AIRCRAFT published by the Joint Aircraft 17FALL ISSUE Survivability Program Office SURVIVABILITY
Basics of the HH-60W LFT&E Program page 7
Aircraft Survivability: New Challenges for a New Global Conflict (World War II) page 13
Blast-Tolerant Composite Structure for Rotorcraft page 23
Threat Characterization: Small Projectiles, Big Impact page 28 Aircraft Survivability is published three times a year by the Joint Aircraft Survivability Program TABLE OF CONTENTS Office (JASPO), chartered by the U.S. Army Aviation & Missile Command, U.S. Air Force Life Cycle Management Center, and U.S. Navy Naval Air Systems Command. 4 NEWS NOTES by Dale Atkinson 5 JCAT CORNER by MAJ Ronald Pendleton 7 BASICS OF THE HH-60W LFT&E PROGRAM by Samantha Block The HH-60W Combat Rescue Helicopter (CRH) is an Acquisition Category (ACAT) 1C program based at Wright-Patterson Air Force Base (WPAFB). The U.S. Air Force program of record calls for 112 helicopters to replace the Air Force’s rapidly aging HH-60G Pave Hawk helicopters, which perform critical combat search and rescue (CSAR) and personnel recovery operations for all U.S. Services. The HH-60W is on the Office of the Secretary of Defense’s (OSD) Oversight List for Live Fire Test and Evaluation (LFT&E). Due to the considerable amount of test
JAS Program Office and combat data available on Black Hawk variants, however, the program developed a Director, 735 S. Courthouse Road Operational Test and Evaluation (DOT&E)-approved Alternative Test Plan (ATP) to meet Live Fire Suite 1100 Arlington, VA 22204-2489 Test (LFT) statutory requirements and obtain a full-up, system-level (FUSL) LFT waiver. This http://jasp-online.org/ article presents an overview of the HH-60W aircraft and the LFT&E program and team.
Sponsor Dennis Lindell 11 EXCELLENCE IN SURVIVABILITY: TORGER ANDERSON by Joel Williamsen The Joint Aircraft Survivability Program (JASP) is pleased to recognize Torger “Torg” Editor-in-Chief Dale Atkinson Anderson for his Excellence in Survivability. Torg has worked at the Institute for Defense Analyses (IDA) for 14 years and has served as lead for the Fixed Wing and Anti-Air Live Fire task Views and comments may be since 2010, where he leads IDA staff in analytical and test efforts to evaluate the survivability of directed to the JAS Program Office. new fixed-wing platforms in support of the Director, Operational Test and Evaluation (DOT&E).
To order back issues of Aircraft Survivability, send an email to 13 AIRCRAFT SURVIVABILITY: NEW CHALLENGES FOR A [email protected] NEW GLOBAL CONFLICT (WORLD WAR II) On the cover: by David Legg The Combat Rescue Helicopter, On 4 September 1939, the Royal Air Force (RAF) recorded its first losses of World War II designed by Sikorsky, will perform critical combat search and rescue when five Wellingtons of No. 9 Squadron were shot down during a raid on German warships in and personnel recovery operations the Elbe estuary [1]. Three months later, a force of 24 RAF Wellington Mk 1a medium bombers for all U.S. military services (Artist rendering courtesy of Sikorsky). (such as those shown in Figure 1) attempted a daylight raid against the German port of Wilhemshaven. These bombers flew in a spread formation to avoid anti-aircraft fire. However, German Ground Control Intercept (GCI) radars tracked the bombers and vectored a formation of single-engine BF-109 and twin-engine Bf-110 fighters onto the bombers. A total of 12 RAF Wellington bombers were shot down for the loss of 2 Luftwaffe fighters [1]. In addition, a total 56 of the 65 bomber aircrew who set off on this mission were killed.
AS Journal 17 / FALL jasp-online.org 2 Mailing list additions, deletions, changes, as well as calendar items may be directed to:
21 EXCELLENCE IN SURVIVABILITY: RICHARD HUFFMAN by Mark Couch The Joint Aircraft Survivability Program (JASP) is pleased to recognize LTC Richard E. Huffman Jr. for his Excellence in Survivability. Rich is currently on assignment as the Chief of
Information Operations Plans and Assessments Branch at Headquarters U.S. Africa Command DSIAC Headquarters (AFRICOM). Additionally, he is an adjunct assistant professor of aerospace engineering at the Air 4695 Millennium Drive Belcamp, MD 21017-1505 Force Institute of Technology (AFIT). He has also served in the Air Force for 23 years as a Phone: 443/360-4600 developmental flight test engineer, working envelope expansion, avionics, and survivability Fax: 410/272-6763 Email: [email protected] testing on numerous weapon systems.
DSIAC is sponsored by the Defense 23 BLAST-TOLERANT COMPOSITE STRUCTURE FOR Technical Information Center (DTIC) and is operated by the SURVICE Engineering Company under ROTORCRAFT Contract FA8075-14-D-0001. by Mark Robeson, Clark Andrews, and Lisa Chiu Military rotorcraft structures may be subjected to high-energy ballistic events in combat DSIAC Program Manager situations. Ballistic threats characterized by an advancing shockwave created by an explosive Ted Welsh blast, alone and in combination with high-speed fragmentation, typically result in significant structural damage for both metallic and composite structures. To address this vulnerability, the Copy Editor Eric Edwards U.S. Army’s Aviation Development Directorate (ADD) and The Boeing Company have collaborated to develop and integrate specifically designed composite sandwich components into large Art Director primary aircraft structures, which have shown good success at mitigating catastrophic damage Melissa Gestido caused by explosive ballistic events [1]. Distribution Statement A: Approved for public release; 28 THREAT CHARACTERIZATION: SMALL PROJECTILES, distribution unlimited, per DoD Office of Prepublication and Security BIG IMPACT Review, Case No. 17-S-2327. by Jonathan Marshall The global proliferation of assault rifles, machine guns, and other man-portable weapons has increased both the frequency and intensity of modern conflict. These weapons, classified as small arms (which typically include up to 23 mm in caliber), are easily obtainable on international markets and are effectively used by untrained personnel. There are an estimated 100 million to 500 million military-style weapons in circulation, in addition to hundreds of millions designed for police or civilian use. In addition, of the 49 major conflicts that have occurred since 1990, small arms and light weapons (such as those shown in Figure 1) were the primary weapons used in 46 of them. Only the Gulf War predominately used heavy weapons [1, 2].
3 jasp-online.org AS Journal 17 / FALL By Dale NEWS NOTES Atkinson
OLDENBURG LEAVES multiple flights of aircraft in both the • Comma-separated values (CSV) JASPO visual and beyond-visual-range (BVR) output files arenas, incorporating value-driven and • Fixes for multiple messages information-oriented principles in its Table-based missile light artillery After 6 years as the Susceptibility structure to provide a Monte Carlo, rocket (LAR) (Type 6 LAR) Reduction Deputy Program Manager of event-driven simulation of air combat COBRA RULES enhancements the Joint Aircraft Survivability Program between multiple flights of aircraft with Uplifts Office (JASPO), Mr. Tim (“TO”) real-world stochastic features. • Missile characteristics Oldenburg is joining Booz Allen Hamilton BRAWLER can be used to analyze the • Mental model to support weapons integration on the effectiveness of new hardware; • Expendables F-35 program. illuminate issues in campaign/mission • Avionics: radar warning receiver models; extend the results of other (RWR), missile approach warning, A retired U.S. Air Force (USAF) lieuten- methodologies; examine tactics or helmet-mounted sight (HMS), ant colonel, TO had a varied and command, control, and communications and helmet-mounted display interesting military career, including (C3) issues; and serve as a high-fidelity (HUD) supporting the Joint Strike Fighter component of a distributed simulation or avionics integration, training, and manned simulator target generator. To request a copy of BRAWLER 8.3, visit systems engineering; supporting F-15 the Defense Systems Information avionics upgrades; and serving as a BRAWLER 8.3 includes Air Force Analysis Center (DSIAC) website at Royal Australian Air Force/USAF Research Laboratory-funded directed https://www.dsiac.org/resources/ exchange officer for stores clearance, as energy enhancements, generic sensor models_and_tools/brawler. Questions a B-52H flight test engineer, tri-Service objects, National Air and Space can be directed to the BRAWLER Model missile lethality analyst, and USAF/U.S. Intelligence Center-funded enhance- Manager, Mr. Dale Johnson, at 571-256- Army (USA) wargame modeling and ments, and JASPO-supported small 2120 or [email protected]. simulation specialist. projects. These enhancements include: A graduate of the University of Arizona NEW VERSION OF ESAMS Directed energy weapon (DEW) duty (with a B.S. in aerospace engineering) RELEASED factor model and of California State University (with DEW calibration utility an M.S. in mechanical engineering), TO Version 5.3 of the Enhanced Surface-to- New DEW Rmax envelope type also worked for McDonnell-Douglas Air Missile Simulation (ESAMS) is now Generic sensor interface Aircraft Corporation before joining the available. This simulation provides a Missile multi-band radar cross Air Force and for the Defense Threat one-on-one framework used to evaluate section (RCS) Reduction Agency after his Air Force air vehicle survivability, estimate Single-shot egmain retirement. effectiveness, set requirements, and JAAM lightweight interface develop tactics. Detailed data have JASPO-supported small projects Please join JASPO in wishing TO and his been abstracted from intelligence • DLD/communications jamming family all the best. information and incorporated into the • Infrared (IR) cueball aircraft model to provide comprehensive dataset representation of radio frequency NEW VERSION OF • Vulnerable-area check for MD land-based and naval-based surface-to- BRAWLER RELEASED gun model air missile systems. The user can • Time-space-position information specify the threat site layout in various Version 8.3 of the BRAWLER air-to-air (TSPI) data input for scripted ways, including rectangular grid site combat model is now available. The players arrays, circular site arrays, or model simulates combat between
AS Journal 17 / FALL jasp-online.org 4 semi-circular arrays, or by specifying endgame evaluation (which is useful Questions can be directed to the ESAMS specific sites one-by-one. Missile fire for systems without detailed Model Manager, Mr. Benjamin Vroman, control, guidance, aerodynamics, and signal-based fuze models) at 937-904-5607 or benjamin.vroman@ movement are also patterned. The Detonation evaluation for all entities us.af.mil. model details the characteristics of both in the air ground and missile seeker radar. ESAMS New target assignment code in the models aircraft from their signature data generic track model, which allows and optional vulnerability data. user to select primary target for cueing the fire control radar (cue to ESAMS latest enhancements include: the fastest target, target closest to site, etc.) and added kill removal for New models legacy towed decoy. Pedigree documents A Chaff Model overhaul To request a copy of ESAMS 5.3, visit the A new Generic Fuze Model that DSIAC website at www.dsiac.org/ allows fuzing on all entities for resources/models_and_tools/esams. JCAT CORNER by MAJ Ronald Pendleton
the Air Force Life Cycle Management Center at Wright-Patterson Air Force Base (WPAFB). CPT Cain transferred from the active force and spent her last tour at the Air Force Research Laboratory at WPAFB as a research engineer and an executive officer. In the civilian capacity, she is currently a machine learning engineer at Riverside Research in Beavercreek, OH.
