. with nitrocellulose-bed formulations but me found m The IM mushowed that the munition failed the fast cookoff. niouninc composite formulations. . fragment impact an3 spall impact tesu. After review of the alternatives it whs ducmurrd' that the ethnology wu not The role of the thermal docomposition chemistry of readily available to correct all of these deficiencies md the the energetic solid and polymer matrix uc reasonably well research MICIS WCIC dircaod to allocate resources to solve un&rstood. The mergetic solid should have I high these problems. The cxcrcisc funher subsmtiated the nced to innperawe for onset of thermal dewmposition. Nioate esters are inferior to the nitramhe and nitro groups m this respect. 6-4

For the plymu mhx. thmal demmporition should oczur rules to guide the clevelopmcnt of new formulations to at Icmpums u or slightly below that of the energetic solid mitigate rhis hear have mt been developed and rhis dcmmposition should be endolhermic r&er than exothamic. The most effective poly” exhibit thermal decomposition which up~n.cid catalysis is shifted to lower vmperanrra and tewma more mdorhmnic. There charasaktics uc effcctivc betause Lhey bferc with kat kansfu hom the spdl ptx6cle to he energetic solid. Knowledgc of this mechanism har led to effcnive spdl mitigation design rula for new foimularions to mitigate the lhraL . .

Fylure 2. Energy relea frwn granular propolhnt beds inpac(ed by shaped chgejets of varying charadenstics

There are some data which indicae that the I mechanical properties of the popell~ltire impormr Wise found that elastomeric materials were less violent him the 0 more brittle plastic composite propellant formuladom where Fgure 1. Thennophywcal pmcea invclved in spall initidion 01 gun mergy. grain gwmeuy and buming rates were similar (Ref Popelk&. 15). Both Ramsty md Liu have shown thar the violence of rspsnse increases whm HVI a~ursat low tempuannes (Ref 16-17). Thus a major thrust of new formulation Hvrwelociw Impact. 7he HVI mechwim because it is development is to improve propellant toughness. very mmplex and not well understocd is cunently the subject of intense research. CE HVI has baen s~diedmuch more Limited experimental sndies have been conducrcd on than KE HVI due to the experimental difficulties in working KE HVI. Lymw et J. (Ref 18) have recently conducted an wih the latler. experimental study which demonstrated the uitical role of armor and storage on the response of 120-mm munition to As a jet paerrares a granular propellant bed. an this threa~ Impact of a KE peneuator on target rounds with intense reaction occurs in the high pressure region combustible camidge case showed a mild reaction when the immediiuely in from of the jer Flash x-ray sNdia of this bare round was impacted and a slightly higher reaction when process by Watson and by Ramsey have shown thar materials the camidge was contained in iu aluminium storage Nte. divide into nvo distinct rypes of behavior (Ref 13-14). In When the KE peneRator parsed through armor lrfore Type 1 materials. the reaction at the jet tip appears to decay impacring the tube and camidge. the reaction gave a 2 to 4 significantly in velocity as it sprc;ds radially: ar the reaction times higher blast impulse. Results similar IO those without proceedr away from the jet axis. it mkcs on many of the mor, have been found for the response of 105-mm characteristics of a mvectivc halcombustion process munition to 65-g hagmenu at veloities > 800 m/s. With 0 where pressure. buming raw. surface area. md propellant thc inuolction of armor. the response seems to be dominated mergy arc mnuolling factors. In Type 2 materials, the by prompt reaction to spdl impact where the large volume of reaction proceeds in the radial direction at a sustained spall causes I much larger segment of the popellant to supenonic rate, though mt ncccssarily u rhc velocity of e full bc”e involved in th~rcaction. detonation. Type 2 materials exhibit much parer violence of IWtion Evaluaion Tcctmiqucs. Two tests have been dcvcloped to examine a propellant’s rcspome to spall: The hot fragment Wuson (Ref 14) has recently shown thar the energy conductive ignition tes~conduclcdin a laboratory. and rlre CE relcared in the blast wave is roughly popomonal to Lhe generared Spau rwge ICSL The former allows new kinetic energy of the jet dcpositFd in the popcllar~bed formulatiom to be wrcened rnpidly while final pwf of a duing the pmeuation procar as hhom in Figure 2 The formulation’s impact clraractnistics must bc cvaluarcd with the kinetic energy is .ppoximalrly [V x Dq,wkc D is the fmal field tcst where the malerial is exposed to a hear spccr” ja diamcta afta beakup. Typc 1 behavior 0ccuTs when the similar to thar exFUted on rhc b.ttlefield. response devi- markedly from this correlation. while my . formulatiom have bxn shown to follow this relationship. it is Because of he complex mechanism no useful not yet clear what chemical 01 physical properties of the laboratory wale test habeen devised to rank the rsponse of propellant most affect lhis response M detaminc the uansition different prop ell^^ to HVI. Many larger xale experimental pint to Type 8 from Typc 1 bhvior. Thus. effective design tshniques have been clevelopab d of which involve the use of a shaped charge. These techniques differ pincipally in the 6-5

mow of mwrial used md mmna in which the energy greater arrgy th~JA2 together with a Iowa ballistic rel-ed is med.Cwmtly the BRL is using the PLUC- tanperamre coefficient. It mlintaina the HVI nwivability Pendulum test devised by Wuron where the blast impulse sharaEvrLticr of the munition compartment md exhibits from M impacted propcllant bed is measure with a lmllistic high rcsismcz 10initiation by apalL pendulum. Tk jzt characteristics (diameter. tip velocity. residual energy) can be varied to charanerLe different New Matmials for Advanced Solid Rodants. The majar formulations. emphasis in the devclopment of new formuladons has been on composica whac an energetic solid is dispmed in a polymer Because munition comparunent survival is the ma&. Composites allow movement away from the limiiing ultimate pass/fail criterion for US tmk ammunition scaled thermal sauitivity characteristics of niuoccllulosc. Figure 3 compartment ~CIUhave becn developed. These tests enable shows uends in the development of new high energy low the system environment to be evaluated without the huge ws1s vulnerability propellants. mociated with full vale live fie testing. Unlommately. , results from tkre tests CM only be rslnted to the full scale The search umtinues for new mergetic solids which results by empirical correlations. Effons 10 develop useful exceed the mrgy md density of RDX but with less thermal modeling tools ue undenuay. md stock sensitivity. Polycyclic and bridged nivamines as well as suained ring niuamines are families of new energetic I Current Smte-of-the-An Solid Propellanu. 7he US has several materiais mth much p-omise. Examples of these include propellants which have undergone extensive field testing to CL20 md TNAZ. prove their ability to provide acceptable vulnerability levels on the battlefield Tests include large scale wmponcnr ~CIUas Mwy of the polymers uwd in mket propll~~have well as full scale live-fire resting. been evaluated in gun popellants. While properties have been amactive, the dificulty of mnuolling the cross-linldng NIC XM39 is a low vulnerability "mine composite reaction during mixing and exmsion have not allowed these propellant developed lo replace M30 propellm in the 105-mm materials to be exploited M456A2 HEAT camidge. It was designed to swive the severe spall impact threat environment within the M60 series Thermoplastic elastomers have great potmtial for lank. several reasons: elastomeric mechanical properties. hennoplastic -sing properties. pa! flexibility in JA2 is a conventional double-bare formulation used in achieving specific smcture md chemical proprde~.e=. Non- 120" tmk cannon ammunition for the MlAl lank. This energetic as well as energetic polymers me being evaluated. propellant is vay sensitive to the pall beat but this is not sigruficant in the MlAl where the "ition is separated Plasticizers arc key ingredienu bsause of their from the crew by blast doors. JA2 exhibits excellent response influence on energy. mechanical propenics. and processing to HVI as measured by both the plate-pendulum and charafteristics. A wide range of energetic md non-energetic wmparhnent tests. materials are evaluated as part of our material development program. New materials exploit the niuamino md .ndo moieties for superior energy and reduced sensitivity relative to niuato moieties.

Slowly. a set of design rules is being developed to sueamline fhe raLher empirical process of selecting the optimum plasticizn. One new and promising approach is the use of molecular modeling software to elucidate polymer- plastikr intaactions and evaluate the pomtial of new plasticizers.

Processing. The production process can greatly affect the vulnerability characteristics of a formulation bough changes in micmsmcme md mechsnical proprder. Observations of individual grains with a scmning electron microwope have &~tectrd mix to mix variations in minosmclurr which correspond 10obsaved changes in the vulnnability respmse to HVI. When the usc of the merging technology of win Tll" Srm P.-"g screw extrusion tswmes more widesped .nd combined with I I I I I I I online measurcnunt of zhlogical propsRiw. the variations 1550 Ism ut0 1)s uo Leul 1ooo due I0 proassing ue ex+ lo be signiticmlly reduced. Historical Development The HVI response of a composite formulation has FQure 3. Recent trends in US gun propelbnt devebpment bccn shown to increase as panicle sire of the energetic solid k~ases.ke arc llso some indicaOons of panicle shape M43 is a high energy. bw vulnerability niuamine effects. Great emphasis is currently being placed on studies wmposilc propellant dcvclopcd for tk lOS-mm M900 in rhis area APFSDS clmidgc for thc,MI fa&. Like XM39. it is a niuamlr composite propellw~ It was designed to provide 6-6

h “my. a primc objstivc of c~cNwak is lo propehccmbe~cdwto pVi& ilnuxa in dkmver dcsign rules thu &fine the rhcmical md physical muulc velocity WirhDul ~corrcspondingincruse in propcrdes of a propellmt w thu it would be possible to marimurn chmnbn ~I~SUIC. A velocity incrUre of 2.3% rpecify propellam ingredicnu I .piori in a& to met h.s been demonstrued m nmerm gun iyatems by replacing perfmure resu;ramnU ml to mitigate I parridu threat the mdmd men-pcrforucd &rains with those of thc OT Fll” Of hUU. while rhiCVcmCnt Of Ihh god U Sdl ninetux-pafontion gmcuy. fu in the funus pur progress has Lum mdc ml extmsivc muerial dunbases have becn esublishcd. Along the way, wo gmcrations of bw vulnerability popcllmu have been dcvclopcd

4.13 Bnlllstk Applkmtbns \\ UlhUely. the pcrformimm of all gun lmmch . ayavms is ccmsulincd by wme puswe or mleration thu cm be toler& by the payload mam by wmc maximum pres” envelq that can be wirhttood by the gun r~kThe formu consainl is o&& the rcope of . this diwussion. but the lutn is nitid m the discussion which follows. - The basis of the interior ballistic cycle is I TRAVEL compuitionbetween the rate of gas generadon (from buming of the propellant charge) and the rate of incrrasc in Figure 5. Projedile ba.w peswre vs Ira& br various pqdard wailable volume (a mlt primarily of motion of the geamel~ projectile down the bore). Gmnsrx too much gas early in 0 the balbtic cycle md themaximum p-esnne limitis There ue practical limits to rhis philosophy of ex&; inprticnl terms. thirplsces a limilonthe grain &sign. md while large (perhaps monolithic) ]gains initial buming surface. Lam in the cycle. however. the with vay many pcrforations m mdm investigation. pmjatile moves Qwnbrc. md L much higher mass prcductionof ruchdigurations arc difkdr Cumnt gmruion rue isrquiredtokcq gun pressures from effom &css both extrusion nd casting techniques. but fdlq so low as to be meffecmal. sirre propellant turning efforts main in the early devclopmcnr stages. Advantages. r- fall mnespmdiily with the falling ~ICSSWC the however. in fcrms of bothloading dcnsiry mdtuming grcatcst possiblc bwring surface rrm is required late kn the surfse progrrssivity ue obvious. An dmuc md perhaps ballistic cycle. even more utiactiva rpprosh to providing I highiy progressive. monolithic popelling charge involves the use of very high begrate WR) propellsrus, md is discussed in a sutsquml section of his papa.

Deterred or inhibid moellanu. Chemically &tored ball propeUan1 has long bcEn used m small-culiba guns (Ref 19). Application to large caliber propellant mnfigurruions focusu on the use of &mats or inhibitors on the oum regressive PlrIacCs of multi-paforated lpains to reduce or even eliminate buming in the regions thereby increasing the net effect of bunling on the progressive pxfoiar;on rurfsces. Wnfommalely. detenmt vchmlogy mnains as much M P( u I uiencs bth in tp~of ballistic analysis and in Iams of production and quality conuol. Funha. thc mncrpt is gemally nor utrutive in Uisting gun Figure 4. Surfaca area as a Wiof tadion bum !a various configurations with limitrd chamtu volumu. where the loss Popel& Beomek. in total tncrgy urociad with the &mui regions cmof be offset by inuured total charge weights. Inhibitor Thir rcquirment for a lrogrcssivcly Mi muings both simpler in umccpt md perhaps more hmingnnfre har iedtotheUY:ofwh81mhom Is universally qplicabls m wiving omsidnable amt ‘pOgTUSiVC pain gmmemes.’ Single-pafmucd right UlPlIh, bUl. =Of YeI. pSUltfddabkpOdllCdon cirdar cylindcn have givm way to Yym-. ninema-. and dUllCIlgCd. cvmthuty-Yycnpdorucd gnins. ehcimusingnumtas of perfmlnanr providing m incrusmg propom’on of the total Rearmed energy relcsse concern. Rcanning to Fip4. grain dace thu pws with h distance while the we note that classid ippmachcs to rhicving pogressivity “dcgnssivc” exmior nuface mlins reluivcly unchanged. fall fu shut of the Opimum profile dictaled by thc Surface pofdes forseveral such gmeuies uesbwnin volume liter& as the projectile moves doambore. Figure 4. while their qualitative effect on gun performance Pmicularly dcsirnble would be a pogrammed energy rclure is Wificd in Fipurr 5. Nov that the hwurc in pmgrusivity propellant & for which m ima-rcasc in mass dlwi the effmive us-c of grcua urul charge weights: more ;mation rue muM be programmod to mmmQKe a: the 6-7 nwst efficient time in the buming process. Thu. Ivery high by wdlblc chunk volwne. 7hc largest gdna arc. of lolding density charge could te anployed with0111 ova- mursc. obuimbk in new gun aystcm6 designed to uke full psllriration urly in thc cyck. yet the pugrammed inaurc advmmgc of such chPge durigna. in mrgy relee lfvr peak ~CSSUIC muld .66u~rmtal burning of the charge before pjectile uir from thc gun Consolidated charncs. It is worth mentioning briefly thnt thc tube. Ipplication of the ~cmsolidated shugc mnqt to large caliber grms mndnuea IO rcceive meinmest hugh with unmnarLablc success to date (Ref 21). This concept is bud on .~hi~inghigher bading densities bj wmpxting PARTIALLY CUT, MULTIPERFORATED STlCK wnvmtional granulnr propellants hughthe UM of solvation mdior heat The hitial reduction in wailable surface raulling from the intimate callact belwccn grains followed by I subsquat hruin daa.re u the wmpacted charge durmsolida~~sduring Lnnning may also bc a means of inneasing pmgrcrsivity of the overdl charge. While exmmely amactive in wmpta ximulations, the mncep is hampered in reality by m inwmplete undersunding of md mu01 over me ~lidalionmd huprcading NCTLUud by manufxolring .nd reprcducibihty problems. No suoxssful large caliber drmonsuation of rigruficant performance inam via this icchniquc is k" to these authors. Current Air Force PROGRAMMED-SPLITTING SnCK (PSS) and Army efforts IO dcvelop wnsoli&ted charge munitions in smaller calik. bweva. .pp"r to making substantial PPSS.

VHBR monolithic propellant charac. Higher perfonnance solid propellant charges require more total emgy in the gun chUllbcr AND pOper F0P-g Of thc mUQ release LO maintain downbore pressures without inauring the maximum breech pressure. The VHBR monolithic pmpellant chxrge (shown below) employs I very high burning rate pmpeUanL allowing the use of much thicka bum distances (webs) without leaving unbwned propellant u the adof the Fgure 6. Exarrple 01 "64 grain geometries. interior ballistic cycle (Ref 22).

Figure 6 depicts a family of such mcepts involving sirher chemical or physical pogramming of emgy rrleare. The layered propellants (cylindrical 01 mu) would consist of lower burning RE m4or emgy propellants on outside curfaces to which the burning would be limiwd undlaftu peal: ~CSSIXS. Then. I iignifcmt iwrmse in energy relcaw would be programmed to wmmcnce with SINGLE-PERFORATED buming of thehigher brining rrtc wor ""gy oms VHBR propellant. Corrcpually. any numba oflayas muld be employed to a cncrgy pofie. Fgure 7. VHBR mondihc propelhng charge. Rxdcally. however. even two LyaS hSVe becndiffcdt IO prcducc md mcnt efforts focus on the physical dog. Thepropellant cantha be cut into awnridge ULSC u know - pmgrammed rptirting stick propllmt (Ref 20). one 1mg+ single-paforation grain (ra&~ than hundreds or This vmion of programming relies on I significant even thousands of much smaller grsnula). with the outside irrreaW m burning rurfee lfvr peak prusm+ rhieved rurfec-e inhibid from bnning by thc CLV itself. Since the when the burning of the outside lupal surface of thc stick charge mnsisu of Isingle grain Ivery high loading dmsity ruchcs m mhddcdpray ofalits. thewre-aes. and can be 8chieved (in fact. heperforation sonfiguration can be thc heenvelops the dditional surfaced (sg Figure 4). Any optimized with r~pcftto my pmjectilc intrusion]. Mer. -ctheu ""ups cm be dcsigned IO ksd LO 14..un since ir brms only on thc inna surface. Ivery progrcsrivc to peak prer~~~.u &own in Figure 5. with inaurcd geomeay is vhicved downborepsurrs rurmpMying the mumpdonof iNxdchuge wciglu Solid propc Uant mvelina charae. A6 mentioned hvc. higher @onname requires more mui emgy AND proper SipExUu performance gains (+ S-I(W6 m muule pgrunming of thc energy reluse. To achieve muale velocity) can be uptcrcd bom his funily of mncepls ~m v~lociticsin ~XOCSSof 2 km/s very high popcllmt charge in volume-limited gun designs, since Iv"y high blding to pojcctilc mass ruios (CW) uc rsqldnd posing densky is VhiNablC Using theu armdally solid cylindm. numerous hndcru; on the systan, nor the least of which is I Even lager gains can bc expected in aystems cumndy very Luge breech pxanc in or& to commlmlutc .dequsu limited by m~imum~CSSIXC 01 deratjon ruha thm downbore persu~to resh rufh velocities. 6-8

An dtcmative to inuusmg the ~LI(of the significant rductim in tcmpnmuc sensitivity rndcr gropcllant chpgc m the chunbn is to &id pnt of the cmrin ignitionllodii conditions. It is poslllhld that charge to the pjcailc iuclf (Ref 23). Thus. gucs ue lccllized ignition may kad to uvm ampanion of the gmcrued at the b.x of the pOjeCIik. rrd prasurc bsses propcllnnt bed dcfommh of pins. md occlusion of from gun chbcr to projectile brw me not suffered. wme of the avdable brining wrf.ce during hupread. However. the mass of the kNeling charge itself must be shthe mCC&Cd p0p"fiCS Of the grh UC mlcrsted dong with the re51 of thc projccdlc. Therefm. tanpxsme dcpcndenr. thiseffect my be much more a mdcoff uisn thu das not fava use of the kweling ponounud u high tanpcnarru. dclnying he onset of charge lmtil very high vclocitia uc rrquired. F'unha. combuition famuch of the charge and aigniifiuntly reducing aevm mshmid as well as mmbustion rcquirancnrs ue the hmlSC in prtSUrC Oth& fxpcctcd for hot pl.ced on the mvcling charge. Current interest cams on charge. Suocesful exploitation of thb behavior 'would use of m VHBR (vcry high turning I&) eweling charge rquuc rdiable conk01 of the pmces% md qpPr;& (shown below). KO thu simple gmmemu may k uud op6"ion of grain chip. which pvide dcquav rkcngth to nkvivc the lunch envknmml and k"i1 the r%cJauivc forces to the Mimxncks m mucdd nib brll popcllanr~ projatilc. during thc rolling ~OCCSS. 'Ihcir 'prc~ce.pparmdy reduca "pcramre smsitivity by lcading to M inmare in buming dax when ftred cold Cold conditioning rcsults . in mhmd brirlle fracmre of the lninmacks ill the propellant during thc iarly buming prous. Again. reliable control is rcquirrd for full exploitation.

Dmlidation of a compacted charge cw significwlly impact the progrcsivity of the overall clwge. The tanperme dcprrdence of this deconsolidation Fgure 8. VHBR ltavelng charge. peers. a result Qf the mshanicd railima of the 0 compacted manix. can seduce or even climinau: the Temperameampenration kdmiques. An extranely temperamre sensitivity of the base p0peMaru. rmartivc appoach m improved performance is the ranoval of propelling charge tcmpaature sensitivity. dowing A variety of conkol lube :primas have been opaation undn dl mbicnt conditions u thc sane suggested An example of the mepcis shown m Figure 9. maximum chamber prusurc u that normally rr&ami only They povidc different initial pOjCdk positions md with hot hringr (Ref 24). Accompan*g inncara in vclocitia. -ding OTI ranperm. prior m ignition of mude velocities u ambient conditions m on the ohof the main charge - tbucby draing errrly projectile kavd and 3.7% for most high pnformarre gun sysm. Suoccrsful wuntaing the tanperanrrc mitivity of paformwur that tahniqucs must reliably and reproducibly counter the usual would orhenvix OCCUI. A number of pojeailc options PC increase m reaction kmctics (which kanslata inm pmpcllant umeivlble which could dta early motion as a frurtion buming ratcs) aswriakd with increases in initial oftanperamre hugh rlrh mechaniimsu changes in propellmi tanperamre. Always amditioning the stowed available volume or bore raistanc~. A brcech mshwirm anmunition u thc high tanperamc lit on board the wvc~po" could be dcsiped that saua popellwt tanperme and rysmncould provide M easily azhievable rrd fail-safe dtas available volume aoxTdingly. Almuively. it could tahniquc for exeazting the tu~cfi~~of vmperanne sauc prasiPization nuc or kvel and provide a rapid chwge insensitivity. To dau this appoazh has mt bun accepted. in volume. A similar device could be irwrporated mm the chamber t all either locally or dismbutrd cimunfamtially Chemical dditives. long used m the rocket as a layn of some OompeJSible matrrid. propellmtindustq U, dm bigrues md inhence 0 temperame unsitiuity. have not tem ~ccrssfully dcvclopcd for gun popcllwu. Yek it is well know ha wmc gun pmpcllant formulations exhibit sigrulicantly CONDITION FOR MAIN CHARGE IGNITION AT 21'C: gxum tcmperannc vnsitivity than do othm. Suxxssful I-- development of chcmicd control of ranpp-m sensitivity would povidc me of the easiest means of impoving ovalu rystcm performma porriblc. e-- A Y....-my mechanism may be ruperimposod on Lk wmul mbustion precess 10 &eve a nct hurdng I& u mbim tanpnmua similar to thu mdy CONDITION FOR MAIN CHARGE IGNITION AT HOT I.IMIT: dgody u the hat limir Poraiblc lgprorchcs include tk use of microwava to rapidly hut ttK popellant in rim to the hat Limit just before or "g fhg. extrmnlgas inj,tion to r& bumjng nus for mol charges. 9d Lur e>-- sDinuluion to dta ructim rues.

C& mmpositc pmpellant formuluions which m urily defomubk un& m&

4.13 Vubcnblllty Impllatbns d Advanced Ropuklm the VHBR we bvc. this mrrep rmy pwnt a vrious CWetpLr survivability chalcngc. Howeva. this may be mitigwd if the mveling chuge is limircd in riwhuss. Euh of thw &and Impllsim correpr have different ud largely unknown htluenccs on munitions Temcaaolre Commation Techni~ues. The mahmical rwiv8biliry. Bdon thc mcchmistic imigh16 glincd Q is tshniqucs for ~cmpcrlturccompenauion ahould have liulc pors~%kIO make mepjections htthe IM .apccu of cffm on rwivability. Chemical ulditivw which boost bw thcw dvmctd conccps. For dl of these mncepu. wnsitivity pressure b,uning rues should dvasely affect thc rcspo~eto to cpdl impact initiation should be dominated by the buic HVI u should the m"cep of rroring pmpellanu at their chcmical md "nophysical pmpcnies of the formulation opp-adng Ianpnarurr d.Thus the folloaing disFussion will focus on the HVI rrspnwr Bauof the US mquirr"Is for m. dl new propulsion umccpu will &go thorough evaluation in the Roarasive Grain Geometries. hpllant grain gmmeby has exploratory md dvmccd development luge ud myof the bcen chom to have a pmnounccd cffa! on HVI responw. lbove pojations will be evald. For grenulu charges. blast impulse deacara u grlin size imeaser md thm incrraws vain lftcr going through a minimum. This effar .ppears to be mnnolled by surface area 43 REGENERATIVE LIQUID PROPELLAW GUNS and fracture susccpubility at mdu grain sizes while critical diameter for vhga detonarion reaction swcars to be liquid propellant guns (LpGs) have brcn the focus of impOrtM1 It larger dimetcrs. ncse effecrr ue formulation periodic research effons in the Unid Statcr cine the lur and thrcar dependent. of course. Also. for some formulations. 1940's (Ref 25). A wide variety of gun mncepu md liquid it has been obscrved that stick popellant geometries can result propellanu have bccn investigated in the course of this in a increase in responrc kvel; this may be due to the ability r-ch which. una recently. hu mu with only limited of the rcection to sp~eadmore rapidly through the bed. Luge success. Ova the krt tc~lyears, LPG rcscnrch m the US hss monolithic grains may present a particular challenge bccause bcen focused on the rcgmerativcly injected gun "qt of thcir lmge diametn md bccause the burning rates of the utilizing a hydmxylammonium niuate (HAN) bud liquid formulations uscd may have to be higher than for mnvational popcllan~This gun md popellant combdon hu -tly grain duigns. bcen sclated u the gun propukion system of choice for the Army's AdvdField Anillcry Systcm, AFM. De& or Inhibited Rorellant. The per- of a duurent or &bitor could be beneficial to those popcll~t~which exhibit the more bmign Typc 1 behavior barure of the Injection Piston similarity of this praas to 8 convective combustion wave I LP Reservoir where redd himing mIcs should hsve 8 retarding cffccr Of mmc. this effect auld be mitigwd drperding on the delay unril the higher energy inner mre is reacid md it is even possible for the hvler core popellmi propmics to grussly ovuwhelm the inhibitor efftn. As thcsc mnctpu arc used to inuease the chage boding density. HVI blur respmsc should be expencd to increase if aeatcr mounts of augy Ue 8vlilable.

