PATROL COMBATANT MISSILE HYDROFOIL- DESIGN DEVELOPMENT AND PRODUCTION- A BRIEF HISTORY by David S. Oiling and Richard G. Merritt Boeing Marine Systems
Published as Boeing Document 0312-80948-1, December 1980, and in the January-February issue of IIHigh-Speed Surface Craft," London ABOUT THE AUTHORS
DAVID S. OLLING - Mechanical Specialist Engineer, PHM Variants Preliminary Design
BS, Mechanical Engineering, University of Washington, 1967
With Boeing 21 years
o 17 years in Advanced Marine Systems design, preliminary design, engineering liaison and testing organizations
RICHARD G. MERRITT - Manager of PHM Variants Preliminary Design
BS, Civil Engineering, Yale University, 1950 MS, Civil Engineering, California Institute of Technology, 1951 Degree of Civil Engineer, California Institute of Technology, 1953 Executive Program in Business Administration, Columbia University, 1967
With Boeing 17 years
o 1 year as engineer with U.S. Naval Ordnance Test Station, Pasadena, before joining Boeing.
o 6 years on airplane and missile system structural research.
o 21 years in advanced marine system technology management, including supervision of hydrofoil technology staff, project design, and preliminary design groups.
o Member of American Institute of Aeronautics and Astronautics, serving on AIAA technical committee on marine systems and technology.
o Author of 12 articles in scientific and professional journals. PATROL COMBATANT MISSILE (HYDROFOIL)
Design, Development and Production - A Brief History by David S. OUing and Richard G. Merritt, Boeing Marine Systems
INTRODUCTION 1974. Its completion (PHM 2) was later incorporated into the production program, In 1972 three NATO navies formally agreed reference 3. to proceed with the joint development of a warship pro ject. The United States took the Major Events leadership before the "Memorandum of Understanding" was signed by the Federal Developing a new, sophisticated naval ship Republic of Germany and Italy and awarded system requires a considerable investment a letter contract to The Boeing Company of time, talent and money. The U.S. Navy for the feasibility study and the design and acquisition process, historically, results in construction of two Patrol Combatant Mis about a 7 -year development cycle for the sile (Hydrofoil) lead ships. definition, design and first unit construction of a new ship platform, references 4 and 5. Earlier in 1970, the NATO Naval Armament As the schedule of major events shows, Group (NNAG), composed of representatives figure 1, nearly six years elapsed from the of eleven NATO nations, had recommended signing of the letter contract for the design that a hydrofoil with fully-submerged foils and construction of the lead ship, USS was the answer to the operational require Pegasus, in November 1971 to her com ments for a common fast patrol boat carry missioning in July 1977. The earlier exami ing surface to surface missiles. The NNAG nation of ship alternatives and configuration had studied different concepts of vehicles, choices required over two more years. but the final choice of the group was a ship Again, referring to 'the major events chart, configuration based on the PGH 2, Tucum figure 1, over ten years will have elapsed cari, also built by Boeing, which would be from the start of the lead ship program the prototype for future fast patrol boats. before the five production ships will join The original concept had called for an oper USS Pegasus to make up the planned six-ship ational displacement of 140 tons. However, squadron. in meeting the requirements of the partici pating governments and, in particular, the Pointing out the span of time for developing U.S. Navy, it was determined that the mini PHM-class hydrofoils, a system involving mum displacement that could do the job was new technologies, new design criteria and a design of 228 metric tons, references 1 new equipment innovations, is not intended and 2. to be critical. The application of additional resources could have reduced the elapsed While the initial contract called for two time, but the extent of the reduction cannot lead ships, program cost growth forced sus be known. The point to be made is that the pension of work on the second ship in August design and development phases have been
1 EUROPEAN PGH 2 PROPOSAL DELIVERY DEPLOYMENT CARIBBEAN U 'Sl 'Sl'Sl u GROUNDING TUCUMCARI L\ &:::6 I DESIGN AND VIETNAM I PRODUCTION DEPLOYMENT MEMORANDUM OF CONTRACT I UNDERSTANDING SIGNED I U.S. ANNou~7CED ITALY DECISION EXPLORATORY DECISION TO NO PRODUCTION COOPERATIVE PHM GROUP 2 ESTABLISHED PROCEED SHIPS PROGRAM NATO . \l \l "V \7 COMPLETED PROGRAM PROJECT GROUP 6.6..6. .6. ESTABLISHED FRG·ITALY FRG DECISION ISSUED LETIERS NO PRODUCTION OF INTENT SHIPS SURFLANT I I DEPLOYMENT CARIBBEAN LETIER CONSTRUCTION DELIVERY TO EXERCISE CONTRACT CONTRACT OPEVAL SURFPAC (READIEX U.S. LEAD SHIP I I \7 V Y 'Y 'Y 'i7 1-80) PROGRAM PRELIMINARY 6 PHM ,.6. <6 <6 RIMPAC (PHM ,) DESIGN LAUNCH SOCAL EXERCISE I DEPLOYMENT
START I PRODUCTION PROPOSA~ AWARD / DELIVERIES PRODUCIBILITY V \7 <;j PHM 3 \J PRODUCTION V STUDY . .6. \ PROGRAM RFP I PHM 4 )J ISSUES PHM 5 V
NEGOTI ATIONS PHM 6 V COMPLETED PHM 29 I I I Figure 1. Major Events Leading to NATO PHM Program and Operational PHM Squadron