Training continues to be an ongoing JCAT need, and work has been under- way to improve the JCAT training area
Figure 1 LTC Barrett Performing an Assessment While Deployed in 2013. located at WPAFB. JCAT is collaborat- ing with the School of Aerospace The Air Force (AF) component of the their service and wishes them well in Medicine, which manages the site. Joint Combat Assessment Team (JCAT) their future endeavors. Currently, the site contains only a has recently experienced some person- wrecked T-6 and C-130 aircraft, although nel changes. LTC Arild Barrett (pictured At the same time, AF JCAT has gained other aircraft—in particular, a rotary- in Figure 1), a valued team member for two new valuable team members, 1LT wing asset—are actively being sought. 5 years, retired from the AF on 1 July; Dan Adducchio and CPT Lindsay Cain. A joint Navy-Air Force JCAT assessment and LTC Chuck Larson (pictured in Figure 1LT Adducchio transferred from the Air training event was conducted at the site 2), who has been with the JCAT National Guard and has been working last March, and another is planned for program since 2005 and the Officer in for JCAT on the side for approximately September. This is a great opportunity Charge of the AF component since 2011, 1 year while his transfer paperwork was for the JCAT cadre and others to refresh will be retiring on 1 November. JCAT being processed. On the civilian side, he assessment skills on a regular basis. thanks LTC Barrett and LTC Larson for is Deputy Chief for F-15 Operations at
5 jasp-online.org AS Journal 17 / FALL Figure 2 LTC Larson (Standing Third From Left) Mentoring New JCAT Cadre Members During a Trainging Exercise.
Collectively, the dates for the 2018 JCAT LT Andrew Logan pioneered the training curriculum have been finalized. combined DLE/JCAT role during his tour Phase I is planned for 22–26 January and successfully established lines of 2018 at Fort Rucker, AL. Phase II is communication with mishap reporting, planned for 5–9 March 2018 at China maintenance, and safety personnel and Lake, CA. Phase III, also known as the in providing JCAT training to the other Threat Weapons and Effects (TWE) DLEs. CPT Michael Macchia has now training seminar, is planned for taken his place and continues the 10–12 April 2018 at Hurlburt Field, FL. standard of excellence. Air Force JCAT More information regarding the TWE intends to have at least one JCAT- will be announced at a later date. trained DLE in theater at all times to respond to any hostile fire incidents. In addition, the AF JCAT has joined forces with the aircraft structural Though the JCAT mission has been engineering community to maintain a around a long time, it unfortunately is JCAT presence in the area of responsi- not well known in Air Force circles. To bility. To address the dearth of JCAT remedy this situation, we are striving to capability down range after the give JCAT orientation briefings as often withdrawal of assessors from as possible. In May, LTC Barrett briefed Afghanistan in October 2014, JCAT has the 10th Air Force Combat Planning to date sent three Depot Liaison Council held at the Naval Air Station Engineers (DLEs) to the JCAT training Fort Worth Joint Reserve Base in Fort courses at Fort Rucker, China Lake, and Worth, TX. The audience was com- Hurlburt Field. posed of intelligence, surveillance, and reconnaissance personnel, who were The great benefit to using DLEs is that briefed on the JCAT mission using the they are already trained in aircraft battle EXTORTION17 incident as a real-world damage repair, which includes docu- example. menting the hostile fire damage to aircraft, a skill common to JCAT. DLEs operate from several bases, including Al Udeid, Al Dhafra, Ali Al Salem, and Bagram, providing on-site aircraft structural engineering support and depot coordination, as well as JCAT support as an additional duty.
AS Journal 17 / FALL jasp-online.org 6 BASICS OF THE HH-60W By Samantha Block
COVER STORY LFT&E PROGRAM
The Combat Rescue Helicopter, designed by Sikorsky, will perform critical combat search and rescue and personnel recovery operations for all U.S. military services (Artist rendering courtesy of Sikorsky). The HH-60W Combat Rescue Helicopter (CRH) is an Acquisition Category (ACAT) 1C program based at Wright-Patterson Air Force Base (WPAFB). The U.S. Air Force program of record calls for 112 helicopters to replace the Air Force’s rapidly aging HH-60G Pave Hawk helicopters, which perform critical combat search and rescue (CSAR) and personnel recovery operations for all U.S. Services. The HH-60W is on the Office of the Secretary of Defense’s (OSD) Oversight List for Live Fire Test and Evaluation (LFT&E). Due to the considerable amount of test and com- bat data available on Black Hawk variants, however, the program developed a Director, Operational Test and Evaluation (DOT&E)-approved Alternative Test Plan (ATP) to meet Live Fire Test (LFT) statutory requirements and obtain a full-up, system-level (FUSL) LFT waiver. This article presents an overview of the HH-60W aircraft and the LFT&E program and team.
BACKGROUND CRH PROGRAM existing models, and other tests) in its MILESTONES determination of the additional testing Sikorsky’s HH-60W CRH is built on the and analyses required to support the reliable and battle-proven UH-60M Notable past and future milestones for LFT&E program. Black Hawk and customized to the the CRH program include the following: rescue mission, making it the most The LFT&E strategy presents an affordable option for the Air Force. The Air Vehicle Preliminary Design approach to determine the system-level aircraft will have significantly improved Review (PDR) – April 2016 survivability (susceptibility and vulner- combat radius, an expanded weapons Training Systems PDR – August 2016 ability) of the aircraft, as well as assess suite, and a modern, state-of-the-art Air Vehicle Critical Design Review the occupant force protection. The integrated mission systems and (CDR) – May 2017 initial strategy was approved shortly self-protection suite. Training Systems CDR – September after contract award and was updated 2017 (planned) following Air Vehicle PDR. The strategy The $1.4 billion engineering and First Flight – Fall 2018 (planned) continues to be reviewed at LFT&E manufacturing development (EMD) EMD completion/Required Assets Working Group meetings at least contract includes development and Available to Support the Customer’s quarterly to address any necessary integration of the aircraft and rescue Initial Operating Capability (IOC) changes/additions as the program mission systems, delivery of nine – Summer 2020 (planned). moves past Critical Design Review and HH-60W helicopters, and a training into qualification testing. system. The training system includes: LFT&E OVERVIEW The LFT&E Working Group was estab- A weapon system trainer (full-motion lished prior to the Air Vehicle PDR and The overall goal of the CRH LFT&E simulator) meets quarterly to review the status of program is to conduct a comprehensive An operational flight trainer the air vehicle and training systems evaluation of the system’s survivability An aircraft system trainer design and qualification efforts, to (aircraft, aircrew, and passengers) to An avionics desktop trainer review draft vulnerability and suscepti- expected ballistic and advanced threats A landing gear part task trainer bility assessment efforts, and to plan while completing its mission. The CRH A hoist part task trainer upcoming activities. team is capitalizing on applicable Type 1 training previous LFT&E activities to the Courseware. greatest extent possible, incorporating LFT&E TEAM AND
the results of previous testing, verifica- APPROACH
tion activities, and analyses (vulnerability combat data, qualification The CRH LFT&E team is led by the tests, system safety, crashworthiness, LFT&E Manager at WPAFB’s Helicopter
AS Journal 17 / FALL jasp-online.org 8 Program Office and the Survivability CRH System Specification. Sikorsky any mitigation options. Recent lead at Sikorsky. Members of the team began this effort by conducting a analysis or testing affecting crew include the: detailed Survivability Analysis Plan, survivability on rotorcraft and the followed by iterative submissions of ongoing Joint Aircraft Survivability Helicopter Program Office a Vulnerability Analysis Report. Program (JASP) Crew and Passenger Sikorsky Aircraft Company Because this analysis focuses on Survivability study is being moni- DOT&E/LFT&E specification threats only, it is tored for useful information. 704th Test Group necessary to supplement it with an Nuclear, Biological, and Air Force Life Cycle Management LFT&E-led ballistic vulnerability Chemical (NBC) Threat Analysis Center (AFLCMC) Combat analysis that includes threats of - The LFT&E team is leveraging any Effectiveness and Vulnerability interest outside those noted in the relevant analyses or assessments of Analysis Branch (EZJA) specification document. The Final the CRH (or comparable platforms) to Army Research Laboratory (ARL) BVA will consider three levels of kill: evaluate the effects of NBC threats Survivability/Lethality Analysis attrition, forced landing, and mission against the system. The data will Directorate (SLAD). abort; as well as three flight modes: verify the ability of the CRH to high and fast, high and slow, and low operate and be maintained following The approach for the CRH LFT&E and slow. exposure to NBC threats and the program is divided into several catego- Integrated Survivability ability of the CRH to be decontami- ries of analysis/assessment, which are Assessment (ISA) - The major nated using standard detailed as follows. activities supporting the ISA are decontamination procedures. susceptibility studies evaluating the Modeling and Simulation Laser Threat Analysis - The likelihood of threat engagements in (M&S) - The CRH LFT&E program is LFT&E team is leveraging any realistic combat environments. In using M&S to investigate questions relevant analyses or assessments of assessing CRH’s susceptibility to the related to the vulnerability and the CRH (or comparable platforms) to chosen threats, the intent is to use susceptibility of the aircraft. evaluate the effects of low-power mission profiles, aircraft configura- Programs used include COVART, laser threats against the aircraft’s tions, and flight paths representative AJEM/MUVES, MOSAIC, sensors. The role of each sensor is of the CRH in a combat scenario. RADGUNS, ESAMS, and RPG being evaluated through Failure The goal of these studies is to Engagement Model. Modes Effects and Criticality evaluate the anticipated engage- Analysis or Damage Mode and Initial LFT&E Survivability ment timelines (i.e., detection of the Effects Analysis and mission Analysis - The initial LFT&E threat by the CRH, as well as essential equipment list. The survivability analysis is defining detection and engagement of the analysis will include a description of susceptibility, vulnerability, and force CRH by the threat) and threat the susceptibilities and vulnerabili- protection issues; identifying footprints and to determine the ties of the sensors of the aircraft to sources of ballistic vulnerability and probability of kill given an engage- laser threats. susceptibility data to support the ment (Pk|e ) for the aircraft with program; determining more detailed respect to the selected threats. Electromagnetic Pulse (EMP) analysis plans and timelines; and High-Power Microwave Occupant Casualty Analysis clarifying LFT&E threats of interest; (HPM) Analyses - Per MIL-STD- - The occupant casualty analysis and coordinating efforts between all 464C, the CRH shall comply with goes beyond direct injury from a LFT&E team members. EMP/electromagnetic emissions/ threat and will include casualties electromagnetic interference Ballistic Vulnerability Analysis caused by indirect effects, crash, or requirements and shall be capable of (BVA) - The CRH statement of work hard landings. The injuries and operating from and near Navy (SOW) and the associated contract resulting casualties are consolidated surface ships. The LFT&E program data requirements list (CDRL) state and analyzed, along with relevant is leveraging analyses or assess- that Sikorsky will execute ballistic combat data or other data, to ments of the CRH performed vulnerability analyses to verify the identify trends and help determine elsewhere in the program to
9 jasp-online.org AS Journal 17 / FALL evaluate the effects of EMP and Velocity screen (2nd Celotex back stop HPM threats. screen not shown)
QUALIFICATION AND OTHER TESTING
Early component qualification testing on the program includes the complex testing of the newly designed fuel cell, an HH-60W-unique component (see fuel Test article test stand setup shown in Figure 1). Qualification test activities include those detailed in MIL-DTL-27422D and MIL-STD-810G. The Phase I test series provides a foundation for Phase II and LFT&E test activities planned for late 2017 through 2018. This challenging test series will ensure the fuel cell materials and design are robust enough Fluid collection Fluid collection buckets pans to withstand the combat environment in which the HH-60W is designed to Figure 1 Fuel Test Stand. operate. The LFT&E program is leveraging the qualification test concerns to CRH leadership. The status activities as a foundation for the LFT&E of LFT&E efforts is presented by the testing of this mission-critical LFT&E lead at the program’s quarterly component. Program Management Reviews. All developmental test, LFT, M&S, and Other focuses of LFT&E testing include analysis results will be incorporated into ballistic characterization of the cockpit a final LFT&E consolidated report seats, cabin and cockpit armor, refueling submitted to DOT&E LFT&E. lines, and any other vulnerability or susceptibility reduction features on the ABOUT THE AUTHOR aircraft. Items of interest in the Ms. Samantha Block is the CRH LFT&E occupant casualty assessment include team lead for the AFLCMC/WIHT the primary aircrew seats, rescue team Helicopter Program Office. She is a seats, isolated personnel litter system, graduate of Michigan Technological and emergency egress systems on the University and was commissioned aircraft. The LFT&E team actively through the Air Force Reserve Officers’ monitors all program risks that may Training Corps (ROTC) program. She potentially impact the timeliness of the was formerly an active duty contracting LFT&E efforts, or design trades that may officer before becoming a civilian have an impact on system-level or Program Manager. occupant survivability, and reports
AS Journal 17 / FALL jasp-online.org 10 EXCELLENCE IN SURVIVABILITY TORGER ANDERSON
by Joel Williamsen The Joint Aircraft Survivability Program (JASP) is pleased to recognize Torger “Torg” Anderson for his Excellence in Survivability. Torg has worked at the Institute for Defense Analyses (IDA) for 14 years and has served as lead for the Fixed Wing and Anti-Air Live Fire task since 2010, where he leads IDA staff in analytical and test efforts to evaluate the survivability of new fixed-wing platforms in support of the Director, Operational Test and Evaluation (DOT&E).