Roar8nmed Enerw Release Concqns. FM the Lyered conccps similar umsiderao'ons should hold u for the detmed or inhibited grains. Thc programmed lpliuing rtick charge may show some hefit baause of the bw MOUN of initial surfsx uu u well u the gram mechanical rucngth of the Damper stick.%. Fgure 10. Regenera!ive liquid propehnl gun mncepl. Consolidated charges. The effsra for ammlidrted charges ue exwted to be similar to thc detmed 01 inhibited pain The regenerative liquid popcllmt gun (RLPG)inmior . cue. Thc bw initial surface .M of the chge in iu ballistic cycle is controlled by thc injcction of the LP into the coMoli&ted form md the pmr mcchmical mqhg for shock combustion chbm(Fig. 10) md, thus. by the motion of the kuumission ktwm base - '__may be bcneficid. regcnaurre piston. In the simple in-line piston RLPC Expuimenral data arc few md eOnnichg u this time. More dcpid in Figure IO. thc injetion orifas me initially ruled cxwive expclimmts pe to be amduaed. thc LF' is loaded into the popelluu rcrenoir. nd a pojectile is pldLt the "ne to the hneL A ~SSMv6~6 time WRMonolithic Ropelline Char~c. The higher chge charuuristic of a aimple in-line RLPG is peraued u Figure l&g density and highu burning ~ICA uwciakd with this 11. The IB p"ss is initid by m exlanal igniim chmge mrrep should pcs~ntrnae dulltnges to munition which p"& the combustion chbm. 7% gupsure nwivrbility. for- the injaticm puton runvu& mmprmsing thc LP m the reservoir. The differential .ru of the mjation pism from Solid Ropellmt Tia~~lingCharge. A.ppliuion of this the ambustion chbnto the reservoir rerva to amplify the mrrep quires muaisls with very high b\pning rats. Like combustion ge perms. producing a higha ~CSSWCin the 6-10

W "voir ad, thus. providing the pnm rrquirod to firings have hen mdwted in a variety $of ulibers up to 155 break thc aifn vrls md injcct Impcllmt into the mm. Two gmcrations of 155 mm RLPGI; have hen built md combustion chunk. The second phase of the IB pmceas is tcslcd, the fust gmerdon fixmc wu hsignal to p00Vidc m ignition delay. during which thc piston mntinucs to move ballistic data in Lrgc cdk.while the wmnd wu daigncd runv~d.injsting ddidonrl Wrvhich -ulatesin thc to drmonstmc most of the functional char.curistics of a combustion chamber. This acrumulated LP thm ignh md fieldable p system. Morballistic investigations. both rqidly bvnc @hru three). hging the chamber to openting cxperimcnrnl md thtotrdul. have tux conmWted in plrdel psure and uulmting thc piston w iu muimum velocity. with the large ulik gun mgincrring md 1sI1 effom. 'bse Phue fow is often charrtcriwd by I ~CSS~Cplateau in the expcrimmlal invcrtigadons have kad to m irmrraKd simple in-line RLPC contipaion. This plamu is undnsmding of the RLPC poccs~ which has been

~~ u a qurri- rrable equilibrivm in which the volume incorporated into interim ballistic "pum models (Ref 31. Lnuw m the combustion dumber md the flow of 33). Thew models awdydescribe thc FLPC IB FCCXSS combustion grvs down tube arc brlmed by thc combustion and arc mudncly used in dnta malyris. gm design md new of beshiy injected LP. Phax fom mds with the completion cotup evaluation (Ref 34-36). . of piston travel and pOpel~anlcombustion. The fdphase is thc usual expansion of combustion gses aftu 111-bumL In the liquid ppellant aha bod wdiand development program thac becn mnductcd "rompassing: buic chcmistry; cxtasivc physical chcmical md hazards . chsrrmidon; pmluction process dcvclopment; md 0 IGNITER FUNCTION applicdona systems studies md malyrs. As I pri of this @ INJECTION . LP ACCUMULATION effw extensive hazards. insensitive munitions and @ COMBUSTION OF LP ACCUMULATION Vuherability testing har been mn&cted u nod above. - have. of addressed only fimdammtal LP 0 0UASI.STABLE EOUltlQRlUM These tcsts necessity. L @ EXPANSION &,he nvrogatc Ann- PISTON DAMPING SPIKE propmies and the charactdtics of LP in 2 I"" PISTON TRAVEL COMPLETE trampdon md vehicle sroragc containers. At prrwnr. the 'ALI-DURN1 propellant has pasred d the rquired tesw of the Jomt 0 Smiccs Inunsitive Milnitions Critcrin. with the exaption of 200 I sympathetic detonation test in which the inteqxetuuon of the limited test results does not led to 3 clear corrlusion. Additional testing ia plumed to &us this question. While '0 1.0 2.0 A.0 6.0 v 3.0 5.0 the resulu of thae tests have lnded to confirm the pMcruial TIME (mi) of the LF' u L reduced sensitivity matrrid, they have llso anpharized the systnwi nature of the problem i.e. the nced 10 Fgure 11. Typal pcenure-lime hbcoty bc a regeneative liud ueat the popellant, thc packagi md storage conccpu. md Pepelm gun. the vehicle &sip as ib integral system in order to rdalizc minimum systcm VUiTlersbility. The US cmdidate liquid propelh~ rbcmrly designated XM46. is L stoichiomuric mixture of The key technical md cngineaing chdcnges for the hydroxylmonim niue WUCI md &icthwolammonium liquid popellsnt gun M generally mto gun and propellant nimte. Thc formulation md chemical popmic~of this cucgories. In the gun uca the presmu: of high frqtiency propellant .re dacTited in dctail m the livraturc (Ref 26). pressure oscillations in the combustion garcs is !he key ncar XM46 har been rbwn in !.sing to psssess I variety of tam technical challenge. These oscillations are not teldto desirable charanaistia. however. m the context of this rcpon. the bwn bequcncy. longinrdinal pressure waves which are the key char83erktics of thc LP arc the difficulty with which rerponsiblc for bwhblows m convmdond solid propCllM1 it is ignited if not mnfud. its relativc inwnsitiviry to impxi guns. The primary mccm raised by the p- of hsc md shock and iu favorable rrsponre in I variety of hszards oacillafjons is their cffcct on sensitive projectile mponcnu. 0 md insmsitive munitions tests (Ref 27-31). c.g. fuzes. 18th thm thc potential for combustion mmlalics or gm damage. In the longa wnn. the key developmmtal The modvation bchind the r&g cffom to develop mgineaing challenge of the RLW is reliability in I field LP gunr over thc last forty ycus is the potential for realizing environmm. This issue will be the focus of intense the pervasive syskms befirs offered by I fluid propellant. enginkg effon u well u test md evaluation during the These puntid bcnefiw include rrdufed fuilirirarion md dcvclopmm~p00cas. In the popcllani 5- the primary popehtmnr,inacsxdlogisticeff~msymdcffectivencsr. challmgc is the engineering md design of the mmponents and f Lnused ufcty hugbut thc military rystem incldmg inbumture which will facilitate ~~~~sfulinkgradon of I redd vulnerability m chc blcfield, si *-;;ed gun lquid propllant into the field Army. Theinclude mt only .u&on md innurcd gun system @om" md pmdunion facilities. storage md trmrporution amtrincrs. cffcnivencsa. Thus thc Ncccasful fvlding of m LP gun hmdling quipmar. ac.. but .Im new poadmes ud syucm would have L mapr impact on 111 rrpens of the doctrine massmy to opdmizc op" with L tiquid miliury system. beginning u chc pmduction kvel. prop ell an^ Aglih in the mntext of this rqpat. anphuis must bc given IO systems dcsign in wJa to axpbit the mduced Thc ament liquid propellnnt gun pogrpn in thc sensitivity chrr.nCrirtiis of the LP md opcimkc safety md United Statu was initid in me lnrc 1970's with Gcnd VUiTlenbility reducticm. Elccuk faking thc kui in gun &sip ud terting md ths hyMSUlllhg lUFOnSibility for ra inVCStigdOll5 Uld The regmauivc liquid popllmt gun bas been popeht dcvelopnenr s* mu dmc, rcvdthouamd test designued u the tysm of chi= for MAS. boweva. rhm 6-11

m tubsmtial technical mgineaing dullages to be resistive huting of the eleceical current fbwing through the ovuaane behm fielding such 8 system. Thaefore. LF' Plasm .ppcur. u pMu. to be the most "of the novel gun propulsion wnappu being pued by the Army. h the MAS cmnponmt miDmtionprogram proFscb. the ihntiijed challenges will be .ddrcsscd ud it is probable W givm Initial Configuration dequau. ruotuces. they will be **tirfictorily resolved. . Thmfore. it -highly possible thu fie1d;np of m LP millcry systcm wuld begin Pound the yeu 2ooO.

4.3 ELECTROTHERMAL-CHEMICAL GUN PROPLZSION

Elecmthamal-=llemical (ETC) guns ue8 brod class of hybrid gas dywnic gun pvpulsion wnaprr which utilize .Initiation of Plasma into Propellant Bed I wmbination of clccmcal and chemical magy wurces. These mrrcps have their origins in the pun elecuothamal . (ET) propulsion wnceprr which .ppcar in the hypcnelaity tilaanrre of the 1960's md again in the 1- 1970's md carly 1980's in the work of Goldstein and Tid" of GT Devices, Irr. The "pure" ET popision amcept involves the uae of elecuical energy to nw a high tempcramre plasma which mix= with ud vaporizes m inen working fluid to gnmav the high ~CSSUICgas Iveded to .ccclcmte 8 pojecde. Inteiaction/Combustion/Vaporizalion of Plasma and Propellant a The original motivation for the ET propulsion mncept was inncased mdevelocity. Indeed. much of the carly suppon for this work was provided through the SDI program in which ultra-high velocities wm the objective. Sice the mlc energy source for the propulsion pmccss is elecuical materials which produce low molecular weight gas when vaporized can be ured Thus. the ET propulsion concept can be viewed as 8 single stage. clecuically powered light gas gun. with the umdanl advantages of such systuns in the Fgure 12. Int& Mlistk process tw eledrolhwmal gun popukion hypmclocity regime. Systans evaluations of ractical mncepl. applicarions of the ET wnccpt quickly lead to the redimtion that clecuical magy rquiremmu ue of the same orda as In the mid-1980's due in large part to the mionale hsefor elecuomagnetic guns. thus making power component outlined atave. GT Devices under wnum U, the Army and md system tshnology L key driva md reducing the FMC Corporation using IR&D funding began exploring hybrid mactivmas of ET wrrepts in the =tical ucna for my electrothermal propulsion coxqxs in which some portion of ncar-tum .pplica!ions. the energy was provided by m energetic wowfluid or propellant A schematic depicting the iruaior ballistic process In the mid-1980's hein large part to the &de of these wncepu is pe~entedin Egure 12 The basic outlined &we. GT Devices under wnum to the Amy ud digurntion is quite similar to thar of a bulk-lo& liquid FMC Corporation using IRBD funding began exploring hybrid propellant gun. The mergetic propellant initially & the a elecborhmnal propulsion conceprr in which some portion of combustion chambn between the breech m-d projectile bau. the cmgy was provided by an energetic workmg fluid or The elccuical energy is employed to pmaaw 8 plasma in a ppellmt A schrmatic depicting rhc inmior ballistic pmccss capillary which is located exmal w the combustion chamber. of these amceprr is presented in Figure 12. Thc basic usually umchcd to or pan of the brecch mechanism. The wnfiguration is quite similar to thar of a bulk-loaded liquid process is initiated by the application of thc high voltage popellant gun. The energetic propellant initially fdls the mss8 fme fuse wire connecting dectroder u eihmd of combustion chamber buwem the bnech m-d projectile base. the capillary. Thc fuse is vaporized generating a plasma The elcnriul energy is employed to gmuaw L plasma in a through which dditional current is passed. funha heating the apiUmy whish is louted exmal to the wmbustion hbu, plasma As 8 result of Ac high pressure gmaarrd in the usually .tuchcd to or pur of the brecch mechmirm. The ~.p~dq,hot plasma with trmperaturcd on the orbof 20.W p~ofcar is initid by the application of the high voltage - 30.000 K is the injected into the p"~.The mass lost muss L fuu hrse wire cormcaing elecuoder u either ad of through plasm8 injection is replaced by ablation of the thc cqiUmy. Tlx hrse L vqmW gmaating L plasma "id lming the plasma capillary. The plasma "pcmolre through which dditional currat is pass4 fwthn heating the md pssurc in the upillary m then maintained by the . plasma As 8 result of Lhc high FCSSMgmaarrd in the resistive heating of the clecnical suncnf flowing hughthe upillary. hot pimawith lanpcrmcd on he orbof 20.000 Ph

~ 30.W K is the injected into the propellanr The rmsa bat through plrrma injmion is repllecd by &lation of the The ETC inkor ballistic po~essis quit, wmplu. mrrrill lining the plasm cqilhy. The plasma mpmc involving m iniw mixing of plasma md propelh to md pezrurc in mC ..pill& arc thm msimhed by the initiated dcwmpositioR followed by the ruction of the tulk 6-12

of the propellant in L highly mublc hydrodynamic FMC Corpnath has wntinued investigations of their envimnmm driven by the injection of additional plma CAP, mncepl. though they have llso cxpld propellnnu This environment .ppears similar to that mwlm~~edin the other than their original hydrogen peroxide - hydrosubon bulk-loa liquid propellant gun. ud it is rrrronable to bipropellimt mixaves. Both group have pogessed toward mticipnte that phmommlogical descriptions of the IB their objectives Mdn wntruxs with I variety of Covenunent pocesses will. therefox. be War. agencies M well as heir om~CSOUIFCS. Armyaponsad eKom have been focused mainly on mti-mor wlicntions. The ~ractivefcanms of &is mnctpt ue: the though there is interest in 0th pasiblc tactical missions. - potential reduction in required clechicd enagy in wmpar;son However. the Army's goal of danonstruing muonable. to the pure elecuolhamal and the elecmmagnetic proplsion rcpe-ble ballistics with an rccptlblc pmplLaru while comps; the ix-reued loading density possible through bull- achieving a significant performmcx &use has yet to be loading of the popellwt; the potential to utilize mn- rCaliz.4. In parallel with md in suplan of, wnuacmr effm. traditional popellant chemistries which may provide inncased the Army has initiated experimental md thmrctical mtuior propellant rpccific energies and/or redd propellant ballistic reaearch pojer*a. The objeaives of these pojcns are vulnerability: and the potential to utilize elccoical energy to to idmtib novel propellant &als for use with m ETC tailor the combustion of the propellant and th~&ytailor the gun, to cxpcrimentally investigate the ETC interim bsllirtic projectile bax pessure to mncare gun performance. The pocess in order to idenrib key paramem md develop and rationale for the nxn~t"est in the ETC prophion concept undnsmding of component prm. md to develop . in the UniwJ Sues is bared on there pomtial benefits. If wmputer models of h IB po~ess.Related programs hvc these benefits can be redid. ri&icant paformance been initiawd by the Defense Nuclear Agency for artillery imeases will be possible within existing gun envelopes. In .pplicatio~and the US Navy ~6 L fuwc Closc-in Weapon panicular. it has bcen suggested lhat imcascs in muzzle System (CrWS). Le. a potential phalanx n~lacement(Ref 39). mergy of 5CLlCKI% are possible in existing 120 mm ud 155 nun gun systems with relatively modest investments of The technical challenges faced by Lhe proponents of elecmcal energy. The potetuial for ~bstantidlyreducing the ETC are outlined above. Control of the mlerior clecmcal power requirements is very attractive since both ballistic process. i.e. wnuol of propellant mmbustion, must be 0 dependence on advances in power Icchnology and the vehicle demonstrd This requires. LS a minimum railoring of the inlegrdon burdens would be reduced. thus potetuidly pressure I& rate to limit projectile jerk md achieve the reducing time for rcalizslion of practical system. desired maximum pressure. Paformmcc impovemeni. my .Is0 require wnuol of rhe IB po~essdm maximum pressure These potential bmefits uc 111 based, u Icasl m pan to pennit tailoring the pessure p-ofile. In my we, a on the sumption that electrical emgy can be ulilized to rubstantial performanu: imease. i.e. higher muzzle mergy or wntrol the wml~~tionof the pmpellant (either hughdirect velocity than is possible with L solid propellant in a given gun wnml of the propellant reaaion rate, a wntrol of mixing conliguration. must be drmonstrated for tactical .pplicatiom and surface- generation. or both) (Ref 37). It has bcen shown of an ETC concept to be amaaive. Repentabiliry sufficient to rhat a relatively mall mount of electrical energy can be used meet Army dispersion id wurq requiremenu mwt dw, be to initiate the ETC p~o~ess.It is hssumed that the application demonstraid A pedictive modeling cqability is desired to of additional electrical energy (through a plasma) during ~ppo'1bRUlstic research ud radonal gun design. Fimher propellant combustion cm be utibmd to conml propellant these ui&s must be met wing a propellant which is fieldable combustion At pesmt. it is not clm to what degree this in the Army system. This discussion das not address issues wnml can bc realized mr is it clear how much electrical relaed to the electrical power supply. nor does it ddress energy would be required to achieve that mnuol. After issues generally ddrersed later in the development &e. maximum pessure. it appears pohsible to mainrain pojectile Howeva. these issw require mideration 16 the lcdrnology base pressure by the ddition of plasma mergy to kat the begins to "ne. combustion gases ud thus realize an irncaw in gun pcrlormm. The energy required, which can be estimaed in To this point. the potential impact of EIT technology 0 L simple thumodynamic malysis. is large md efficiency on the -itive mmutions issue has :not bcen dressed dcacases rapidly in the later uages of pojectile uavel. except to note that the potential for wing non-traditional chanistries might lead to popellants with reduced sensitivity Ballistic conml md elsmcal energy requirements (Ref 40). Given the very early stages of ETC rcsearch it is have bcen two of the primary ETC research issucs in the US difficult @nmake rubsrantive smmts regarding the amce lbou 1986 (Ref 38). GT Devica and FMC Corporation characteristics of a systan yet to be defined. This is llso the hVC ICm8bled the kUWVatOI6 in Dc ldUWlOgy. case for the clectrical power supply since little is known about hugh "tly other private fmhave begun work m the the mitivity ud vulnizability of existing wmponcnu. tniirh .rcL las the inn& umgy ud power chity wmpunenu required in the fume for tactical ~licatimsof clstric guns. GT Dcviws. in wnjlmaion with General Dynamics Lmd Syslcm4 has f& their efforta on low molecular In summary. the !ZIT propllsion amcept ilolds weight propellants md reduction of the electrical enagy potential for substantial systuns bcncflls if Ihc key lechnology . rcquiranent in m !ZIT gun IO leas than 5-10% of the total issua can be resolved slfisf.aOrily. Existing data is required energy. Thia of onuse mems that 90.95% of the inadequate w ruppon rational pojcclion~ of technology energy is nrpplied by Chemisuy. In Ihia effm rhey have mawdon, however, if the techical objectives of the Army's explored L vuiety of mntraditional propellants. LI well as ongoing LTC program ue met ova the next few yurs. Illanate methods to generate plasmar ud to use than to development of an ETC gun system during the fust deude of COlWOl the iNCliOl hllislk pOCCSS. the ncxt mauy may well be possible. 6-13

4A ELECXROMAGNETIC GUN PROPULSION A hefil Of CkCIIk plM the potcndd for Nbstantidy enhnrvcd SyCmp5fOr"ce. ChhS Rgarding The otha propulsion tcchmlogicr. includii the this enhpncement have two major themes: Inaured hytrid clsrmthmnal pmpulsion. discussed in this pppcr rcly projectile velocity wiU improve kthality .gainst armored on the expansion of prunnkd popcllant gasses. An LpgcLs. innurre the air defense Lcepoul range. md ex- the clccaomngnetic (EM) gun uses instcad invnsc magnetic fields range Of fUe NppOn WuponS. The Of CnCIgCUC spplied locally to Ipojatilc. miring pvlxs of clectriul propellant will llro hefit vuhcnbility and logistics. * poWR LI the UhhSC energy WuIce. Development of m EM "nmt system will rred to mnrry I number of &and mpu""Lu md technology mas: hypcnelaity opnuion. new types of gun hnek IXW hypavelocity projectiles md clslrkal poW~rupply wmponcnuy. The pxing technical Wenge is reddon in aysm mass md velum+ which is by thc electrical powu supply. ?kre has bccn great impmvement during the .lqnmc nu. I*"llPI , past five years. htNbstwtial rimher reddon is required.

The US Amy Armament Rcscarch Dcvclop-ncnt md .1 ...... Enginsering Centu (ARDEC) lends the US program for tactical weapon applications. Amor defeat is the focus application driving choices of component tcchnology rcquiranents. The program dms to field electric amment sysm in the 201ot titnebam+ md will involve ichoice between elauomagnedc and clec~~olhsrmaltechnology in the Fqure 13. herk geomstks. Mgnetic Welds and fwces in the in".The Suategic Defense Initiative Organization (SDIO) &gun (bh) and thm migun (righ!). program is motivated by swgic and theater missile defense sysums. EM gms fall into two hasic classcs. railguns and soilguns. Thae differ in the gmmqof xhieving dmed Two 90 nun I.boratory rdgwwith i9 megajoule magnetic fields. md of coupling the rcn111.m forces to shieve (MJ) mdeenergy capability are opnational. The one at the projectile eleration (Ref 41). as scchcmatically shown in Univmity of Texas Cmter for Elecuomahanics (UT/CEM) Figure 13. As a rule. railguns m correprually md is powered by six homopolar gmuauns. md is used to gunncnically hlnpler. md have Icwu impedance (i. e.. develop the technology for solid projectile matmes. The require higha ament md low5 voltage for i Specific other, at the Maxwell Lbs-operaled GIM Fmrite. has a propulsion task). They have received far more dcvelopmmtal capacitor-based power hupply. and hswith arc UIMIUICS. inention, despite the povntial for greater energy efficiency Expxinents an underway Lt both sitcs to establish i data from coilguns. Coilguns bc"e more uusctive u larger base in the 2 to 4 kmkc velocity regime. They address mass dedue to more efficient coupling and the difiiiculties vs velocity uadeoffs for amor defeat. md support W nun rrsocid with pr- switching may impose velocity limits projectile dcvclopment tests. lower than those for rdlgunr. Design and fabrication of 9MJ "SLEW Rospsts for EM guns arc intrinsically Wed to the (sabot-launched electric gun kinetic energy) projectiles is tshmlogy for generating their power requirements. A being pezfonned mnuactually u the Kman Corp md the megajoule-wale mule energy requires gigawatt-male pulses LTV Corp. The cffons involve variations in sabot and for the millisson& of the wleration event. Power supply matme wfiguration. as well as in pmeuation mechanism lppoxha ixlude mainly rotating machines which provide (solid VI segmented md configurations). Major pezfomwce pulses from indally stodenugy. md capacitor-bad pulse issues an launchability, Mbor discard. tipoff. velocity forming networks. rcpoducibility. md flight and terminal effecrs. Railgun taring of inibl &signs is undaway at interim energy levels. A subsrantid litu~cis ivailablc to describe the evolution of thc requisite ComPJnmt technologies ova the Hardware is wming on line which uLa the put decade. Roxedinngs of the five meetings of the biannual tcchnology out of the Iaborntory. in two separate developments . "Elsrmmagnctic Lunch Symposium" .re mnvmimlly that &as fisr-order integration issws: (1) A rceraible (Ref 42-46). The rapidly growing body of sclf-an~multiple shot "skid" railes .ptem weighmg Eu~upemactivity was rcpesmvd u irecent Symposium in 25 mcmc tons will be tested next year. Its 90 nun dgmis London (Ref 47). powered by a "mmpulsator" (compcnrated pllsed alwm~~r). md is being fabricated ~t the Univuaity of Texas Centu for Because they require m popellant medium EM guns Elauomahanics. The compllsu~rwill &&VR30 MJ to the - M m pIhCiplc &liver velocitia WCU hve thm of any rdlgun breech ifactor-of-tm &axe over my prior machine other p.Velocities up to 6 km/= have bem achieved of its E&. (2) FMC is completing a stand-alone repuuble with railguns in nummu6 hhatariu (Ref 42-47). Enugy httery/sapacitor-bared power supply. m mnsponablc efiiciency is not suongly dcpedm on mdevelocity until tniler-like housing, which will also be rudy for testing in neu 6 Ws. where in prxtice new mshnnisnu lppmlly 1992. ?his "Puke Power Module" (F'PM) is designed to Limit both CfFIcinry md .chicv.blc vclocity. deliver 8 MJ plxs to an elauothcrmalchemical WC)lod 6-14

but lpplies to EM grm ckvelopncnt rlm. a i hirtep at In rum ekmnuplic p :poplkion prnnius reducing total puke forming netwok (PFN)energy dmriry. rignificarit perfcmnance dvmces ind hefirs mer conventional u"e~tsysm. Mwwer. riflicmt 'p- The tactical program is rimmed for i follow-an md weight roduction iue projeclcd if lrrl when the rrccssary dvanccd tecimology &monruuion (Am) to begin in ~IC pwu supply rbwlsizing has bcal rhieved TIE 1995. hUance crirnil hvc bcen dewfor the Am. md monumental challcn]:~ of developing. inrcpuhg md a component mamuion program b in placc IO meet them. weapmizing thc wmponent lshnologiea dcrminly irivolve This includcs thc technologies required for (1) power rysmn Icrious ncw diffia~ltics.come of than mt obvwur mvi. . downsizing to 10 Ukg delivered cncrgy dcnsiry for the TUTAL FuLu power ryslcnx (2) 0pd"on of 45 WBORE RAM ACCELERATION FOR GUNS hypnvelocity utihty. prdcularly for thc mu-mor applicarion; md (3) ckvclopnmt of bamVmaam mtcrf.ces Higher perfom chcmiul PmpCllMt skurges (and wlution of related impcdimcnu) that enable robusl. rcquire more total energy in the gun chhAND ip~pn high-perfomuna wcapon tystrms. The Amy receives prog"ing of the maw rcleasc to mrinrain downbore pl-g and exocluion uskmce m this compmt prrssurcs without increasing the maximum khpmslm. mimation propfrom iu Federally Fded Rescarch and To achieve muzzle vclccitics in excess of 25Ws. very high Devclopncnt Ccnm WFF0.Z). the Institute for Advmced pp~ll~tcharge to projectile mnss ruios (CN)arc requirrd Technology u the Univusity of Texas. Cross-linksbetween posing numnous buntns on thc rysmn. mt thc lust of thc Amy lactical pogm ud the SDIO strategic me have which is a vcry huge bhprum m or& IO been idatifid, md will be uploirrd. communicate dequatc downbore prrs!"~s to Rafh such velocities. Eleceic propulsion wnceprs, pPnisularly Improved nwivability md impnwt logistics clecuomagneric. offer real hope for providing a nearly r" benefirs uc expxted to follow from the replafemcnt of .ccclnation profdc, dlus removing the ~zquirrmcrufor very vulnerable chemical gun propell~t~wiih diesel fuel m iu high breech pasurcr, bur. as we have SCQL mllycay quivalenr This will apply on the battlefield and throughout with than signikicrm other burdas. thc manufacolring md logistics chain The trdtoff is the 0 need for rotusmas md survivability in d thc compncnu of An dtanative .pproach to inoulsing thc mass of the m manat system far more kchnically complex thw. popcllant charge in the chmnbm is application of ramjet conventional propellant guns. technology to inbore propulsion.'Thc micannon accr,Ieruo~. depicted ,schchcmadcally in Figure 14. miWr of a projectile. The elecnical power system while having lower resembling the an&y of a ramju. uaveling through a mugy &miry (and thueforc morc "managcable"vulnerability gun tube which .as LS the outer cowling. The tube is filled issues than mrgctic mstcrials). is of special mcnn. As tk with a gawous hrVoxidim mum. md the combustion mcrgy dmsity of capacitors. barmies. inductive devices or process eavels with rhe projectile. gcntzuing thrust which rOtaMg machinery mCle%SCS, thCU vuinaability and damage vcelsntcs the pro*tile down the mbe to vcry high potential is likely to imeaw as well. More spdicCommmu velocitia. Thus one has the mjm dviuuagc of a traveling in this uca must await the compncnt mmuarion which will charge without the burdm of accelerating the popllan~with develop spzific power mmponmuy. thc projectile. Projectile vclocitics rraching the Chapnw-Jouguet detonation rpmd of ttic mixm haw: been Thm 5e prmpccu for dsncased &-5mor thmreticaUy .ssociatej with a rubsonic. thermally clwked VOhlC. Mdb bCreUCd Stowed pO@k load hSWllhg combustion mode; Ilnivasity of Wiuhington 1csu have thcir polrntial benefit ULn be dcvcloped ud op4imiwi yielded velocitics in utcess of 26 Wswith 70 g projcrtiles hypnvelociry projectiles .IC smaller md lightex than in a 38." bore mbe using this mode (Ref 48-49). conventional ones. ud thcy will not have big popell~t-fJIed cupidgcs rtrafhed to them. These bcncfiu multiply m a qsmn senx bcuusc they rlm mean rodwed ammunition I 0 hpndling and loading nquiremcnu. An imponant ~tchnical uncmainty rt lhis pint is the bnnleficld c~ectivmessof lighm. rmallu po)ectila with &tic mugy qual to R heavier. lugu pojectilcs.

Reddrocoil will k uscciated with EM guns for two "s: for L given pojectile kinetic energy. rrmller hyp-velocity projectiles have lower momentum uansfu. In ddition no propellant gacer Eontribute to rmil in m EM gun. The mlicipllcd frm-of-wo mil rodumon will rcmicc the mil cyamn ad, hm% thc toul bystem wcighr

Additiond pohpect~ for mcrelsrd iystan efftnivmess involve rymrgism with the &muages of d+lecuic drive UnL sysmnr. md with EM m protection technologies. A reducwn in convcntiond blast md tmoke Fgure 14. Ram canmn rloceletatrx mncap( sign- M rlm be expeclcd Several investigators predict velocitics as high as 9 Wsfrom various deumativc canta~~tionm& thcorcticdy 6-15

rrsociated with the run rcckrua ~onccpl(Ref 50). Sysm rwivlbility ma be rignifiiuuly imuscd if Expsimentation in this mu. only now bepirming. is of less-sensitive munitions. packaging. storage bcuion. potential interest to wmmunities .ddressing poblems wmpmbnentation. mkmal potedjoh and exdmor associated with hypervelocity penemtion studies, the National protection me combined in synergistic fashion Much pogress Aerospace Plmc @ASP). and potential strategic &fense is being mdc in "anding UI least qualitatively the &sign missions. guidelines for impved s)mgism. It is in the amtcxt of m inlegrued Worh to systcm vuhmbility reduction. that . Effons to develop lugeclliber rmn rcelerators ue heat-specifc '"sensitive" systems are possible, wen with cwmlly ongoing u the FrmwGmnan Research Insimte in "kss-sensitive" munitions Mid on bod. St. Louis. France. md u the Ballistic Research Laboratory. Atcrdem Roving Gmund in thc US (Ref 51-52). In 6. ACKNOWLEDGEMEhTS. ddition. NASA is sponsoring m experimmd program to exploit detonation modes of run/mam propulsion at velocities The uthm would like IO bnk Lh. Ron Dm for . hve4 Ws in a medium uliter launcher. suggesting this AGARD paw be prcsentcd smuizing current advanced gun propulsion work in the USA. Wc are Numerous technical poblans. both of a fundamend grateful to MI. P. Serac from PicbyArsenal who was very , and practical nature. main to be solved before ram helpful in providing background on Army policy md acceleration ksmnes a serious wmder in the field of directions. We hnk Dr. R. Frey for pesendng a -tical gun poplsion. Undersmding. wml. and technologist's pnsptive on insmsitive munitions issues. optimi7aton of the fluid dynamicsheaction kinetics in this environment present a formidable challenge. Incorporation of 7. REFERENCES: this emerging technology into a practical weapon with acceptable safcty. reliability, ud slwivabiliry charactcriatics 1. Joint Service Requirement for Insensitive Munitions. June as well as performance kvels offers even greater 1987. uncertainties. Asscssment of the IM CharSElaistics for such accelerators has yet IO receive serious mention. 2. MILSTD-2105A " Hazard Assessment Tests for Non- Nuclesr Munitions", dtd 8 Mar 1991.