Figure 2. PGH 2 Tucumcari
2 Figure 3. PGH 2 Tucumcari Foll System (Retracted) successfully achieved and the time to The PGH 2 incorporated a unique foil sys accomplish this is the same or shorter than tem, figure 3. The principal features were a for other na val ship systems. canard foil configuration; trailing edge flap control on all foils; a steerable forward Figure 1 also shows the major events for strut (rudder); and an Automatic Control PGH 2, Tucumcari. Because Tucumcari was System for roll stability, altitude control, the basis for the PHM design, a brief review ride quality control and banked, fully coor of its design features and operational his dinated turning. The canard configuration tory is in order to see where the principal where about one-third of the dynamic lift of features impacted the PHM design. the ship is supported on the single foil forward and two-thirds on the two foils aft PGH 2, Tucumcari has been conclusively demonstrated to pro vide superior roll and directional stability The PGH program to develop a hydrofoil and control at all times. This becomes gunboat was initiated in late 1965. Two extremely critical in very hea vy seas where ships were authorized, based on a perform the possibility exists for broaching the for ance specification. Grumman was awarded ward foil in large waves. a contract for PGH 1, Flagstaff, and Boeing for PGH 2, Tucumcari. The resulting While the location of the roll authority designs were significantly different. As the (forward in conventional or airplane while result of the evaluation of these two ships in aft in canard configuration) is not particu tr ials in the United States and service in larly significant for operations in calm seas Vietnam, the features of Tucumcari, figure where the foils are always submerged and 2, were chosen as requirements for the fully wetted, it becomes very critical in NATO PHM program, reference 1. rough seas. In the case of a forward foil broach, the difference in response between Tucumcari is best recognized for its water canard and conventional can be dramatic. jet propulsion system. Propulsion was pro The forward foil broach on a canard config vided by a Rolls-Royce Proteus turbine driv uration results in no rolllng moment. The ing directly a two-impeller double-suction forward foil broach of a conventional con centr ifugal pump. Boeing chose this pump figuration can result in severe rolling. The design for its extreme simplicity and mini steerable forward strut adds to the control mum number of moving parts. It had an lability of the canard arrangement foilborne aluminum housing and rotor assembly with a and provides desirable steering forces when stainless steel drive shaft. After 5 years of the ship is hullborne. Tucumcari could operation, the pump remained in essentially safely operate foilborne in rough water at the same condi tion as when installed. There least one sea state number greater than the was no evidence of corrosion, erosion, or slightly larger PGH 1, Flagstaff, with its cavi tation damage. airplane foil configuration. 3 An Automatic Control System (ACS) is pro PHM DESIGN AND DEVELOPMENT vided for continuous dynamic control of the ship during takeoff, landing and all foilborne Boeing's immediate task in late 1971 - early operation. The requirement for an ACS is 1972 was to determine the feasibility of established at the outset by the fully sub designing a NATO PHM so as to meet the merged foil configuration which trades performance goals of the three participating inherent roll stability for superior riding governments, the United States, the Federal quallties in sea conditions. In addition to Republic of Germany and Italy. The objec providing ship roll stability, the ACS con tive was examined from the standpoint of trolled the ship height above the water three al terna tives for missi on suite, in par surface, caused banking in turns and reduced ticular the surface-to-surface missiles. ship motions caused by waves. Automatic (The U.S. Navy, of course, was interested in foilborne control was based on the concept installing Harpoon missiles, FRG desired of "feedback" control. Ship attitudes, rates, Exocet and Italy was interested in Teseo). and accelerations were sensed and compared The feasibility baseline design and para with desired values. The differences were metric studies were to provide the data and processed by an electronic control computer alternatives which would allow the partici and became electrical commands to pating governments to knowledgeably select hydraulic servo actuators. The actuators the major and primary performance and moved mechanical linkages to position the configuration characteristics to be incorpo control surfaces, causing the ship to respond rated into what was called the "NATO PHM so as to minimize those differences. Standard Design". Baseline ship cost esti mates, by element, were also developed in Foilborne turns were accomplished in a order to provide information on the effect banked (coordinated) fashion. This caused of configuration choices on cost. the centr ipetal force required in turns to be provided predominantly