modeling, and evaluating aircraft and DOT&E to expand their efforts survivability and weapon lethality. Then, beyond traditional (vulnerability-ori- as programs develop, he monitors the ented) live fire testing and analysis to testing and modeling performed by follow developmental and operational contractors and begins sculpting a final test activities, as well as broaden the report to Congress to support a Beyond DOT&E BLRIP reports to provide Low-Rate Initial Production (BLRIP) comprehensive descriptions of fixed- decision. Torg takes an active part in wing aircraft survivability. helping programs consider survivability enhancements in light of mission After his graduation with a B.S. in requirements, potential threats, and aerospace sciences from the University operational tactics, including specialized of Minnesota in 1974, Torg gained survivability equipment, such as dry bay 5 years of operational experience as a fire extinguishers, fuel protection U.S. Navy flight officer, flying A-6E Torg jokes, “I knew that my plastic systems, crashworthiness, egress, etc. Intruders as a bombardier/navigator airplane model-building experience as a with the USS John F. Kennedy. This kid and throughout my life would “Aircraft systems are somewhat unique applied experience helped give him a somehow benefit me.” in how they survive,” Torg said. “Their well-balanced view of the roles of lightweight designs limit their ability to operations and equipment in enhancing And indeed it did. Torg’s most notable tolerate threat hits, so preventing hits aircraft survivability. He then worked achievements have been in leading the (susceptibility-reduction) is often the for the next 24 years at United Pentagon’s Live Fire Test and Evaluation most significant part of the survivability Technologies Research Center (UTRC) in (LFT&E) of the F-35 Lightning 2, P-8A strategy. Although the Live Fire law Hartford, CT, becoming a senior Poseidon, EA-18G Growler, C-27J Joint places the primary emphasis on testing research engineer. Cargo Aircraft, and the E-2D Hawkeye, vulnerability with respect to potential as well as coordinating the efforts of user casualties, it has to equally “That research experience” Torg said, other Pentagon analysts in two dozen consider the susceptibility to attack and “gave me a lot of knowledge in testing a other aircraft and air-to-air weapons combat performance of the system. So wide range diverse systems and systems. understanding the susceptibility evaluating differing types of physical becomes a major part of the effort.” problems, from aircraft gas turbine Early in the life of a program, Torg and combustors and fuel systems to his staff coordinate the development of To gain this understanding has required scramjets, hydrogen fuel cells, and high a Live Fire Strategy that outlines the Torg and his fellow researchers in IDA power lasers. I gained expertise in the scope and resources needed for testing,
11 jasp-online.org AS Journal 17 / FALL types, capabilities and limitations of bringing in outside technology experts endeavored to use this approach on many instrumentation techniques, and to describe the capabilities and every aircraft platform on DOT&E LFT&E much of my career was dedicated to potential for instrumentation in several oversight. understanding and implementing, then areas. The community was informed developing, optical and laser-based about laser-based measurement In 2008, Torg also organized and led a diagnostic tools for combustion and techniques for temperature and species round-table event at the JASP Program other measurement applications.” concentrations, high-frequency- Review meeting to discuss and begin response pressure sensors that had developing an approach for better The greatest emphasis was the develop- capabilities beyond those being assessing aircrew casualties, consistent ment and use of a Coherent Anti-Stokes employed in LFT&E at the time, and with the wording of the Live Fire Test Raman Spectroscopy (CARS) system advances in high-speed video imaging law. This meeting initiated efforts that that could make temperature and that could improve our understanding of led to the current aircrew casualty species concentration measurements in LFT&E test results. These meetings assessment approaches. realistic aero propulsion systems. It were successful in linking the technolo- was for this work that, in 1990, Torg gists with LFT&E testers, resulting in Finally, as a private pilot, Torg has received the UTRC Special Achievement improvements in the community’s test accrued 1,200 hours of flight time in Award for CARS measurements in a techniques and measurement results. light aircraft and earned certifications full-scale hydrogen scramjet combustor as an instrument and a commercial pilot. as part of the National Aerospace Plane Torg also recognized that the under- Encouraging kids in math and science program. Also during this time, he standing of the science of combustion has also been a long-time interest of his, authored three patents for designs for a outside of the LFT&E community was and while in Connecticut he started an solar air conditioner system, a fuel cell well beyond the tools we use to initiative called FlyingKids, giving inner power plant inlet, and a novel pulse evaluate the potential for ballistically city kids a chance to fly airplanes at his detonation engine concept. Torg also induced fire, and he developed an flying club. In his spare time, he also earned a Ph.D. in mechanical engineer- approach for incorporating that under- tutors local middle schoolers in math ing in 1992 from the University of standing into our survivability and science and leads them in IDA’s Connecticut (while working full time at assessments. A more scientific annual Minnie Howard Math Day. UTRC). His dissertation addressed the approach was encouraged, and LFT&E understanding of planar gaseous analysts were coupled with technolo- Congratulations, Torg, for your detonation waves using Rayleigh gists from the Lawrence Livermore Excellence in Survivability and for your images generated by a high-power National Laboratory to bring in their many contributions to the Department pulsed ultraviolet laser. understanding of the mechanisms that of Defense, the survivability community, control the likelihood of fire to our and the Warfighter. “Based on my prior career at UTRC, I problems. And that effort is still recognized that there is a lot of test, ongoing. ABOUT THE AUTHOR measurement, and analysis technology residing outside of the LFT&E commu- Based on his LFT&E experience at IDA Dr. Joel Williamsen currently serves as nity that could be brought to bear to and his operational Navy experience, a live fire analyst for IDA and a senior solve LFT&E problems,” Torg said. “I felt Torg also led an effort to support DOT&E advisor for JASP. He has more than that the LFT&E state-of-the-art could be in establishing an Integrated 35 years of experience in aircraft/ significantly enhanced if the community Survivability Assessment approach, spacecraft survivability and weapons could understand and employ some of evaluating aircraft systems for overall lethality. For his many efforts in the this knowledge.” survivability (susceptibility and vulner- field, he received the American Institute ability). This approach was shoehorned of Aeronautics and Astronautics Torg has worked throughout his career into the C-27 Joint Cargo Aircraft Survivability Award (AIAA) in 2012. to try to infuse this understanding in the assessment, but its first real trial came Dr. Williamsen holds a bachelor’s community. From 2005 through 2007, with the assessment of the P-8A in degree in mechanical engineering from Torg held “Instrumentation Roundtables” support of the Full-Rate Production (FRP) the University of Nebraska and a Ph.D. at the JASP Program Review meetings, decision. IDA has subsequently from the University of Alabama in Huntsville.
AS Journal 17 / FALL jasp-online.org 12 AIRCRAFT SURVIVABILITY: NEW CHALLENGES FOR A NEW GLOBAL CONFLICT (WORLD WAR II)
by David Legg
Figure 1 Aircrews of No. 149 Squadron RAF and Their Vickers Wellington Mk la’s at Mildenhall, Suffolk (© IWM [C 423])
[EDITOR’S NOTE: This article is the second in a series of historical aircraft survivability articles. The first, which covered pre-World War I through World War I, was published in the spring 2017 issue of Aircraft Survivability.]
On 4 September 1939, the Royal Air Force (RAF) recorded its first losses of World War II when five Wellingtons of No. 9 Squadron were shot down during a raid on German warships in the Elbe estuary [1]. Three months later, a force of 24 RAF Wellington Mk 1a medium bombers (such as those shown in Figure 1) attempted a daylight raid against the German port of Wilhemshaven. These bombers flew in a spread formation to avoid anti-aircraft fire. However, German Ground Control Intercept (GCI) radars tracked the bombers and vectored a formation of single-engine BF-109 and twin-engine Bf-110 fighters onto the bombers. A total of 12 RAF Wellington bombers were shot down for the loss of 2 Luftwaffe fighters [1]. In addition, 56 of the 65 bomber aircrew who set off on this mission were killed.