5. CONCLUSIONS 3. Baldini. L., "High Velocity Propellant Gun". 36th Meeting, Aeroballistic Range Assxiation, Ocr 1985. Advanced gun popllsion efforts in the US clcarly focus on both impoved ballistic pxformance and increased 4. Colburn. J. et al.. "Hypervelocity Firings From a 7-in survivabiliry. T~lyinsensitive munitions remain an ideal to HARP Gun". Ballistic Research Lnboratoly Repon (in be sought but never fully amined. Realistically OUI objective publication) are less-sensitive munitions when compared With mnventional propellant munitions. Both catain liquid propellants and 5. Boggs. T.L.. and Dm. R.L.. "HdStudies for Solid HELOVA propellants offer chemical approaches to less- Ropellwt Rocket Moto~."NATO Advisory Croup for smsitive munitions. For elecuomagnetic guns. the intrinsic Aerospace Research md LkvelopmmL AGARDogrqh beard of energetic propellants is replaced by inaeased No316. SEplemk 1990. unourus of less smsitive diesel fuel curried on-board md he presently unknom hazardvulnerability charactnistics of high 6. OPNAV INSRUCnON 8010.13B. "Depanmm of the enagyfigh power storage devices. This approxh promises at Navy's Policy on Insensitive Munitions(IM)", 27 lun 1989 least in pinciple major Qneases in system vulnerability. EIecuothmal/&mical gun propulsion is exploring 7. NAVSU INSTRUCITON 8010.5B. " Insensitive dmative chanisbies and unique physical .pproaches to Munitions Rogram Planning and Execution". 5 DeC 1989 0 rhieve signifcant +ctions in munitions sensitivity. Power train hazard issues, while qualitatively similar to those of 8. MILSTD382E NOTICE 1. " System Safety Rogram electromagndc guns. ue expected to be quantitatively lrss Requirements ". 1 JuI 1987 signifkant due to the rtduced elecoic powu and energy rcquirements. The in-bore -jet cnnmn is clcarly in a vcry 9. NAVSEA INSTRUCTION 80205B. " Qualification md urly experimental stage md liule can be raid definitively Final (TYPE) Qualificuion Rocodures for Navy Explosives hutits systems potential nor its asmciued hazard issues. (High-Explosives. Propellants. and Py~schnics)*, 16 May 1988 clmcru US "sitive munitions test methodology is likely to ksmne more sophisticated with inademphasis 10. Nonon, J.. "Qualification of 5-Inch. 54Edik and 76- on evduaticm of system "sensitivity" lgainrt cxpcctcd beats Millimeex Navy LOVA Ropellant". Indim Hcad Technical rather than simply isolued munitions sensitivity. This requires Rcpon IHTR 1428, 28 Dec 1990 rulirtic &scriplions of Ihc likely beats that munitiondsystcma ue expea& to survive. These uc ohm 11. Rocchio. IJ.. Reeves. HI. md May, LW. 'The Low difficult to &he md cnm.aus is lometimes difficult to Vulnerability Ammunition Concep-lnitid Fusibility". BRL rhicve. Yet this informarion is mkal to my malysis MR-2520. Ballistic Research Lnboratory. Abadem Roving poee~ud often will detmnine the rpsific @st methodology Ground, MD. August 1975. IO be ClnplOyCd for Ihc WdUUhl Of ~VaSyStQnS vulnerlbilily. 12. Kuo. K.K.. Hsieh W.H.. md Hsieh K.C. "Modeling of Hot Fragmrm Conductive Ignition of Solid RopeUanls with 6-16

Appliution to Melting and Ev.p~ritimof Solids". BRLCR- 26. Klein. N, "Lquid Ropcllants for Uu in Gw". & 607. Ballistic Reserrch &amy. MD. Much 1989. Ropubicm techno lo^!, Vol. 109 of Rolpe~in Aammlutics and Aeronautics. AL&\ Washington. D.C.. 1988. 13. Ramsey. J.. Los AlmsNuional Laboruory. private mmmunicatioq 1990. 27. Cruice. W.J.. "Classification of Liquid Gun Propellants and Raw Mawrials for Trursporuilon md Surrage", 14. Watson. J.L.. 'The RM~Cof Gun Propcllanls to ARBRL-CR- 0054. Bnllistic Rexxch Lhatory. Abcrdern Exmal Sdmuli". Rdgsof the 1% Inlemational Proving Ground. MD. May. 1981. Symposium on Bdstics. Vol. I. pp.62-71. Novanbcr 1990. 28. Her".% W.. Grelecki C.. Rtino. (3. md Scals. 'W.O.. 15. Wise. S.. 'The Dcvelopmeru of the Merhodology of "Hazard Classificiition of Liquid Propcllmrs", Studying the Rcspmre of Propellant to Shaped Charge Jet ARAED-TR-88018. Scpranbn 1988. Direct Impact". Rccmdings of the 3th Physics of Explosives Colloquium. Avipon. Frmce. July 1982 pp., 7.544. 29. Havms. JA.. "A Renew of IHarard Aasesment Rccubnes for Liquid Gun Ropellaits". BRL-CR-537. 16. hay. B.W.. Campbell A.W.. Ginsberg. MJ.. and Ballistic Research Laboratory. Aberdeen Prming Ground. Ramsay. JB.. "Detonation Chara~lnisticsofCun Ropellmts". MDJovcmber 1984. . ~cccdineaNmIh IIntcmational)... Sv"ium on Detonation OCNR-11j297-1. August 28 - Sepmba 1. 1991. Vol 1. pp: 30. Scnls. W.O.. "Vulnerability Studies for a Liquid 537-544. Ropellml System". BRLTR-2646. Ballistic Rcsunch Laboratory. Abcr&en :Roving Ground, MD. April 1985. 17. Lu. P.. Fishbum B.. Hui. P.. Grabosky. A,. Phcm J.. and Lieh. R.. "Shaped Charge Jet Impact Gun Propellant 31. Wojciechowsh. J.Q. u al "Insensitive Munitions Tes~ing Phenomenon Low Temperature Effect". private on Liquid Propellmt Pa MILSTD-2105A. Proceedings of communication, 1990 the 51h Inmational Propellard md Roplsion Symposium Novanber 1991. a 18. Lyman O.R.. Harrison. 1.T.. md Mclaughlk J.T.. "Response of M865 to KE Peneuator Auack for Three 32. Coffee. T.P.. "An Updated Lumpcd Parameter Code for Propellant Fills". BRL TR-3270. Seprembex 1991. Regenerative Liquid Propellwt In-line Guns". BRLTR-2974. Ballistic Research Laboratory. Aber&en Proving Ground, MD. 19. Levy, M.W.. 'The Use of Dements in Small Arms Decanber 1988. Propellants - A Comprehensive Review". FA-TR-TI-37. Frankford Arsenal Philadelphia. PA.. March 1977. 33. Morrison. WI.. and Coffez. T.P.. "A Modified Ldgrangc Ressure Gradient for the Regmative Lliquid Propellant 20. Robbins. F.W. and A.W. Horst. " High- Gun". BRLTR-3073. Ballistic Research Laboratory. Aberdeen Progressivity/Density (HPD) Propelling Charge Concepts: Roving Ground. MD. Jmuary 1990. Progress of Rogammed-Splitting Stick Propellant". BRLMR- 3547. Ballistic Research Laboratory. Aberdeen Roving 34. Coffee, T.P.. Wren. G.P. md Morrison. W.F, "A Ground MD. Sepicmber 1986 Comparison Buwm Experiment and Simulation for Concept VIC Regenerative Liquid Ropellmt Guns: 1: 30 :m*. 21. May. I.W. ad A.A. Juhas~" Combustion Rocesses in BRLTR-3072. Ballistic Research Laboratory. Aberdeen Consolidated Ropellants". BRLMR-03108,Ballistic Research Proving Ground. MD. IDeCanber 1989. Laboratory. Abcrdeen Roving Ground. MD. May 1981. 35. Coffee, T.P.. Wreh G.P. and Monism W.F.. "A 22. Robbm. F.W. md D.L. Krucdnski "Calculated Gun Comparison Buwcen Experiment and Simulation for Concept Inmior Ballistic Effects of In-Drpth Buming of VHBR YIC Regenerative Liquid Ropellmt Guns: E, 105 m"'. a Propellant". BRLTR-3059. Ballistic Research Laboratory. BRLTR-3093. Ballislic Research Laboratory. Atmdes~ Aberdeen Proving Ground. MD. November 1989. Proving Ground. MD. April 1990.

23. TompLins. R.E. KJ. White. W.F. kle. md A.A. 36. Wren. G.P. Coffce. T.P.. md Morrison. W.F.. "A Juhahs Traveling Charge Gun Firings Using Very High Campariaon Buwcen Experiment md Simulation for Cancept Burning Rate Propellants". BRLTR-2970. Ballistic Research VIC Regenerative Liquid Ropellmt Guns: IU; 155 mm". L.boruory. AMRoving Groud.MD. DMnber 1988. BRLTR-3151. Ballistic Rrsesrch Laboratory. Abevdeen Roving Ground. ME, .:qxember 1990. 24. Krucdnski D.L. md J.R. Hewig Tempnature Compensation Techniques md Technologies: An Overview". 37. oberle. W.F.. "l.lstroIhcmuI Gulls - A 'Iheoretical BRLTR-3283. Ballistic Research L.boratory. Aberdeen Investigation of Factors for Optimal Pcrlw"". BRL-TR- Rming Groung. MD. Cktober 1991. 2999. lune 1989.

25. Monivm W.F, Knapton. 1.D.. md Bul". MJ.. 38. Obcrle. W.F. md White. KJ.. "I3shothmnal Gun "Liquid Ropellant Guns". Gun Propulsion Technology, Vol. Technology and Perfor": An Analysis of Smdl and Ixge 109 of Progress in Astronautics tad Aeronautlcs. AIAA. Calibex Ballistic Data". BRLTR-3238. Ballistic Rcscarch Washing- D.C, 1988. L.boruory. Aberdem Ifovmg Ground, MD. 1591 6-11

39. Marelli. W. and Otak. W.F., 2lecUothcnlChcmiul 47. "' gs of the 3rd European Sympsimn on EML Gun Roprlsion m the WNIUJ Sutca". P"' gs of the Fifth Ttchnology". April 16-18. 1991 (unpublished). Intrmuional Gun Ropclluu snd Ropllsion Symposium Novanbn 1991. 48. Bru~ha.A. P., C. Knowlen, K. A. Scott. and A. Hemberg. "High Velocity Modes of the Thermally Choked 40. hocdmnn. E. d obnie. W.F.. "A Suncy of the Ram Amlaator." Roceedings of the 4(xh Aaoballlstic Volumetric Energy of Candidate Ropell~ts for Range krsocation Meaing. PariS. France. Seplember 1989. Elsuothcrmd-Chrmiul Combdons". Rocccdrngs of the Ffi lnlcnutimal Gun Ropellaru ud Propulsion Symposium 49. Bmcha. A. P.. E. A. Bumham. C. Knowlea A. Novcmber 1991. Hemkg, ud D. W. Bogdmoff. "hitiation of Combustion in the Thmally Choked Ram Aocelnamr." 18th 41. ha, T. md P.Kanmey. "Fast Elecuomqnetic Intemationd Symposium on SkkWaves, Sndai Japw. July L.mhas", IEEE Tr~s.aionSon Magndcs. Vol MAG-19. 1991. 1569-71 (1983). 50. Hemberg. A,. A. P. BNC~". and D. W. Bogdanoff. 42. IEEE T~n~ctionson Mlgncticq Vol MAG-18, No 1 "Ram Accelerator: A New Chemical Method for Accelerating (1982). Rojectiles lo Uluahjgh Velocitia. AlAA Joumal. vol. 26. pp. c 195-203. 1988. 43. IEEE T~n~cctionson Magnetics. Vol MAG-20, No 2 (1984). 51. Nusca, M.I.. "Nummcal Simulidion of Reacting Flow in Thermally Choke3 Ram Accelerator Projectile hunch 44. IEEE Transactions on Magnetics. Vol MAG-22. No 6 System." ALL4 Papa 91-2490. presented U the (1986). AlAAlASMEISAE 27th hint Ropulsion Conference ud Exhibit. Smammto. Califomin, lune 1991. 45. IEEE Tr~~fdonson Magnetics, VolZ.5, No 1 (1989). 52. KNcz)mski. D. L. "Analysis of Ram Accelaation for 46. IEEE Tmnsactiom on Magv%ics. Vol27, No 1 (1991). High Velocity ApplicitionS." AIAA PapcrB1-2488. peamLed u thc WASMWSAE 27th Joint Propulsion Conference md Exhibit. Smmncnto. Califomin, June 1991.

Discussion

QUFSTION BY DFFOURNFAUX. NIMIC; You said that electric guns would not solve the problem of warhead vulnerability. What about using an electric gun to accelerate (up to Mach 2, say) a solid fuel ramjet- sustained projectile fitted with a fuel-air warhead? This system would require no gunpowder, no rocket propellant (the ramjet uses atmospheric oxygen) and no high explosive (same reason). This is partly a joke, but it might constitute a line of thought.

ANSWFR; But then NlMlC would be out of business! More seriously, this is an insensitive, truly "insensitive" approach looking for an application in the far future. Technically, solid fuel ramjet projectiles suffer from difficult launch and flight problems which have not yet been overcome. Fuel air explosives are limited primarily to soft target kills. And the risks in Electric Guns development are still formidable. Great line of thought!

7- 1

MBB-DEVELOPMENT OF INSENSITIVE PEX-CHARGES Dr. Manfred Held Messerschmi tt-88lkow-Elohm GmbH 8898 Schrobenhausen. F.R.G.

Introduction: Notwithstanding this, reaction shall not resp. must not occur, even not partial detonations. A detonation always , The designation "Sensitivity" Comnly used for brings about destruction of the direct surroundings and general test results obtained on high explosives endangers persons within the closer area. respectively high explosive charges comprises a variety of different test procedures applied on "Initiability" means the minimum pressure and also the mi- high explosives resp. H.E. charges. nimum projectile velocity at which detonation occurs in full extent. For test purposes, the limit between reaction and With this variety in potential test procedures, detonation is determined, whereby this detonative induction however, different high explosive and H.E. charge can also be desirable. With stimuli by fzr inferior all the a characteristics are determined as they are also saw. mre or less violent transformations occur. applied for varying conditions and statements. In general. the individual test procedures and test Types of Stress: methods must be familiar to permit recognition and judgement of statement value, statement meaning The various stress types are subdivided into five catego- and a correct assignment of the factor achieved, ries: as in mst cases the designation chosen is the same. that is "sensitivity". - mechanical - electrical Sensi tivi tv Cateqor ies - shock'wave - projectiles The various test procedures are subdivided and - thermal. contenplated in accordance with their statement capacity regarding : There is a variety in different stress types and test in- stallations for the above mentioned categories which are - Handling Sensitivity (UK: sensitiveness) only in part standardized internationally. Within the in- - Survivability dividual stress types, these stirmli often also render - Initiability (UK: sensitivity). varying statemnt values regarding a.m. sensitivity categories. a The aspect "handling sensitivity" is the mst critical one, as when handling high explosives It would certainly be beyond the scope of this paper to list resp. H.E. charges and processing them. reaction and describe all standardized tests and the large number of should be avoided to the utmst extent during raw tests which have been conducted by several individual in- material handling, preparation and processing of stitutions. the sam and when carrying out a normal transport. . But practically any test, which, in a historical point of Regarding the munition "survivability" during its view certainly bases on events, has its meaning even if it utilization it is essential to preclude reaction is presently not very informative as regards to all material even under extremely strong loads and extreme systems and configurations of use. environmental conditions. The corresponding trials simulating launch acceleration resp. extreme stresses, such as high altitude drop tests, form Test Matrix part of this criterion. For several tests H.E. reaction may even be admissible, but if possible, Figures 2) and 3) show the problem representing the basis in a very mderate way as for exanple during the for at least the major part of the various test methods and fuel-fire-test. In practice, such stresses repre- procedures. sent in mst cases "rare exceptions". On one hand, varying quantities are planned and used for the tests. Reaction probability, however, is in many cases also a function of the test quantity provided. 7-2

Condition of test specimen and surrounding also With the survivability tests we obtain the vulnerability of has an essential effect on the resulting reaction the HE charges or of the amnitions. The tests are ge- intensity. It is necessary to distinguish on one nerally conducted on the charges or aimunitions and the hand between raw material in a powder state and threshold is no reaction or low order reaction, compared granulated material and on the other hand between with high order reactions. HE charge types - in mst cases available in a solid state - manufactured by casting, pressing, The initiation tests show us initiability - i.e. how easily . extrusion etc. and most of all to determine if the high explosive can be initiated. The threshold will be they undergo tests without a casing, that is defined between "reaction" and "full detonation". The saw without confinement or if they are comprised in a ples are in this case comnly high explosive charges. casing, which means confined. The samples are either powdered or solid and their stimrli Charge size and confinement exert considerable thresholds depend on a lot of parameters (fig. 5). such as . influence so that a nuber of tests should be type of HE or conposition. phlegmatization of granulates. carried out only on the actual warheads. As. how- bulk density or porosity, grain size or grain size distri- ever, good comparison capacities with various bution, also on the quantity and certainly, very much on the , material systems are required, the test vehicles confinement. used are chosen by random. All the tests for the different stimrli can be categorized Another aspect is that applying a load, nomlly in (fig. 6): no reaction is desirable which is mst of all - mechanical tests important for the handling of lhigh explosives. - electrical (electrostatic) tests - shock tests In case excessively strong loads are applied. for - projectile impact tests exaople placing the nunition in a fuel flre under - tenperature tests. which reaction resp. burning-oFf of an energetic substance is unavoidable, a moderate. smooth bur- The different tests for each category - except for electri- ning, but no violent reaction, most of all no cal tests - are sumrized in tables. The individual tests detonation with blast and frawntation effect to for each category are listed, the samples generally used as the surrounding is admissible. This means that for powder (P) or HE-charge (C) are indicated, further, if the the survivability tests the reaction shall be very test is useful for handling sensitivity (Ha) or for survi- moderate and mild, if it is unavoidable. vability (Su) or initiability (In) and, finally, the test will render the limit between no reaction I reaction (R) and This is rmst of all important when the H.E. charge reaction I detonation (0). mass is high as this renders a big radius for the destructive effect. This is not as critical for The first example is given in fig. 7 for the mechanical smaller H.E. charge masses as their total ener- tests. The individual tests which are not very famous such getic resp. performance capacity is also minor. as Skid, Susan, Spigot and Gun Set Back test are sketched in fig. 8. The first part (fig. 4 to fig. 21) comprises the test and inspection procedures admissible for H.E. The same procedure is repeated for the shock tests (fig. 9). charges which are explained and assigned to the Description is given more in detail for the instrumented gap. individual stinuli types. test, with which it is also possible to obtain the build-up distance as a function of pressure, the so-called pop-plot The second part (fig. 22 to fig. 38) gives expla- diagrams (fig. 11). and also for the mdified gap test with nations on specific new definitions for tests to typical results (fig. 1.2) and the mlti gap test (fig. 13). accept less sensitive high explosive charges or. The d'fferent3 projectile impact tests are listed in fig. 14. more precisely, less sensitive warheads. The p t law is detmnstrated for a well detonable high explosive charge - PBX 9404 - with electric gun or flying . First Part - General Tests plate, results see (fig. 10). ' The tests for the handling safety render the sen- Results of flat faced projectiles against PETN are given in sitiveness of the samples. As a. result, we nor- fig. 15, with shaped charge jets against conposition B char- mally get the threshold between no reaction J ges in fig. 16. reaction. Specimens in a powder state are generally used for these tests (fig. 4). 7-3

The various temperature tests are listed in The slow cook-off test is, in the opinion of the author, an fig. 17. These tests can be physically subdivided extremely rare phenomenon. On the other hand, this test is in: - Constant temperature tests expensive when being conducted on real warheads. Maybe it - Increasing temperature tests should be used on standard configurations as a screening - Constant heat capacity. test for HE materials, but not really be seriously taken into account as a safety or survivability test (fig. 29). * The sanple nwst be carefully arranged in a confinement to provide always the same heat conduc- The drawing is a little bit improved for the bullet impact tivity and well reproducible results, as shown in test (fig. 30). - fig. 18, with the One Dimensional Time to Explo- The fragment inpact test requires fragment velocities of sion test (ODTX). The fuel fire test is also a 8300ftlsec. with fragment masses of 169 (fig. 31). These typical test with increasing temperature as a very high fragment velocities are not very realistic. Only function of time. The sample should be a real one warhead should exist with these static fragment velo- warhead (fig. 19). Surprising is that a real cities. But here we should take a rmre realistic parameter brightly gluing sphere of 20mn diameter is not pair in fragment mass. resp. velocity. Survivability tests , able to bring a cast TNTIRDX charge to a violent should cover all accidents which happen exclusively with 99% reaction (fig. 20). or wax. 99.9%. but never with 99.999999%.

A sumry is given in fig. 21 on how to better The procedure applied for the swathetic detonation test is distinguish between tests and their purpose: clear (fig. 32 and fig. 33). - Sensitivity tests with intended non reaction - Survivability tests with non high order Shaped charge tests are described too nwch in detail with reaction and regard to shaped charge geometry and speciflc shaped charge - lnitiability tests to determine the limit liners. The important parameters for the reaction threshold between reaction and detonation. of SC charges are jet tip velocity and jet diameter. Gene- rally it is not possible to receive identical raw materials Second Part - MIL-STO-2105A Tests and production procedures throughout the individual NATO countries and thus liners which are required as indicated in The specifications for tests on insensitive high the above document (fig. 34. fig. 35, fig. 36 and fig. 37). explosives (less sensitive high explosives) acc. Furtherrmre it is very difficult to create a high explosive to MIL-STD-2105A carried out on 19-1-1990 are il- so little sensitive that it will not react violently by the lustrated in this chapter (fig. 22). impact of the 81mn shaped charge jet with tip velocities in the range of 9mnIus or reduced to 6 - 8 mnlus by cover pla- The verbal descriptions of the individual explo- tes. sive reaction levels (fig. 23) are visualized in fig. 24 with regard to pressure output and frag- Sumrizing the tests for less sensitive high explosives mentation of the casing. (insensitive high explosives) acc. to MIL-STD-2105A: - Fast cook-off test (fuel fire test), bullet impact test, A different response category was used in UK for sympathetic detonation test and spall impact tests are RATTAM tests (fig. 25 and fig. 26). But after the realistic tests for amnitions. presentation of my paper I have learnt by a letter that now UK is using very similar ranking - Fragment impact tests with 169 and 8300 ftls are over- response criteria to MIL-STD-2105A. driven. - Slow cook-off tests take place only very rarely. The item numbers and test sequence for - The shaped charge tests as described above cannot really MIL-STO-2105A are again shown in fig. 27. be reproduced because of the too specific descriptions The partially verbal description on the fast given for the individual parts. cook-off test or fuel fire test is given in But generally, the test with the 81mn shaped charge is an fig.28. unrealistic goal for warheads. 7-4

General Tests

Handling Sensitiveness Survivability initiability (UK: Sensiitivity)

Specific New insensitivity Tests . Summary

Figure 1 a

Test - Matrix

W a 21 I- C .-0 + a U m W CY

Figure 2 7-5

Tests for HE-Charges

0 no Reaction

0 Standard Warheads 0 Real Warheads

Figure 3

/ r

Type of Stimuli

. Sensitivity Vulnerability lnitiabllity U No Reaction/ No or Low Reaktionl Reaction/ Reaction High Reaction Detonation

*Powdered Charge Charge Figure 4 I 7-6

Phlegmatisation Bulk Density Grain Size Grain Forms Quantity Confinement

Figure 5

Tests II

-- I

r-0 [-=Projectile Impact

Figure 6 mMechanical Tests - Reac Test ~ Result Made

Impact " Ha

Friction Ha

Vert. Acticator S"

WBSET S"

Skid *' S"

Spigot S"

Gun Setback S"

1 Drop Hammer

120blique Impact

Figure 7

Mechanical Survlvabllity Tests

Skid - Test Susan - Test

Lealher Cup Seal Aluminlum Cap,

-Seigot - Test Gun Set back Test (Schaefer E91)

ianlflo" OBViEB\ d

1.5

Targel TilShack Tests

Reaction Test Probe Result Made Type

Cap C 5" R Go1 No-GO

Prim. Charge C I" D mg PETNISyig. Gap C in 0 P min . Instrum. Gap C (5u)lin (R)ID 1. d=f(p) Aquarium *1 C S" R Jpct) dl , Mod. Gap C Suiln RID p

Multi Gap C 5" R n .P min

Wedge C I" D (t). d=@)

'1 Low Amplitude Shock Initiation 0

Figure 9

One Dimensional Tests

Elylnq Plate

Optical hls t t

I 0

Figure 10 7-9

Instrumented Gap Test

Test Set - up_ Detonator Donor Acceptor

Streak Record

Explanation of Streak - Record Shock Wave

Break Through suosreetonauon

Results

Figure 11 7-10

Modified Gap Test

Test Set - up

Results

0123456189 up [musj

Figure 12 7-1 1

Multi Gap Test

3 5 9 12 15 Gap (mm) Figure 13

Projectile Impact Tests €7- Test 'robe - Result - -Made

Flying Foil C In 1, d=f (vi. ti)

Flying Plate C I" 1. d=f (vi, 11)

Bullet Impam C S" Go I NO Go 5.55.7.52.12.7

Flat Faced C I" "I, cr Projectile

instr. F. F. P C SU 1. d=f(vi)

Inslr. Shaped C S" t. d=l(ui. Dla) Charge Jet

Multi-Fragments C SU n . Yi or BulleIS -

Figure 14 Projectile Impact Tests

30 cai. p-T> -Projectiles

F. F. P. (gJ-m 1‘---7El

Norm - Casing - - -- I 51 -25 -+

- Neoprene Pad

-Standard Pipe Cap 2”

Results - nation eaction - a nation eaction - Delonatlon eaction - - nation no Reaction - 0 500 1000 1500 Norm Projectile Impact Velocity (mls)

Figure 15 7-13

Instrumented Shaped Charge Test Test Set - ups HE In Contact

Barrier Streak - Slit Framinqs & Streak

Test Results

HE I" COmM HE with Air Gap

1- 1- 5 6 7 6 910 12 15 20 &Pa,

Figure 16 7-14

DTemperature Tests ~~~~~

Test Probe Result

UTMGAIOSC Pl(C) Ha T

Self ignillon P T ! Ha ~nc.Burning '1 P ~ Ha t: NO Dee.

Cook-Off '2 t=f(T). Fragm. ! s' Fuel Fire 1. Fragm.

Fragm. Pincer c.m.T

*' or ignition or Small Scale Burning Test or Stahihlilsentesl

'2 or One Dimensional Time 10 Explosion Test (oorx) or Small Scale Burning Tube Test or Time to Explosion Test

Figure 17

ODTX

-1y. Glan~iNul

Test Svstem

Mlcr~phone I I i I yi Solenoid .c I TC - t Ai. Tube I TC - 2 AI. Tube j 4 /_j, I

L i Canliol Bunker

Figure I8 7-15

Fuel Fire Test .

1500 x 1000

Figure 19 7-16

Fragment Pincer Test

Heatinq up Thermocouples Sphere Dia 10-20 mm

..*

Result5

Test Set - up TNTIRDWWAX 49/50/1, Steel Spherfi 20 mm Dia. Mechanical Load 2000,"Sealed"

600°C Gb

Figure 20 7-17

/ Y Y SensitivityL! D f* Survlvablllty [ lnltlabllltyI! 0 A/ - // No High Order No Reaction Full Detonation Reacllon

Figure 21

MIL-STD-2105 A (NAVY) 19.Jan. 1990

NOTE nhis hh. dated 19 January IP90. \INCH-POUND] picpard by che Naval Sa Syaems Commmi MIL-STDZlO54 (NAW (OS). hax no1 ken approved anl is ruhje;.t 10 mOdificLiOn. DO NOT USE PRIOR TO SUPERSEDiNG APPROVAL. F'rajecl SAFTm24) DODSTl32105 (NAVY) 9 September 1982

MILITARY STANDARD

HAZARD ASSESSMENT TESTS FOR NON-NUCLEAR MUNITIONS

AMSC AREA SAFT

DISTRIBUTION STATEMENT A: Approved for public release: distribution is unlimited.

Figure 22 7-18 MIL-STD-2105A (NAVY)

Explosive reaction levels.

a. Detonation Reaction (‘Type I).The most violent type of explosive event. A supersonic decomposition reaction propagates through the energetic material to produce an intense shock in the surrounding medium, e.g., air or water, and very rapid plastic deformation of metallic cases. followed by extensive fragmentation. All energetic material will be consumed. The effects will include large ground craters for munitions on or close to the ground, holing/plastic flow damage/fragmentation of . adjacent metal plates and blast overpressure damage to nearby structures.

b. Partial Cetonation Reaction (Type 11). The second most violent type of explosive . ever . Some, but not all of the energetic material reacts as in a detonation. An intense shock is formed; some of the case is broken into small fragments; a ground crater can be produced, adjacent metal plates can be damaged as in a detonation, and there will be blast overpessure damage to nearby structures. A partial detonation can also produce large case fragments as in a violent pressure rupture (brittle fracture). The amount of damage, relative to a full detonation, depends on a the portion of material that detonates.

c. Explosion Reaction (Type 111). The third most violent type of explosive event. Ignition and rapid burning of the confined energetic material builds up high local pressures leading to violent pressure rupturing of the confining structure. Metal cases arc fragmented (brittle fracture) into large pieces that are often thrown long distances. Unreacted and/or burning energetic material is also 1 hrown about. Fire and smoke hazards will exist. Air shock are produced that can cause damage to nearby structures. The blast and high velocity fragments can cause minor ground craters and damage (break-up, tearing, gouging) to adjacent metal plates. Blast pressures are lower than for a detonation.

d. Deflagration Reaction (Type IV). The fourth most violent type of explosive event. Ignition and burning of the confined energetic materials leads to nonviolent pressure release as a result of a low strength case or venting through case closures (leading porVfuze wells, etc.). The case might rupture but does not fragment; closure covers might be expelled, and unburned or burning energetic material might be thrown about and spread the fire. Pressure venting can propel an unsecured test item, causing an additional hazard. No blast or significant fragmentation damage to the surroundings; only heat and smoke damage frorn the burning energetic material. - e. Burning Reaction (Type V). The least violent type of explosive event. The energetic material ignites and burns, non-propulsively. The case may open, rnelt or weaken sufficiently to rupture nonviolently, allowing mild release of combustion gases. Debris stays mainly within the area of the fire. This debris is not expected to cause fatal wounds to personnel or be a hazardous fragment beyond 50 feet. f. Propulsion (Type VI). A reaction whereby adequate force is produced to impart flight to the test item in its least restrained configuration as determined by the life cycle analysis.

Figure 23 7-19

Explosive Reaction Levels MIL-STD-2105A (NAVY)

+===/ . Type I1 Partial Detonatlon

Type V Burning

Figure 24

RAlTAM Tests UK

Concern by the Royal Navy about the safety of explosive munitions mounted or stored in ships, particularly guided weapon warheads, led in the UK to an assessment programme generally known by the acronym RATTAM (Response to ATTack on AMmunition). The aim of the programme was to obtain the necessary data to advise the RN on the risk to RN ships carrying particular weapons, ifthose weapons were subject to terrorist attack.

It was decided to use the following weapons for the tests; they are readily available in UK service and are typical of what a terrorist might obtain:

__Code Weapon A (0 7.62mm AP

A (ii) 0.50 in AP

B 20" HE

C 84mm HEAT

The weapons were fired a explosive munitions protected by a 6mm mild steel plate representing the ships side; in some tests the protective plate was not used. The 0.5 in AP has been used most in the tests.

Figure 25 7-20 Response Categories (RATTAM - UK)

Six categories of response were decided upon for the munitions under test:

(I) No response

(11) Burning -the explosive filling ignites and burns, The munition case may open up but the munition is not moved propulsively.