by the lift capabil The initial effort determined that the per ity of the fully submerged foils rather than formance goals could be attained with any by side forces from the struts. Turn coordi of the three mission sui tes but the displace na tion enhanced crew comfort during high ment in each case was greater than a target rate turns because the accelerations due to value of 170 tons. In fact, by the time the turning were felt pr imar lly as slightly feasibility baseline design was completed in greater forces normal to the deck rather April 1972, the design full load displacement than as large lateral forces. Fully coordi was established at 228 metric tons including nated, rough water turns were accomplished a 9.5-metric ton margin for growth during in relatively steady fashion in spite of varia the service life. tions of the wetted areas on the struts. Another major task in the first days of the After service in Vietnam, Tucumcari toured NATO PHM contract was to study the feasi Europe for the NATO navies in 1971. Jane's bility of designing and constructing the ship Surface Skimmers stated, "The vessel which using metric units in order to achieve the has con tributed most to winning over NATO objectives of a cooperative design in the na vies (to hydrofoils) is undoubtedly the most cost-effective manner. The approach Boeing Tucumcari-" Upon its return to the involved review of each major element of United States, it was placed in service with the PHM design specifying metric units for the Atlantic Fleet amphibious forces. In new elements and using imperial units for November 1972, during night operations in elements already developed in those units. the Caribbean, it ran upon a reef while The initial cost impact was estimated to be operating foilborne. Although the ship was about five percent on design, five percent repairable, the cost of repairs was not con on procurement and an initial ten percent sidered warranted in view of the imminence impact on maintenance and support items. of the PHM, which would incorporate many of its unique features. It has been removed The decision to "go metr ic" can now be from the records of active ships and has viewed as very favorable. The engineer been dissected for engineering knowledge of ing designers had no problem in changing its components. their thinking to metric equivalents. It
4 represents a significant first in U.S. ship building experience. The canard foil system arrangement, as Some of the principal systems will now be described for Tucumcari, was a given from discussed including the rationale for their the outset of the pro gram (see figure 5). selection. It is of interest, in some cases, to The forward foil/strut system has always compare the feasibility baseline ship with been a steerable tee configuration which the final design for PHM 1 to see where stows ahead of the bow in the retracted changes occurred and why. posi tioo identical to Tucumcar i. The aft foil system was configured as a structural HuH Lines bent rather than individual tee foils. This resulted in greater structural and hydrody The hull lines were developed to satisfy namic efficiency but necessitated retracting considerations related to accommodations, the system rearward behind the transom for weight, intact and damaged stability, a two shallow water, hullborne operation. These compartment flooding criteria, seakeeping, retraction constraints along with the strut hullborne resistance, takeoff resistance, and length requirements dictated by sea state, foilborne wave impacts. The considerations determined the location of the foils relative determining the resul ting hull shape are to the hull. The final distribution of foil illustrated by figure 4. area, fore and aft, was then determined by the ship center of gravi ty location. The resul ting length overall and maximum beam for the feasibility baseline design were 39.5 meters and 8.4 meters, respec tively. This hull accommodated the LM2500 gas turbine for foilborne propulsion. Minor refinements in equipment and arrangements finally resulted in a slightly longer hull. PHM 1 and the production series have a length overall of 40.5 meters and a beam of 8.6 meters.
The hull, at all times, was designed as an all-welded structure fabricated primar lly from 5456 aluminum alloy.
BOW FLARE, FREEBOARD FORWAAO DETERMiNED BY HUlUORNE AND Figure 5. Foil System Arrangement FOll80RHE SEAKEEPING OONStOERATIO"'5
PRISMATIC cofFF ICIEHT. OISP'\..ACEWEHT lEHGTl1 RAr;o, The feasibility baseline configuration re ANO lENGTH BEAM RATtO DETER Lee DETERMINED BY MINED BY ARRANGeMENT, sulted in a distribution of foil area of 32 CANARD ARRANGEMENT HUllBOANE RESISTANCE, WEIGHT ! -3" FORWAROll AND STAeILITY OONSIOERATJONS 7 percent forward and 68 percent aft. This
HUll. CUTOUT OH£AMiNEO t b~'~~I~~~R:y // has not changed much even as other systems 8Y fOil SYSTEM ARRAfrrfGE i OECK SPACE,STABllITY. / MENT CONSIDERATIONS ~ 1 AND RADAR SIGNATUA£ have changed drastically. For example, the fREE80AADAfT /' CONSIDE'RATtONS ~'-_"""' _____ production series has foils arranged with ~r.J~~~O BY // f:'ONSlOERATIONS/' / 31.8 percent of the total foil area forward ,/7 / and 68.2 percent aft.