13 jasp-online.org AS Journal 17 / FALL The post-mission debriefs uncovered become arguably the best escort fighter lethality. In the early phases of World that several of the aircraft caught fire aircraft of the war—once the British War II, German ground forces were when hit, and the recommendation was replaced its Allison engine with a typically protected against ground made that the aircraft be equipped with Rolls-Royce Merlin engine. attack aircraft by either fixed or mobile self-sealing fuel tanks. The RAF also 20-mm anti-aircraft cannon. In the noted, based upon these and other While attempts were being made to mid-to-late years of the war, these missions, that the bombers could not reduce the vulnerability of their respec- would be replaced or augmented by defend themselves against fighters tive aircraft, the Allied and Axis air more lethal single- or multi-barrel during daylight missions. This conclu- forces soon learned that their aircrafts’ 30-mm and 37-mm anti-aircraft cannon sion eventually led the RAF to embark armaments required improved lethality. and single-barrel 40-mm anti-aircraft upon its night-time bombing campaign Early versions of the RAF’s Supermarine cannon. against Germany. Spitfire Mk I and II and Hawker Hurricane fighters were each equipped This increase in threat caliber was RELEARNING THE LESSONS with eight .303-caliber machine guns. primary driven by the increased OF WORLD WAR I As aircraft equipped with self-sealing robustness of the U.S. Army Air Force fuel tanks and armor became much more (USAAF) P-47 Thunderbolt, the RAF common during 1940, it proved neces- Typhoon, and the Soviet Air Force IL-2 During the years between Word War I sary to concentrate machine gun fire at ground attack aircraft designs. and World War II, the air forces of the much closer ranges to the target However, it was not uncommon for world soon forgot the costly lessons aircraft. The RAF quickly discovered these aircraft to return to base after learned over the trenches of France in that these .303-caliber rifle bullets could being impacted by even these rounds. World War I. Unfortunately, these not carry enough incendiary or explosive These were the types of lethal defenses lessons would have to be quickly to guarantee success and had insuffi- with which Allied fighter-bomber pilots relearned (by the previously mentioned cient penetration capability to defeat had to contend throughout most of the war. RAF Wellington bombers, for example) armor reliably. in the early years of World War II, prior to the involvement of the United States. THE P-47 During one documented encounter During this time, Britain freely trans- between a Luftwaffe Dornier DO-17Z ferred the lessons learned to the U.S. The Republic P-47 is representative of bomber and an RAF Spitfire, approxi- government and aircraft manufacturers. U.S. aircraft manufacturers’ attempts to mately 200 rounds were required to And in relatively quick order, U.S. keep pace with evolving wartime down the bomber. This encounter also manufacturers were including survivabil- requirements for performance, lethality, highlights the robust design (excluding ity features due the requirements and survivability. The P-47 would evolve fire prevention) of military aircraft of this stipulated by the RAF. to become arguably the best close air era. Later versions of the Spitfire Mk II support fighter-bomber and one of the and subsequent Mk’s included a mixture For example, when the U.S.-produced best fighters of World War II. of 20-mm cannon and .303- or .5-inch Curtiss P-40A Tomahawk fighters machine guns. Early versions of the arrived in England, the RAF restricted its In 1939, the XP-47A aircraft was Luftwaffe’s Bf-109, including those use to units deployed in England until originally conceived as a lightweight, involved in the raid on Wilhemshaven, these aircraft were equipped with armor high-altitude interceptor. It was already included a mixture of 20-mm and self-sealing fuel tanks. These powered by a 1,150-hp liquid-cooled cannon and 7.62-mm machine guns. deficiencies were corrected in the inline engine, was armed with two Like the Spitfire, later versions of the P-40B, which the RAF used to good .50-caliber machine guns, had a top Bf-109 also included heavier armament, effect in North Africa. In contrast, the speed of 415 mph, and had a gross including a mixture of 12.7-mm machine North American P-51 Mustang was weight of 4,900 lbs. However, reports guns and 30-mm cannon. developed based upon RAF require- from Europe indicated that more ments, which included armor and firepower, armor plate, and self-sealing Likewise, the Allied and Axis tactical self-sealing fuel tanks. Later, this fuel tanks were required. But the air-defense artillery units soon learned U.S.-manufactured aircraft would XP-47A had insufficient power to bear that they also required improved
AS Journal 17 / FALL jasp-online.org 14 the additional weight, which resulted in 9-mm-thick armor plate to protect the aircraft. His vision was impaired by a a significant redesign of the aircraft. pilot’s back hydraulic fluid leak, he had two bullet A separate plate of “bullet-resistant fragments in his right leg, another bullet The resultant XP-47B design included a glass” installed behind the wind- had nicked his nose, and part of the 2,800-hp air-cooled turbo-supercharged screen for pilot protection on the windscreen had been shattered. He radial for additional power, an armament P-47D Razorback tried to bail out, but his cockpit was of eight .50-machine guns for increased An integral bullet-resistant glass jammed (due to a 20-mm projectile lethality, a top speed of 400 mph at incorporated with the windscreen for impact). 25,000 ft and 340 mph at 5,000 ft, pilot protection on the P-47D self-sealing fuselage fuel tanks for Bubbletop Under these dire circumstances, survivability, cockpit armor for aircrew The air-cooled engine, which LT Johnson headed back toward protection/survivability, and a 11,500-lb eliminated the vulnerable liquid England. Somewhere over France, gross weight. Although the engine cooling system and shielded the pilot unable to maneuver his damaged change was made to improve perfor- from the front. aircraft, he was attacked by another mance, it would also later prove to be a FW-190A. Luckily, this aircraft had significant vulnerability reduction Susceptibility reduction features of the expended all of its 20-mm cannon feature. P-47 included: rounds in an earlier engagement. The FW-190A pilot, Luftwaffe ace MAJ Egon Due to the additional weight, one of the Incorporation of the bubbletop canopy Mayer, made several attacks and fired main P-47B shortcomings was that it for increase threat awareness every remaining 7.9-mm machine gun had insufficient range to permit deep Tail warning radar equipment round into LT Johnson’s aircraft. After penetration and bomber escort into Increased power. exhausting all of his aircraft’s machine Germany. This deficiency, however, was gun rounds, MAJ Mayer then flew addressed by mid-1943 with the The P-47N was the last version of the alongside LT Johnson for almost introduction of the P-47C, which P-47 to be produced. It was a long- 30 minutes, amazingly escorting him to included the capability to mount range (2,200 miles) version designed the English Channel to make sure he external fuel tanks for increased range specifically for service in the Pacific made it. LT Johnson continued on and and a longer fuselage to improve theater. The improved range permitted landed safely at his home airfield in maneuverability. the aircraft to escort B-29 bombers from England. Upon inspection, it was the island of Saipan to Japan. The determined that the aircraft (shown in The follow-on P-47D was the first P-47N was powered by the same Figures 2 and 3) had more than 210 version of the Thunderbolt to undergo R-2800-57 engine as the P-47M. While holes in it, with at least 20 being large-scale production and would the fuselage was essentially unchanged inflicted by 20-mm cannon rounds from undergo many block improvements. The from the D series, the wing was the initial attack. LT Johnson would D-25-RE Block included a “bubble top” completely redesigned to include four survive to become one of the top canopy with improved all-around self-sealing fuel tanks per side. American aces in World War II, with visibility, and the P-47D-40-RA Block 27 aerial victories [2]. In addition, his was the first P-47 to include tail warning On 26 June 1943, LT Robert S. Johnson plane would later be repaired and radar equipment. Subsequently, the would push limits of the P-47C’s reissued to the 9th Air Force’s 36th P-47M, based on the P-47 D-27 to D-30 survivability. While on patrol, his Fighter Group, before being permanently series, was a pure fighter version with squadron was jumped by a formation of destroyed in August 1944. increased power. FW-190A fighters. His aircraft (which he called Half Pint) was hit by 20-mm Ironically, MAJ Mayer was shot down Vulnerability features of the P-47 cannon and 7.9-mm machine gun and killed in action by a P-47 pilot near included: projectiles, which resulted in a fire and Montmédy, France, on 2 March 1944. an uncontrolled spin. After the aircraft He was officially credited with 102 Self-sealing internal fuel tanks, which lost several thousand feet in altitude, aircraft victories in more than 353 shielded the pilot from below and the the fire self-extinguished, and combat missions. front LT Johnson regained control of the
15 jasp-online.org AS Journal 17 / FALL Eglin Field, FL, also documented this vulnerability in its December 1942 “Final Report on Tactical Suitability of the P-51 Type Airplane,” which states [3]:
The coolant and oil radiators are combined into one (1) assembled unit and are located in the belly of the aircraft just behind the cockpit. For the reason that most hits on an airplane in combat are to the rear of the cockpit, it is believed that this
Figure 2 LT Robert Johnson’s Damaged P-47C “Half Pint,” Which Was Later Repaired and Reissued for radiator installation may prove to be Service (Photo Credit: http://www.littlefriends.co.uk - Donavon Smith Jr.) quite vulnerable. It is recommended that the designer of the subject aircraft make a study of the possibili- ties of incorporating a sheet of armor plate to protect the radiator from fire from the rear.
The recommended armor plate was never incorporated in the P-51 design.
During World War II, the combat loss rate per sortie for the P-51 was 1.2% (vs. 0.7% for the P-47). Another World War II study indicated the P-51 was three times more vulnerable to ground fire than the P-47.