(111) Deflagration -The explosive store is ignited leading to rupture and often accompanied by the ejection of unreacted or burning explosive

(IV) Mild Explosion -The explosive store is ignited leading to violent rupture. Unreacted or burning explosive may be ejected. Major pieces of the store may be thrown a considerable distance

(V) Severe Explosion -The explosive store is blown apart with considerable violence. The damage from blast and fragmentation is extensive but less than that associated with detonation, Large fragments are ejected accompa.nied by unreacted or burning explosive. (VI) Detonation a Figure 26

item Number and lest Sequence

ITEM 121 4 6 07 B 0 10 I1 12-18 17 ia 10 20 Ill I I II I I I I IIIII II II 4 RA~IOGRAPHIC b

Figure 27 7-21

Fast Cook-off Test 5.1.5 MIL-STD-2105A (NAVY)

Thermocouples Logistic Package (< 0.1 sed /

Resliaineo Io ,Avo d L a-nching or Fai ng nlo Fb.n

-Time for 1000" F - At Least 1600" F . -Time to Reaction

jo n + Length 01 Test Item -4

Figure 28

Slow Cook-off Test 5.1.6 MIL-STD-2105A (NAVY)

6" F per Hour = 3,3"C I h

Start at 100" F 37,8"C Below Predicted

Reaction Temperature

Continnously Measurement of Temperature

Figure 29 I _"

Bullet Impact Test I 5.1.7 MIL-STD-2105A (NAVY)

High Speed Cameras d nrviden

. I Q' dl -3 Fraamerit Steel Witness Plate -

Notes: d3 = Distance to Test Item dl = Distance to First Velocity Screen dq = Distance to First Blast Gage vp 5o n/sec d2 = Distance to Socond Velocity Screen * d5 = Distance to Second Blast Gage($

Figure 30

Fragment Impact Test 5.1.8 MIL-STD-2105A (NAVY)

High Speed Cameras

Blast

Gage Witness Plate for di\ Fragment Velocity \\ \ \

VF~= 8300 * 300 Wsec Minimum of 2 Test Items. hit by 1 Steel Fragment (1/2)" & 250 grain C 16 g dl = Distance from Fragment Mat to a. Largest quantity of HE Witness Plate b. Most Sensitive Location d2 = Distance lrom Fragment Mat to / Test Item / / d3 = Distance lrom Test Item to Blast Gag+)

Figure 31 1-23

Sympathetic Detonation Test 5.1.9 MIL-STD-2105A (NAVY)

Figure 32

Sympathetic Detonation Test placement of Pressure Gages

Pressure Transducers 4 per string (min)

I d40 I d40 = Distance at which peak airblast overpressure is expected to be approximately 40 psig if all test items detonate

d10 = Distance at which peak airblast overpressure is expected d- lo be approximately 10 psig if all test items detonate d4 = Distance at which peak airblast overpressure is expected to be approximately 4 psig if all test items detonate I dl = Distance at which peak airblast overpressure is expected cI lo be approximately 1 psig if all test items detonate Figure 33 7-24

Shaped Charge Impact Test 5.1.10 MIL-STD-2105A (NAVY)

&Witness Plate ,eWitness Plate

81 mm Precision Steel Witness Plate Shaped Charge 81 mm Precision Shaped Charge 0 Figure 34

Shaped Charge Jet Impact Test 5.1.10.3.2 MIL-STD-2105A (NAVY)

The M 42/M46 grenade shall be conflgured as follows:

Explosive fill: 30 grams of Composition A-5 conforming to MIL-E-14970 Cone angle: Trumpet with 3 radius 0 Dimensions: Height of cone = 1.3inche.s Outside diameter = 1.315 Inches Inside diameter = 1.237 inches Wall thickness = 0.075 inches

Llner description: Copper strlp, cold-rolled, soft annealed, conforming to QQ-C-576 Electrolytic tough pitch Grain size < ASTM grain size I3 Non-earring quality with suppressed cube texture

Body: M 42/M46 body load assembly (without fuze)

Figure 35 7-25

Grenade M 42 IM 46

Explosive Charge Body

Cone

Figure 36

Shaped Charge Jet Impact Test 5.1.10 MIL-STD-2105A (NAVY)

The 81 mm precision shaped charge shall be configured as follows:

Explosive fill: 1,8 pounds of Composition B conforming to MIL-C-401 a Cone angle: 42"

Dimensions: Height of cone = 3.7inches

Outside diameter I: 3.2 inches Inside diameter = 2.91 inches Wall thickness = 0.075 inches

Liner description: Oxygen-free copper conforming to ASTM 6152 with a temper of OS025 Grain size c 50 microns after stress relief NO shear forming Depp drawn anneal

Body: Standard 90" M371E1 recoilles rifle round

Figure 37 1-26

Standard Shaped Charge -

Plastic Alignment Device to Center Booster and Detonator on Machined Copper Liner Charge Axis Explosive, 1,905 mm thick Tetryl Pellet Detonator \ I -

Copper Ltner . . .. -.. - .-......

90 mm M 371 Aluminum Retaining Ring (Machine smooth) Aluminium Casing Note: Liner Thickness not to vary more that .0051mm in any transverse piane and .05lmmm in a Aseltine (1990) longitudinal plane

Figure 38

Spall Impact Test 5.1 .ll MIL-STD-2105A (NAVY)

Shielding Plate Shielding Plats 1-in Thick / RHA Plate

Test Item i-in Thick RHA Plate 81 mm Precision n Shaped Charge --I

5.B'

Minimum of 2 - 4 Spall Fragments / 10 in in presented area (up to 40 Fragments total)

Figure 39 7-25

Discussion

QUESTION BY ?. GERMANY ; What do you think about the value of shape charge testing in the field of insensitive munitions?

ANSWFS; The threat comes from shape charge warheads attacking our tanks, therefore we want insensitive or low sensitivity munitions in our tanks that will have no reaction or mild reaction to shape charge attack. .

e 8- 1

METHODOLOGIE DE CONCEPTION DE CHARGES MlLlTAlRES A IMMUNITE RENFORCEE

G. COUTURIER J. FERRON Developpement Charges Militaires THOMSON BRANDT ARMEMENTS 45240 La Ferte Saint Aubin France

SOMMAIRE 1. INTRODUCTION La conception de charges a ir"nit6 L'immunitb des munitions aux renforcee demande une participation active environnements accidentels est un souci entre le concepteur de la charge et le permanent du concepteur de charges

lormulateur ~ afin d'optlmlser les militaires afin de garantir la securite definitions qui repondent aux specifications d'emploi et la fiabilite d'executions des opbratlonnelles. missions operationnelles. De nombreux exemples souvent tragiques ont demontrk la Cette methodologie a et6 etablie en necessite imperative de developper des exploitant les resultats des ln"nlteS munitions A risques attenues. acquises depuis 25 ans par T B A lors des Btudes et developpements de charges de Les $tudes financees en France par les missiles et de munitions aeroportees. organismes de tutelle tels que le S T P E le 5 T E T et la D R E T ont permis la mise au Des exemples associant T B A (concepteur , point de lormulations explosives de moins de charges 1 et N E (formulateur et s P en moins sensibles et I'etude de fournisseur de compositions expiosives ) I'optimisation des structures des charges illustrent I'application de cette pour ces formulations afin d'assurer la methodologie a I' etude de charges de conformite aux sp6cifications de besoin missiles air/air et sol/air ainsi qu'aux munitions aeroportees forts conflnement. La presente communication effectue la synthese des resultats des developpements LISTE DES SYMBOLES e TBA (Concepteur de charges ) COndUltS en T B A : Thomson Brandt Armenents association avec SNPE (Formulateur et fournisseur de compositions explosives ) , 5 N P E : Societe Nationnale des Poudres et en presentant: Explosifs -le5 reSUltats des immunites acquises DGA / s T P E : Direction Generale de dans divers configurations struturales avec I'Armement / Service Technique des les differents explosifs disponibles a Poudres et Explosifs I'bpoque des developpements, DGA / S T E T: Direction Generale de -le logigramme de conception des I'Armement / Service Technique des Engins charges a immunitt! renforcee afln de Tactiques . satisfaire aux specifications actuelles DGA / D R E T : Direction Generale de I' d'immunite Armement / Direction des Recherches et Etudes Techniques 2 SPEC I FI CATIONS ACTUELLES OGA / DCN / STCAN : Direction Genbrale D'IMMUNITE . de I'Armement /Direction des Constructions Navales / Service Tecniques des Les immunites Speciflees dans les nouveaux Constructions et Armes Navaies Programmes de developpement des charges de missiles et des munitions aeroportees 8-2

destinees a I'Armee de 1'Alr ou la Marine sont recapitulees dans le tableau i CI apres:

EPREUVES EVENEMENT DOCUMENTS A UTlLiSER A I I-

INCENDIE

IMPACT DE BALLE ACOMEUSTION 1 19/1/1990 2/58 05/90 IMPACT D' ECLAT5 'LUSSEVEREOUE MIL-STD-210SA ER 8541 /I9 ITDGA/DCN/STCAN *"******** ACOI1EUSTION i PROJET i OBP 42242 1 N' 9282-4 i - I 19/1/1990 I NON PAS DE 1 DOD-60559 [ IETONATION PROPAGATION (MIL-STD-2105A IBR 6541/23 ~ITDGA/DCN/STCAN~ 4396 PAR DELA 1 PROJET N'Io,",'-5 PROJE; 3 INFLUENCE 1 I DElONATlON 19/1/1990 I CHUTES ASDEREACTION MIL-STD-2105A ITDGA/DCN/STCAN 1 PROJET 1 I N' 9262-3 1 - I 19/1/1990 1 7/55 I TABLEAU 1

3. ANALYSE DES RESULTATS D'IMMUNITE hexogene /liant plybutadiene ont mis en ACQUISE DEPUIS 25 AN5 PAR TEA evldence les comportements suivants du chargement agresse dans une structure

3.1 Chargements en hexoghe tolite . assurant le "dkconfinement " des produits de decomposltion : Le5 resultat5 des epreuves d'immunites ( cf tableau 2 ) appliquees aux charges de -Epreuve incendie type feu de kerozene: missiles alr/air et air/sol developpees dans -arret de la reaction de les annees 1960/1970 en utilisant des decomposition des I'instant oh I'ouverture chargements principaux en hexogene / tolite de la stucture assure la mise a l'air libre du armatures de fibres de verre mettent en chargement , evidence I'importance de I'influence de la structure et de I'interface structure / -non transition decOmPOSltlOn chargement sur /deflagration / detonation I'acquisltlon de I'lmmunite I'impact par -Impact de balle et obus: balle : la presence d'une protection -reaction limitbe a une combustion thermique en slllcone interposee entre la en cas d'impact d'obus de 20 mm , ou de structure en acier et le chargement balle de 7,62mf11. Principal confere aux charges I'imminitb a la balle perforante de 12.7mm -Detonation par Influence : 3.2 Chargements composites a liants -non detonation dans les conditions inertes de stockage de ia charge experimentee Ces resultats ant ete confirmes et Le developpement d'explosifs Iiants a completes lors du developpement : inertes dans les annees 1970 chez SNPE a permis I'emploi de chargements de -soit de nouvelles charges de missiles a sensibilites reduites par rapport a gerbes '' focalts&!es"(gerbes etroltes 2 bords I'hexogene / tolite . Ces chargements quasi paralleles ) utilisant le m@me type presentent en outre de tres bonnes d'explosif et des structures assurant le caracteristlques thermomecaniques dans ies alconfinement des produits de Plages des temperatures d'emploi des decomposition ( cf tableau 3 ) . Lors de missiles developpes a cette epoque ( -54 'C i'application de ces epreuves nous avons , +90'C ) Observe : Les epreuves d'immunite aux -une reaction llmitee d la combustion environnements accidentels appllquees 6 la en cas d'impact de balle perforante de 12,7 Premiere charge a eclat5 d gerbe divergente mm ( cf tableau 3 1 equlpee d'un chargement en 8-3

CHARGEMENTS EN HEXOGENE / TOLITE RESULTATS D'EPREUVES D'IMMUNITE A L' IMPACT DE BALLE DE 12.7 MM A LA VITESSE D'IMPACT DE 850 M/S

EQUI PEMENTS INTERFACE CHARGEMENT TYPE DE BALLE RESULTATS CORPS DE CHARGE CHARGE DE CHARGEMENT EXPLOSIF ISOLE PERFORANTE ABSENCE DE MISSILE PAR UNE ENVELOPPE DE PRO- REACTION AIR/AIR TECTION THERMIQUE TRACANTE COMBUSTION MAQUETTE DE CHARGEMENT AU CONTACT PERFORANTE DETONATION VULNERABILITE AVEC LA PAROI DE MAQUETTE STPE 31 ( 1 ) (1 ) Les epaisseurs de paroi des deux types d'equipement sont comparables TABLEAU 2

CHARGEMENTS COMPOSITES A LIANTS INERTES RESULTATS D'IMMUNITE AUX EPREUVES D'ENVIRONNEMENT ACCIDENTELS

PARTICULARITES DE EPAEUVES RESULTATS DEFINITION CHARGEMENT ISOLE DE LA INCENDIE TYPE FEU DEBUT DE DECOMPOSITION ET EXPULSION MISSILE AROI DU CORPS DE CHARGE DE KEROZENE DU CHARGEMENT APRESOUVERTURE DU AIR/AIR PAR UNE ENVELOPPE EN CORPS DE CHARGE. PERTE DE MASSE DU A GEREE AOUTCHOUCSYNTHETIOUE CHARGEMENT NEGLIGEABLE. DI VERGRENTE )ISPOSITIF DE DECONFINE OBUS DE 20MM DE MASSE 30 KC 1ENT PAR OUVERTURE DU A 190M DE L'ARME OUVERTURE DE LA STRUCTURE CORPSDE CHARGE BALLE DE 7.62 MM :OMBUSTION PARTIELLE DU CHARGEMENT -GENERATEURDECLATS A 500M DE L'ARME PREFRAGMENTE CHUTE DE 5M NON DETONATION PAR INFLUENCE SANS REACTlON PYROTECHNIOUE. (ENTRE AXE ENVIRON I MI CHARGE DE -CHARGEMENT NON ISOLE INCENDIE TYPE FEU DECONFINEMENT ET COMBUSTION MISSILE DE LA PAROI DU CORPS DE DEKEROSENE AIR/AIR CHARGE EALLE DE 12,7 MM COMBUSTION A GERBE -DISPOSITIF DE DECONFI- AP A 850 M/S FOCALISEE NEMENT PAROUVERTURE DE MASSE I2 KG )E5 FLASOUES DE CHARGE NON DETONATION ESORGANISATIONCOMPLETEDURECEVEUF -GENERATEURDECLATS PAR INFLUENCE SANS REACTION PYROTECHNIOUE PREFRAGPiENTE (ENTRE AXE ENVIRON 0.27 MI -ENROBAGE EXTERNE EN RESINE DE FAIBLE MASSE CHUTE DE 511 PAS DEREACTION PYROTECHNIOUE VOLUKIOUE -CHARGEKENT NON ISOLE PERFOR ANTE DE LA PAROI DU CORPS DE CHARGE IEBUT DE REACTION PUIS EJECTION DE LA -DISPOSITIF DE DECONFI- lNCENDlE TYPE FEU PARTIE ARRIERE PERMETTANT NEMENT PAR OUVERTURE DE KEROSENE L'EXPULSION DU CHARGEMENT EN DEHORS DE LA FUSEE DE CHARGE DU CORPS DE CHARGE -CORDS DE FORTE EPAlS- SEUR rABLEAU 3 x-4

-le deconfinement de la charge et la 3.3 Conclusions de I'analyse TBA combustion du chargement en environnement Les Immunltes specifiees peuvent etre "feu de kkrosene 'I, acquises en associant des le debut du - la non detonation par influence dans development le formulateur et le concepteur le5 conditions d'emploi operationnel en de charge , afin de selectionner les tubes lanceurs ( tube lanceur en fibre de formulations qui presentent les meilleurs

verre de falble epaisseur ) ~ performances par rapport aux efflcacites -salt de charges perforantes de imposees par les specificatlor\s de besoin et munitions anti pistes presentant un tres qui offriront les meilieurs garanties d'immunit6 . Les quatre facteurs les plus fort confinement (corps de forte epaisseur ) et equlpees d'un dlspositlf axial de importants qu' 11 faut associer lors de la definition de la munition sont : deconfinement . La connaissance du comportement de ce type de munitlon est -emplol d'un explosif 6 forte pression actuellement limitee d celle du d'initiation (cf tableau 4 ) I comportement en incendie "feu de kerosene" -structure de charge equipbe d' un ( deconfinement du corps de charge et com- dispositif de deconfinement , bustion du chargement ). Des etudes de comportement en non detonation par -interposition si necessaire de Influence et ImDact de balle sont en cours materiaux attenuateur de choc a I'interface chargement / corps de charge

ou 6 I'exterieur de la charge ~ -emPloi de composition presentant de bonnes caracteristiques thermomecaniques garantlssant un bon comoortement d I'lmpact de ball,?

TYPE D'EXPLOSIF I REPF~PRESS ION^

HEXOLITE A HEXOGENE B LIANT POLYBUTADIENE B HEXOGENE CH LIANT POLYBUTADIENE C OCTOGENE LIANT POLYBUTADIENE D 90 A 100 COMPOSITION TEf?NAIRE CONTENANT DE L'HEXOGENE E I40

TABLEAU 4

4 LOGIGRAMME DE CONCEPTION DES Ces munitions sont : CHARGES A IMMUNITE RENFORCEE -une charge air/air anti aeronf Le logigramme d'etude de charge 6 (explosif C ) , immunite renforcee aux environements -une charge so1 / air anti missile et 1 accidentels est represente sur la figure anti aeronefs ( explosif C ) , Sur ce loglgramme apparait clairement les activites coordonnees du formulateur et du -une bombe perforante anti pistes concepteur (explosif E ). Ces exemples de realisation demontre que 5 EXEMPLES APPLICATION DU I'acqulsition de l'immunlte aux environement LOGIGRAMME accidentels ne se traduit pas ineluctablement par une reduction de Les developpements des munitions citees performance si I'immunite est prlse en dans le paragraphe 3 ont conduit 6 la compte des le debut du developpement . Dans conception de munitions A immunite certaine mission ,antipiste par exemple I' renforcee qul utilisent des chargements etude de renforcement de I'immunite a principaux et des relais d'amorqage conduit a une amelioration de performance realises en explosifs dont la pression d'initiatlon est voisine del00 Kbar 8-5

LOGIGRAMME DE CONCEPTION

PERFORMANCE D'IMMUNITE I I I EFFICACITE ENV I RONNEMENTS OPERATIONNEL ACC IDENTELS

I REGLES DE CONCEPTION i REDUITE POUR LE BALISTIQUE DU THERMOMECANIQUES I I CHARGEMENT I I DU CHARGEMENT I II rr- SPECIFICATIONS TECHNIQUES DU CHARGEMENT I FORMULATION DE COMPOSITIONS I CARACTERI SATION DES COMPOSITIONS I

PREVISIONS THEORICIUES DE PERFORMANCES

I IEVALUATION DES PERFORMANCES I ET DES IMMUNITES- I SELECTION DES COMPOSITIONS I

OPTlMlSATlON DES FORMULATIONS ET DES STRUCTURATION DE CHARGE I AVANT PROJET DE CHARGE

Figure 1

9- I

"LESS SENSITIVE EXPLOSIVES"

N.H.A. van Ham, A.C. van der Steen and 1.1. Meulenbrugge Prim Mauriu LdbDratory "0 P.O. Box 45, 2280 AA Rijswijk TheNetherlands

INTRODUCTION

Explosives are the active ~on~tituentsin ammunition. rhcir high energy Bonding Agenl output per unit of time is used for propulsion and lcrminal ballistic action. The interaction betwcen the explosive and the binder has always be a This caoabilitv is also a Continuous threat to thc user and the civilian problem becausc of thc fact thate~plo~iv~~arc morc polar in nature where surrouniings due to the pas~ibilityof unwanted reactions. ihc binder has more the chancterisiics from non plar molecules. This can The vulnerability of ammunition 10 heat (cg. fuel fire), bullcVfragment be solved by the use of banding agents: a banding agent is a moleculc with impact and sympathetic detonation was recognised a$ a high priority a palar sidc that can interact with thc explosive surface, and a "on palm side problem be solved; especially far the battleficld situation it was proven that has a bettcr affinity to thc binder system. The bonding agent ,with by operation rcsearch studies that inuoduction of InSCn~itiveMunitions proven qualities in PBX formulations, we have chosen for this study is (IM) is of vital importance to SUN~VC. Dantwol. To improve the existing munitions. thc munitions must be considered as a total concept: Propellants explosives and pyrotechnics must bc of a less sensitive nature: in the case of accidcntal reactions the munition is capable Pioslicirer ofvcnung the overpressure quickly by venting holes. This can be integrated The mechanical properties of a plastic bindcr can suongly bc influenced by thc use plasticizer. its physical and chemical properties it in the miinition dcsien (erenade. booster CUD. rcckct motoii. of a Due to can be situated between the long polymcr chains and in this way it can act as B kind of lubricant. If thc plasticizer is tw volatile it can cxudatc from the For practical rmms it was decided 10 make usc of cxisting enplosivcs: the binder marii this makes the movement of the long polymer chains morc dcsensitising action is established by the addition Of B (commercial availablc) polymcr bindcr (plastic bindcr: PBX =Plastic Bonded ~Xplosivc). difficult, resulting in chain rupiurc and consequent crack formation. As a plasticizer wc isodccylpelargonaal (IDP). This rcport dcscribes the rcsearch done in this field. The first part of the used rcsearch conccnualcd on the influence of thc binder on the PBX syslcm, the second part was dcvoted to the influcnce of the explosives manufacturing Wetting Agent process. panick size and panicle shape This is a processing aid the problem is to disuibute 85 % of a solid loading over a viscous liquid. The wetting agcnt acts like a soap: in this way lhc solid cxplosive is moistened more quickly and thc overall viscosity of thc mixturc is lowered so we still have a caswblc mixture. In this study wc used Lecithine as a wetting agent.

l?qIXplosive Thc important features of the exp1osivc arc: 1. Wcll availablc 2. High density 3. High mclring/decomposition

tempemlure.lemoemturc. Most .~promisingommisine explosivesexolosives that fulfil this~~ dcmands~~ ~ ~~~ arc thc niuamincsniukncs HMX and RDX. In or&order Lo achieve a solid loadine of 85 % and I mort it is necessary to make use of bimodal and multimadal particlc size disuibutions. The explosive cryslals must be void Cree and of a regular shape, for practicd reasons we sWrlcd with induslrial grade cxpl0sivcs from Dyno.(No)

PBX composition PART I The influence of the binder Pre-poipmrl iiordener The binder wc havc chosen Consists of HTPB (Hydroxy Terminatcd Poly- The influence of the binder was studied by varying Ihe HTPB/IDPI ratio Butadienc). Thc reason for this choice was thc cxccllcnt, well-described (ref. 5. part 11). in this way the cross-link density was varied between 0.7 mcchanical properties of this binder; HTPB is used in rearonable quantities and 1.0. AS explosives wc used RDX and HMX. the RDX onginarc from in the rockc1 motor indusuy. HTPB Consists of (50 molecules) chains of DYNO. hirtadicne which are ahle to form a network bv their fnnrtinnil (OH =

~~ ~ I lile TdI(Tol&e'Di Isocyanatc). kor this sGdy we uscd isophorodiiso- Detonation ~elwityand prcsswe were determined to check the performance cyanattc (IDPI) bccausc it is less volatile. The functional NCO group of the of the enplosivc. The NOL Large Sale Gap Tcsl was uscd Lo delcrmine the ls~cyanatereacts with thc OH group of the HTPB. Depending on the shock Sensitivity (3). This mcthod demands a large number of experiments and test Lo "distanw to detonation" OHiNCO ratio it is possihlc Lo conV01 the number of cross-links between lherefore another was used determine the thc polybutadien chains. A low number of cross-links rcsults in a sticky (a and the "time lo detonation". Normally the wedge Est is used to determine these parameters, but wc used a slightly different and simplcr test mcthod. lot of reactive groups are still prescnt), dcformable product, which cannot be uscd in ammunition. A high cross-link density (nearly all the reactivc With OUT test it is not possible to follow the acceleration of the shock wave groups havc rcacted) rcsults in a vcry hard. brittle product. The optimum during initiation. cross-link density will be between those exucmcs. Exoerimental

I The poly-butadiene chain has an unsatwated C-C band, which can react PBXes, attent&must be paid to the particle size diSuibution of the with oxygen (stimulated by light). TNO has studied the influencc of aging crplasive companent. At the "NO-PML normally a bimodal mixture is onPBX,and thccffectoftheadditionofanti-oxidantsloimpmvctheshelf- used far thc RDX-based PBXes and a Uimodal mixture for thc HMX based life. It was proven that anti-oxidants likc DTBHQ (2.5 Di Tcrtiair Butyl PBXCS. Thc limits of the partick distributions and the pcrcentagcs uscd in Hydro Quinone) and Flcxronc (N phcnyl N cyclohcxyl p phnylenc diaminc) the bimodal and rimodd mixturc~arc given in Table 1. The two kinds of improves the aeine behaviour of binders in PBX. RDX were obtained from different sourccs: both contain about 6 wt% HMX. 9-2

Table 1 Particle size distribution 01 the explosives and the Results percentage used in the bimodal and trimodal mixtures. In Table 3 the results for the different PBXCSare summmized.

~~ Explosivc panicle six Wl% Table 3 Detonation and shock sensitivity for the PEXes (I"

I50 - 14W 53.3 10 - 50 33.4 PRDX-I PRDX-I I'RDX-I1 PHMX- 1w - 5w 13.3 Cross-link density 1.0 0.7 1.0 1.0 0.7 . RDX-I 2w - 5w 66.0 IO - 6a 34.0 D (kmh) 7.9 8.0 7.9 8.2 8.1 RDX-I1 250 - 600 50.0 P* (GPa) 19.5 19.5 20.0 23.0 22.4 10 - 50 50.0 P(50 %) (GPa) 3.2 3.2 3.7 3.0 3.0 Initiation dismncc 10.9 10.5 20.9 16.5 19.6 Polyurethane was used as a binder in the PBXes. Thlhc binder composition is given in Tablc 2. The cross-link density was varicd by changing thc 0 4.1 4.2 7.5 5.7 6.6 NCOIOH ratio between 0.7 and 1.0. The lhydroxyl content of the HTPB was checkcd by standard methcds involving acetylation.

Table 2 Composition of PBX (WX).

-Explosive 85.00 HTPBnPDl 10.19

IIDP 4.50 ~ Lecithin 0.20 Dant~ol 0.10 Flermnc 0.01

Table 4 Shock sensitivity lor Several explosives as determined by the NOL Large Scale Cap Test

Explosivc ncssedicas1 P (50 %) (CP,)

RDX 1610 P 1.O I RDX/war (9 1/9) P 1.7

A vcry simplc test was used to oblain a ~C~SUICfor the dislance to initiation and thc time to initiation of the eaplosivc (Fig. I).In this lest the ~amcdonor system was cmployed as far thc NOL gap lest, but now with a bare cylindcr of erplosivc (d = 50 mm). With a sue& camera the shmk front in the PMMA WBP followed (back lighting). AS SW~as the shmk W~YC~ntcrs thc explosive, light is no longer dctcclcd by thc camera. HOWCVCC,aftcr an "initiation dismncc" (initiation time). a detonation wave RCSUIISburning tube tests and fragment attack test UK with intensive light emission is generated. The light emission can be cnhanccd by ailaching a piece of Sellolapc to the erplosivc. RARDE Bumine Tuh- TcU

"li"Bd9 hkxionof test sec UOAQP 7 202-01-006 56 7 Dcscription of Reaction Categories

kgm of Rcaction Observation RUCtiO" Description

0 fails 10 ignite 01 1 buming cnd cap not cjecrcd 1 prcssurc burst duc 10 end up($)ejecrcd buming 2 dchption 2 to 9 tube body f?agn,ents 3 cxplosion 10 Lo 100 tube body fragments 4 dclonation > 100 tubc body fragment

Figure 1: Test set-up to determine the distance to initiation and ~ showinr evidcncc ofdcmnalion time to initiation, 1-delonalor. 2-suppod plate, 3-tetry1, 4-PMMA, 5-streak slit, 6-Sellotape, 7-explosive. 9-3

Results Table 5 Burning Tube Test Results (Non Standard Conditions) - - ""on ""on 3. Avp. It mot f. %S MY - - [rags I 1 - - - - 'PXZUOIM6 2 2 i 'PX-2001M8 S 1 3 1 3 3 1 2 1 1

IU-z3 2 , 1 1 2 2 1 1 I 1 2 2 1 0 S 2 114 2 I 2 3 3 1

IW24 2 2 1 2 2 1 1 L 1 2 2 1 10 1 4 2 7 2 2 1

'E 4 10 8 2 1 (2 4 8 1 3 1 2 1 2 2 1 2 2 1 3 2 1 1

5 19 2 53 3 Yl

IU-61 5 3 1 114 5 2 114

IU-63 5 4 5 1 1N

IU-67 6 4 2 1 2 I 1 1

INrcrc8m.d 5 4 1/11 5 4 1 1 3 3 1 2 1 IN 5 12 5 5 3 7 4 13 2 2 1 2 2 i 3 3 1 3 2 1 L L 1 2 3 1 INI !lake i 2 1 ? 3 1 - - - -

There was "cry lilllc raclion in illis lcsl. Thrcc oul OS Ihc cighl samples ignited and blew oli an end cap, dcspiic ihc heavy clamping lhai wits cinploycd. These rcsuIls indi~at~Lhal RUM7 has slighlly lowcr cnplosivcncss lhal RUM1 and RU-63, but lhis could be a consequence OS Ihc coniincmcnl employd. 9-4

Fmement Attack TaVK Thc experiments also show that the masuremcnts of the initiation distance and the initiation time are much more sensitive than the NOL gap kst I (e.& an initiation distance of about 3 mm is found for pressed It is Twdsscriolion NATO AOP 72Ql-Es-@?3 "in. see aurcxpeticnce htsmall differences between merent batches ofa PBX can be observed with this lest method. This is also conk" by the results for Observation the HMX-based formulations with different cross-link dcnsities.