The length of the struts, chosen to allow
BASIC DEAORISE foilborne operation in 5-meter waves, has onUIMINW8Y ", STA81l1TY AND FOILBORNE: changed very little from inception in 1971 . "NOZZlE OUTLET ANO TUNNEL>" IMPACT OOHSIOE RA nONS OET£RMINEO BY MAOHNfRY MIN :l3o.g ARRAI' 10 Dimensions: length ov... a!!, foil. down 40.5m Armament: (1) MK 75 7~/62-d11 OTO Meier. gun (2) Harpoon miuile canister launchers Beam, main deck B.6m (2) MK 136 Mod 0, 4.4";" 1.... 1'ICher$ Over.1I aft foil span 14.5m Draft, loil, up 1.9m Ammunition: (400) 7fknm rounds Draft, loils down 7.1m (B) Harpoon surface-tO"IUrface missiles, RGM-84A·3 Heigl1t 01 bridge, hullborne 6.Bm (24) MK 171 Mod 0, chaff cartridges Small arms, ammunition, and pyrotechnics Height of bridge, loilborne 11.1m Full·load displacement 241.3 metric ton. Command and surveillance: Foilborne propul"",,: (II General Electric LM2500 gas turbine engine Command and control: (2) ANISPA·25B diSplays 111 Aerolet liquid Rocket Company waterlet propulsor Navigation: (1) ANISRN·170MEGA Hullbome propulsion: (2) Motoren·und Turbinen·Union (MTU) (1) SMA 3TM20-H radar MB8V331TC81 diesel engine. (11 Pl41E gyrocompass and vertical 121 Aerolet liquid Rocket Company referenCE wateriet propulsors with nozzle (1) Ul~100·3 underwater log steerinq and re.,;erser assemblies (1) DE~723D depth sounder Electrical (2) AIResearch ME831·800 gas turbine engines, each drlvlOg one gener ator (1) Windspeed and direction system rated., 200 kW (250 kVA), 400 Hz, (type FI 450V, three phase Dead·reckon jng tracer Interior communications: (1) MCS 2000 intercom, announcing, and Fuel D,.sel oil p"r MIL·F·16B84INATO F·761 alarm system or JP·5 p"r MIl·J·5624 (NATO F 441 Hull Welded 5456 aluminum Exterior communications' 111 AN!URC-80 vhf transceiver (158·1621 12) AN/ARC· 13B(V) uhf transceiver (225400) Fods and struts Welded 17-4P1-1 COrfOSolOn~res'stant steel (2) ANIURC·75(V) hf transceivers (2·30) Accommodations 24 berths 11) Radio teletype system Complement 21 othrers and enlisted perronne! Surveillance: (I) AIMS MK XII IFF system Provisions. 5days Countermeasures Rapid bloom oftboard ch.ff ESM (weight, space, power reservatlons~ F ire control MK 92 (Mod 1) gun lor. control system Harpoon shtp command·launch control set ANI'!mG·' (V) Figure 7. PHM 3 Series General Figure 8. Mission Equipment Characteristics and Principal Subsystems H UlLBORNE WATERJET ~PROPUlSOR ~ ENGINEER'S OPERATING STATION HUlLBORNE DIESEL DAMAGE CONTROL STATION FOllBORNE WATERJET CREW HEAD r- CREW MESSROOM .r PROPUlSOR / BOSUN LOCKER (PlSl MAGAZINE AND STORAGE AREA FOILBORNE CPO BERTHING DIESEL TURBINE CREW LIVING SPACE AND PUMP FOllBORNE TURBINE MACHINERY ROOM AUXILIARY MACHINERY MACHINERY ROOM NO.3 ROOM ~ AUXILIARY MACHINERY ROOM NO.2 Figure 9. PHM 3 Series Platform Deck 11 MAST MUL TlZONE AIR-CONDITIONING UNIT RBOC LOCKER OFFICER OF THE DAY HELMSMAN '- PILOT HOUSE RBOC LAUNCHER (PIS) '-, OUTSIDE AIR-CONDITIONING UNIT FUEL,REPLENISHMENT AT SEA STATION '~'----LlFERAFT 01 LEVEL AUXILIARY MACHINERY ROOM NO, 1 HARPOON MISSILES FOILBORNE TURBINE AIR INLET PASSAGEWAY MK 75 76-mm/62-cal GUN SSPU NO, 1 COMMANDING OFFICER'S ANCHOR WINDLASS FOILBORNE STATEROOM TURBINE EXHAUST LlFERAFT LlFERAFT MOORING LINE TAKEUP REEL MAIN DECK Figure 10. PHM 3 Series Main and 01 Level Deck Plan CREW LIVING SPACE ELECTRONICS EOUIPMENT ROOM COMMUNICATION ROOM AUXILIARY PILOT HOUSE MACHINERY ROOM NO, 1 MK 75. 