OTHER AIRCRAFT
In addition to the incorporation of armor and self-sealing fuel tanks typical of USAAF, U.S. Navy (USN), and RAF Figure 3 Detailed 20-mm Projectile Damage to LT Johnson’s P-47C fighter aircraft, several Soviet fighter (Photo Credit: http://www.littlefriends.co.uk - CPT McGarrigle via Chuck Zarkis) aircraft designs included a form of fuel THE P-51 aircraft was used in the close air tank ullage inerting. Portions of the support and airfield strafing role toward inert gases that formed the engine exhaust were collected, cooled, and The P-47 Thunderbolt and P-51 Mustang the end of the war. pumped into the fuel tanks of the were both robust designs capable of Yakolev-1 and 9, Mig-3, and Lavochkin absorbing significant structural damage, Edgar Schmued, chief designer of the (LaG)-3, 5, and 7 fighter aircraft. and they both included self-sealing fuel P-51, explained that using the Mustang tanks and armor for pilot protection. for ground attack was “. . . absolutely Soviet fighter ace Ivan Kozhedub stated [4]: However, the P-51 had one significant hopeless, because a .30-caliber bullet vulnerability not shared by the P-47— can rip a hole in the radiator and you Later on, I had many occasions to the P-51’s liquid-cooled engine. And this fly two more minutes before your admire the strength and staying vulnerability became more critical as the engine freezes up [2].” The Army Air Forces Proving Ground Command at power of this plane (LaG-5). It had
AS Journal 17 / FALL jasp-online.org 16 excellent structural mounting points Command (e.g., Lancaster, Halifax, and the first Integrated Air Defense System and an ingenious fire-fighting system, Stirling) were, like their fighter counter- (IADS). Designated the London Air which diverted the exhaust gases parts, of robust design and incorporated Defense Area (LADA), this IADS brought into the fuel tanks, and once saved armor protection for the aircrew and together units composed of coastal and me from what seemed certain death.” generally self-sealing fuel tanks. Thus, inland observation posts, sound they could, on occasion, survive the locators, searchlight and AAA stations, Ivan Kozhedub would later become severe damage inflicted by near-by balloon aprons, and fighter aircraft. This the top scoring Allied ace of WWII with bursts of German 88-mm, 105-mm, and IADS was reconstituted during the late 62 victories, including an Me-262 jet 128-mm anti-aircraft artillery (AAA) 1930s with the addition of the “Chain fighter. projectiles (provided that no fire was Home” early warning radar system and initiated). However, a direct hit by any was key to the RAF’s Fighter Command Although not commonly known, the of these projectiles would mean almost success over the Luftwaffe during the Japanese also included vulnerability certain catastrophic loss. Battle of Britain. reduction in their aircraft designs. The Mitsubishi A6M2 Zero/Zeke entered Because the RAF bombers flew at night In parallel, the Germans also developed service in 1940 and quickly became without escort fighter protection, they a similar IADS to defend Germany known by the Allies for its inherent were particularly susceptible to fighter against aerial attacks. This system overall vulnerability. This vulnerability attack. These radar-equipped night included Ground Controlled Intercept was corrected much later in the war fighters could inflict severe damage in a (GCI) directed night fighters and with the introduction of the A6M5b matter of seconds due to their heavy radar-directed 88-mm, 105-mm, and Model 52 version in 1944. This version armament of multiple 20-mm and 128-mm AAA. Freya radar, operating at includes a CO2-based dry bay fire 30-mm cannons. Some of these cannon 120–166-MHz and with a range of extinguishing system and windscreen were mounted upward in the night ~200 km, provided early warning of armor [5]. fighter’s fuselage to enable attacks incoming Allied aircraft. unobserved from beneath the bomber. Additional vulnerability reduction In an attempt to stem the losses, some Würzburg-Riese radar, operating at improvements followed. The A6M5c versions of the Lancaster, Halifax, and 560 MHz and with a range of ~70 km, Model 52 added armor plate behind the Stirling were equipped with fuel tank would be used to direct the AAA and/or pilot and a fuselage self-sealing fuel ullage inerting systems. The engine night fighter aircraft. Early Luftwaffe tank, and the A6M6c Model 53c added exhausts of these bombers were also night fighter aircraft were equipped with wing self-sealing fuel tanks [5]. equipped with flame dampers to hide a Lichtenstein FuG 220 radar operating the glowing exhaust from night fighter at 33/82/91/118 MHz with a detection In another case, the Japanese observer crew observation. range of ~4 km. Later aircraft were reports from the European conflict were equipped with FuG 240 “Berlin” radar acted upon by the designers of the ELECTRONIC WARFARE: operating at 3.250–3.330 MHz with a Kawasaki Ki-61 Tony fighter. The Ki-61-I A NEW TYPE OF BATTLE maximum detection range of ~ 9 km. In Ko (1942) included self-sealing fuel the case of night fighter aircraft, GCI tanks as well as pilot seat and headrest would typically guide them to within a The aforementioned survivability armor. The Ki-61-I Otsu (1943) added few kilometers of the target aircraft. At features could be considered a natural thicker self-sealing fuel tanks, thicker this point, the radar operator onboard progression of the improvements pilot seat and headrest armor, and the night fighter would guide the pilot to implemented in World War I, but World radiator armor (the Ki-61 was equipped within visual acquisition or firing range. War II became the catalyst for the with a liquid-cooled engine). The Ki-61-I Understandably, these developing development a whole new kind of Hei (1943) and Tei (1944) versions added capabilities led to an ongoing game of battle—electronic warfare. a CO2-based dry bay fire extinguishing “cat and mouse” over the night skies of system [6]. Germany and occupied Europe. During the closing stages of World War I, and in response to German Zeppelin and The heavy bombers of the USAAF (e.g., To counter these radar-directed threats, bomber raids, the British implemented the B-17 and B-24) and RAF Bomber British scientists developed a variety of
17 jasp-online.org AS Journal 17 / FALL countermeasures, which were employed selectively by RAF Bomber Command aircraft. For example, the Airborne Cigar (ABC) radar jammers jammed the German VHF communications and navigation aid frequencies. A German- speaking operator on board the bomber would monitor the German communica- tions to make sure all frequencies were jammed and could also provide false commands to German night fighter crews.
The Mandrel jammers (such as those shown in Figure 4) jammed the Freya Figure 4 Three Mandrel Jammer “Blisters” on the Bomb-Bay Doors and an ABC Jammer Antenna on the Top early warning radar. These jammers of the Fuselage and Lower Forward Fuselage Nose of the RAF Bomber “Jane” (Australian War Memorial) periodically stopped transmitting for 2 min to prevent night fighters from homing in on the Mandrel transmission.
Window strips (the invention of which is credited to Joan Elizabeth Curran of the Telecommunications Research Establishment) were strips of coarse, black paper with thin aluminum foil stuck to one of the sides. These strips (known in the United States as chaff) were cut to be either a 1/2 or 1/4 wavelength of the frequency of the target radar. As the bundles of Window were dropped from an aircraft (such as shown Figure 5), they separated to form a vast cloud of metallic strips. These Figure 5 Bundles of “Window” Released Over a Target in Duisburg, Germany, During Operation Hurricane. Note the Large Aerials on Top of the Fuselage, Indicating the Presence of an ABC Jamming Device as Well clouds would send back an exceptionally (© IWM [CL 1405]) strong echo, and when dropped in great numbers, they swamped the enemy’s aircraft. So, in the spring of 1944, they Monica was replaced by the Boozer radar. One of the main targets of German night fighters were equipped passive radar warning receiver (RWR). Window was the Würzburg-Riese with the FuG 227 passive radar receiver This RWR would provide bomber crews anti-aircraft gun laying radar. to detect and track the Monica emis- warning when their aircraft were sions. The FuG 227 range was detected by German Wurzburg GCI or Monica was a tail-mounted radar that ~62 miles. Luckily for the British, on the FuG 202/212 Lichtenstein airborne entered RAF service in early 1943. It morning of 13 July 1944, a FuG interception (AI) radars. It was intro- provided audible bleeps as a warning of 227-equipped German Ju 88G-1 night duced into service in the spring of 1943. an aircraft approaching from the rear. fighter mistakenly landed at the RAF A display was mounted on the pilot’s However, a German night fighter could base Woodbridge. After examining the instrument panel and the radio opera- “hide” among the bleeps generated by FuG 227, the RAF ordered Monica to be tor’s position, and lights warned if the reflections from other bombers flying in withdrawn from all RAF Bomber aircraft was being tracked. A yellow trail. By March 1943, the Germans had Command aircraft. light indicated the aircraft was illumi- examples of Monica from shot-down nated by a FuG 202/212 AI radar, and a
AS Journal 17 / FALL jasp-online.org 18 red light (hence the name “Boozer”) indicated that the aircraft was illumi- nated by a Wurburg GCI radar.
The Handley Page Halifax (which produced the “Jane” bomber in Figures 4 and 6) is representative of British aircraft manufacturers’ attempts to keep pace with evolving wartime require- ments for bomber survivability. Notable vulnerability features of the Halifax included the following:
12 self-sealing fuel tanks (fuel containment and fire reduction) Figure 6 A Window-Dispensing Chute Just Aft of and Below the Opened Rear Fuselage Hatch of the RAF Fuel pumps inside fuel tanks (compo- Bomber “Jane,” Which Is Also Equipped With Exhaust Dampers to Hide the Glowing Engine Exhaust From Visual Detection by German Night Fighters (Australian War Memorial) nent shielding) Fuel tank cross-feed (component night and the implementation of the extraordinary. The casualties suffered redundancy) previously mentioned (and other) by the Eighth Air Force were about 2 self-sealing oil tanks (containment electronic warfare countermeasures, half of the USAAF’s casualties (47,483 and fire reduction) the Bomber Command’s losses out of 115,332), including more than Fuel tank nitrogen inerting for all fuel ultimately surpassed those sustained by 26,000 dead. tanks (fire/explosion reduction) the USAAF during daylight operations. Air-cooled engines (component According to the Bomber Command USAAF battle casualties in all overseas elimination – liquid coolant) Museum of Canada [7]: theater of operations include 40,061 Engine fire extinguishing system (fire killed and 18,238 wounded [9]. reduction) The successes of Bomber Command General rugged construction (critical were purchased at terrible cost. Of LESSONS TO BE component redundancy). every 100 airmen who joined Bomber RELEARNED Command, 45 were killed, 6 were Likewise, notable susceptibility reduc- seriously wounded, 8 became Immediately following World War II, the tion features of the Halifax included the Prisoners of War, and only 41 emphasis for airpower was placed on following: escaped unscathed (at least the delivery of nuclear weapons. The physically). Of the 120,000 who unprecedented demonstration of the Monica active tail warning radar or served, 55,573 were killed . . . . uranium bomb “Little Boy” on Hiroshima Boozer passive RWR Of those who were flying at the on 6 August 1945 and then the pluto- ABC, Mandrel, and Window counter- beginning of the war, only ten nium bomb “Fat Man” 3 days later had measures incorporated on percent survived. It is a loss rate instantly changed how the military (and special-mission aircraft comparable only to the worst the world) viewed warfare. Such Engine exhaust dampers. slaughter of the First World War weapons seemed to make major trenches. Only the Nazi U-Boat force conventional conflicts unthinkable, at suffered a higher casualty rate. STRATEGIC BOMBER least for a time. Unfortunately, this LOSSES IN THE WAR OF situation would not last long. And as And the USAAF Eight Air Force did not with the survivability lessons learned WESTERN EUROPE fare much better. Reportedly [8]: during and forgotten after World War I, the same cycle would be repeated in Despite the RAF Bomber Command’s During World War II, one in three subsequent conflicts in Korea and decision to fly in what was originally airmen survived the air battle over Vietnam. calculated to be the relative safety of Europe. The losses were
19 jasp-online.org AS Journal 17 / FALL ABOUT THE AUTHOR survivability programs have continued over the years. Look for an article in a Mr. David Legg is currently the Fixed- future issue, on how this mission was Wing Aircraft Branch Head of the Naval accomplished.] Air Warfare Center – Aircraft Division. With 33 years of experience in the aircraft survivability discipline, he has References also served as the Survivability Team [1] Royal Air Force. “RAF Timeline 1939.” https:// Lead for many U.S. Navy aircraft and www.raf.mod.uk/history/rafhistorytimeline1939.cfm, weapons programs, and he assisted in accessed May 2017. the rapid development and [2] Wagner, Ray. Mustang Designer: Edgar implementation of tactical paint Schmued and the P-51. Washington, DC: Smithsonian Institution Press, 1990. schemes for in-theater U.S. Marine Corps helicopters during Operation [3] Army Air Forces Proving Ground Command. “Final Report on Tactical Suitability of the P-51 Type Desert Shield/Storm. Mr. Legg was Airplane.” Eglin Field, FL, 30 December 1942. named a NAVAIR Associate Fellow in [4] HistoryNet. “Aviation History: Interview With 2011 and holds bachelor’s degrees in World War II Soviet Ace Ivan Kozhedub.” http:// mathematics and mechanical www.historynet.com/aviation-history-interview-with- engineering from Saint Vincent College world-war-ii-soviet-ace-ivan-kozhedub.htm, accessed May 2017. and the University of Pittsburgh, respectively. [5] Juszczak, Artur. Mitsubishi A6M Zero. MMP Books, 2015.
[EDITOR’S NOTE: The on-again-off-again [6] Wieliczko, Leszek. Kawasaki Ki-61 / Hein Ki-100. Kagero, 2014. effect described herein caused most of these survivability efforts to dry up [7] Bomber Command Museum of Canada. “Bomber Command’s Losses.” http://www.bombercommand- between wars, which was the reason we museum.ca/commandlosses.html, accessed May established the Joint Technical 2017.