Sub eonelusions Part I No visiblc sign of rcaclion after pencuatian of the From thc rcsults the lollowing conclusion^ can be drawn: septum by thc projectile Hint ofa burning reaction which has faded rapidly, no 1- The particle size disuibutian and passibly thc geamclry of the particles obvious consumption or erplosivc have a large influence on the scensitivity Detachmcnt of the seplum, up to 20 % of cxplosive wnsumcd 3 Septum detached, vehicle intact or broken into largc 2- Although thc donor sysrcm is the sa", the rcsults far the NOL gap lcst fragments. mom than 20 % oiexplosivc consumed and the iniliation distance test cannot be compared directly. However, 4 100 % of ~xplosivcwnsumcd in a very violent hause the latter test requires considerably fewer experiments md also reaction charactcrizcd by breaking up Of vehiclc into smms to be more sensitivc, funher investigations with this test method very many small fragments showing evidcnce of shear ~ecmfcasihlc

Results 3- The scnsitivity of a PBX towards shock initiation is not influenced markedly by the cm~-linkdensity variations of thc plastic binder. In the Table 6 deflagration 10 detonation modc as secn in thc burning tu& lese lime is a visible tendcncy that high cross-link density givc ri~c10 more sensitive explosives. Thc possiblc cxplanatian for this difference is thc dynamic charactcr of the shock WBYC: rhc binder act as a kind of liquid in this case, lound no. Septum matcrial Projectilc yelocity Degreeofrcztioi so ihc numbcr of cross-link$ is not of importance. From the shock sensitivity work we noticed a rather large influence from the crplosive particle siie and shape, it was decided to study this in more deb1 in the 10 Stcel 814 1 second period. 7 " 897 0 6 " 971 I PART I1 Influence of explosive particle size and shape. 1 " 1099 2 9 " 1390 2 Gcnemlly it is assumcd lhat thc polymer rcduccs the sensitivity of the 8 " 1428 2 cxplosivc LO inadvert stimuli considciably. A great dcal of research has been 2 " 1438 2 carried out 10 characlcrizc thc properties of LhC PBX in rclation to the type of polymcr uscd [I]. In part I wc havc secn that thc influence of the bindcr 5 " ISM 4 by ?s cross-link dcnsily was very minor. In pan 11 wc concenuatcd on thc 4 " 15Y7 4 eiplosivc particlc sizc and shape. 3 " 1669 4 ~

Initiation of Explosives This lcst was carried out according to SCC No 36 and a rangc of lcsl dam Due to hear. friction and shock waves, explosives can decomposc. If the on other matcrials can be found thcrc. Whilc thc results for RU-67 arc quile number of decomposing cxplosivc molecules per unit of volume encecds a god thcy arc not cxccptional for B PBX. Thc throshold for ignition is Certain limit the heat afrcaction will decomposc the remaining explosive (very) approximately 800 mi$, which compares with approx. 900 mis for resulting in a selfsusbncd reaction. Studics of the initiation of cxplosi~es have revealed that the iniliation of erplorives is stimulated by the imperfections in the explosive (6). Each deviation from the idcal crystal suucture caiises the con~tit~cntlattice se&viiy of thhe explosive in the large Scalu Gap Teil (LSGV. The valuc ions to free themsdvcs mmeasily from their fixed position^ in the laitice. of 1500 mis would be equivalent lo a median gap of 3.3 GPa in the LSGT The first dcviation in a lattice is formed by thc surface itself: the ions and, thcreforc. RU-67 is less shock sensilivc than cast-creamed TNT but prescnl in the suriacc have lesser bonding compared to the ions in the moic sensitive than some other PBXS middlc of Ihc lattice, so thcy can be removed with less encrgy. Thc ions at the edges and comers can k removed even mort rapidly comparcd to the normal surface ions. DiSC"SSi0" Cryslals have many natural imperfections likc vacancies, edge and screw Thc diffcrenccr in thc sensitivitiCs of thc two RDX-based formulalions dislocations, faults, cracks: bur also impurities (sometimes inuoduced 10 could be awribcd to thc small differcnces m the ratio of finc and coarse CreatC a special characteristic, we call this dopants\ give rise LO a crvsral RDX used to obtain a bimnlill minlurc; PRDX-I1 conmains a larger fraction SLIUC~UICwith an increased mobility and reactivity. of iinc RDX (see Tablc 1). Moulard found distances LO initiation of about From thc above il is obvious tha panicle size and shape are vcry impanant IS mm and 23 mm (3 ~rsand 5 us) for thc coarse and fine RDX-bascd features if Ihc level of cryslal faults and impurities can be kept constan1 be PBXcs. respectively. These valucr were obtaincd for an initiation picssurc the production prtress. of aWut 5 GPa. In our cxperimcnts thc pressure in thc plcxigla~~at thc The morphology of thc high cnplosivcs uscd in ihc PBX and in particular intcrfacc is 4.2 GPa. Assuming the Hugoniot of thc PBX to be U = the cryslal si?. disuibulion has received a 101 of attention in ordcr LO modify 2.3+1.Xu ihc prcssurc in the PBX is aboul 4.7 GPa. Sincc thcsc prcssurcs the scnsitivity (2). arc about the same it is not surprising thal thc rcsults of both tcsts are It is only reccntly that a more rcgular shape of the e~plo~ivepanicles is compaiablc. HOWCVC~.Moulsrd comparcd finc and coarsc RDX considered as a tool to decrease the sensitivity of auuded, pressed as wcll lormulaiions whilc in our cxpimcnts thcm is only a small difference in as cast-cured cxp1osive charges (7). the ratio of the bimodal mixture. The grcat dificrenccs we obscrve for thc different formulations could be caused by th~crysml properlies of thc RDX, Dyno has used a simple method to produce spheroid particles. TNO~PML such as thc cryrlal geomeuy. has processcd cartcured HTPB-based PBXcs with diffcmnl barches of RDX and has measured thc shock smsilivity.

From a comparison of ihc NOL gap lest dalii and thc iniliation distances it appears that both test mcthds give information about diffcicnt swgcs in To oblain a high solid load in the PBXcs a bimodal mixture of coarse thc shock initiation process. The iniliation distance is detcrmined by (about 300 um) and fine (about 20 wm) RDX is uscd. In this study thc initiating the cxplosive with a pressurc pulsc of 4.2 GPa, which is shock sen~itivityof PBXes with RDX @en directly from thc produclian considerably highcrlhan theprcssurcs found in theNOL gap lest. Thcrcforc lin~and PBXCS with RDX which has gonc through additional processing thc measurements of thc detonation dirtancc probably only give S~CPSLO increase thc spheroid character of the coarsc atid fine crystals have information abut thc final smgcs of thc pressure build-up to detonalion, been compd. whilc the gap lest results refer 10 thc full shock inilialion proccss. Thc shock scnsitivity has been determined with a raher simplc gap tcsl which determines thc distance and timc VI detonation for different initiation preSSUIS. 9-5

Experimental Table 7 Average panicle size (d(0.5)) and 10 % and 90 % Thc RDX is produced by the well-known acetic anhydride process values 01 the panicle size distribution of the RDX (Bachmm pmess) and recrystallircd in acetone. samples (Fm) Spheroidization of the crystaIs is carried out by loading angular RDX crystals in RDX saturated ~cctonc.Next thc mix is agitated and the tcmperaturc is raised and maintained at a predetermined level. When the dcsircd sphcroidization obtained by partial dissolution and erosion is rcachcd, thc suspension is dischargcd 10 a filler and washed. The reacLor uscd has a total volume of 150 litrcs. It is equipped with a &bladed turbin agitator, 2 balflcs. hcating jacket, reflux condcnser and B flush-mountcd dumping valw The agitator shaft has a wakr swl and the agitator speed can be continuously regulated. The filter consist of a simple nutche equipped with a heating jackct and opcntcd by YBCUUIII. The particlc size distribution of the fine samplcs differ considerably. Thc The reactor is first loadcd with a saturated solution of RDX in acetonc at "on-iiwtcd sample has a wry wide distribution with a maximum around rmm tempemturc. The acetone has a conccnuation to water between 90 and 20 pm while thc spheroidired sample has a rclativcly narrow disvibution IM %. Appronimatcly 30 kg Of RDX is loaded and the agitator started. Thc with a maximum at 52 wm. It was not possible to obtain Smaller parliclcs. tcmpcralure is raiscd Lo 50 "C and agitation is maintained constant for 3-5 The Same type of cracks as arc observed for thc Coarse Smpk are obscrvcd hours. Depending on the crystal size. thc agitator tip speed is sct normally for this fine sample. bctwmn 7 and 14 m/s. The suspension is discharged to Ulc nutchc and the amtom is Sucked off to a filtrate tank. filter cake is washed wilh watcr. Thc Both coarse samplcs contain less than 1.0 wt% HMX whik the amount of As rquired, the product is finally fractianed and by mixing of fractions the HMX in the finc samples is in betwccn 6 and 7 ~1%. rcquired sixdistribution is madc.

Typical scanning clecuon micrographs of lhe non-ucaled coarse and finc Bimodal mixtures with a coarselfine ratio of R = 64/36 of tht "on-vcatcd sample taken directly from lhe production line and of the spheroidizcd samples and lhc spheroidizcd samplcs have becn used in fhhe PBXes. Also a coarse and line sample angivcn in Figure 2. Thc panicle siz distributions bimodal mixture Of the spheroid comsc sample and lhc "on-treated linc of thcsc samplcs arc piesenlcd in Figure 3 and some chanctcrisuc values arc sample has bet" uscd to investigatc the influencc of thc difference in thc summarizcd in Tablcl. particle size distribution of thc fine samples. The tap density of these mixtures at R = 64/36 arc 1380, 1380 and 1440 kdm3 respectivcly. The coarsc samplc mkcn directly from thc production line Contains typical irrcgularly shaped agglomcratcs and more or less angular singular crystals. The sphcroid cmsc pariiclcs are more oval and small cracks arc observed at thc surface. Thc psrticl~sizc distribution of both coarse samples is about thc samc

Figure 2. Typical scanning electron micrographs of the non- treated coarse (a) and fine b) sample and the spheroidized coarse (c) and fine (d) sample. 9-6

A polyurcthanc binder (H"B and IPDI) and a IDP plasticiler arc tho main ingredicnls of the polymcr binder. A1.W Daill~~olwas added LO improve thc bonding ktween the non-polar polymer and the polar ciplosive crystals. PBXes were cast under vacuum and alkr curing the density was found LO be 1580 kgh" indicating that hardly any voids are present in the PBX. A morcdelaileddescriptionofihecastingpmccdurecank foundin(8).

~ .

40 -E -E D e 30 a c D .-0 20 5 20 .-c .-c ._.- 10 , I, 0 I 10 s , 0 3.0 3.:; 4.0 4.5 5.0

initiation prea8ure IGPal

Figure 4. Distance Io detonation for the PBXes with non- ,<,I, , , ,\ treated RDX (0). spheroidized RDX ( D) and , ,__-- , . 0 spheroidized coarse and non-lrealed fine RDX (t). 10 100

PARTICLE SIZE lm) However kause thc parliclc size dislributions of the linc smplcs diffcr considerably the sensitivity of a PBX with a bimodal mixture of spheroid Figure 3. Pallicle size distribution of the coarse (a) and fine (b) coarse particlcs and non-treated fine pmiclcs has also bcen measured. Its samples; -:non-treated and sensitivity curve lies just below the CUYC found for the PBX with the .... :spheroidired spheroid pilrticlcs with a Critical prossure Of 1.75 GPa. This relative incrcasc in the sensitivity as compared to thc spheroid panicles is contrary to trends obscrved clsewhere where the scnsilivily decrcascs with a decreasing particle siice. This could also be an indication that also for the A simple gap test is used LO determine thc timc and dismcc to detonation line fractioii of thc bimodal mixture the paniclc shapc is ~OTCimportant of a barc PBX cylinder of 50 mm diameter and without any confinement. It then the particle size. consis~sof a teuyl booster (I = 50 mm. 0 = 50 mm and p = I510 kp/m3) in combination with a plexiglass aucnumr of the ~amediameter. A sue& cw" rccaids thc shock wave through thc plcxiglass (back At thc moment it is not yet clear what reason^ C~USCthe shift in lightning) and the moment and position the shock W~YCenters the PBX. sensitivity. Also thc position and lime the detonation wave cmergcs from the side Firstly, it might be that, despitc lhc vacuum casting tmhnique used, surfacc of thc PBX is recorded by thc slr& camera. Thc initiation distance microscopical voids are foimcd on the surface of thc crys!As during the 0 and time are determined for different initiating prcssurcs. i.c. lengths of the casting process. Although lhe densities of all teslcd PBXCSarc thc s" plcxiglass BtlC""Bl0'. within 0.2 wl% it could be that thesc microscopical voids arc more likely In c00mst with thc wcdge kst a sphcrical diverging shock wave is uscd to LO occur on Lhc surface of the lrrcgularly shaped surfaces of the "on-treated initial~the sample. Also thc diswncc to detonation is not dctermincd on the crystals and act as "hot spots" during initiation, The rdc of the small ccntral axis but on thc surface of the chargc. However, from thc sueak cracks obscwcd at the surfacc of the spheroid parti~bsin thc initiation recordings wc lcarncd that on arrival a1 thc surface a detonation W~YCis proccss is not yct clear. propagating in thc forward and backward dircction. Sincc the vel~cilicsof both waves are about qual they can probably k asctibcd to the spherical cxtension of a dctonation wave smting on the central axis of the chargc. A SCCOnd possibility could be the content of HMX in RDX. nlhc HMX is For this reason it can k assumcd that the rcsulls obtained with thc prcsent found both as impurities in RDX crystals and as relativ~lypure crystals in test will not diffccr cansidciably from wedge Est rcsuI1s. thc fine fractions of the crystal dislribution. During spheroidization HMX is dissolved lading to a lower content Of HMX in the final product. This dissolving cffmt might also be an explanation for thc cracks observcd at thc Results and discussion surfacc of the spheroid. The relatively low pcrcentage of HMX at thc . nercs~lls obtained far the thrce diffcrent PBXCSarc prcsentcd in Figurc 4 surfacc of thc RDX particlcs could bc conneacd to the lower shock SC"5iti"itY.

A third pm~ibilitycould be rclatcd to the mcchanical strength of the crystals. Angular crystals will be more susceptible to shear forces than the spheroid crystal. The mechanical slrenglh of thc spheroidized samples could also k incrcascd because theSe crystals havc bocn stincd for several hours during which lhe crystals with less strength arc crushed down and removed. Sub conelusions I1 References This study was started to investigate in how far the particle shapc (1) Gwi. M.A. van , "Plastic bindcrs in high cxplosivcs 12th lntemalional influenccs the sensitivity of an cxplosive. A~WI canrercncc Or ICT,Karismhe, 333 (1981) Spheroid panicles werc oblaincd with a rather simplc techniquc and also the (2)Moulard H., Kury I.W.and Dcclos A,, "The effect of RDX parUcle sizc shock sensitivities werc dcrermined with a mther simple gap 1~~1.Taken on the shock SCnSilivity of cast PBX formulations". Proc. Eighth into account that thc quality of the crystals could bc improved by Symposium (Intemational) on Detonation, Albuquerque, NM 902 (IYUS), optimizing the spheraidizalion prwess and that no attempts have been madc Moulard H.. Declos A. and Kury I., "The effml of RDX paniclc siie on to optimize the bimodal mixture to particle size and paniclc size thc Shock sensitivity of cast PBX formulations", 11. Bimodal compositions, disribution the results are still impressive because the few additional steps Proc. lnlcrnational Symposium of Pyrotechnics and Explosives, Beijing . in thc production process rcsultcd in a reduction in thc shxk Sensitivity Of 304 (1987). 0.6 GPa. It is very likely that optimization of the production and thc (3) Price, D., Clairmont Jr., A.R. and Erkman, J.O.. "The NOL Large processing pmcters will givc at least a comparabic reduction lading to Scale Cap Test 111. Compilation of Unclassified Data and Supplementary an erplosivc which has an even lower Sensitivity than CompB. Information for Interpretation of Rcsu~~s",Naval Ordnance Laboratory, NOLTR 74-40 (1974) (4) IJssclstcin, R.R., "Reaction ZO~CMcasurcmenu in High Explosive Tho sphcroidization proccss could bc improved in Several ways. For ~~~~~~~i~~waves by M~~~~of shock induced polarization ~~~b~~~i~~ cnamplc, it works best if one sms with a narrow fraction of crystals and ~l~~~ a,,'27 (1986) becausc tw wide fractions will rcsult in either crystal break-up of the (5) Swallonc G.M, and Field E,, proc, R, sot, Land, A 379, 389 i1982), largcst sizcd crystals or lcss spheroidization of lhc smaller sized crystals. (6) Mirhra I,B. and ~i~f~, LJ., de , to inSenSitiYe Also the mcmr and stirrcr design and *C agitator Speed could be adlusted 10 cnplosives'', 19th international Annual Conference of ICT 1988, 25-1, thc specificd crystal sizc. The tcmpciature of thc ~olvcntand the type Of ~~l~~h~1988 solvent used will also influence the quality. i.e. the shw and the (7) stcen, A.C. van der, verbeek, H.J. and Meuienbrugge 1.1.. "Innucncc smmthness of the surface, of the crystals. of RDX crysral shape on thc shock sensitivity of PBXcs", Preprints Ninlh Optimization of the bimodal minturc applied could also rcducc thc (Intcmational) On 23, 'Onland lYx9 Slecn , A.C. van der and Vcrbeck, H.J., "Initiation Delonadon sensitivity, From OthCI investigations it is known that particles below (8) and of 20 pm reduce the sensitivity and in this respect changes in the coarse finc RDX and HMX -B-Based PBXcs," Proc 19th Intcmational Conference ratio, within the limitations of thc castability ,,f the sample, could of ICT on Combustion and Dctonalion Phcnomena, Karlsruhc, BRD. 1988: also to published in Propellanu Enplosivcs Pyrotechnics reduce the scnsitivity. Somc results will be published in thc near futurc. be and (1990)

An advantage of thc increased spheroid character is the improved piocessibilily and castability of thc PBX. This might lead to even higher solid loads of about 88 % which reduces thc need for cncrgetic polymers. In how far thc sphcroid panicles influence the mechanical propertics of thc PBXes is undcr investigation at thc moment.

Conclusions Thc influence of partick size and shapc on lhe shwk sensitivity Of explosives is dominant to the influence of the bindcr by its cross-link density. This can be explained by the dominance of the explosive (85 %) in the composition: thc mcchanical srcnglh will ~ronglybe influenced by 1hc defccts in thc crysrals, also thc bonding of the polymcr to the surface or thc crystals can be of importance. If thc bindcr is only lwscly cannecled lo thc crystals, the cxplasivc partidcs can be separated by mechanical action. A major improvemcnt in dccrasc of shock scnsitivity of enplosivcs can still be rcachcd by making explosive particles without defects and of uniform sphcncal shape. Only aftcr that it makcs sense to look after the optimum bindcr composition,wilh the optimum (cross-link) densily, and the best shock impedance. Discussion

QUESTION BY MAY, US : Would you expect this effect to also hold for much smaller particle sizes?

ANSWFR' I wish I knew, but I do not know. I assume you mean 1-10 micron size spherical particles, that size is very hard to produce 0 consistently. I don't think there are any really good methods to define these size particles.

QUESTION BY MAY, US: What would be your guess?

ANSWER: I really don't know. Low Vulnerability Characteristics of an HMX-based Explosive

r I. Hooton Energetic Materials Division Defence Research Establishment Valcartier P 0 Box 8800 . Courcelette, Qukbec Canada GOA 1RO

1. SUMMARY or improve their low vulnerability characteristics. Several Cast-cured plastic-bonded explosives (PBXs) with a aspects of these formulations have been considered at this reduced vulnerability to unplanned stimuli are currently time, including processing, chemical, physical and beimg developed. The explosives described in this paper mechanical properties, shock initiation sensitivity and are based on HMX and an inen binder. The effects of the performance. solid loading, the particle size distribution of the HMX and the curing agendpolymer ratio on the physical, chemical. 3. EXPERIMENTAL mechanical and rheological properties of the explosive were investigated. 3.1 Formulations The explosive formulations discussed here were based on 0 The detonation ..oroverties of the most vromising- HMX and an inert binder. The binder was composed of formulations were evaluated and compared to Composition R45-HT hydroxy-terminated polybutadiene (HTPB), dioctyl B and CX-84A. a PBX developed at DREV and based on adipate (DOA) and toluene diisocyanate (TDI). Two an inen binder and RDX. The shock sensitivity was different solid loadings were investigated, 84 and 85%. A measured by means of the DREV Gap Test. The bimodal distribution of Class JII and Class V HMX was detonation velocity was also evaluated. The performance used and the effect of the particle size distribution was of these explosives was initially evaluated by measuring investigated by incorporating two different Class IIYClass their ballistic capacity, determined from the lateral V ratios, 70/30 and 80/20, into the formulations. Two acceleration of metal plates. different curing agent/polymer ratios, 1.1 and 1.2, were also employed to determine the effect of this parameter on 2. INTRODUCTION the mechanical properties of the explosive. The percentage Defence Research Establishment Valcartier has been of plasticizer remained constant at 35% of the binder for involved in the development of cast-cured plastic-bonded all of the formulations. The formulations are given in explosives for approximately 20 years. This work began Table 1. with explosives based on an inen binder and RDX. The objective of the work was to develop explosives with an 3.2 Processlng equivalent or improved performance compared to The explosives were processed in a 4CV Helicone mixer Composition B but with an improved response to hazards. from the Atlantic Research Company. This mixer has a One of these explosives, CX-MA. was thoroughly studied capacity of 1 US gal. The explosives were mixed at 60°C. 0 (Refs 1, 2, 3, and 4) and was found to exhibit a lower The binder ingredients were mixed under vacuum and the vulnerability to unplanned stimuli. The vulnerability of solids were then added in three or four increments and CX-84A to several hazards. including fast and slow cook- mixed after each addition The explosives were mixed for off, bullet impact, heavy fragment impact and electrostatic one hour under vacuum before the curing agent was L discharge. was tested These tests resulted in no reaction added. The optimum mixing time was determined by or burning only, as specified in insensitive munition measuring the viscosity of samples from a test mixture at requirements, for all these tests except the heavy fragment 10 minute intervals with a Brookfield viscometer. The test which produced a light partial explosion. Its shock optimum mixing time was determined to be 1.5 hours. The initiation sensitivity was thoroughly evaluated with the viscosity of all mixtures was measured before and after the Calibrated Shock Wave Test (Ref 5) and the formulation addition of the curing agent with the Brookfield 1 was optimized with respect to its shock sensitivity (Ref 6). viscometer. The pot life, the time between the addition of Its performance, however, was only 87% of that of the curing agent and a significant increase in the viscosity, Composition B as measured by the Standard Cylinder Test was determined by constantly measuring the viscosity of a

.) (Ref 7). sample with a Haake Rotovisco RV12 viscometer. The explosives were cured at 60°C for 3 or 4 days. The RDX was replaced by HMX in order to increase the energy of the explosives but at the same time to maintain The density of the cured explosives was measured with a 10-2

Table 1: Explosive Formulations

Formulation 1 I Formulation 2 I FormulatioiGoJ II I+I

HMX Class V 25.2 16.8

9.5 DOA 5.6 5.6 TDI 0.8 0.8 0.9

Quantachrome COT. picnometer. Helium was used as the prelistep in the characterization of an explosive's displacement gas. The hardness of the PBXs was performance before more extensive tests such the Standard measured with a Shore A durometer. Cylinder Test are canied out. The explosive samples were machined into slabs 26.2 * 0.05 cm by 8.4 i 0.005 CM and 3.3 Characterization 2.0 i 0.005 cm thick, The charges were initiated with a The cured explosives were characterized by measuring their line wave generator (Ref 10). The detonation velocig was e mechanical properties in tension with a Instron Universal measured by ionization probes. The metal plate and Testing Instrument Model 1122. The samples were detonation gas angles were determined from images conventional JANNAF dog bones. The explosives were obtained from a flash X-ray system. cut into slabs and the dog bones were cut with a die. These properties were measured at both ambient 4. RESULTS temperature and -40°C. Some samples were conditioned at The viscosity of the explosive mixtures for the 4'C for 14 days and their mechanical propaties were formulations outlined in Table 1 are given in Table 2. It then measured at -SOT. No si&icant change in can be seen that the final viscosity is slightly higher for the mechanical properties was noted as a result of the formulation loaded with 85% HMX, 4.0 kP compared to conditioning and no embrittlement effect was observed as 1.6 kP for 84% HMX loading. The effect of particle is expected with an HTPB binder-based explosive. distribution on the viscosity for formulations with 84% solid loading is less pronounced. The viscosity increases The detonation velocity of the formulations was measured from 1.6 kP for a Class IIVClass V ratio of 70/30 to 2.6 kF' by both ionization probes and streak camera on samples for a Class WClass V ratio of 80/20. Some initial studies 5.08 cm in diameter and 15.0 an in length. The charges with 85% HMX loading indicate that the effect of particle were initiated hy a plane wave generator of the same distribution is more significant at this loading. The diameter. The ionization probes were placed at 5.08 cm viscosities before the addition of the curing agent fall in intervals and the velocity between each of the probes and the range 12.0 to 10.11 kP. between the first and last probe were measured. The pot life for these formulations is also given in Table e The shock initiation sensitivity of the formulations was 2. Once again the formulation with 85% HMX loading has evaluated hy the DREV Gap Test on samples 3.18 cm in a pot life which differs significantly from those for the diameter and 7.62 cm in length Two tetryl pellets, 1.59 other formulations. The pot life for the formulation with . cm in diameter and 1.75 cm in length, served as the donor. 85% HMX loading is 137 min compared to 285 min for a The barrier in the DREV Gap Test is made of aluminum similar formulation with 84% loading; the pot life for the formulation with 85% solid loading being approximately The ballistic capacity of the explosive formulations was half of that measured for the others. Additional studies measured by the lateral acceleration of metal plates have confumed that these formulations have a shorter pot propelled by the explosive's detonation front. The ballistic life when 85% solid loading is used imtead of 84%. The 1 performance of the explosive is defied as the energy pot lives for the other formulations fall within a sb,orter transferred to the plate. The detonation velocity, metal range of values, 285 to 224 min, the shortest being that for plate angle, and detonation gas angle are measured the formulation with the higher Class IUClass V HMX experimentally, and the optimal energy transfer, optimal ratio and higher viscosity. . energy efficiency, Richter coefficients, chemical energy and the Chapman-Jouget pressure are calculated (Ref 8). This The hardness of these formulations is fairly constant and test was developed in France (Ref 9) and is used as a falls within the range 68 to 63 Shore A. The highest value 10-3

is that for the formulation with the higher curing Changing the curing agent/polymer ratio seems to have the agentlpolymer ratio; however, as a preliminary evaluation, most dramatic effect on the elongation of the cured these differences could not be considered signifcant. The explosives. The particle size distribution appears to be slightly more effective in changing the value for the ~ density of these formulations is in the range of 1.62 to 1.63 Mg/m3, the density of formulations with 85% solid loading maximum stress than the other formulation parameters. A beislightly higher than those with 84% HMX loading. decrease in temperature results in an almost doubling of the value for the maximum stress but has very little effect on . The results for the mechanical properties testing are given the elongation. in Table 3. The values given are for the maximum stress and the elongation at rupture, measured in tension. The The detonation velocity for formulations with 84 and 85% particle distribution in this case had a much greater effect loading are compared with those for CX-84A and on the value for the maximum stress than on the elongation Composition B in Table 4. There is an significant increase of the sample. The elongation decreased from 26.07 to in the detonation velocity of formulations with 84 and 85% 24.98% when the HMX Class IIVClass V ratio was HMX loading compared to CX-84A and Composition B. increased from 70/30 to 80/20; however, the value for the The detonation velocity for the HMX-based formulations maximum stress decreased from 0.62 to 0.53 MPa. are 8351 and 8200 4sfor formulatiom with 85 and 84% Increasing the ratio of the curing agent/polymer ratio from solid loading respectively, compared to 7908 and 7892 4s 1.1 to 1.2 resulted in an increase in the value for the for CX-84A and Composition B respectively. maximum stress, from 0.62 to 0.69 ma,and a signifcant decrease in the elongation of the explosive, from 26.07 to Ballistic capacity experiments have also been conducted on 15.71%. An increase in the solid loading produced a formulation with 84% loading. These results are 0 explosives with a lower elongation, 26.07% for 84% HMX compared to those for CX-84A and Composition B (Ref 9) loading compared to 20.35% elongation for a similar in Table 5. The detonation velocity of 8197 4sis in formulation with 85% solid loading, without effecting the agreement with the value measured on cylinders 5.08 cm value for the maximum stress. in diameter using both streak camera and ionization probes. The detonation pressure was evaluated at 27.9 GPa. This

Formulation Viscosity (kP) Pot Life (min) Hardness (Shore A)

Before Curing Agent After Curing Agent

1 11.2 1.6 285 63

2 12.0 2.6 224 67

3 10.8 2.0 258 68

4 11.6 4.0 137 65

Table 3: Mechanical Properties of Formulations

Formulation Room Temperature 4ooc Stress Elongation Modulus Stress Elongation Modulus ma) (%) (MPd ma) (%I Wa) 1 0.62 26.07 5.02 1.24 22.92 23.652

2 0.53 24.98 4.95 1.14 24.24 19.30

3 0.69 15.71 8.71 1.35 17.48 17.48

4 0.62 20.35 6.62 1.02 16.89 26.79 10-4

Table 4: Detonation Velocities of Formulations

Explosive c F Formulation 1 II Formulation 4 I 8351 II . CX-84A 7908 11 II Composition B I 7892 II