76 mm/62 all GUN HARPOON MISSILES AUXILIARY MACHINERY ROOM NO, 3 DIESEL AND PUMP MACHINERY ROOM BOW THRUSTER NORMAL AUXILIARY MACHINERY ROOM FOILBORNE WL MACHINERY ROOM NO, 2 Figure 11. PHM 3 Series Inboard Profile 12 PRODUCIBILITY STUDY of bulkhead webs was provided by insert plates butt welded in the plane of the web. After the completion of PHM 1 and before Residual stresses caused by welding resul ted the PHM 3 design was started, a producibil in excessive distortions at the corners of ity study was performed to determine ways these insert plates. to simplify the ship's design in order to reduce construction time, reduce overall Brackets and chocks were added to achieve welding (a high-cost item) and improve the stiffener continuity which, because of poor end product. This study integrated engi weld accessibility caused by low profile and neering design with advanced construction dose stiffener spacing, were difficult and technology. costly to install. See comparison of bulk head stringer configuration, figure 16. In order to best illus tr ate the changes resulting from this study, a typical trans PHM Production Design verse watertight midships bulkhead was chosen as a representative example of a hull The PHM production design resul ted from structural element which was to be rede extensive study of PHM 1 design and con signed, figure 12. struction problems. Many parts were used, access to welds was difficul t and subsequent fi t- up was time-consuming due to weld dis tortion. The resulting PHM 3 Series bulk head design is shown in figure 13. Figure 12. PHM 1 Bulkhead ", PROOl)CTIOr¥"":::::' BREAK PHM 1 Hull Design "RODUCT10~ PRQOVCTlON BREAK BREAK In order to reduce the amount of welding and the resulting weld distortions, a decision Figure 13. PHM 3 Bulkhead was made at the outset of PHM 1 design to use wide-ri bbed extruded panels wherever Key features of the typical bulkhead design practical considerations of fabrication and include offset stiffeners, snipped stiffeners, material usage would permit. These panels thicker skin gage, panelized bulkhead seg were used eXtensively for decks and side ments, provisions for penetrations and a shell and were initially intended for use on design integrated with the manufacturing bulkheads; however, the introduction of plan. large local loads in the bulkheads caused by foilborne wave impacts on the hull bottom The termination of bulkhead stiffeners on a made the use of such panels im pr actical. beam header at a production break below the main deck simplifies installation and fi t In accordance with previ ous designs, bulk up of the deck module. It also provides for head and deck stiffeners were intentionally an area in which an orderly arrangement of aligned on PHM 1 and watertight collars electrical, hydraulic and piping runs can be were provided at the intersection of longitu made. Production design bulkhead penetra dinal deck and side shell stiffeners and at tions necessary to accommodate these sys the bulkhead web. PHM 1 bulkhead stiff tems are unencumbered with the presence eners were designed for structural contin of bulkhead stiffeners, a more efficient uity through the platform deck area. arrangement than on PHM 1. The design provides for a maximum of panelized weld Accordingly, typical bulkhead construction ing (mechanized welding of stiffening mem consisted of "tee" extruded stiffeners bers to the web) of bulkhead segments. One welded to plate web. Local reinforcement such bulkhead segment is shoVvTI in figure 14. 13 To ensure good fit-up and minimize the need 13 bulkhead, there are 75 percent fewer for trimming on installation, panel segments individual parts, a reduction of 58 percent are trimmed to net size by routing after all of the length of welds, an estimated 71 welding is complete. An increase in the percent fewer fabrication manhours and an basic bulkhead web gage permits a reduction estimated 68 percent reduction in total in the number of bulkhead stiffeners and cost. All these reductions were gained with thus the amount of welding compared with a less than a five percent increase in PHM 1. weight. SLOTS FOA PANElIlEQ I"ENETI'IATION "lATfORIII aECK STIFFf~~RS ~ITTIMGS PANEUZED UPPER BULKHEAD? WF.B STIFf!!::NER LEFT UNWElOED ~ IN THIS AREA. FOR MANUAL ~ SLOTS FOR """'FUZED .