Coordinating Group on Aircraft [8] “Eighth Air Force Combat Losses.” http:// Survivability (JTCG/AS) in 1971. One of personal.psu.edu/kbf107/Losses.html, accessed May the main missions of the JTCG/AS was 2017. to establish survivability as a design [9] “Army Air Forces Statistical Digest: discipline so that it would continue as a World War II.” Second Printing, Office of Statistical Control, December 1945. major player when no one was shooting at our aircraft. The JTCG/AS (now the Joint Aircraft Survivability Program [JASP]) was successful in doing that, and
AS Journal 17 / FALL jasp-online.org 20 EXCELLENCE IN SURVIVABILITY RICHARD HUFFMAN
by Mark Couch
The Joint Aircraft Survivability Program (JASP) is pleased to recognize LTC Richard E. Huffman Jr. for his Excellence in Survivability. Rich is currently on assignment as the Chief of Information Operations Plans and Assessments Branch at Headquarters U.S. Africa Command (AFRICOM). Additionally, he is an adjunct assistant professor of aerospace engineering at the Air Force Institute of Technology (AFIT). He has also served in the Air Force for 23 years as a developmental flight test engineer, working envelope expansion, avionics, and survivability testing on numerous weapon systems.
and integrate it into the survivability Investigation Into the Flow Structure in research programs running at Wright- the Vicinity of a Wrap-Around Fin.” Patterson and Eglin Air Force Bases (AFBs). Thanks to Rich’s efforts, the The follow-on assignment for (then) 2LT class now includes hands-on demon- Huffman was to the Demonstration strations and tours at Sensors Branch in the Air Vehicles Directorate of Directorate of the Air Force Research AFRL. The flight test bug bit him in that Laboratory (AFRL), the National assignment, having to miss graduation Museum of the U.S. Air Force, and the from AFIT to support test planning at survivability ranges of the 704th Test Edwards AFB. Rich worked primarily on Group. Additionally, the class travels to the Advanced Fighter Integration Eglin AFB to participate in the Threat Technology (AFTI) F-16, which was a Weapons Effects Seminar. research testbed managed in Dayton but flown out of Edwards in collabora- Rich was plugged into the survivability In 1994, Rich received a B.S. in aeronau- tion with the National Aeronautics and community after inheriting the weapons tical and astronautical engineering from Space Administration’s Dryden Flight design and aircraft survivability course Purdue University. While at Purdue, he Research Center. Despite Rich’s two sequence as a new faculty member at was also a cooperative education aeronautical engineering degrees, the AFIT in the fall of 2007. For many years, student with the Foreign Technology Air Force tried to turn Rich into an the only school that taught aircraft Division, now known as the National Air electrical engineer as he developed combat survivability was the Naval and Space Intelligence Center. After antenna, navigation, and flight control Postgraduate School (NPS) at Monterey. graduation, he received a commission systems. His favorite demonstration However, in the early 2000’s, through from the Reserve Officers Training Corps program to be involved in from this some interchanges between NPS and Program and entered the Air Force. His assignment was the Automatic Ground AFIT, aircraft survivability was added to first assignment was to AFIT as a Collision Avoidance System (Auto- the AFIT program as well. graduate student. Rich graduated from GCAS). This system, which was AFIT in 1995 with an M.S. in aerospace installed into the F-16 in 2014, overrides As the third instructor to teach the engineering. His thesis, which was pilot control of the aircraft at the last course in 4 years, Rich took the given the department’s Best Thesis minute to prevent imminent collision opportunity to revamp the curriculum award, was titled “Mach 2.9 with nearby terrain.
21 jasp-online.org AS Journal 17 / FALL Rich’s next assignment was to the Air assigned to Detachment 1 of the 586th ABOUT THE AUTHOR Force Test Pilot school as the Chief of Flight Test Squadron at White Sands Dr. Mark Couch is currently the Warfare Instrumentation, where he was Missile Range (WSMR), NM. Rich was Area Lead for Live Fire Test and Evaluation responsible for the calibration and in charge of the team that provided in the Operational Evaluation Division at maintenance of the special instrumenta- planning and support for weapons the Institute for Defense Analyses (IDA). tion systems on the fleet of test aircraft testing on the sprawling WSMR test Prior to joining IDA in 2007, he enjoyed a for training test pilots and flight test complex. The team supported numer- 23-year Navy career flying the MH-53E engineers. Rich also applied to be, and ous programs, including the Advanced helicopter. He has a Ph.D. in aeronautical was accepted as, a student at Test Pilot Medium-Range Air-to-Air Missile, F-35 and astronautical engineering from the School while at the schoolhouse, Lightning II, F-22 Raptor, Joint Direct Naval Postgraduate School and has taught graduating with class 2000A. Attack Munition, Small Diameter Bomb I numerous courses in aircraft combat and II, and the Massive Ordnance survivability. Next, he was assigned to the 411th Flight Penetrator. Following this assignment, Test Squadron, where he executed test he was chosen for a back-to-back missions on the F-22 Raptor as a test command tour, taking command of the conductor and test director. He spent National Radar Cross Section Test the next 4 years as part of the Secretary Facility at WSMR. of Defense-directed test acceleration program, testing the airframe, avionics, Rich left New Mexico in 2016 for a staff envelope clearance, and weapons tour at Headquarters AFRICOM, where, separations of the aircraft. as mentioned previously, he currently serves as the Chief of the Information In 2004, Rich was accepted into AFIT’s Operations Plans and Assessments faculty pipeline program, which sent him Branch, which focuses on integrating to the University of Illinois with a nonkinetic activities such as electronic follow-on requirement to teach at AFIT. warfare into the Theater Campaign Plan. In 2007, he completed his doctorate in aerospace engineering, with a disserta- Rich is also an Associate Fellow of the tion titled “An Experimental American Institute of Aeronautics and Investigation into the Effect of Plasma Astronautics and a member of the on the Flow Features of an Antenna Measurement Techniques Axisymmetric Jet.” Association. In addition, he has authored or coauthored more than 40 Following his time at Illinois, Rich articles and papers in aircraft survivabil- became an assistant professor of ity, navigation, fluid flowfields, and aerospace engineering at AFIT. In his measurement techniques. 4-year teaching tour, he was the deputy department head and advisor for 19 Rich currently lives in Stuttgart, master’s and 3 doctorate students. He Germany, with his wife of 13 years and taught aircraft combat survivability to their three children. more than 150 students and continues to serve as adjunct assistant professor Congratulations, Rich, for your as well as one of the lead instructors of Excellence in Survivability and for your the JASP-sponsored annual aircraft distinguished contributions to today’s combat survivability short course (for and tomorrow’s aircraft survivability the past 8 years). community.
In 2011, Rich competed, and was selected, for command. He was
AS Journal 17 / FALL jasp-online.org 22 BLAST-TOLERANT COMPOSITE STRUCTURE FOR ROTORCRAFT
by Mark Robeson, Clark Andrews, and Lisa Chiu
Military rotorcraft structures may be subjected to high-energy ballistic events in combat situations. Ballistic threats characterized by an advancing shockwave created by an explosive blast, alone and in combination with high-speed fragmentation, typically result in significant structural damage for both metallic and composite structures. To address this vulnerability, the U.S. Army’s Aviation Development Directorate (ADD) and The Boeing Company have collaborated to develop and integrate specifically designed composite sandwich components into large primary aircraft structures, which have shown good success at mitigating catastrophic damage caused by explosive ballistic events [1].
To address small-volume, enclosed characteristics covering (1) compression The full-scale test article configuration aircraft structure, ADD and Boeing and tension strength, (2) density, and (3) (shown in Figure 1) was designed to be collaborated to develop subscale compression load-deflection curves with representative of small-volume primary composite sandwich panels, which were progressive failure mechanisms. Now, aircraft structure. The assembly shown to mitigate advancing shock- successfully integrating the shockwave consists of a metallic spar, carbon/ waves from representative explosive mitigating sandwich structural concepts epoxy spar box, and fastened doublers ballistic events at close proximity [2]. into small-volume primary structure, via that reinforce holes in the spar box. The This damage-mitigating sandwich full-scale test articles, is shown to spar box is made of carbon/epoxy face structure has been developed by improve composite structure ballistic/ sheets with crushable core engineered engineering the core with tuned blast tolerance. with specific characteristics (strength,
23 jasp-online.org AS Journal 17 / FALL Fasteners and an Arbitrary Lagrangian Eulerian (ALE) approach. ALE combines both Lagrangian (where each individual node of the computational mesh follows the Metallic associated material particle) and Spar Eulerian (where the computational mesh is fixed in space and the continuum Hole moves with respect to the grid) Doublers formulations, such that the computa- tional mesh may be fixed in space or Composite Spar Box Blast-Attenuating Structure move with the continuum. Both analysis methods were executed with the finite Figure 1 Full-Scale Test Article Configuration element (FE) code LS-DYNA. density, and yield behavior) to mitigate the explosive blast shockwave. The empirical explosive approach Assembly of the structure is accom- defines the pressure environment using plished with riveted fasteners. Test curves that are fit to test data. The articles (shown in Figure 2) were structure of interest is modeled using
fabricated with varying spar box Figure 2 Fabricated Test Articles the Lagrangian FE formulation, and a laminate definitions, metallic spar unique pressure-time history is defined configurations, and hole doubler correlate with the analysis. Using data for every element subjected to the blast. configurations, but with the same core and observations from the first round, The time histories are defined by peak configuration. the analysis was modified to better pressure, pressure pulse duration, and represent the pressure environment pulse arrival time, which were derived FULL-SCALE created from the ballistic threat and from empirical test data and depended BALLISTIC TESTING improve correlation with the damage on the charge characteristics and observed. The second round of testing distance between the element and the (shown in Figure 3) was then executed charge. The explosive source is defined Ballistic testing was conducted at the to demonstrate the accuracy of the by the user, including location, mass, ADD range (in Fort Eustis, VA) to improved analysis. round casing (if applicable), and shape. evaluate the structural response of the The pressure-time-history for an full-scale test article when subjected to element is calculated as a function of the pressure environment created by the BLAST ANALYSIS distance from the defined explosive specified high-energy (explosive) threat. source and user inputs. Data gathered during the full-scale test The overpressure environment on the included high-speed video and photogra- interior of the structure, resulting from For the present ALE approach, the phy. The objectives of the test were as the explosive event, was modeled explosive material and air domain are follows: analytically by Boeing (Mesa, AZ) using two approaches: an empirical approach modeled using an ALE formulation while 1. Evaluate the damage tolerance and blast-mitigating effects of the candidate structures against the ballistic threat. 2. Collect performance data (via observed damage, high-speed video, and photography) for analytical model correlation. Two rounds of ballistic testing were
conducted, with the first used to Figure 3 High-Energy Ballistic Testing
AS Journal 17 / FALL jasp-online.org 24 structural components are modeled using IML Facesheet Cracks - capability of the full-scale test articles. a purely Lagrangian formulation. The Overpressure The test setup is shown in Figure 5. Each interaction between the ALE domain and of the two test articles was fastened to the Lagrangian surfaces is simulated laboratory structure, and test loads were with definitions of Fluid Structure applied by a single actuator to simulate Interaction (FSI). The pressure environ- flight loading. Data acquisition included ment and resulting pressure-time history load, strain, and displacement. Strain due to the explosive materials are a was measured by four axial strain function of the resulting FSI. gauges, two on either side of the test article as shown, to verify the applied Due to the complexity of the ALE loads. Displacement was measured at approach, it is significantly costlier (up to the upper corners in the lateral direction 40 times the simulation clock time) than by string pots on the right-hand side of the empirical model. However, compari- the test article. son of the approaches resulted in IML sufficient confidence in the empirical Facesheet Max Strain First, cyclic testing was conducted at approach for it to be used for correlation load levels ranging from level flight to with test results. More detail on the enhanced limit design loads. Several test analytical models can be found in blocks of progressively increasing Andrews et al. [3]. magnitude were defined from a baseline Cracking in aft spar level flight to an enhanced limit design BLAST RESULTS AND load, corresponding to a full unrestricted CORRELATION flight envelope. The full test schedule provided 6,600 cycles of representative As stated previously, the first round of flight. After successful completion of the ballistic testing was used to correlate cyclic test, a static test was executed, and improve the analysis. The pre-test including static test to failure, in which damage predictions for the second round Max Strain failure loads exceeded ultimate design of testing were generated with the loads. improved empirical analysis, and they Figure 4 Analytical Predictions Corresponding to Damage agreed favorably with the damage observed (as shown in Figure 4). High strains, predicted between the aft spar holes and along the inner face sheet of Displacement the composite spar box, indicated a risk Load String Pot Actuator of moderate cracking. Some cracking at Load Fixture these locations was observed in test. Significant damage to the metallic spar was not predicted and was not evident in test. The only notable damage to the Displacement metallic spar was due to cracking String Pot between shrapnel penetrations. Strain Gauges RESIDUAL STRENGTH TEST
Following the ballistic testing, residual strength testing was conducted at the Base Fixture ADD Structures Laboratory (in Fort Eustis,
VA) to evaluate the post-ballistic Figure 5 Residual Strength Test Setup
25 jasp-online.org AS Journal 17 / FALL RESIDUAL STRENGTH ANALYSIS Predicted Residual Residual strength FE analysis was conducted on the full-scale test article. Strength Test Response Min Strain Maximum and minimum principal strains are shown in Figure 6 for the composite spar box at design limit loading. Extreme compression strains were predicted to be relatively low. Failure was predicted when the local peak strain at the damage hole reached the
materials ultimate compression strain. Increasing Strain Running loads were extracted from the analysis for the bays in the metallic spar, assuming crack propagation between Figure 6 Residual Strength Analysis for the Composite Spar Box shrapnel holes. A panel buckling analysis was also conducted for each of Spar Rivet Spar Crack Propagation the remaining bays. All pre-test Line and Buckling predictions, including failure modes in the composite spar box and metallic spar, predicted no failure during cyclic testing. More detail on the analysis can be found in Andrews et al. [3].