Table 5: Explosive Characteristics from Ballistic Capacity Evaluations

Formulation 1 CX-84A

0 (dd) 1.618 1.554 1.717 8197 I 7908 I 789% 0

p - density D - detonation velocity Po - detonation pesslne Eo - chemical energy K@- maximum kinetic energy

is the same as the value obtained for Composition B and 1.16 an for Composition B and CX-84A respectively. A is higher than the value of 25.4 GPa obtained for CX-&A. small difference can also be noted as B result of a change The kinetic energy appears to be lower than that of in particle size distribution. Composition B Composition B having a kinetic energy of 1230 J/g compared to 1114 J/g for the formulation with 5. DISCWSSION 84% HMX, but higher than that of CX-84A (1076 J/g). The development of an insensitive explosive must be However, further experiments, such as the Cylinder Test, considered not only from the point of view of the are needed in order to evaluate the performance of these properties of the fmal products but also from a processing 0 explosives more precisely. viewpoint and for this reason these characteristics have been included in this evaluation. Since this is a The shock initiation sensitivity was evaluated with the preliievaluation of this system of explosives, the DREV Gap Test for two formulations with 84% loading. initial objective was to determine the formulation limits One of these formulations had an HMX Class E/Class C with respect to processing and the resuiting sensitiviq and ratio of 30/70 and the other had a ratio of 20/80. These performance characteristics. values are compared to those for Composition B and CX- 84A (Ref 1) in Table 6. The barrier thickness of 1.16 cm Since these formulations are intended for cast-cured PBXs, for the shock sensitivity of CX-84A is higher than the the viscosity of the mixture is a very important value for the fmal formulation. Improvements were made consideration in their processing. The particle size in the formulation to reduce the shock sensitivity; however, distribution did not have a great effect on the viscosity of the sensitivity was evaluated with the Calibrated Shock the mixture for 1M% HMX loading. Viscosity Wave Test (Ref 6). There is a signifcant improvement in measurements of 2.6 kP for a HMX Clilss WClass V ratio the shock sensitivity of these formulations. The barrier of 80/20 and 1.6 kP for a HMX Class WClass V raeio of thickness for formulations with 84 and 85% HMX loading 70/30 were determined. A greater effect is observed for were 0.79 and 0.73 cm respectively, compared to 1.14 and formulations with 85% solid loading since the viscosity is 10-5

Table 6: Shock Initiation Sensitivity

Explosive Gap Thickness (cm)

Formulation 1

Formulation 2 11 CX-84A I 1.16 II Composition B 1.14

already higher and therefore the particle distribution has a There is a significant increase in the detonation velocity for greater effect on the viscosity. formulations loaded with 84 and 85% HMX compared to Composition B and CX-84A. These values have increased The pot lie of 137 min for the formulation with a higher from 7900 m/s for Composition B and CX-84A to 8351 solid loading represents a value significantly lower than and 8200 m/s for formulations with 85 and 84% HMX that for formulations with 84% HMX loading. This value loading respectively. IS ahnost half of that for formulations with 84% loading; however, either value in this range is considered An initial evaluation of the performance of the explosive acceptable. All the values for the hardness fall within a was carried out with a ballistic capacity test. There small range, 68 to 63 Shore A, and therefore this need not appears to be some improvement in the performance of the be considered when fmalising the formulation. Therefore, HMX-based formulation compared to CX-MA, the kinetic the processing of formulations having parameters within energy being 1114 J/g for the HMX-based formulation and this range of values is possible; the only restriction might 1076 J/g for CX-MA, but this must be further evaluated be on the particle distribution at 85% HMX loading which with a more precise test. The detonation pressure could present a problem in optimizing the sensitivity determined in this evaluation was the same as that for characteristics of the explosive formulations. Composition B, 27.9 GPa, which is higher than the value of 25.4 GPa determined for CX-MA. It is also necessary Since the mechanical properties of the explosive affect to evaluate a formulation with 85% HMX loading in order their vulnerability, the optimization of these properties is to determine if the increase in loading will result in a an important step and gives another indication of the signifcant increase in performance. This, along with the limitations and effects of various formulation parameters on processing and sensitivity data, must be considered when the explosive properties. The effect of reducing the finalizing the formulation. percentage of fme particles in the particle distribution is to reduce the maximum value of the stress from 0.62 to 0.53 The particle distribution does affect the shock initiation MPa. for formulations with HMX Class WClass V ratios sensitivity of the explosive as can be seen from the of 70f30 and SODO respectively, without affecting the increase in barrier thickness from 0.73 to 0.79 cm for elongation si&icantly. This must be considered if the fomulations with HMX Class WClass V ratios of 80/20 particle distribution must be modified to meet sensitivity and 70f30 respectively. This must be investigated futher requirements since further modifications to the formulation and the effect of an increase in solid loading must also be would be necessary to compensate for this. Increasing the evaluated. solid loading results in a decrease in the elongation, from 26.07 to 20.35% for formulations with 84 and 85% HMX 6. CONCLUSIONS loading respectively, without affecting the value for the Further work must be canid out to evaluate the shock maximum stress which remained at 0.62 MPa. Increasing sensitivity and performance of these formulations more the curing agenwolymer ratio results in a signifcant precisely. In particular, formulations with 85% loading decrease in the elongation of the explosive, from 26.07 to must be evaluated to determine the effect of the increase in 20.35%. for a 10% increase in the curing agenwolymer solid loading on the shock initiation sensitivity and the ratio. In addition to this, the value for the maximum stress performance. More precise evaluations must be conducted increases from 0.62 to 0.69 MPa for the same increase in with the Standard Cylinder Test and the Calibrated Shock curing agent/polymer ratio. Experience with CX-84A has Wave Test in order to optimize the formulations with indicated that the elongation for Formulations 1 and 2 respect to processing, shock sensitivity, performance and should result in explosives with a low vulnerability (Ref 6); fmally the vulnerability of the explosive. however. it will be necessary to increase the value for the maximum stress. 10-6

7. REFERENCES 1. Drolet, J.F., Lava, R.R., B6Ianger. C. and Walker, 7. Pasman, H.J., Walker. G.R. and Matte. Y.. "Castable G.R.. "Castable Plastic Bonded Explosive CX-84A". Composite Explosives: Evaluation of Output by the

DREV M-2564/81, October 1981. Standard Cylinder Test". DREV R-4094118,Mqy 1978. c

2. Drolet, J.F. Lava, R.R. andPelletier. P., "Plexibility 8. Parinaccio, R., "Ballistic Capacity of Trigran in the Processing of Castable Plastic-bonded Explosive", DREV R-4539/89. May 1989. Explosives", DREV M-2597/82, August 1982 . 9. D6foumeaux. M., "Transferts d'hergie dnns la 3. Pelletier, P. and Drolet, J.F., "Curable Plastic Bonded propulsion par explosif', Sciences et Techniques de Explosive (CX-84A) - Production Scale-up'', DREV M- i'Armement, 3' et 4' fascicules, Paris, 1973. 2673/84, June 1984. 10. BBlanger, C., Walker, G.R. and Matte, Y., "Some 4. Pelletier, P., Drolet. J.F. andlavem, R.R., "Composite Explosive Devices for Generating Plane Waves", Explosive CX-84A Material Specification", DREV DREV M-2572/82, January 1982. M-2603/82, August 1982 11. Bellanger. C., "?bUthode d'&aluation de I'Explosivit6 5. BQanger, C. and Matte. Y., "Shock Sensitivity of CX- des Explosifs", in "Combustion and ReactionKinetics", 84A and Composition B to Flyer Plate Test", DREV Fraunhofer-Institut fiir Cbemische Teclmologie 22nd M-2642/83, September 1983. International Annual Conference, July 1991. Paper 10.

6. BQanger, C.. "Formulation Parameter Study to Reduce 12. BQanger, C. and Walker, G.R., "DREV Setback 0 Shock Sensitivity of Cast-cured PBXs", DREV M- Simulator: Design and Performance", DREV R- 2986/89, May 1989. 4274/82, November 1982.

Discussion

QUESTION BY LENBERGER. FRANCE: Have you utilized rubber plates so as not to deteriorate the test facility? 0 ANSWER: We have never used rubber plates at the DREV. Soft steel plates permanently protect the concrete walls and we have used wood for additional protection. 11-1

ESD TRAITS OF BULK PROPELLANT UNDER PRESSURE , Claude I. Menill, Propellant Development Section, OL-AC Phillips Laboratory, Edwards AFB, California 93523-5000 USA Jo Anne Askins, Research Center for Energetic Materials, . New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801 USA

ABSTRACT Astronautics Laboratory) was one of several laboratories that initiated solid propellant ESD Since the Pershing booster motor incident studies. Goals were to find adequate test occurred in 1985, much has been leamed methods for observing ESD sensitivity, to about how to test for electrostatic discharge rank ESD sensitivities of various solid (ESD) characteristics and what factors propellants, to discover what variables influence ESD initiation sensitivity for solid influenced ESD behavior, and to determine propellants. Small propellant samples have procedures for reducing ESD risks. These shown enhanced ESD sensitivity when placed studies are continuing. 0 under pressure. Since changes in bulk solid propellant ESD traits under the influence of The US ESD test at the time of the Pershing elevated pressures were not found in our incident had been adapted from procedures literature surveys, equipment was Fabricated used with pyrotechnic and ammunition primer so that pressure effects on ESD behavior of a materials. Solid propellant sample sizes were hydroxy terminated polybutadiene (HTPB) not specified on the basis of their suitability propellant could be observed. In addition, a for exhibiting ESD sensitivity. In our limited additive study was conducted to see if laboratory this was interpreted to mean that large ion salts could reduce the ESD initiation very small sample sizes could be used. sensitivity of a sensitive HTPB propellant Samples that we tested at that time were about 12.7 mm (millimeter) in diameter with thicknesses about 0.6 to 0.8 mm. Our criteria -1. BACKGROUND for a failure was the appearance of smoke and/or fire. Since smoke or fire never ESD initiation is a significant hazard with appeared in our solid propellant testing with some hydrocarbon binder solid propellants the small disc samples, lack of ESD risk was filled by ammonium perchlorate (AP) and assumed. aluminum (Al), especially, hydroxy terminated polybutadiene (HTPB) propellants. A much better ESD test was what we call the This hazard was dramatically brought to "French test" (Ref. 1). French investigators at United States (US) attention with the case SNPE (Societe Nationale des Poudres et bursting "Pershing" incident in Germany. The Explosifs, Kent and Rat) employed large violent event involved a HTPB propellant samples that provided smoke and fire indi- installed in an electrically nonconducting cations of solid propellant ESD sensitivities. motor case. Some questions asked following Their samples were 90 mm diameter by 100 the incident were: Why didn't the ESD tests mm length cylinders. These samples were that were used indicate the degree of hazard? roughly 7000 times larger than those How could we adequately test to see if ESD employed in our initial ESD test method. initiation was a significant hazard? Were other propellant types ESD sensitive? What Our laboratory adopted the French test and were ways to diminish or remove propellant found after some experimentation that ESD hazards? indicarions of bulk solid propellant ESD sensitivity could be obtained with more Our laboratory (Now a part of the Phillips sensitive propellants using cylindrical samples Laboratory and formerly named the Air Force as small as 19 mm diameter by 38 mm length Rocket Propulsion Laboratory and the (Ref. 2). These samples were less than one 11-2

fiftieth the mass of the original French Corp with thin (0.69 mm thick) sheet samples propellant sample. See Figure 1 for ESD of a HTPB propellant (Ref. 3). In the Thiokol sample size comparisons. This smaller study 0.69 mm thick samples of a HTPB propellant sample size was adopted for use at propellant were mechanically squeezed our laboratory because our small experimental between metal plates while adjustable voltage mix capacity made fabrication of an adequate charges from a capacitor circuit were applied. number of ESD propellant samples using the Pressures ranged from normal ambient larger sample size difficult. The primary pressure up to 55 atmospheres (810 psig). difference in test performance was that the Threshold initiation voltages were recorded larger cylindrical samples bumed to for a number of thin HTPB propellant sheets completion much more frequently than the over the pressure range as shown in Figure 2. smaller samples. A brief bright burst of flame Values ranged from roughly 5000 to 6000 from one or more locations with the formation volts at ambient pressure down to roughly 600 of cracks was the typical positive response of volts at 55 atmospheres (atm). Thus, the main the smaller samples when they reacted to interest in the bulk HTPB propellant study elecmc charging at ambient pressures. Phil was to see if large samples would exhibit an Gibson at our laboratory also showed that order of magnitude decrease in. threshold cylindrical propellant samples 9.5 mm diame- initiation voltages over a similar pressure ter by 25 mm in length were too small to range as did the thin solid propellant samples. produce smoke and/or fire indications under conditions similar to those that gave positive -2. EQUIPMENT DESCRIPTION responses with the 19 mm diameter by 38 mm length cylinders (Ref. 2). Thus, the problem Several features were desired in designing with the earlier US ESD test was that thin disc pressure application equipment for conducting propellant samples at normal ambient ESD studies on a HTPB propellant. (1) A pressures were tm small to give smoke and/or robust system that could be reused fairly fire indications. Later we came to the conclu- frequently without equipment failures. (2) A sion that abrupt passage of current (electric test system that minimized pans replacements breakdown) through a propellant sample and refurbishment efforts during a number of always provides the possibility of ignition. test trials. (3) A system that could completely Electric breakdown became our minimum contain a violent sample explosion if it measure of a positive ESD response. Electric occurred. In this case the subscale bulk breakdown had often occurred in the earliest propellant ESD test sample was desirable ESD tests without smoke but with very minor because it was small enough to be contained material ablation noted in some instances. It in a modest sized. chamber if explosive is difficult to specify how sensitive a behavior was exhibited. (4) Capabilities to at propellant will have to be before it becomes least 40 KV and 48 atm (1000 pia) pressure. an appreciable ESD accident risk. However, (5) Use of niuogen gas pressure rather than laboratoly ESD solid propellant tests have mechanical pressure. been only crudely related to rocket motor hazards by determining if a propellant under Figure 3 shows a cross sectional view of test is more or less ESD sensitive than a the ESD test chamber that resulted from the propellant involved in a prior accident. considerations above. Descriptions of the chamber parts are given below. Investigation into changes in threshold initiation or breakdown voltages of bulk HTPB The cylindrical chamber was constructed propellant as a function of applied pressure from 3140 alloy steel. Intemal dimensions seemed a desirable area to explore. Bulk with end plates installed were 178 mm propellant ESD hazards appeared to be more intemal diameter (ID) by 424 mm length. appropriate for rocket motor hazards where This was a volume of about 10.5 liters. large pieces of propellant are installed rather Chamber walls were about 15 mm thick. A than for thin samples. In any event, a heavy electric conductor led from the pressurized bulk propellan: study would cylindrical chamber to the ESD grounding complement the work completed by Thiokol system. 11-3

End plates were made from 304 stainless Electrode configurations were relatively steel alloy. The upper end plate was 76 mm complicated as shown in Figure 3. At the thick and the lower end plate was 35 mm bottom of the chamber the lower elecuode

/ thick. Segmented lock rings inserted into started as a 6.4 mm diameter rod of 304 cylindrical chamber grooves were used to stainless steel alloy that had an integral 3mm hold the end plates in place. Double 0- thick plate of 12.7 mm outer diameter located . rings were used to avoid gas leakage around 6.4 mm from one end of the rod. At the other the end plates. O-rings were lubricated with a end of the rod a 3.2 mm diameter hole 12 mm thin film of a heavy Krytox oil (DuPont, deep was drilled. This hole served to fit with perfluoropropylene oxide). Use of hydrocar- a banana plug connector attached to the bon and silicone oils resulted in such a high ground wire that would be attached during friction load following propellant burning that ESD testing. The lower electrode rod was the upper end plate was very difficult to passed through the bottom insulator so that the remove. Perhaps, the Krytox oil had a lower integral plate remained inside the chamber. capacity for dissolving hydrogen chloride gas The plate prevented electrode blowout. from propellant combustion than the other Resting atop the inside end of the lower lubricants. The lower end plate rested against electrode rod was an electrode extension rod a hard aluminum alloy ring grooved to a depth of 12.7 mm outer diameter containing a 6.5 that would fail in shear allowing the lower end mm cavity to fit over the upper end of the plate to be forced out of the chamber if lower rod and terminating in a 6.4 mm internal pressure exceeded about 350 atm. diameter end for a distance of 6.4 mm. Placed This seemed an unnecessary safety feature for over the 6.4 mm end of the extension rod was the ESD tests since test pressures did not a 6.4 mm thick plate of 102 mm diameter exceed 69 atm. made of 304 stainless steel alloy. A 6.5 mm hole was drilled through the center of the plate Nylon electrode insulators were used to to admit the 6.4 mm extension rod end. These encase 6.4 mm diameter, 304 stainless steel, loose connections had to be polished electrode rods. The insulators extended frequently to remove high resistance solid beyond the end plates 5 1 mm or more to help corrosion products. prevent sparks arcing from the electrode rods to the end plates at test voltages up to 40 KV. On top of the plate a graphite cup was set to Insulator outer surfaces were tapered as they contain the propellant samples during test. passed through the end plates. With intemal Graphite’s electrical conductivity allowed it to diameters of 38 mm and exiting diameters of form the sample contacting part of the lower 25 mm the insulators were prevented from electrode system. Graphite’s heat resistant being blown out during testing. The inside qualities also permitted propellant samples to end of the upper electrode insulator was burn without damage to either the graphite preferably covered with two layers of thin cup or the chamber walls. The graphite cup Teflon tape (12.7 mm width). Teflon tape is was 177 mm outer diameter (OD) by 44 mm often used as a thread lubricant in our thick at the perimeter. A cavity was formed in experimental equipment. This was found to the graphite by reducing the thickness to 13 be desirable when the upper insulator became mm in the center for a diameter of 54 mm. . a short circuiting element due to charring Eight 25 mm half diameter channels were upon exposure to gaseous combustion machined vertically around the cup outer edge products during previous tests where samples for facile passage of gases around the graphite burned in the pressure chamber. Ordinarily, cup. the Teflon tape was reinstalled about every other ESD test under pressurized conditions The fust upper electrode system had a 304 that produced bulk sample combustion. RTV stainless steel alloy, 6.4 mm diameter rod silicone glue was used to seal the electrode passing through an upper electrode insulator. insulators into the end plates. RTV adhesive The upper rod through the insulator was also used to seal around the electrode terminated with an integral 3 mm thick plate rods. having a US number six threaded hole into the 11-4

rod at the plate end and a 3.2 mm diameter diameter in place of the previously used 25.4 hole of 12 mm depth drilled into the other end mm diameter contact. As before a 6.4 m of the rod. The 3.2 mm hole had a banana diameter upper electrode rod passed through plug connector attached to the high voltage the nylon insulator. It was much longer (350 system inserted in it during testing. The mm) than the earlier electrode rod. No threaded hole allowed a US number six screw adhesive was used to seal the electrode rod in to hold a wire connector on the electrode rod its path through the nylon insulator. For attached to a short length of flexible, sealing, the new upper electrode rod was multistrand steel wire. As with the lower rod passed through a 6.4 mm diameter Swagelok passing through the nylon insulator, the upper tube fitting that was threaded into the outlet electrode rod was put through the insulator so end of the nylon insulator. The Swagelok that the integral plate was inside the test fimng was equipped with Teflon ferrules that chamber. At the other end of the multistrand permitted the electrode rod to slide through steel wire, a rectangular steel plate (about 25 the fitting when loosened and to be securely mm by 19 mm by 1.25 mm thick) was sealed when tightened. The inside end of the attached using another wire connector and a rod was threaded and an internally threaded US number six bolt. 304 stainless steel sleeve of 9.5 mm outer diameter by 12 mm length was screwed onto A terminal part for the initial upper the threaded end. The 9.5 m sleeve electrode system was an upper sample contact prevented electrode blowout during measuring 25.4 mm outer diameter by 19 mm pressurized operations. In addition, the 9.5 thick. This cylinder was made of 304 mm diameter sleeve and rod end was the stainless steel alloy. The comer of the electrode part contacting propellant samples cylindrical contact on the side resting against during subsequent tests. As before, the the propellant was rounded with a radius of opposite end of the electrode rod contained a 3mm to inhibit comer discharges. A 3.2 mm 3.2 mm diameter hole 12 mm deep so that it hole was put through the center of the could accept a banana plug attached to the propellant contact to enable acceptance of a elecmc system hot line. This second upper banana plug attached to a magnet structure as electrode system was placed in the retracted described below. position when the upper end plate was being moved. Prior to testing the upper end plate The remaining bulk sample upper electrode was installed, the Swagelok fitting was parts were a rectangular magnet (about 22 mm loosened, the rod depressed until contact was by 22 mm by 5 mm thick) secured made with the propellant sample, and the horizontally to the bolt end of a banana plug Swagelok fitting tightened. After the hot line connecter that was inserted into a 3.2 mm banana plug was inserted into the outside end diameter hole drilled into the center of the of the electrode rod, the system was ready for cylindrical stainless steel sample contact. elecmc charge experimentation. This upper Once a propellant test sample and upper electrode. system was an improvement since it electrode contact with magnet structure was contained fewer parts and intervening placed in the center of the graphite cup, this connections did not corrode. Another flexible wire structure, steel plate, and magnet difference with the new electrode system was attached to a stainless steel contact served as a that threshold breakdown voltages seemed to magnetically formed elecmcal path to the be approximately half that with the other samples. upper electrode system. No sketch of the new upper electrode system is provided. When elecaic arcing around the sample was suspected during ESD testing of 0.64 to 0.69 As can be seen in Figure 3, a gaseous mm thick propellant samples, an adjustable nitrogen feed line and an exhaust line were rod upper electrode system was fabricated and connected to the test chamber through the used in place of the upper electrode system lower end plate. The operation of these lines described above as shown in Figure 4. With were controlled by remote control valves this electrode the diameter of the upper placed in the lines. A pressure sensor was propellant contact was reduced to 9.5 mm connected into the nitrogen inlet line between 11-5

the nitrogen feed control valve and the propellant sample was recorded. Some chamber. A 0.7 mm wall 25 mm outer variations in threshold voltages were diameter stainless steel tube about 125 mm observed, and the lowest voltage recorded for ~ long was held by a fitting to the chamber any number of samples under the same outlet hole through the lower end plate. A pressure and temperature conditions was stainless steel wire mesh screen was inserted called the threshold initiation voltage or . into the 25 mm tube next to the chamber threshold breakdown voltage. outlet port. Glass wool was stuffed into the 25 mm tube atop the wire mesh to help filter For the purpose of readily observing the out aluminum oxide particles carried by gases effects of temperature and pressure upon exhausting from the chamber following propellant ESD characteristics an ESD operation of the chamber where a propellant sensitive HTPB propellant was formulated. sample bumed. The glass wool filter system This was given the name, ESD-1. This was added when it was found that aluminum propellant contained 12% HTPB binder, 10% oxide particles seriously shortened the service each of Valley Metallurgical H-3 (3 Micron) life of the remote control exhaust valve. and Alcan MDX-65 (6 micron) spherical aluminum, and a bimodal distribution of 200 and 16 micron ammonium perchlorate. This -3. DISCUSSION was a good propellant in most of its e characteristics, except that it was more ESD During ESD testing, a HTPB propellant hazardous than desired for use in rocket sample was placed standing at the center of motors. A detailed formulation is provided in the graphite cup, the upper end plate was Table I. The high ESD sensitivity came installed, and contact made with the upper primarily from its small aluminum particle electrode system to the propellant test sample sizes (6 and 3 micron), its high aluminum either magnetically or by direct electrode rod content (20%),and its high solids loading contact depending upon the upper electrode (88%). If less ESD sensitive propellant were structure used. Test pressure was adjusted to desired, the formulation would use a larger a predetermined value, and, through a size of spherical aluminum, a lower aluminum switched capacitor operation, the sample was content, and a lower total solids content. pulsed up to 10 times with a preset relatively low voltage. If no sample breakdown A large number of test samples were cut occurred, the preset voltage was typically from a block of ESD-1 propellant. These raised 1000 volts for the bulk sample testing were cylinders of 24 mm diameter with 38 and the pulse operation repeated. Voltage mm lengths. Some thin propellant sheets of steps for the thin propellant sheets were 100 0.64 to 0.69 mm thickness were cut from the volts. Increasing step increases in imposed cylinderical samples to provide thin samples voltages were continued until the oscilloscope for testing to see if our results would be e registered a large voltage drop with a massive generally similar to that obtained by the current surge (electrical breakdown). Under Thiokol Corporation in their HTPB propellant elevated pressures bulk samples (38 mm long) tests. Since Thiokol was using a different always bumed to completion. With the propellant formulation and held thin propellant burning a temporary pressure propellant samples under mechanical force increase of about 40 atm occurred and a between stainless steel plates, comparison of thermocouple placed against the outside of the the results under similar but gaseous pressures test chamber wall registered a short lived was desired (3). temperature rise of 20 degrees Celsius or a more. These were all indications of a positive When ESD testing started at the existing test. With thin samples and bulk samples ambient pressure and temperatures found in under one atm conditions, only physical the Mojave Desert during June and July, inspection of samples and voltage and current breakdown voltages often exceeded 30 KV. changes indicated propellant electric This was unexpectedly high and may have breakdown. The lowest voltage that would been due to the following factors: (1) The provide an elecmcal breakdown of the ESD elecmcal test circuitry had been recently replaced using new components so that atm values. From a safety standpoint the voltage capability could be raised from about refreshing conclusion is that bulk propellant 40 KV to near 100 KV. This included ESD threshold propellant initiation levels do removal of a series resistor of loo0 ohms and not get overly sensitive at elevated pressures. changing from a 9.5 mm diameter electrode Even at 69 atm [.he sensitive bulk propellant sample contact to a 25.4 mm diameter did not react until the voltage was many KV. electrode sample contact for the hot electrode. This means that as pressure is applied to bulk (2) Much higher ambient temperatures were propellant structures the ESD hazard being experienced, 25 to 42 degrees Celsius, thresholds can stay at relatively high voltages. than during earlier fall and winter testing which ranged from 5 to 20 degrees Celsius. Following the initial pressurized bulk During one working day ambient temperatures propellant experiments, thin sheets of ESD-1 could often vary from about 25 to 38 degrees HTPB propellant were cut from test Celsius. As a result a temperature controlled cylinders. Test samples were selected that had recirculating air system was connected to a thicknesses in the range of 0.64 to 0.69 mxn. cardboard box installed around the test cham- During initial thin propellant sample testing at ber. This allowed testing at relatively constant one atm, electric breakdowns at one KV were temperatures independent of the outside observed. Examinations of the samples under ambient temperatures. After minimal test did not show any bum spots or cracking experimentation, test temperatures were main- that would be expected if an electrical tained near 10 degrees Celsius since it was breakdown of the thin propellant sheets took preferred to test below 30 KV. place. Since the voltages seemed close to that required to jump around the propellant Figure 5 contains 69 atm (1OOO psig) data sample, a new upper electrode rod structure as exhibiting a declining trend for threshold described above was fabricated and installed. ESD-1 bulk propellant initiation voltages as With the new 9.5 mm diameter upper test temperatures were reduced. Repeat- electrode propellant contact, rather than the ability of threshold breakdown voltages were previously used 25.4 mm elecnode contact, highly variable, but average values declined about 7 mm of air gap was added to the path with decreases in sample test temperatures. A needed for arcing around the propellant series of one atm trials showed a similar sample. Table I1 exhibits the results of two declining trend for threshold initiation pressurized tests and two tests at ambient voltages as test temperatures were reduced. It pressure. Elecmcal breakdowns of the ESD- appeared that threshold breakdown voltages 1 thin sheets occurred at 500 and 700 volts were reduced from roughly 27 KV to 15 KV under 46 (670 psia) and 38 (550 psia) atm in going from 35 to 10 degrees Celsius, pressures, respectively. For the 500 volt respectively. breakdown only a minor dark stain and a small pit were visible evidence of propellant ESD-1 24 mm diameter by 38 mm long breakdown in the pressurized test. Complete propellant cylinders were tested at a variety of sample buming was obtained following the pressures. Minimum breakdown voltages for 700 volt breakdown. Tests at one atm showed each sample were recorded. Figure 6 shows a thin sheet propellant elecmcal breakdown plot of this data. Some of the data points are failure twice at 1400 volts. No complete the same result for two experiments. sample buming was noted. When elecmcal Although the data show rough variation in breakdown occurred in the one atm tests, threshold breakdown voltages at any pressure, small smoky stains and small black pits were a broad band trend toward lower initiation observed on the thin propellant samples at the thresholds with increasing pressure is points where breakdown took place. These apparent. In contrast to the Thiokol thin breakdown results were quite different from propellant sheet data where threshold voltages Thiokol’s results obtained with their 0.69 mm declined to about one tenth of the one atm sheets of HTPB propellant (Ref. 3). First, the values under about 55 atm conditions (Ref. 3). 1400 volt breakdowns indicated that the ESD- bulk propellant minimum breakdown voltages 1 propellant was more electrostatic sensitive seemed to diminish only to about half the one than the Thiokol HTPB propellant. Second, 11-7

the violence of reaction by the thin ESD-1 areas. The thin propellant projection would propellant sheets under elevated gas pressures provide enhanced ESD susceptibility versus at electric breakdown was much milder than rounded comers, the bonded rubber covering obtained in the Thiokol study with propellant would add increased ESD vulnerability due to samples squeezed between metal plates. its capability to mechanically confine elevated When Thiokol’s thin samples between plates gas pressures once chemical reaction was under mechanical pressure had elecmcal started, and the thin propellant connection to breakdown, loud explosive behavior was bulk propellant would help ensure that sus- usually observed (Ref. 3). This was probably tained buming would occur once an ESD due to combustion gases producing much event was initiated. A second sensitive zone higher pressures in small regions around could be on the sides of case bonded rocket breakdown points than could be obtained motor grains where imperfectly installed under pneumatic conditions. Third, the ratio insulation sheets had small width cracks between threshold initiation voltages at one between them. Again, the enhanced ESD risk atm and roughly 50 atm pressure conditions factors of thin propellant attached to bulk was about 2 to 3 by the gas pressurized tests propellant and mechanical confinement would versus Thiokol’s ratio of about ten. be obtained. Squeezing of propellant samples to smaller thicknesses would be expected to further During production operations stray voltages decrease threshold voltages under pressure of lo00 volts are easy to obtain, but with slow between metal plates. Thus, the Thiokol data deliberate movements during material and would be expected to have larger threshold equipment transfers triboelectric voltages can voltage ratios because of the thinning effect be usually controlled to less than 5000 volts. mechanical pressure would have on the From this point of view manufacturing and propellant samples. The similarity between field operation ESD safety would be greatly the ratios of threshold breakdown voltages at improved if thin propellant projections on one atm to gas pressurized conditions, roughly moror grains, sharp irregula propellant edges, 2 to 3, for both thin and bulk propellant mechanical confinement, and rapid frictional samples seems logical if no perturbing factor, movements could be avoided or minimized. such as sample thinning, is added. If such features could be controlled, ESD incidents would be unlikely except with the Thin propellant samples exhibited a lower more ESD sensitive propellants. tendency to sustain buming once elecmcal breakdown occurred than the bulk propellant Prominent characteristics of HTPB ESD samples. This might be caused by increased sensitive propellants are high metallic fuel opportunity for heat losses in electric contents, high total solids content, and breakdown zones. Thus, it seems logical to extremely high elecmcal resistance. All ESD assume that sustained buming might always sensitive propellants that our laboratory has result from electric breakdowns once observed conrained metallic fuel, usually propellant masses became large enough. powdered aluminum metal. How would the factors of metal content, high solids loadings, Rocket motors without electrically conductive and extreme electrical resistance act 10 motor cases or exterior coatings could have produce ESD vulnerabilities? Metal fuel small zones that would be more ESD sensitive particles would provide very high than the remainder of the motor structures. temperatures to aid growth and sustaining of These special ESD sensitive sites would combustion processes. High metal contents probably contain tapered thin propellant grain and smaller particle sizes would mean that protrusions and confinement provided by gaps between metal particles would be smaller adhesively bonded surfaces. Two examples of than otherwise. Smaller metal particles would ESD sensitized areas are shown in Figure 7. also mean that particle heat capacities would Propellant grain ends terminated with feathery be small so that high particle temperatures tapered thin propellant projections overlaid by could be readily achieved if high temperatures bonded insulation or flame inhibiting rubber were developed by ionization processes in would be probable ESD most vulnerable binder touching the metal particles. High 11-8