- ALIGNMENT WITH FUEL TANK WE. I(~~LSO~ STIF~H'EAS BULI\~4(AD STIFFENER STifFENER StOTS FOR f;ULL PtA TING STfFFfN"fRS i/~ PANELIZED PLATFORM DECK CLOSEOUT COLLARS Figure 14. Panelized Bulkhead Segment Figure 15 is typical of design detail devel PANE UlED Fun oped to provide simple a&c:;embly/subassem TANK BULKHEAD bly fit-up with a srnall number of loose parts and maximum access for the welder. Note Figure 15. Typical Bulkhead Design Detail that the manual alignment of stiffeners above the platform deck is the only fit-up on assembly required with this design. The PROOIX'TKlN OUION panelized fuel tank bulkhead segment which is machine profile routed after subassembly welding is a part of the welded lower hull module. Slots are pre-cut in the bulkhead with sufficient clearance to permit easy installation of the platform deck onto the lower hull module. The flat bar longitudi nal stiffeners on the platform deck provide ADAPTERS j '0' for a simple one-piece collar closeout with STIFFENER ALlGfIIMfNT good welding access. The vertical bulkhead HULKHEAll ClOS(-OV'I' STIFffNfR stiffeners are intentionally offset from the COLLARS S'f1f'HN€R platform deck stiffeners in order to accom ..."" UGNMENT RI:OI)IAEO ~£I"'FO"'CEMENr aUlKHtAD modate the fi t-up detail shown. The bulk FOR FUEL INERTIA SiIHfNrA LOADS head stiffeners above the platform deck are left unwelded for a short distance on the Figure 16. Comparison of Bulkhead Stringer panelized bulkhead segment to permit man Configuration ual alignment with stiffeners below the deck prior to final weld closeout. This is in Examining the results of the study for the contrast to the fi t-on-assembly approach entire hull shows a 49 percent reduction of and difficul t weld-behind flanges configu individual parts, a 59 percent decrease in ration used on PHM 1. Figure 16 should be total weld length and a 720 percent increase examined in order to allow better visualiza in the use of mechanized welding. The tion of the differences in the two bulkhead estimated hull weight reduction was about configurations. The contrast in the two nine percent. Therefore the additional engi designs is evident when comparing these neering effort (cost) did accomplish its illustrations. This contrast is even more objective; a simplification in design, a evident when numerical comparisons are reduction in production cost, and an made. For this specific example, the figure improved end product. 14 PHM Strut and Foil Design Early in the operational life of PHM 1, The same kinds of manufacturing improve cracks appeared in the skins of the foils. ments such as fewer individual parts, less Detailed investigations showed that mater weld length and increased mechanized weld ial fatigue was the major source of failure. ing were investigated in the strut and foil Detailed fatigue load spectra were obtained design. The use of Electron Beam (EB) from full-scale ship tr ials, tests were con welding for heavy gage steel structure (foil ducted to determine material fatigue prop billets), and Plasma Arc welding for high erties and a detailed design resulting in rate straight line weld in medium gage significantly lower stresses and smoothing structure were identified as construction of stress concentrations was completed. simplifying, cost effective measures. The This design along with the study of its resul t of this study was a less complex but producibility resulted in totally new foil and heavier foil system, although much of the strut structure. The foil structure is weight change can be attributed to the created from large thick billets, Numerical upgrading in the system's strength and Control (NC) machined for interior contour fatigue capability. with welded upper skins. This ellmina ted most welds from the lower surface of the This study was conducted at a time when foil which is the predominate tension sur the knowledge of the PHM 1 design and face. The skin welds in the upper skins were construction problems were still fresh in located in order to improve their weldability mind, thereby taking advantage of recent tl and inspectability. The foil section was also IIlessons learned • changed f rom a N ACA 16-206.5 to NACA 16 306.5, an increase in camber. The dif ferences in the structural configurations are shown in figure 17. 