RESIDUAL STRENGTH RESULTS AND CORRELATION
The full-scale test articles were subjected to the cyclic loads without failure or observable damage growth. With cyclic loading complete, the full-scale test articles were statically loaded to failure (as shown in Figure 7). For the measured test loads (Table 1), yield load is where strain response first Spar Box deviated from linear, and is due to either Crack a failure in the composite or yielding or failure of the metallic spar. The first SPECIMEN 1 SPECIMEN 2
specimen initially indicated yield Figure 7 Residual Strength Test to Failure behavior at 155% of design limit load Table 1 Measured vs. Predicted Failure Loads as a Percentage of Design Limit Load when a crack in the composite spar box grew between the spar box holes. Measured Predicted Yield Load Ultimately, failure occurred when the Test Predicted Yield Metallic Composite composite spar box separated from the Article Yield Failure Mode Spar Spar Box metallic spar along the rivet line at 209% of design limit load. For the 1 155% 209% n/a* 167% Composite Spar Box second specimen, the initial yield 2 172% 191% 163% 197% Metallic Spar behavior occurred at 172% of design
AS Journal 17 / FALL jasp-online.org 26 limit load, when cracks in the metallic for evaluation of ballistic/blast tolerance including a multidisciplinary focus on the spar began to grow, and quickly resulted and residual strength. FE analysis development of ballistically tolerant in ultimate failure at 191% of design predicted resulting damage and residual structures, aircraft configuration design, limit load, when the metallic spar strength of small-volume aircraft and, most recently, production support of buckled. structure when subjected to a ballistic drive systems. He holds a bachelor’s and a event. After two rounds of ballistic master’s degree in mechanical engineering The analytically predicted failure (yield) testing, post-test correlation demon- from Northern Arizona University and loads correlate well with those mea- strated that empirical analysis is Arizona State University, respectively. sured in the testing (Table 1). For Test suitable to accurately predict structural Article 1, composite spar box yielding at response and damage modes for Ms. Lisa Chiu has worked as a structural 155% of design limit load was within ballistic events of this magnitude. analyst for The Boeing Company for 10 20% of predicted yield at 167% design Specifically, high strains predicted in the years, focusing on analysis, simulation, and limit load. For Test Article 2, initial composite face sheets were shown to testing of composite structures. Currently, buckling and crack propagation in the correlate to cracks resulting from the she serves as the principal investigator for metallic spar at 172% of design limit extreme overpressures. The test several research and development load was within 10% of predicted articles were then subjected to residual programs focusing on survivability, buckling yield at 163% design limit load. strength testing. Both specimens durability, and damage tolerance. She is a The specimens generally hold more load exhibited cyclic, yield, and ultimate Boeing designated expert in ballistic than predicted. strengths in excess of design require- structural analysis and ballistic test ments, clearly demonstrating the execution for composite structure. Residual strength test loads are capability of the engineered structural Ms. Chiu holds a B.S. and M.S. in summarized in Figure 8, with the core solution to mitigate the damage mechanical engineering from the University ballistically damaged test articles due to the ballistic event while contrib- of Massachusetts Lowell loaded cyclically to 105% of an uting to the strength of the candidate enhanced design limit load and loaded rotorcraft structure. ACKNOWLEDGMENTS statically to 209% and 191% of This research was partially funded by the enhanced design limit loads before ABOUT THE AUTHORS Government under Agreement No. failure. These cyclic and static strength Dr. Mark Robeson is an aerospace engineer W911W6-11-2-0014. The authors thank results demonstrate the exceptional with the U.S. Army Aviation Development the U.S. Army’s ADD and the Boeing durability and damage tolerance of this Directorate. With more than 27 years of AH-64 Modernization Office for their design. research and development experience, he financial and technical support of this
209% currently serves as a U.S. Army Aviation research. 191% Missile Research Development and Engineering Center Experimental References 105% 105% Enhanced Design Limit Developer (designated technical expert), Baseline Design Limit with expertise in aviation structures and [1] Chiu, L., D. McCarthy, C. Andrews, A. Harris, and Steady Forward Flight vulnerability reduction. He is also active as M. Robeson. “Durable and Damage Tolerant Composites Aft Fuselage Technology.” Proceedings, a structures and materials technical expert 1 2 AHS 71st Annual Forum, Virginia Beach, VA, May Cyclic Test Max Load Ultimate Static Failure in the Joint Aircraft Survivability Program’s 2015. Vulnerability Analysis and Reduction Figure 8 Residual Strength Test Loads [2] Chiu, L., D. McCarthy, and M. Robeson. “Blast Subgroup. Dr. Robeson has a B.S. in Attenuating Aircraft Structure,” Proceedings, AHS mechanical engineering and an M.S. and 69th Annual Forum, Phoenix, AZ, May 2013. CONCLUSION Ph.D. in engineering mechanics from Old [3] Andrews, C., L. Chiu, and M. Robeson. Dominion University. “Analysis and Test of Composite Rotorcraft Structure A specifically engineered structural core Subject to Ballistic Events,” Proceedings, AHS 73rd Annual Forum, Fort Worth, TX, May 2017. solution was developed and integrated Mr. Clark Andrews is a mechanical into a full-scale test article, representa- engineer with The Boeing Company. He tive of small-volume rotorcraft structure, has 7 years of industry experience,
27 jasp-online.org AS Journal 17 / FALL THREAT CHARACTERIZATION: SMALL PROJECTILES, BIG IMPACT
by Jonathan Marshall
Figure 1 Marines Unearth Several Large Weapons Caches
The global proliferation of assault rifles, machine guns, and other man-portable weapons has increased both the frequency and intensity of modern conflict. These weapons, classified as small arms (which typically include up to 23 mm in caliber), are easily obtainable on international markets and are effectively used by untrained personnel. There are an estimated 100 million to 500 million military-style weapons in circulation, in addition to hundreds of millions designed for police or civilian use. In addition, of the 49 major conflicts that have occurred since 1990, small arms and light weapons (such as those shown in Figure 1) were the primary weapons used in 46 of them. Only the Gulf War predominately used heavy weapons [1, 2].