solid contents would also reduce gaps would be expected to decline and the ESD between metal particles as compared to lower vulnerability would also diminish as solid levels. If electric breakdown paths compared to untreated KJ-15 propellant. through a metallized propellant jump gaps . through binder material between conductive Resistances for 7.6 mm thick by 76 mm metal particles, the smaller gaps would take diameter discs of both KJ-15 and the boride lower voltages to traverse the accumulated doped KJ-15 propellants were measured as " gaps through the high resistance binder shown in Table III. A value of 8 times 10 to materials. The extraordinary high resistance the 13th power ohms was obtained with the of the binder would cause the cross section of KJ-15 propellant. The salt doped analog the path through binder to be very small. propellant gave about 4 times 10 to the 13th Conductive paths through binder probably power ohms. Although the propellant con- involves ionized material. Ionizing processes taining the tetrabutylammonium 1 typically involve high temperatures, that are tetrabutylboride salt was lower in electrical well above the melting point of aluminum resistance, the change was smaller than oxide films that coat aluminum particles. expectcd. This could mean that either the salt Melting of aluminum oxide films on wasn't appreciably soluble and/or that the aluminum particles has been said to be dissolved material didn't have any appreciable necessary for efficient aluminum combustion. free ion concentrations. Once a localized temperature was high enough for aluminum burning, flame propagation ESD testing of the KJ-15 and salt doped a without quenching would be probable. analog propellants in the form of 24 mm diameter by 38 mm long cylinders took place If the initiation scenario above is correct, at ambient temperatures of about 10 degrees reduction in the ESD sensitivity of metallized Celsius and one atm. Our ESD test equipment propellants might be accomplished by at the time was the model that preceded the increasing the cross sectional area of electric one used for the pressure testing. The one breakdown paths through binder material. atm, minimum threshold breakdown voltage This would decrease electric breakdown path for the KJ-15 propellant was 6 KV as com- peak temperature and as a result, the ability to pared to 9 KV for the boride salt doped start aluminum burning. propellant. Although the increase in threshold breakdown voltage was only 50% of the Increasing the elecmcal conductivity of a untreated propellant value, it would probably solid propellant would spread out an electrical contribute substantially to ESD safety. This breakdown path. If mobile ions could be would happen because higher voltages are introduced into the binder, electrical more difficult to obtain and the greater conductivity would be enhanced. Since propellant conductivity would reduce the time HTPB binders are extremely poor ionic that an elevated elecmc charge on the solvents, special chemical structures would be propellant would take to become dissipated. a required. Large ion salts having low melting points would be expected to be the most Since the upper electrode system had changed soluble. from the 25.4 mm diameter propellant sample contact to the 9.5 mm diameter propellant To test this concept of ESD desensitizing salts contact, retesting of ESD-1 samples seemed tetrabutylammonium tetrabutylboride was put proper to see if changes to the ESD elecmcal into a KJ-15 propellant formulation at a 0.1% equipment had changed threshold breakdown concentration. With the exception that all the voltages. With the new upper electrode aluminum was H-3 (3 micron, Valley system minimum breakdown voltage for two Metallurgical) the KJ-15 formulation matches ESD-1 24 mm diameter by 38 mm length that of the ESD-I HTPB propellant. The salt samples under 10 degree C and 42 atm was selected because it was the only one at the conditions was 5 and 4 KV. With elevated 9 time in our chemical supplies containing large pressures the ESD-1 propellant samples ion structure. If the boride salt was soluble to burned to completion. At ambient pressure an appreciable degree, propellant conductivity two ESD-1 samples had electric breakdowns 11-9

at 11 and 12 KV with cracked samples being explanations for this behavior have been recovered. These results were greatly formulated. different from those obtained earlier with the , larger 25.4 mm diameter upper electrode -4. SUMMARY contact. That is, 12 to 15 KV under 40 to 60 atm pressure and 10 C conditions and 18 to 22 Interesting characteristics appeared during . KV at ambient pressure. There was no clear examination of aluminized HTPB propellant explanation on why the two to three fold reactions to high voltage exposures as reduction in threshold breakdown voltages pressures were varied from one atm to 69 atm would be caused by an electrode change. (1015 psia). F’ropellant ESD vulnerability was Thus, propellant testing after the upper considerably reduced at one atm pressure as electrode change should be referenced to the compared to pressures above 30 atm. Thin ESD-1 propellant threshold voltage values HTPB propellant (0.64 to 0.69 mm) was obtained with the same electrode system. found to react at minimum breakdown voltages about one third or less of minimum I For added soluble salt testing breakdown voltages for bulk HTPB propellant hexadecylmbutylphosphonium bromide was (38 mm) at one ampressure. This ratio purchased. This salt seemed desirable decreased dramatically at 42 atm pressure because its melting point was low, 57 C, and where the thin propellant threshold breakdown its structure contained an even larger ion than voltage was roughly one eighth that for the the boride salt. An analog to the ESD-1 bulk propellant. While the bulk HTPB propellant was made by substituting 0.1% of propellant threshold breakdown voltage the phosphonium salt for 0.1% of the HTPB decreased in going from one atm to 68 atm, prepolymer in the propellant formulation. the change was only to about half to one third This was tested in 24 mm diameter by 38 mm of the one atm voltage. A similar propellant length cylinders at 10 C using the 9.5 mm threshold breakdown voltage ratio was diameter upper electrode contact as shown in obtained with thin HTPB propellant under Table 111. Two cylindrical samples of the gaseous nitrogen pressures. This minimum ESD-1 analog propellant containing the breakdown voltage ratio for thin HTPB hexadecylhibutyl phosphonium bromide gave propellant for one atm and 30 to 60 am one atm and 10 C breakdown voltages of 26 pressures, is less than for similar Thiokol data and 28 KV. Inspection of the analog where thinning of the propellant samples propellant samples following the test showed under mechanical rather than pneumatic no damage for the 26 KV breakdown, pressure can be used to explain why the indicating elecuic arcing around the sample; Thiokol tests showed greater sensitivity at and the 28 KV sample exhibited large cracks elevated pressures (Ref. 3). This indicates that and a few missing surface fragments. Since bulk propellant, such as in motors, can be the improvement in minimum breakdown relatively safe to ESD conditions since many voltage was about twice that obtained for the KVs can be required for ESD inidation with ESD- 1 control samples, these results indicated reasonable propellant formulations. However, even better ESD desensitization than by the bulk propellant would be substantially less earlier tetrabutylammonium teuabutylboride ESD safe if connected to thin propellant salt. projections in motors. Even sharp comers on propellant probably have some considerable When the hexadecylmbutylphosphonium measure of thin propellant ESD bromide propellant was tested at 10 C and 42 characteristics. atm of gaseous nitrogen pressure, a surprising results were obtained. There were threshold Comparisons between mechanically confined electric breakdowns at 5 and 6 KV. This was between metal plates and gas pressure essentially the same as for ESD-1 propellant environments for thin HTPB propellants control samples tested at the same conditions. exhibited much more violent reactions for the Thus, the ESD protective properties of the case of mechanical confinement. This is phosphonium salt seemed essentially to likely due to the much greater local pressures disappear with 40 atm conditions. No around intemal breakdown zones because of 11-10

the rigidity of the confining structures. 1. "Static Elecmcity Phenomena in the Manufacture and Handling of Solid In motors the most ESD vulnerable sites Propellants", Ralph Kent and Roger Rat would contain confinement and thin propel- (SNPE), Proceedings of the 20th DDESB lant attached to bulk propellant. In these Seminar, Norfolk, VA, Volume I, pp 883-899, situations confinement ESD sensitization and 24-26 August 1982. thin propellant ESD sensitization would be . combined with the flame sustainability of the 2. Phillip Gibson, Air Force Rocket bulk propellant. To minimize motor ESD Propulsion Laboratory, Private vulnerability with any given propellant, thin Communication. propellant projections and sharp propellant grain comers should be avoided. Since flame 3. L. E. Davis, Thiokol, Inc., Brigham inhibitor coatings on the ends of propellant City, Utah, Private Communication. grains would add ESD sensitization through their confining qualities, these also should be avoided, if possible. Perhaps, the most powerful method of reducing propellant ESD sensitivity would be through careful selection of components going into the propellant formulation. If thrust performance could be slightly compromised, HTPB total solids could be reduced below 88 percent and the aluminum content could be reduced below 20%. The characteristics of the aluminum particles should also be taken into consideration. Spherical aluminum is safest for ESD conditions and the particle sizes should be larger than that used in our ESD-I propellant (3 and 6 micron). Introduction of large ion salts has been demonstrated to have beneficial effects upon HTPB propellant ESD vulnerability at one atm but not at 40 am. Since only about 0.1% of the ionic materials are needed for substantial ESD sensitivity improvements, these materials are a viable way of attaining a measure of propellant and motor ESD resistance.

Since it is very easy to generate loo0 volts or more electric charge during moving operations, propellants and motors should have threshold breakdown voltages much greater than lo00 volts. If a propellant had a minimum breakdown voltage greater than 10,ooO volts under low temperature and confinement conditions that might be encountered, it would probably be ESD safe in careful (deliberately slow) moving operations. . -5. REFERENCES 11-11

H 1 FRENCH CYLINDRICAL SUBSCALE SAMPLE, I SAMPLE, 1110 GMS 11) e4 1'3 GMS . (30) L E. DAVIS. THIOKOL C0RP.- PRIVATE COMM. 11) KENT AND RAT, SNPE. DDESD SEMINAR, 1902 FIGURE 1. ESD PROPELLANT TEST SAMPLE FIGURE 2. MINIMUM BREAKDOWN VOLTAGE SIZES VERSUS PRESSURE, 0.7 MM HTPB

0 @GRMmE ELECTRODE CUP

FIGURE 4. ADJUSTABLE UPPER ELECTRODE SYSTEM FIGURE 3. PRESSURIZED ESD TEST CHAMBER

35, I TABLE I. HTPB ESD SENSITIVE

0 % INGREDIENT VOLTS R-45M. MPBPREPOLYMER 0.96 20 DO& DIOCTYLADIPATE 2w 0.10 Kv FLEXZONE 6H. N.N-DIPHENYL PHENYLENEDIAMINE I5 DTBH. DITERTIARY BUTYL HYDROOUINONE 0.06 TEPAN. 3M BONDING AGEM 0.10 10 001. OCTADECYL ISOCYANATE 0.04 IPDI. ISOPHORONE DIISOCYANATE 0.14 MICRON. H-3. VALLEY METALLURGICAL 10.00 5 AL 3 5 10 15 20 25 30 35 40 AL 6 MICRON, MDX45. ALCAN 1o.M) TEMPERRTURE, DEGREES CELSIUS AP, 200 MICRON AMMONIUM PERCHLORATE 43.00 AP, 10 MICRON AMMONIUM PERCHLOPATE 25.00 FIGURE 5. MINIMUM.BREAKDOWN VOLTAGE . - TOTAL IO0.W VS TEMPERATURE, HTPB BULK PROPELLANT 11-12

VOLTS 10 Kv FEATHER EDGE ATGRAIN END

05L1 0 10 20 30 40 50 GO 70 PROPELUANT ABSPRESSURE.ATM FIGURE 6. THRESHOLD BREAKDOWN VOLT- AGE VS PRESSURE, HTPB BULK PROPELL. FIGURE 7. PROBABLE ESD SENSITIVE SITES FOR ROCKET HOTORS TABLE 11. MINIMUM BREAKDOWN VS PRESSURE FOR THIN ESD-1 SAMPLES TABLE 111. ESD DESENSITIZING SALTS THICKNESSES .OS4 TO 0.69 MM TEMPERATURE. 10 C 0 TEMPERATURE. 10 C. 9.5 MM DIAMETER ELECTRODE 8.5 MM DIAMETER ELECTRODE PROPELLANT RESISTANCE PRESSURE MINIMUM PROPELLANT PRESSURE.ATM VOLTS, KLI OHMS ATM BREAKDOWN VOLTAGE, KV ESD-I. THIN 1 1.4 KJ.15 (HTPWH-3) OX 1013 1 6 ESD-1. THIN 1 1.4 ANALOG (HTPBM-3/0.1% 4X 1013 1 9 ESD-1. THIN 37 0.7 TETRABUTYLAMMONIUM ESD-1. THIN 40 0.5 TETRABUNLBORIDE) ESD-1 (H~rPBB86MICRON) 1 11 ESD-I 42 4 ANALOG (HTPR086 MICRON/ - 1 26 0.1% HEXADECYLTRIBUWL- MODERATE ESD HAZARD INCREASE WITH ELEVATED PRESSURES PHOSPHONIUM BROMIDE) GREATER ESD SENSITIVITY WITH PRESSURIZATIONAND THIN ANALOG 42 5 PROPELLANT MECHANICAL CONFINEMENT GIVES STRONGER REACTION MOTOR ESD SAFEN AVOIDS THIN PROJECTIONS . ESD VULNEMBIUTY PARTiALLY REDUCED BY LARGE ION SALTS

FIGURE 8. SUMMARY, ESD TRAITS UNDER PRESSURE 11-13

Discussion

> QUESTION BY COLE. CANADA: Did they investigate various concentrations of ion salts and attempt to find a optimum level?

. ANSWFR; They did try 1% of ion salt but it seemed to interfere with propellant cure since it resulted in soft propellant. However, this propellant did seem to have reduced ESD sensitivity. Samples with .01% of ion salt were also produced but not tested.

QUESTION BY MAWBEY. UK: I believe that SNPE found that multiple discharges would progressively degrade the material so that although ignition did not occur on the first discharge later events would cause ignition. Have you found a similar behavior? a ANSWFR; In our test procedure we typically treat the propellant sample with ten pulses (voltage applications) at each voltage level or stop when electric breakdown occurs. If no sample response occurs with ten pulses, the voltage is incrementally raised until propellant reaction occurs. It is very common that ~QLIII reswnse occurs on the first ou Ise, but at some later voltage application at the same voltage level. That is why we conduct pulses at each voltage as we proceed with the testing. If you start with a subsequent sample with an initial voltage 15% above that providing electric breakdown with an earlier sample, you get predominantly breakdown on the first voltage application, but not always.

QUESTION BY COUTUIER. FRANCE?: The present results show a great sensitivity to temperature. The greater risk therefore seems to be a during manipulations when the weather is dry and cold. Have tests with negative temperatures been done? What are the results?

ANSWFR; Since someone else had determined lower temperature influence on HTPB propellant ESD breakdown, we were only interested in the temperature range of interest with our experiments and our particular propellant. It is clear that if temperatures were further reduced that threshold or minimum . breakdown voltages for the HTPB propellant would have continued to decline. So far, we have only completed a limited amount of work with the ESD characteristics associated with the large ion salt additives. Investigation of breakdown voltages of the large ion salt added propellants to lower temperatures at one atmosphere might be interesting. c .

- a

I 2- 1

Development of a Minimum Smoke Propellant Based on Glycidyl Azide Polymer and Ammonium Nitrate

P. Lersard, L. Druet, S. VUleneuve, S. Thlboutot Defence Research Establishment, Valcutier P.O. Box 8800. Courcelette Qu6bec, Canada. GOA 1RO M. Benchabane, D. Alexander Bristol Aerospace Limited P.O. Box 874, Winnipeg Manitoba, Canada, R3C 2.54

SUMMARY polybutadiene/ammonium perchlorate propellant in terms of Composite rocket propellants traditionally developed and smctural integrity, energy density, stability, sensitivity and produced in Canada are based primarily on ammonium burning rate flexibility. perchlorate (AP) dispersed in a polybutadiene (HTPB) binder. Depending on the atmospheric conditions. such This paper discusses the progress made at the Defence propellants can produce a significant amount of secondary Research Establishment, Valcartier to develop such a smoke which is undesirable for certain applications. To propellant. Specifically. the characteristics of a baseline, overcome this problem, the Defense Research Establishment minimum smoke formulation. which meets minimum criteria Valcartier (DREV) has initiated the development of a for processing safety, chemical stability and mechanical minimum smoke, low vulnerability propellant. The new integrity, are described. This baseline formulation falls short propellant uses ammonium niuate (AN) as the oxidizer and of the performance of an AP/HTPB propellant. Means of glycidyl azide polymer (GAP)as the energetic binder. The improving the performance are then described. efforts made and the characteristics of a baseline minimum smoke formulation are described. This formulation meets 2. REQUIREMENTS minimum criteria for processing safety, chemical stability and mechanical integrity. It falls short of the performance of 2.1 Essential an AP/HTPB propellant. Means of improving the The essential requirements for the baseline propellant were: performance are described. a. processing risk no greater than conventional 1. INTRODUCTION reduced smoke composite propellant. Quantitatively All existing high-energy propellants used in solid rocket this means impact and friction sensitivity values for motors are deficient in at least one of two aspects: signature the uncured formulation , as measured on BAM or detonability. Conventional composite propellants using testing apparahues, equal or greater than 15 J and ammonium perchlorate as the oxidizer are non-detonable 30 N respectively. under normal conditions but generate large amounts of b. processability, i.e. reasonable end-of-mix viscosity. hydrogen chloride, a corrosive and toxic gas that contributes curing time and the absence of sedimentation to the formation of secondary smoke under certain frequent during cure. atmospheric conditions. Furthermore, current high-energy C. chemical stability: defined as no more than 2 ml/g minimum-smoke propellants contain large quantities of of gas evolution when subjected to a vacuum nitramine explosive that makes them detonable in tactical stability test (VST) at 100°C for 48 hours. missile configurations. d. room temperature mechanical properties adequate to cast simple test motors. One approach to resolve this dilemma is to develop a composite formulation in which most or all of the 2.1 Desirable ammonium perchlorate is replaced by phase-stabilized The ultimate goal is to have a formulation with energy, ammonium nitrate (PSAN). Unfortunately, ammonium nitrate density, structural integrity and burning characteristics . is not as oxygen-rich or as dense as ammonium perchlorate. equivalent or superior to a reduced smoke composite To regain the lost energy, it is therefore necessary to replace propellant. These values can be quantified as follows: the inert binder. typically a urethane cross-linked polybutadiene in the AP propellant, by an energetic one. In a. a specific impulse value (Isp) of 240 seconds. this context. a binder based on a mixture of a glycidyl azide b. a density of at least 1.6 g/ml.

polymer (GAP) and one or more commercially available C. structural inteprity: at ~ 54'C, elongation at nitroplasticizers is receiving a great deal of attention, the maximum strength greater than 25% and a goal being to produce a GAPpSANhitroplasticizer maximum strength at room temperature greater propellant that approaches a conventional than 0.6 MPa. 12-2

3. PRELIMINARY STUDIES 3.2 Ballistic Performances Prior to formulating a complete propellant system. numerous The theoretical performance of several formulations studies were conducted to assess various potential ingredients comprising GAP, annnonium nitrate and one energetic from the points of view of energy, stability and compatibility plasticizer were determined. Using a thermochemical code, and sensitivity. As well an exhaustive series of tests was the theoretical specific impulse (Isp)of each propellant conducted to optimise the binder system (e.g. without system was calculated as a function of Ihe relative quantity oxidizer). of its three components. In this way, uiiangular composition- performance diagrams were developed for each propellant 3.1 Ingredients system considered, an example of which is shown in Fig.1 The PSAN was procured from the Hercules Aerospace for a composition including TMETN as the plasticizer and Company of McGregor. Texas. The polymer used was some HMX (10%) as a secondary oxidizer. The equivalence commercial glycidyl azide polymer called GAP obtained ratio U$ is defined as the ratio of the total number of from Rocketdyne. Canoga Park, Califomia. The plasticizers reducing valences to the total number of oxidizing valences tested were diethylene glycol dinitrate (DEGDN), triethylene per unit mass of propellant. Results show that if the oxidizer glycol dinitrate (TEGDN). trimethylene glycol uiniuate charge consist solely of ammonium nitrate. specific impulses (TMETN) and butanetriol uiniuate @TIN), all were comparable to those of a conventional AP/HTPB propellant obtained from Trojan Corporation of Spanish Fork, Utah. A can only be achieved at plasticizer/polymer ratios of seater 50/50 mixture of bis-dinitropropyl acetal and bis- than 111. Such high values are necessary because ammonium dinitropropyl formal (BDNPA/O obtained from Aerojet nitrate (AN) is a rela.tively poor oxidizer. Such a heavily Limited of Sacramento, California. was also evaluated. The plasticised binder may be advantageous from a processing isocyanates were N-100 from Bayer Canada Inc. in Montr6al. point of view, but the mechanical properties and Quebec and isophoroue diisocyanate (IPDl) from Huels vulnerability of the propellant will likely be adversely Cop in New York. New York. The stabilizers such as affected. diphenylamine (DPA) and methylnimaniline (Mh'A) were prmured from BDH Inc. in MonUEal, Qu6bec. In some cases 3.3 Stablllty/CompatlbiUty Studies di-butyltin dilaurate (DBTDL). from Aldrich Chemical, The method used to evaluate the stability/compatibilily of Milwaukee, Wisconsin was used as a curing catalyst. ingredients and mixtures was described elsewhere (Ref. 1). Testing is performed in a modified mercury-free vacuum

AN + 10% HMX

GAP TMETN +N100 Figure 1

Composition-Performance Diagram 12-3

stability cell for 48 hours at 100°C. Gases produced are Fortunately, effective chemical stabilizers, such as DPA and analyzed using a gas chromatograph. MNA, were found to keep the gas evolution within acceptable limitr, as shown in Table 2. Results were first obtained for GAP, plasticizers and mixtures of them. The BDNPAF proved to be the most 3.4 Sensltivity Studies stable plasticizer. the more energetic TMETN and B'MN All ingredients were tested for impact and friction sensitivity unfortunately being less stable. Further testing revealed on BAM testing apparatuses using standard methods. major incompatibilities between AN and both GAP and Autoignition temperature were evaluated using a DREV BDNPA/F as illustrated below. developed furnace. Results revealed that the niuated esters are by far the most sensitive to impact, with BDNPA/F being the least sensitive of the plasticizers. Table 1 Incompatibility in GAPIANIBDNPNF Mixtures Small propellant batches (25 g) were prepared in a remotely controlled simple glass vial and stirrer arrangement and tested for impact. friction sensitivity and autoignition GAS VOLUME temperature. Later, 100 g batches were prepared in an SAMPLE Atlantic Research 2 CV Helicone Mixer for further evaluation. As shown in Table 3, the sample of GAP/PSANflMETN uncured mixture proved to be very sensitive to impact when compared with the AP/HTPB AN 0.1 propellant. It was found that BDNPAF produced fie least sensitive propellant paste in terms of friction sensitivity. BDNPA/F 0.2 3.5 Oxidizer Studies GAP/BDNPA/F 0.8 On the basis of its availability and good phase stability, GAP/AN 6.0 nickel oxide phase stabilized ammonium niuate (PSAN). containing 3.5% NiO, was selected after a study of available BDNPAIFIAN 4.6 materials and a review of ICT's work (Ref. 2). In the initial propellant processing experiments, the PSAN was not dry

Table 2 Chemical Stability of GAPM-lOO/BDNPNF/AN Mixtures

GAS GAS COMPOSITION ( % ) SAMPLE VOLUME mUg co co2 N1 N20 GAP/N-lOO/BDNPA/F 0.6 0 35 60 5 GAP/N-lOO/BDNPA/F/AN 9.0 1 24 55 20 GAP~-lOO/BDNPAF/AN+2% MNA 0.5 0 44 53 2

AUTOIGNITION IMPACT FRICTION SAMPLE TEMPERATURE Joules Newtons "C AP/HTPB 15-25 30 245 PSAN/GAP/TMETN c1.5 192 160 PS AN/GAP/BDNPA/F 15-25 >360 203 12-4

nor pre-treated prior to use. although care was taken to 4. BASEILINE PROPELLANT minimize exposure to moisture during manipulation. Discrepancies in the results obtained suggested that control 4.1 Formulation of the moisture content of PSAN could have a large A baseline formulation was established by combining the influence on the curing of the propellant. A reliable method best ingredients available from the point of view of . for determining the water wntent of NiO PSAN was sensitivity, stability. mechanical properties and energy. Thus developed and experimented (Ref. 3), allowing assessment of the binder selected was based on GAP cured by a mixtwe of different drying methods and control of the PSAN water IPDI andN-100. The system wasplasticised with BDNPAP, content. The PSAN, as received, shows an average particle in a polymer/plasticizer ratio of 1/1, specifically for its low size of 190 pn and a fairly wide distribution as determined sensitivity and good stability. In some cases, DBTDL at very using a Malvem Particle Sizer. low concentration was used as a curing rate catalyst. The oxidizer consisted of 70% by weight of PSAN containing 3.6 Binder studies 3.5% NiO. The formulation also included 2% by weight of Various binder systems were shldied by evaluating the DPA as a chemical stabilizer. effects of ingredients variation (polymers. clling agents, plasticizers. catalysts) on the strength and strain capabilities 4.2 Mechanical Properties of the resulting binder. The results of the study demonstrated The mechanical properties were determined using an Insmn that it was possible to formulate binders having mechanical apparatus at a crosshead speed of 50 mhinusing standard properties that approach the room-temperature values for the JANAF dogbones. The results are given in Table 4, where current inert plasticized HTPB binder, the elongation being E, and E, are elongation values at respectively maximum higher, 800 vs 600-700% and the strength being lower, 0.06- and rupture strength. while B and Ci I are respectively 0.1 vs 0.2 MPa. in the case of plasticized GAP-based binders maximum and rupaVe tensile strength values, E being the cured with IPDI. Unplasticized GAP binders showed superior modulus. The uncatalysed system showed room temperature strength values (0.250.35 MPa). Systems with a properties that were close to those of an aluminised a polymer/plasticizer ratio greater than one are more difficult APHTF’B propellant containing no bonding agents (Ref. 4). 10 cure and generally shows inferior propenies. The properties at - 40’C were not very good, which is not surprising in view of the relatively poor glass transition Early experiments showed that. in a propellant. curing would temperature of GAP, thus elongation was very low and not occur with IPDI alone. So binders cured with a mixture strength very high. Lower properties were obtained with the of IPDI and N-100 were prepared and studied both in catalysed binder. plasticized and Unplasticized form. The observed tendency was the same for both systems; a very sharp decrease in the 4.3 Pruceslng elongation values, from 800 to 100%. as the N-100 content The baseline formulation. when prepared in an Atlantic increased, while the suess values did not vary very much, Research 8 CV Helicone Mixer at a batch size of 10 kg, ranging between 0.05 and 0.06 MPa. The use of N-100 as demonstrated good processability with end-of-mix viscosities the sole curing agent resulted in harder. less flexible binders between 4 and 5 kF’ and pot-lives in the 3 to 4 hours range. than IPDI-based binders. Although flowability was not as good as a standard

Table 4 Mechanical Properties a

14.1 17.7 ! 026 0.23 1 3.22 I

0.25 0.22 Baseline (with cure 13.5 25.7 0.26 0.21 3.97 caralysr) 5.23 4.22 313 APJH'TPB propellant, the baseline formulation was of potential candidates were screened and effective buming nevertheless castable. rate modifiers have been identified.

4.4 Ballistic Small test motors have been filled with a modified The baselme formulation has a theoretical specific impulse formulation (i.e. including a ballistic modifier) and were (Issp)of 222 seconds, evaluated using the thermochemical successfully fired. Such a formulation is presently being code. Buming rate measurements were performed in a strand transferred to the industry for further development work. burner at an initial propellant temperature of 21°C and three different pressure levels (6.89, 13.76 and 20.67 MPa). 6. CONCLUDING REMARKS Results were correlated using the De Vielle burning rate law. We have succeeded in formulating a baseline propellant that For both the catalysed and uncatalysed baseline propellant meets some of the requirements but not all. The new formulations, a buming rate of 5.2 "ls at 6.89 Mpa and an propellant uses phase stabilized ammonium nitrate (PSW exponent of 0.63 were measured. as the oxidizer, glycidyl azide polymer (GAP) as the energetic binder, and bis-dinitropropyl aceWformal 4.5 Stability (BDNPA/F) as the plasticizer. This formulation meets VST results of actual propellants gave a value of 17 ml of minimum criteria for processing safety, chemical stability, gas produced per gram of propellant for a formulation processability and shows enough mechanical integrity to containing no stabilizer compared to 3.6 mug for one allow casting of simple propellant grains. However, the including two percent by weight of MNA and 1.6 mug for formulation falls short of the performance of the AP/HTPB the baseline formulation that used DPA. propellant but work is going on to improve it.

7. ACKNOWLEDGEMENTS 5. DISCUSSION The authors would like to thank the members of the Process a Engineering Group for their dedicated support and 5.1 DeRciencies Mc. D.L. Smith for his stimulating contribution. The main deficiencies of the baseline formulation are a low Isp, a strength of about a third the desired value, poor 8. REFERENCES mechanical properties at low temperature. low buming rate and bigh pressure exponent. Castability would benefit from Benchabane, M., "A Method for Analysis of Gas an improvement in the flowability of the propellant. Evolution Using a Mercury-Free Vacuum Stability Technique, GC and FTIR. Proceedings of The 5.2 Improvements ADPA Symposium. San Diego. April 1991. The goal was then to improve the baselie formulation in order to bring its performances closer to the requirements set Engel, W.. "Beieag m Phasenstabilisierung von forth at the beginning of this project. To realise this Ammoniumnitrat", Explosivestoffe,Nr. 1/1973, p.9. objective, the baseline formulation was used to study the effect of the inclusion of different additives such as buming Lessard, P., "Determination of Water in Phase rate catalysts, bonding agents, stabilizers and plasticizers on Stabilized Ammonium Nitrate", AIAA 26" Joint the mechanical and ballistic properties, the stability and the Propulsion Conference, AIAA Paper 90-2318, July sensitivity. 1990.