15 mm TYP UNGROUND UNDERBEADS PHM 1 WELDS MOVED TO LOWER 17.8 mm STRESS AREAS NOM NOWELDSON 11 mm TENSION SKINS A1 SMOOTHED OUT AREAS OF STRESS L26.2mm NOM CONCENTRATION Material thickness increased to reduce stress level PRODUCTION SHIPS Figure 17. Comparisons in BL4500 Aft Foil Configuration 15 PHM PRODUCTION depict the assembly sequence and tie it to the actual PHM 3 schedule. The producibility study, as previously dis cussed, was performed to determine ways Assembly Sequence which would facilitiate the PHM production. Methods such as modular construction which The operations in each tool and tool posi tion are commonly used in aircraft manufacture are shown to give the reader an appreciation were investigated and incorporated into the for the complexi ty of the assembly sequence production plan. Work was divided into and of the state of completion at each stage functional areas (metal cutting, welding, of assembly. In order to depict the machining, tube bending, assembly, etc.) to sequence in a less complex manner, only improve the efficiency of the work force representative operations and tools are and to support the modular construction shown in figure 18. Several things should be plan. A master assembly sequence and noted. 1) Parts to be welded are posi tioned schedule was created, tooling was designed in such a manner that welding is predomi and produced, materials purchased and shop nately accomplished in the down-hand, ver orders were written. These shop orders tical or horizontal positions. 2) Where pos provided a list of drawings required, the sible, automatic machines are used to weld tools (jigs or fixtures) to be used, parts and long joints. 3) Electron Beam (EB) welding materials required, the step by step is used, where the part size permits, to join sequence to be used in performing the work thick steel parts in a single pass. These package, quality control procedures and methods help to assure higher quality welds. inspections required, and a start and end 4) Equipment and systems installation and date as well as an estimate of the time to the testing of the systems and ship compart complete the package. Shop orders describe ments are conducted continuously through work packages which can usually be accom out the entire process. This enables rework plished in about 2 hours, but may require as of faulty construction or replacement of Ii ttle as 30 minutes or as much as 8 hours or faul ty equipment at a time when they are more. most accessible. It also reduces the time involved in the final tightness, completion With the above functions accomplished the and acceptance tests. actual PHM construction was begun. The following paragraphs further discuss the Schedule program and schedule, the assembly sequence and the tools and fixtures used in Now that the assembly sequence is in mind, the PHM production program. figures 19 and 20 tie that sequence with a schedule. Although all component assembly Production Assembly Sequence and Schedule sequences are not shown, representative data is presented to allow the reader to The schedule, figure 1 depicting the major acquire a feeling for the relative time events leading to deployment of a U.S. involved in each operation and therefore the Navy operational squadron, ends with deliv complexity of those operations. ery of five PHMs. Figures 18, 19 and 20 16 TOOL 1 TOOL 5 TOOL l' TOOL 8 fOf'lWARO LOWER HULL 8ULkHE;AD ERECTION ....,•• D POWER PLANT D£O(HOUS£ INST"'LL"TION IJtII'PER PILOTHOUSE INSTALLATION 11""f!