Several distinguishing features of small The simplicity and low maintenance of the paramilitary and irregular forces that arms make them suitable for modern small arms also greatly increase their use have played such a prominent role in conflicts. First, their previously in conflicts involving untrained recent conflicts. mentioned wide proliferation makes combatants, as these weapons require them easily obtainable. This availability little training to use effectively as well as In addition to the significant threat they is attributed to new production, remnants little logistical support. Finally, small pose to personnel, small arms projectiles of downsizing militaries, or recycled arms and light weapons can be carried by are designed to penetrate airframes and weapons from previous conflicts. an individual soldier or light vehicle and disable flight-critical systems. Armor Additionally, the rapid-fire capability of are easily transported or smuggled to piercing-incendiary (API) projectiles are small arms (often of 300+ rounds per areas of conflict. Not surprisingly, these designed to release incendiary material minute) allows a single individual to pose combined characteristics of small arms into a dry bay when the projectile jacket a significant threat to military systems. have made them particularly attractive to is stripped. This incendiary material can
AS Journal 17 / FALL jasp-online.org 28 burn and linger in the dry bay long and simulation (M&S) and test & evalua- most significant dry bay fire parameters. enough to interact with fuel and initiate tion (T&E). The purpose of M&S and T&E Also, ProjPen and FATEPEN developers fires, which can be a large contributor to is to develop a specific understanding of continuously investigate and field aircraft vulnerability. component-, system-, and aircraft-level advancements in threat simulation tools. vulnerabilities. A detailed vulnerability Small arms threats also have limited analysis data set is developed and Ballistic testing and data collection countermeasures as they are point-to- combined with a representative three- techniques have also improved in recent point munitions guided by optics that dimensional geometric model to conduct years. For example, an increase in the have no sophisticated acquisition or computer-based simulations to quantify depth and use of high-speed video guidance systems. The primary counter- vulnerabilities. Simulations and testing can cameras has allowed analysts to measures are concept of operations assess the impact of vulnerability decipher minute differences in the (CONOPS) and tactics, training, and reduction features and are often used for effects of small arms projectiles. procedures (TTPs). For example, specification compliance. Recent efforts have identified that low-visibility conditions, (e.g., night these differences have statistical operations) help to conceal an aircraft THE IMPORTANCE OF significance. It is imperative to from engagement. Operators can also THREAT understand the differences between avoid engagement by flying outside of threats, as these data are repeatedly the effective range of small arms CHARACTERIZATION used for verification against program weapons. However, many military specification requirements. Accurate platforms are often used for low-altitude Threat characterization has an important threat data must be captured to perform operations within the threat engagement role in vulnerability analyses. Damage an accurate vulnerability analysis. range (e.g., helicopters, such as the inflicted to components in an analysis is These threat data include physical Russian one shot down by ground fire in measured using specific threat param- characteristics and incendiary function Figure 2, often fly “low and slow” during eters, such as projectile physical data for API projectiles. It is critical to certain mission points). characteristics, incendiary mass, and ensure the physical properties and incendiary functioning potential. Every functioning of a projectile are under- If countermeasures fail or are unavailable, threat used for a vulnerability analysis stood, as these factors can significantly vulnerability enhancement features can must be fully characterized to properly alter expected T&E results. Correlation be used to minimize the risk of small assign lethality and probabilities of between T&E and M&S can also be arms. Examples of vulnerability enhance- damage or kill. Over the years, M&S difficult to track and understand if ments include increasing redundant tools and models have improved in different projectiles are unknowingly systems or adding armor; however, both fidelity and accuracy. As these analyti- being used. actions increase cost and impact cal tools and techniques evolve and performance metrics. improve, our understanding of threats Threat physical characteristics include must follow suit. The Director, projectile dimensions and material data. Aircraft vulnerability and the benefits of Operational Test & Evaluation (DOT&E) Projectile dimensions such as length, vulnerability enhancement features are recognized this need and funded efforts diameter, and core length and diameter measured and quantified using modeling to fully characterize and evaluate the are important to accurately measure across projectile lot samples to identify variations. These variations primarily stem from the wide proliferation across multiple countries, the number and quality of manufacturers, and the circulation of multiple threat types and designs, of which many pre-date the Cold War era. Variations in projectiles can be hidden from exterior appearance (as noted by the variations in identical caliber threats illustrated in Figure 3). Figure 2 Russian Helicopter Shot Down by Ground Fire
29 jasp-online.org AS Journal 17 / FALL CHARACTERIZATION detailed view of the inside of a METHODS projectile. The scans can identify the density of objects constructed of metal, ceramic, and composite and Several characterization methods are can provide accurate measurements to used to measure the projectile build three-dimensional geometric characteristics that play a significant models. CT scanning is cost-effective role in survivability. Computer tomog- and can scan multiple projectiles at raphy (CT) scanning, physical the same time. exploitation, and ballistic characteriza- tion testing are often used in Physical exploitation, or threat conjunction to build a thorough data dissection, is the process of creating set for a specific projectile. These cross sections of a projectile by data sets detail variations or define mounting samples in epoxy and then the physical properties of a specific cutting or grinding and polishing the round. mount for imaging and testing. Threat dissection is destructive in nature; CT scanning combines a series of however, it is the only means to Figure 3 Variations in Identical Caliber Cartridges X-ray images taken from different physically sample the interior of a (Wolfganggross) angles to produce cross-sectional projectile. Material testing, such as Differences in core material, hardness, images. Computer processing is used core hardness, can only be conducted and tensile strength are important to to generate a three-dimensional image on an exposed surface. Additionally, accurately sample. Projectile dimen- of the inside of the projectile from incendiary masses can be examined sions and material data are crucial to two-dimensional radiographic images for specific compositions. precisely capture penetration capabili- taken about a single axis of rotation ties and characteristics. For example, (as shown, for example, in the Ballistic characterization testing is length and diameter affect hole size, variation in the lead jackets pictured in used to analyze penetration, projectile whereas core hardness and tensile Figure 4). CT scanning is nondestruc- dynamics, and function characteristics. strength affect penetration and threat tive evaluation (NDE) and allows a Typical characterization testing fires break-up. Specific to APIs, function projectiles from a sample lot into data include incendiary mass and mounted panels (pictured in Figure 5). location within a projectile as well as Several input factors are varied to function cloud size and duration. The accurately capture variations in amount of incendiary within a projectile projectile dynamics. These input determines maximum function cloud factors include initial velocity, initial size and duration and can vary greatly yaw, panel obliquity, panel material, between threats, which can cause a material thickness, and the airgap large variance in function cloud size and between panels (if testing multiple duration. Small-caliber threats may panels). High-speed video cameras have an incendiary mass on the order of are used in ballistic testing to record 10 grains, whereas a large-caliber threat function type, cloud size, duration, and may have an incendiary mass of mobility. These high-speed cameras 70 grains or more. In addition, the are capable of image exposures in location of the incendiary may deter- microseconds. The images are then mine a threat’s function occurrence rate. played in slow motion to determine Differences in incendiary mass location function type (front face function and can affect how the incendiary material back face function), cloud size, and functions as the projectile jacket is duration. stripped away.
Figure 4 Projectile CT Scan
AS Journal 17 / FALL jasp-online.org 30 conducted to characterize volumes and identify anomalies not easily identified in physical exploitation for use in vulnerability analyses. This projectile characterization information should then be compared back to existing threat data to ensure that the size and compositions are similar. If there are variations, then ballistic
Figure 5 Live Fire Panel Testing characterization testing should be completed to evaluate the penetration CURRENT AND FUTURE Joint Aircraft Survivability Program and/or functioning potential of the EFFORTS (JASP) has funded the Next projectile. These data would then be Generation Fire Model (NGFM), which used to update and enhance the Currently, the Air Force Life Cycle aims to improve fire prediction vulnerability M&S tools. Small Management Center’s Combat capability by improving penetration, proactive investments to understand Effectiveness and Vulnerability energy deposition, fuel deposition, and and characterize threats prior to a Analysis Branch (AFLCMC/EZJA) ignition. The threat data quality is of significant LFT&E series can prevent maintains Pedigree documents that primary importance to enhancing the ambiguity due to variations and can provide the analytical foundation for predictive capability of these models. ensure proper integration of results for weapon system survivability and verification of key performance effectiveness analyses. The “Pedigree Detailed threat characterization begins parameters and specification compli- Document - Guns” [3] report provides with the development of acquisition ance. threat-based input files for vulnerabil- program survivability requirements. ity models used throughout the With so many countries and manufac- ABOUT THE AUTHOR community. The data were primarily turers of small arms projectiles, there derived from intelligence sources and are several variations for threats of Mr. Jonathan Marshall is a vulnerability were reformatted to be compatible the same caliber. Although recent analyst at the SURVICE Engineering with the vulnerability models. The programs have been more specific in Company. For the past 4 years, he has Pedigree documents detail several the threat designation, it is imperative supported aircraft survivability testing and commonly used threats for M&S to be as specific as possible when modeling for multiple rotorcraft and vulnerability analyses. As new data defining projectiles to be evaluated fixed-wing programs. Mr. Marshall holds a (e.g., new physical exploitation or CT (i.e., 7.62×39mm BZ M1943 API), as B.S. degree in mechanical engineering scans) are received, the data are these specifics will drive the M&S and from Wright State University. reviewed and summarily updated T&E requirements. Even minor within the Pedigree documents. variations in projectile designation can References influence vulnerability analyses results, Recently, several threats have had which can be enough to alter specifi- [1] Boutwell, Jeffrey, and Michael Klare. “Small Arms and Light Weapons: Controlling the Real function characterization testing cation requirement compliance. Instruments of War.” Arms Control Association, completed. These data were used to https://www.armscontrol.org/act/1998_08-09/ statistically analyze each threat to It is also recommended that any future mkas98, 1 August 1998. determine the probabilities of each ballistic test program conduct a full [2] Federation of American Scientists. “The Global function type. The Pedigree docu- threat characterization to quantify the Threat of Small Arms and Light Weapons—A Primer.” https://fas.org/asmp/campaigns/smallarms/ ments are currently one of the best important parameters that can primer.html, accessed June 2017. sources to identify and characterize a influence vulnerability results. [3] Air Force Life Cycle Management Center and threat to be used for analyses. Whenever a new lot of projectiles is the SURVICE Engineering Company, “Pedigree procured, a physical exploitation Document - Guns: Non-Exploding Vulnerability Looking to the near future, threat should be conducted to characterize Threat Data.” Wright-Patterson AFB, OH, June 2017. characterization will play a large role the size and materials of the projectile. in upcoming prediction models. The In addition, CT scanning should be
31 jasp-online.org AS Journal 17 / FALL DSIAC HEADQUARTERS PRSRT STD 4695 MILLENNIUM DRIVE US POSTAGE BELCAMP, MD 21017-1505 PAID BELCAMP, MD 21017-1505 BEL AIR MD Permit No. 50
CALENDAR OF EVENTS
OCTOBER 22nd Annual Expeditionary Warfare 49th Combined Light Armor Survivability Conference Panel Defense Innovation Technology 24–26 October in Annapolis, MD 14–15 November 2017 in Albuquerque, NM Acceleration Challenges (and SBIR/STTR www.ndia.org/events/2017/10/24/ewc17 Innovation Summit) Interservice/Industry Training, 3–5 October in Tampa, FL Precision Strike Technology Symposium Simulation & Education Conference www.defenseinnovation.us 24–27 October in Laurel, MD 27 November to 1 December in Orlando, FL www.precisionstrike.org/Events/8PST/8PST.html http://exhibits.iitsec.org/2017/Public/MainHall. 34th International Test and Evaluation aspx?ID=34981&sortMenu=101000 Symposium Gulf Coast Chapter 43rd Annual Air 3–5 October in Reston, VA Armament Symposium 54th Annual AOC International www.itea.org/share/workshops/35-share/ 31 October to 1 November in Symposium and Convention conferences/415-34th-international-test-and- Fort Walton Beach, FL 28–30 November in Washington, DC evaluation-symposium-2017.html www.ndia.org/events/2017/10/31/ www.crows.org/conventions/2017.html c113-gc-chapter-air-armament-symposium 3rd Annual Cyber Electromagnetic Activity Conference 2017 MSS Battlespace Acoustic and DECEMBER 16–19 October in Magnetic Sensors Aberdeen Proving Ground, MD 31 October to 2 November in Springfield, VA Winter Simulation Conference 2017 http://www.crows.org/event/192-aoc- www.sensiac.org/external/mss/meetings/ 3–6 December in Las Vegas, NV conferences/2017/06/06/83-3rd-annual-cema.html list_meetings.jsf http://meetings2.informs.org/wordpress/wsc2017/
MILCOM 2017 55th Annual SAFE Symposium Defense Manufacturing Conference 2017 23–25 October in Baltimore, MD 31 October to 2 November in Orlando, FL 4–7 December in Tampa, FL http://events.afcea.org/milcom17/public/enter.aspx https://www.safeassociation.com/index.cfm/ www.dmcmeeting.com page/symposium-overview 20th Systems Engineering Conference 23–26 October in Springfield, VA JANUARY www.ndia.org/ NOVEMBER AIAA Science and Technology Forum and events/2017/10/23/20th-systems-engineering- Exposition conference NDIA Aircraft Survivability Symposium 7–9 November in Monterey, CA 8–12 January in Kissimmee, FL http://scitech.aiaa.org/ Rotorcraft Structures and Survivability www.ndia.org Technical Meeting 24–26 October in Hampton, VA AAAA Aircraft Survivability Equipment www.vtol.org/structure Symposium 13–14 November 2017 in Huntsville, AL www.quad-a.org
Information for inclusion in the DSIAC Headquarters Phone: 443/360-4600 Calendar of Events may be sent to: 4695 Millennium Drive Fax: 410/272-6763 Belcamp, MD 21017-1505 Email: [email protected]
To update your mailing address, fax a copy of this page with changes to 410/272-6763 or scan and email it to [email protected].