To improve the low temperature mechanical properties, it is Perreault. G. and Duchesne 0.. "Evaluation of necessary to lower the glass transition temperature of the Surface-Active Agents by Mechanical Properties of binder. Work in progress at DREV has &&dy demonstrated Highly Filled Composites". J.Appl.Polym. Sci.. that the replacement of a fraction of the BDNPA/F by Vol. 21, p.3153(1977). a TEGDN. at the cost of some energy, could provide improved low temperature properties while maintaining sensitivity within acceptable limits. Inclusion of the more energetic plasticizers TMETN or BlTN did not provide much improvement in low temperature properties and was detrimental to sensitivity.

The work of Perreault and Duchesne (Ref. 4) on aluminised AP/HTPB propellant has demonstrated the drastic improvement obtainable by the judicious use of a combination of bonding agents and it is believed that the . identification of suitable bonding agents for the PSAN/GAP system is of primary importance for obtaining adequate mechanical properties. Already work is in progress and suitable bonding agents, improving the smngth and showing a positive effect on the stability. have been identified. The addition of a catalyst will be necessary to control the rate of buming and lower the pressure exponent. A number 12-6 Discussion

STION BY BOGGS. US; In one of your slides you showed that you were using phase stabilized ammonium nitrate (P!;AN) having 3.5% NiO. Currently some people in the US are being iold that they cannot use PSAN having NiO. Are there any such restrictions in Canada on . use of NiO PSAN?

ANSWER; At this point is time, there is no formal restriction imposed on us. We are presently in the process of procuring NiO PSAN for continuing our work and the matter of the carcinogenicity . of NiO was raised by our own Supply Department upon reception of the new Safety Data sheet. There is a possibility that the people responsible for environmental questions might have their word to say but it seems likely that we will be allowed to procure small quantities for R&D purposes. We are aware of the situation in the US and are looking for potential candidates to replace NiO PSAN. QUESTION RY WHITFHOUSF UK; The low level and restricted range of burning rate for AN propellants will pose problems for rocket motor e designers. What do you consider the potential fclr improvements to be? ANSWER: The baseline formulation does not include a burning rate catalyst. The modified formulation including a ballistic modifier shows a burning rate of 8 mm/s at 6.89 MPa and ii pressure exponent of around .5 in the pressure range of 6.89 - 27.56 MPa (1000 - 4000 psi). The inclusion of finer particle size oxidizer might help increase the burning rate even further.

KF FRL What might be the reason for the high impact sensitivity of the PSAN/GAP/TMETN sample?

ANSWER: Our experience demonstrates that the TMETNlPSAN combination is the source of the problem. In fact it seems that any e combination of AN (or AP for that matter) with nitrated esiers will result in an increased impact sensitivity. It is reproducible. QUESTION BY MEIVKE. FRG: Which choices; do you use for getting a better performance of the smokeless AN/GAP propellant, if HDNPF/A must be replaced and sensitivity should not increase? ANSWER: Experience have shown that up lo 30% of the BDNPF/A can . be replaced by TMETN or BTTN while maintaining the impact sensitivity at the same level observed for the uncured AP/HTPB propellant. This of course, would result in a slight improvement in performance. Increasing the solids loading is another option. An Isp of 230 seconds might be reachable through careful optimization but this is probably the maximum that can be obtained without jeopardizing the low sensitivity and/or low smokelessness of the formulation. 14-1

THE DESION FEATURES OF ROCKET WTORB RELATINO TO INSENSITIVE MUNITION RESPONSE TO THEW-HECXANICAL STIMULI A C Mason Project Section Nanagel Royal Ordnance plc, Rocket Motors Division Summerfield. Kidderminster. Worcs DYll 7RZ UK

Approximately 500 rocket motors have been Bummary consumed in these IM trials and data from over 400 of these have been compiled onto a recently since the late 1970's myal Ordnance Rocket structured IN database. In these trials the Motors Division has conducted Inaenaitive effects of projectile impact, detonating shells. Munitions trials on approximately 500 solid sympathetic detonation. fuel fires and torch propellant rocket motors and data from over 400 flames have been assessed against various of these have been included in a recently combinations of case etructure. propellant types structured database. These trials preceded the and grain configurations. Testing began in the current standards of MIL-STD-2105 end OB Prac late 1970's and continues to day with trials to 42657 and a6 a result most of these trials were explore the reaction of motors to the newly conducted on an individual basis in order to defined requirements of MIL-STD-2105 and OB Proc understand the basic reponses to e wide 'ewe of 42657. threats. Although the trials were not undertaken as a balanced series of experiments analysis of Although all of the data contained on the the data does permit some useful observation and database are of value the trials were generally comparisons to be made. In particular the results conducted on an individual basis and were not of 0.5 inch bullet impact trials and fuel fire undertaken as a balanced aeries of experiments. (Fast Cook-off) testa are considered to be The sample size of some data Sets are at present particularly relevant to the current UK, NATO and too small to support diffinitive conclusions and USA requirements and these are discussed in in others the trial configurations employed detail. differ from the current requirements of MIL-STD-2105 and OB Proc 42657 and may therefore The general conclusions from these trials be of limited interest. This paper is thus emphasiee the importance of both the propellant confined to giving an outline summary of the IM type and body structure in the response to either database with detailed analysis being restricted mechanical or thermal attack. The database has to the results of the 167 half inch bullet impact enabled the capability of desiging solid test8 and the 36 fuel fire (Fast cook-off) propellant rocket motors to meet bullect impact trials. and fuel fire requirements. over half of the trials on the IN database were conducted against motors using steel strip List of Abbreviation. laminate cases a6 this system was perceived at an early stage of its development to have the A1 Aluminium Alloy abilify to attenuate violent reactions: for those BI Bullet Impact unfamiliar with this method of case construction CB Case Bonded further information is qiven in Annex A. CDB Cast Double Base CF Carbon Fibre Composite CL Cartridge Loaded CMCDB Composite Modified Cast Double Base 2 RO IM Database EMCDB Elastomer Nadified Cast Double Base FCO Fast Cook-Off Since the late 1970's RO RMD has carried out IM HTPB Hydroxyl Terminated Polybutadiene trials on over 500 rocket motors. Some of this IM Insensitive Munitions work was carried out under research funding. and KOA KBY~BI.Overwrapped Aluminium mme was project funded. In the former the aims MOD Ministry of Defence were generally to investigate the reactions of a PLEE Proof and Experimental Establish- wide range of motor types to a variety of ment stimuli. whereas in the latter the interest was RDX Nitremine (used as a Propellant more specific, usually to comply with technical filler) requirements. RO Royal Ordnance RND Rocket Motors Division To aid with analysis and interpretation the data sco slow Cook-Off from these trials are now being added to a SD Sympathetic Detonation computer database. At the same time the SSL Steel Strip Laminate opportunity has been taken to re-classify the UK United Kingdom results in line with the Current . NIL-STD-2105 definitions. ie. 1 Detonation, 2 Partial Detonation. 3 Explosion. 4 Deflagration. 1 Introduction 5 Burning and 6 Propulsion. TO date the results of trials carried out on over 400 motors have As an aid to developing an understanding of the been compiled. When completed it is believed that likely respon~eof e particular rocket motor to the database will help identify trends. suggest an external stimulus. such as a bullet impact or areas for further study. highlight gaps in the a fuel fire. a large number of IM trials has been data, and eliminate unnecessary replication in undertaken by the Rocket Motors Division of Royal future trials. Ordnance. The range facilities used for most of these trails were under the control of the UK Many of the IN trials conducted by RO RND were MOD, with the majority being conducted at PBEE carried out before the advent of MIL-STD-2105 and Pendine. OB Prac 42657 and followed guidelines developed by RMD. Projectile impact trials have been carried out with a variety of bullet types and the effect of blast and fragment impact has been simulated by detonating 105 mm shells in close 14-2

proximity to test motors. Sympathetic detonation Fortunately the procedures used for bullet impact experiments have been conducted by placing a and fuel fire (Fast cook-off) trlals are similar detonator and explosive in the conduit of donor to those required by MIL-STD-2104 and OB Proc motors. The effects of temperature have also been 42657. hence the considerable data gathered from examined by repeating trials on hoc and cold the 0.5 inch bullet impact and the fuel fire conditioned motors. Motors with and without tests are relevant to these. More details on the external insulation have been subjected to fuel results obtained from these tests are given in fires in large and small heartha and the Sections 3 end 4 respectively. influence of rig design on motor reactions has also been assessed. - The results of these trials am summarised in 3 0.5 inah Bullet Impact* Tables 1 to 18. The following Table gives details on the database composition ai8 well a6 a flavour A total of 154, single shot. 0.5 inch bullet of the wealth of information already compiled. e impact trials (as OB Proc 42657) are included in conservative estimate of the cost of repeating the database. In addition information on 4 trials these trials in 1991 would be around Elon. conducted with the simultaneous strike of fwo 0.5 inch bullets and 9 using the automatic fire of three 0.5 inch rounds (as MIL-BTD 2105) is also included. The data from these frials are summarised in Tables 1 to 3. Details of the BI teat procedure are given in Annex 8. Conpodtion of th. RO RnD It4 Databas. Summary 3.1 -0.5 inch Bullet -Total Number of Motors Trials have been conducted again6t SSL. Steel case ConsLructio" 443 XOA. CF and A1 cases. The propellants tested are Cordite. HTPB, CMCDB. CDB and EMCDB the latter Sfeel strip Laminate 243 two with and without RDX. Motors have been fested at conditioned temperatures of -50. -40. -30. Steel 157 -20. 0 and +60°c.

Xevlar Overwound In general these trials were conducted to examine Aluminium 17 the reactions of various combinations of propellant and case construction. The objective Carbon Fibre 15 of the trials being to provide an indication of 0 the IM performance of specific case types and Aluminium 11 propellants together with an assessment of the effects of temperature. Propellant CDB 330 The majority of motors used in these trials were taken from production and development programmen EMCDB 58 and were not specifically built for IM research. tience the trials carried out do not follow an CHCDB 9 experimental design and a number of gaps in the test matrix shown in Table 1 will be apparent. HTPB 13 ow ever. despite this limitation the results obtained do permit some useful observations and Extruded Cordite 33 compari60ns to be made and may be used to indicate direction for future studies. Grain Loading

Case Bonded 296 3.1.1 WTamperature Effsots Cartridge Loaded 147 Regardless of the type of propellant or case Method of Attack material the adverse effect of very low temperatures is clearly apparent in the data. At 0.5 inch Bullet the temperature of -50% the effects of case and Single Shot 154 propellant type are second order. of the seven trials carried out at this temperature all 0.5 inch Bullet produced reactions more severe than burning, ie AutOn,atic Fire 13 six explosions and one detonation. Statistical 0 analysis. based on the assumption that different 7.62 mm Bullet 26 propellants have no effect on the pasdfailure probability, indicbtes that the general 20 mm Bullet 38 probability Of failure at -5PC is 0.91 with 50% confidence. This is no doubt due to the brittle 0.3 mm all 9 nature of all prop$llants at such low tempera- tllres. 20 " Ball 5

Fraglents 17 3.1.2 pTop.llant classificati~ Detonating Donors 141 The propellants represented in the IM database Fire 40 have been classified using the US card gap . definition as either class 1.1 or Class 1.3. All Temperature of the HTPB chargee are Class 1.3. as are the CDB and EMCDB propellarats which do not contain either Below 0% 69 refractories, aluminium or nitramine fillers. The CDB and EMCDB Propellants containing refractory. . 0 - 20% 350 aluminium or nitramine fillers give card gap values in excess OP 70 and are therefore Class Above 20% 24 1.1 by the US definition. However. they are all 1.3C by NATO standards. The results of the 0.5 inch bullet impact trials have been segregated by USA propellant claasification as shown In Tables la and lb. 14-3

A further insight into the propellant/case The trials conducted on the HTPB and EMCDB motors combination can be gained from e statistical allow an assessment to be made of the value of enelyaia of fhe ambient trials conducted on the propellant classification as e means of EMCDBRDx/sSL, CDB CL/SSt, CDB CL/Al. CDB CB/SSL. predicting an IM reaction. CDB cB/steel and c/steel. It can be Concluded from the total number of passe6 and failures from For a given case construction trials acrose the this group of trials that an overall probability temperature range of -50% to +60°C trials have of failure of 0.5 is not unreasonable. For the been carried out on both of these propellant null hypothesis. HO, of equal likelihood of pass types. ~romthese results if can be seen that the or failure. and the test statistic is the IM reactions of the Class 1.3. HTPB propellant probability of this OutCome given HO is true. and the Class 1.1, EMCDB propellant are virtually These data and tent statistics are ab follows:- identical. It should be noted. however. that all of the case types represented in this sample are Pass Fail Total Teat of e laminate type structure and caution should be exercised in relating these results to homogenous cases.

CDB CL/ 18 25 43 0.12 Steel 3.1.3 Charp-a Configuration Effect CDB CL/AI 11 0 11 0.0005 From an initial glance at Table 1 it might be thought that an indication of the significance of CDB CB/SSL 16 0 16 0.00002 whether a charge is cartridge loaded or case bonded could be obtained from the results of CDB CB/ 3 11 14 0.029 the CDB motor trials, the sample sire of the Steel CDB/RDX and CMCDB motors being too small to justify analysis. By restricting analysis to the c/stee1 5 17 22 0.008 steel cased motor trials the effects of temperature can also be filtered out as these were all conducted at ambient. Of the 43 trials carried out on cartridge loaded motors 58% failed By rejecting the null hypothesis if the test whereas 79% of the ca~ebonded motors failed. atatietic is less than 0.05 it can be seen that Unfortunately different class propellants were only one propellant/case combination has given used in these trials end this may also have results consistent with an equal likelihood of influenced the results. The propellant used in paaa/failure. ie CDB CL/Steel. Otherwise all the all 43 cartridge loaded charges was Class 1.3 above combinations using a steel body gave a whereas only 2 of the 14 case bonded charges used larger than expected number of failure8 and class 1.3 propellant. It is tempting on the basis correspondingly the other bodies. SSL and Al. had of the HTPB/EMCDB comparison given in Section statistically fewer failures. 3.1.2 to assume that the class of propellant makes little difference. However, there may be a Pooling ambient trials across propellant types case/propellant interaotion. which it is not gives the following probabilities of failure far possible to teat with the available data. which the SSL. AI and steel cased motors:- could invalidate such an assumption. hence no clear indication of the effect of charge SSL A1 Steel configuration upon BI reaction can be drawn. 95% Confidence p <0.12 t0.24 t0.76

3.1.4 Cam and Propellant Effests 3.1.5 Rig EffcctS TO assess the possible influence of the case and propellant type upon the reactions witnessed if All of the 0.5 inch bullet impact trials included is necessary. to filter out the charge configura- in the database to date were conducted following tion and temperature effects. Ideally this would the procedures described in Annex 8. The rig be achieved by comparing only those results design employed on these trials holds the motor obtained for identical configurations and by retaining both ends in Yee's with loose temperatures. Unfortunately the sample sire for fittings top clamps. any given femperatUre across all case types is too small to make this practical. During discussions with Naval Weapons Centre. China Lake, doubts on the possible influence of However, by considering Just the HTPB and the CDB rig design on the motor reaction were voiced. To class 1.1 case bonded propellant motors. reducing address these concerns five EMCDBRDX/SSL motors temperature effects by ignoring those tests were subjected to 0.5 inch and 20" bullet impact Conducted below -30% end pooling all trials trials. In these tests the rig used was a copy of Conducted at temperatures of -30% and above it the MIC 'A' frame rig in which the motors are is possible to make some initial comparisons Supported in a simulated air carriage configura- between case and propellant types. The data of tion using two launch hangers, the ends are free. Table 1 has been simplified, on this basis 88 All of the motors used in these trials gave shown in Table 18. The results are claaaified a6 reaction typical of this motor, ie. no more either P or F.

Analysing the data in Table 18. row and colum The multiple, impact trials carried Out are wiae. gives an indication of relative BI limited to two case types and three propellants. performance of the various case constructions and also the number' of tests conducted is ineuffi- propellant types. For example looking at the HTPB dent to support statistical analysis. However. column shows SSL gave 2 pass results and 0 fail because of the similarity of these trials to the results, compared to 2 failures and 0 passes for Current MIL-STD-2105 requirements the results are KOA and 1 failure and I pass for CF. Similarly considered to be of interest. examining the KOA row ehows thee HTPB gave 2 failures end 0 paeses. EMCDB, 2 passes end 0 The effect of the simultaneous strike of two 0.5 failures. CDB 2 Passe6 and 1 failure and CDB/RDX inch bullets has been examined on four trials. 1 failure and 0 passes. see Table 2. These Were all conducted against SSL. case bonded motors. three being filled with CDB and one with EMCDB propellant. No reaction more severe than burning was recorded on any of these trials. 14-4

i) -,two offact. Nine trials were conducted ueing the automatic fire of three 0.5 inch bulleta. this trial being At temperatures below -40% the type of case and representative of the Current MIL-STD-2105. BI. propellant type have a second order influence on requirement. Information on the trials is given the ability of the motor to meet the In in Table 3. This shows that one of the requirements for bullet impact. SSL/EMCDBRDX motors did not react. two gave burning reactions and one resulted in At a temperature of -50% there :in. at the 50% deflagration. All of the steel cased motors confidence level. a 0.91 probability of failure exploded. - iil Card Ow as L predictor

The reeulta of trials conducted on SSL. KOA and 4 Fuel Fir. Trial. CF cases with HTPB propellants having e card gap significantly less than 70 cards. gave marginally 1 Data On the results of 36 fuel fire [Fast w~rsereactions then those conducted using the cook-off) teste have been added to the database. aame cases and with EMCDB propellants having a The case materials used in these trials were KOA, card gap of more than 70 cards. However. only a CF. and SSL the latter with and without external small number of trial results are available and insulation. further work would be required to confirm this finding. The majority of these trails were carried out in the RO RMD "mini fuel fire" hoilrth. The advantage It should also be noted that the case types used Of this hearth over larger hearths. such a6 in these trials were of a lamina>-type Construc- required by MIL-STD-2105. is that less smoke is tion. The available data do not allow the generated and it is therefore possible to observe comparison to be made for these propellants far the store during the trial. However. on occasions homogenous cases. and hence the probability of an RO RMD has conducted trials in a large hearth and averiding case influence cannot be ruled out. the results of these have demonstrated that comparable reaction times and responses are iii) -vation .ifsots obtained from both large and small hearths. The data from these trials are aummarised in Table While there is an indication that case bonded 16. Details of the FCO test procedure are given motorr are m~relikely to give reactions more in Annex C. Analysis of these data shows that in severe than burning. this result may have been all of the 36 tests only 2 reactions more severe influenced by propellant sensitivity. More work than burning have been recorded. One of these is needed, with standardised case and propellant 0 occurred with a case bonded CDE/SSL propellant types to confirm this. combination. representing 7% of the 14 teste carried out. and the other was me of the two i") -_Cam Effects tests conducted with a carbon fibre cartridge loaded cos/ssL combination. There 16 Strong evidence that SSI. and A1 cases are significantly better than homogenous ateel No Information is available in the RO RMD cases. Pooling ambient trials across propellant database on steel or aluminium cased motors. types gives the following probabilities of However. work reported by others ~uggeststhat failure, at the 95% confidence level. tO.ll for reactions more severe than burning are typical of SSL, t0.24 for AI and t0.76 for Steel. a homogenous steel case. Although the KOA results might be expected fo be indicetive of e There is insufficient data to enable the ielative homogenous ~1 case it should be noted that line performance of CF and KOA cases to be assessed. cuffing charges were used on four of these trials.

The SUCCes6 of the composite and SSL GtnlCtYleQ 5.2 ~-Fuel Fire in FCO trials arises from the rapid 106s in strength of the adhesive systems used in these Data from the 36 Fast cook-off trials allow the case6 at temperatures above 12Ooc. By the time following conclusions to be made. the propellant attains its ignition temperature the case ha= little or no strength left and hence il Adhesively bonded cases such a6 SSL is unable to retain the pressure needed to and CF Provide a ~ro~enmeans of support an explosion or detonation type reaction. meeting the IM requirements for FCO. For air carriage applications the sensitivity of the adhesive to aeroheat induced temperature iil To survive the aeroheat require- increa6e necessitates the use of external ments of air carried missiles 0 insulation to protect the case. Typically the adhesively bonded cases need equivalent of lmm cork has been found necessary. external insulation. FCO on This haa led to feare that the advantage of external1.y insulated SSL cases have adhesively bonded afructures In FCO might be lost demonstrered that the fime ta first when the case is configured for an air carriage reaction in slightly extended but application. To investigate this concern RO RMD the reaction is limited to one of undertoak a series of FCO trials on externally burning. insulated SSL cases. The results of these trials clearly demonstrate that the effect of external insulation is to delay the fime to first reaction but does not raise the level of reaction above 5.3 Mechanism of Motor Vulncrabilitx that of burning.

5.3.1 Fragment %

5 Conclusion When a fragment penetrates a rocket motor case it usually punches a hole at the enfry point of L somewhat larger hole at the exit. 5.1 0.5 inch Bullet Impas If the fragment ignites and breaks up the Examination of the 165 0.5 inch bullet impact propellant the burning area increases and the teats leads to the following conclusion for solid pressure within the motor will increase rapidly. propellant rocket motors If the nozzle. fragment entry and exit areas are insufficiently large to cater for this increased pressure. high pressure failure. or even an explosion. will result. 14-5

only later did the Insensitive Munitions (IN1 This is the normal mechanism of fragment attack properties of sSL become apparent. When SSL vulnerability associated with COnventiDnal steel rocket motors were subjected to bullet impact and homogenous rocket motor ca6es. fuel fire trials benign reactions. now known to be typical of these motors, were achieved. During With a sfrip laminate case. the area of damage at the period 1972 to 1990 in excess of 200 SSL the fragment exit point is more extensive than it motors were subjected to a range of IN tests of would be in a conventional motor case, due to the which around 40 were fuel fire trials with the strip delamination effect. This area appears to majority of the remainder being projectile impact be proportional to the weight of the fragment. tests. When under these conditions, the propellant ignites. gas flows out of the fragment exit hole Since its development ssL cases with diameter- in rapidly. increases the area of delamination by a the range of 60" to 600" and lengths of up to peeling back of the layers. and results in the 3000mm have been produced. Bodies have been collapse of internal pressure. subjected to pressures of up to 600 bar. operational temperatures as low as -54% and es high as 71%. tropical storage. severe flight 5.3.2 Fuel fire attack loading in missile structures and rough handling trials. When a solid propellant rocket motor is heated externally. it eventually ignites and an SSL cases have been in volume production since explosion may result due to the uncontrolled the late 1950's for a number' of missile systems. nature of the propellant self ignition. notably Rapier and more recently the vertical Whilst this is the mechanism of vulnerability launch Seawolf. TO date around 40 000 production associated with homogeneous motor cases which motore and numerous development motors have been retain their strength well above the self produced with SSL cases. ignition temperature of the propellant, thin is not so with the adhesive structures. When 1.2 nanuiasturing proce.. hubiected to heat, the resin used for bonding begins to break do- at femperatules just above currently two specifications of steel strip. a 100°C (212OF) and at 180% (356OF) has no 0.7%C/2.O%Ni Steel and a 7%NI/17%Cr stainless steel. ae used in SSL tube pmduction. Both Of strenoth~~ ~~~-~~~ remainina. Noat CDB DroDellants isnite at i20oc (z48o~jtb moot (3560~). these materials have an ultimate strength in the depending upon confinement. and clearly. from the region of 2CN/mZ. However. the strip laminate results of the trials. when an adhesively bonded technique has also been successfully applied with motor is subjected to a fuel fire, the resin aluminium alloy. titanium alloy and maraging bonding of the case breaka down faster than the Steel. propellant temperature is raised. At the instant of propellant ignition only a very low pressure Strip is received from the supplier in 300m is required to disrupt the motor case end thus (loooft) lengths in coil form, typical dimensions provide a multitude of paths for gas and to of the strip. suitable for diameters greater than exhaust and thereby prevent an explosive pressure lOOmm (4 inch), are lOOmm (4 inch) wide by 0.25" build-up. (0.01 inch) thick. Prior to winding the strip is prepared by passing 5.3.3 Design Criteria for 1.U. it through a degreesing solution to remove oil. shot blasting both sides to remove oxides and RO RND has been able, through the extensive range texture the surface and then passing it for a of trials and subsequent analysis. to define second time through a degreasing solution. A thin design criteria for 1.N. which are currently layer of an epoxide adhesive is applied to the being used with solid propellant rocket motor strip and dried in a heated tower. The coated designs. strip is then recoiled and may be stored far up to mix months without deterioration of the adhesive or metal strip.

The metal strip is helically wound onto a heated -A -A mandrel so that there is a small gap between successive turns of the helix. Additional layers Strip Laminate Rocket notor Cams of strip are added until the desired thickness is obtained. each layer is wound in the same 1.0 what is Steel strip Laminate? direction but the helices are staggered.

Strip Laminate rocket motor cases are made by When winding is complete the mandrel temperature helically winding e number Of layere Of metal is increased to partially cwe the adhesive. strip coated with a Suitable adhesive onto a After an appropriate time the mandrel is cooled mandrel of diameter equal to the desired bore of and the tube is removed and cut to length. the finished tube. End fittings and any other attachments. such a6 When subjected to mechanical loads bodies made by launch feet, are then bonded onto the tube. The the sSL pr-oceas behave in the same manner as surfaces to be bonded are prepared by shot homogeneous bodies of the same material strength. blasting, degreasing and priming. The tube and components are assembled into a jig, to emure Details of the history behind this process and a eccuracy of alignment. adhesive is pumped in to description of the manufacturing technique are the bonding cavities and the whole assembly given in the following sections:- transferred to an oven for final cure. 1.1 Hi.rol'l The finished motor body may be lined, painted and filled in exactly the same way aa e body made by The Steel Strip Laminate (SSL) technique of an other process. rocket motor case mannfecture was perfected af Royal Ordnance FmD in the early 1950's. The simplicity, flexibility and short lead time of the manufacturing process were the key motivating factors driving development, but the ability to utilise ultra high strength steels was an added attraction of this unique method of case construction. 14-6

* The temperature from the thermocouples. the time from ignition to the attainment of a flame Bullet Impact T.st Procedure temperature of 550% and fhe time from 550% to motor failure is recorded. A graph of flame The general arrangement of the teat set up is temperatYre versus time from fuel ignition to shown in Figure El. motor failure is produced. Data from blast overpressure gauges are also tabulated and The motor mounting rig is rigidly located such plotted. that it0 longitudinal axis is at 90° to the line of fire of e 0.5" Erovning machine gun. positioned at e distance of 30m 0.5m. The gun barrel is at the same height pis that of the centre point of the target. Bleat overpressure gauges. Piero Electric Type 'E'. are positioned Acknowledgment either aide of the mounting rig at 45O right and 135" left to the line of gun fire and at This work has been carried Out with the support of diatances of lm. 2m and 5m from the point of Procurement Executive Ministry of Defence. impact and exit on the motor.

Bvllet velocity measuring equipment. cine cemeras and a colour VCR are located as shown in Figure 81.

The gun is prepared by firing 'warmera' and zeroing rounds.

when all items are sited and their operation has been satisfactorily confirmed the motor is taken from the conditioning chamber and positioned into the test rig. The gun is zeroed on to the aiming point of the motor and an instant of strike foil switch is attached to the motor over the aiming point. The gun ia loaded end all instrumentation is started. When recording equipment is at operating speed the gun is fired. a After firing. still photographs of the rocket motor debris are taken before any hosing down Or manual disturbance. A record

A tabulation of peak overples6Yre. shock arrival time and duration of pulse is obtained for each overpreasure gauge and a time trace of pressure is also produced.

annex c

Fast Cook Off Tast Procedur.

RO (RMDI Mlnl Fuel Fir.

The motor mounting rig also contains its own fuel hearth and is constructed from 3 x 62" length- of 15" x 4" RSC. welded together to form e tray 62" x 45" x 4" into which the motor support cradle is fitted auch that the bottom of the store 1s not leas than O.2m above the fuel surface.

This rig is placed in the centre of the fuel fire arena. Piero Electric blast gauges Type 'A' I2 a off1 are positioned 3m from the store (either sidel.

The rocket motor is secured into the rig. TWO flame temperature thermocouples are eituated 10" below the centre of the motor. off set 40-60mm either aide and connected to a recorder. See Figure C1.

Sufficient fuel (AVCATI or commercial Kerosene Grade 'E' (DEF 2403) to sustain 8 10 minutes fire is poured into the hearth. Water from a low pressure supply is then added until the level of the fuel is 0.2m below the bottom of the store. TO aid ignition. petrol is floated on top of the fuel. The petrol is ignited by means of an electrioally initiated puffer inserted into an opened Wortar Augmenting charge. surrounded in petrol soaked cotton waste.

A colour cine. framing at 10Opps. running for 2.5 minutes and colour video Camera with VCR. sound and CCTV are employed to record the trial events. - __

HTPB EMCDB EMCDBiROX CDB CC IX rdite MCDB CL CB CL CB CL CL CI

50 -30 -20 +60 50 -30f60 -40 AMB -30 AMBi I -40-30AMB +60 30 +< -30 iMB AN ~ -- NR 1 2 2 8 1 1 1 1 5 16 1 1 SSL D E 1 1 1 1 ...... Det ...... NR 1 B 17 3 5 1 Steel D E 25 11 16 ...... Det ...... NR B 1 1 2 1 KOA E 1 1 1 1 1 ...... Det ...... NR 1 B 1 1 1 CF E 1 1 1 1 ...... Det ...... NR 7 B d AI D E Det -

NR NoReadion E Explosion B Burning Reaction Det Detonation D Deflagration TABLE 1 0.5 INCH SINGLE BULLET IMPACT 1 CLASS 1 .I PROPELLANT * 1