{TIALI "$SEMBl 'y POSITION , , " . LOA.O "NO WE LD LOCAH PAINT INTEAIOR • SILLS • LOWER HULL "$SEMel Y • FAAMING • """LY ANTI5WE.t.T COATING • TA"NSVERSE BULKHEADS 9THAOUGH 33 .02 DECk _ TR"NSOM • ...,.,LyP."'NT - l.O~ITUDIN"L eULKH(AOS INSTALL • GFUI,TlNG SUPPORTS • OVTflTTING "ND FURNISHINGS~ WELD • INSULATK>N TOOL 5 • BULkHE .... DS .... NO TR .... • C"8lfNG OuTFITTING ANO TEST N~ _ ELECTRIC"l- ELECTAONIC EQUIPMENT TO LOWE R HUL L POSITION 5 - COMPAESSFO "IR SYSTEM LOCATE AND WELD • PILOTHOUSE CONTROL CONSOLES INSTALL • PROPVLSION MACHINERY FOUNDATIONS - Dun ITTING "NO FURNISHINGS _FUll TANK FRAMES ANO eULKH{:ADS _ TUBING "NO PUMPS UNDER F I'B PROPUlS<.:*\ • fiRE DETECTION SYSTEM _LOWER FRAMf 8 [0"0 • FUEL STRIPfI'ING PUMP AND GAUGE _CVK • FIB ENGINE EXHAUST sT"CK _ F 18 ENGINE. Gr .... RBOx A.ND PROPULSOR TOOL 5 _ AlA INTAKE/eXHAUST ASSEM8l Y • Kf E LSONS SYSTEMS INSTALLATION • H!8 L"ROPULStON PL"NT AND EOUIPMfNT (P ... GODA' .OUTBOARD FRAME AND BULKHE"D ASSEMBLIES POSITION 4 • EOS RACK AND CABINFl • GUN SYSTEM LOtAH AND WELD • FLAG S1"MFS LOCA.TE _ ANCHOR SYSTEM • FR~ SH WA TE R 1 ANK on AILS .rLAT BAR STRINGERS - MAIN DECK ASS[M6L Y • ELECTRICAL CABLES TRANSIT • BOW ASSEMB l Y BLOCK ING ARTI • SHfll PLATING 1ST Wfl.O • !:U:CTRIC"L CABL£S INSTALLATION (CONTINUE I - BULKHEADS • AUXILIARY SYSTEMS PIPING AND TUB INC .MAIN_ CVK [)£CK SPLICE • ACOUSTICAL ENCLOSURE TOOL 4 • REMAINDER FRESH WATER SYs'TEM LOWfR HULL JOIN AND SYSTEMS INSTALLATION LOCAl[ AND WE LD • Rf~AINOER POLLUTION CONTROL SYS'T~ M • REMAINDER ECS SYSTEMS • FRAME 7 • REM"INDER RATPROOFING _ LOWER SHE LL PLATING ST A 6-.8 .PLATFORM DECJo:; STA S-9 FACTORY TESTS _ffaWATERDUCTS _ STANCHIONS AND AAILS MAKf AU. FINAL CUTOUTS LOCAn AND WHD LOCAH ANDWFLO • COAMINGS _ DrCKHOUS[ EOUIPMENT FOuNOATK)NS • "FT DECK HOUSE ASS~MBL Y • STANCHIONS • MISCELLANEOUS FOUNDATIONS _ ~FLL PLAT[ CLOSEOUT • PfNETRATION FITTINGS • STRINGER SPl ICE S _LIFELINE STANCHION BASE fITTINGS _ BROW FITTINGS INSTALL LOAD AND WELD _ SAFETY TRACK .FLAT BAR STRINe,FRS • POll unoi'll CONTROL SVSl[M • ~RESH WATER SYSTEM _SHFll PLATlfIKj • SfAWAlFA $YSTFM • FRAME 76 • HYDRAULIC SYSTEM _FLAT BA.R STRINGER SPLIClS • ENVIRONMENTAL CONTROL SYSTEM _ BALANCE Of SHE L l PLATING _ fLfCTRICAL C"SLES _MISCE LLANfOUS ~·OuNOATlONS _ f"LECTRICAL ELECTRONIC fOUIPMfNT _ FUEL SYSTEM •_ FIXEDANODE FINSS • fiRE PROTECTION SVSTlM .SFA r:H[ST FOUNDATION _ ACOUSTIC AND THERMAL INSULAT ION nXH 5 • Hf8 SPF. ED tRANSDUCER f OuNOAr ION • OUTF ITIING AND FURNISH IPoIGS _ Hffl PROf'UL $ION INLfT HYDROFOIl. INSTALLATION .COMPRESSfD AlA SYSTEM POSITION 7 INSTAll • PROPULSION SYSTEM COMPONfNTS • ARMAMEl'I4t H1UlPMFNT _FUFL TANK MANHOLE COVFRS _ GYROCOMPASS SYSTEM _ Pl UMBING _ BOW [)()()AS AND ACTuATOR • FITTINGS AND VAL ves PAINT Il'I,IlFRI()R PRESSURE TrST FACTORY TE STS _FUll TANK<; AND PIPINC PAINi _BILGE INHRIORS _ E XTFRIORS COMMON TO TOOL 5 SUPPORTS AFT HYDROfOil "$SEMBL Y TQOL6 M II, 1"'1 orCK ASSFMBL Y _ MAST TOOL 12 _ SERVICE PLATFORM iRADAR PYLONI BOW ASSE MB l Y • HF ANTENNA _ CLOSE·OUT MAIN OfCK FORWARD HYDROFOil lAFTER FWO STRUT INSTU ASSEM8l Y INSTALL TOOL 12 • ... 1< 92 GFCS ANTENNA _ NAVIGATION RAO"'R ANTENNA BOW Assr MfH Y • FWD AND AFT HYDROFOIL LOAD AND Wf LD _ ACTUATORS _MAIN DrCK • AFT HYDROfOIL SWIVELS • HYDAAUlIC TUBf HOSES • ACTUATOR SUPPORT SUBASSfMBL Y _ UPlOCKS LOAD AND WE l D _L0NGITUDINAL BULKHEADS .SULK.HfADJ (UPPER) • LIMIT SWITCHES _DECK PLATES • FORWARD FRAMES • f LfCTRICAL CABLES TRANSIT SLOCKING _ DECK GIRDERS • SILL AND BACKUP STRUCTURE lCOMPLfHI _ TRANSVERSE DECK BEAMS .I'LA TF OHMUlCK • MAST, DECK.HOUSE. AND BElCM·DECK _GI.,)N FOUNDATION • BULKHEAD 3 (LOWERI fLfCTRICAl CABLE INSTLS !COMPlETEI _ SOL LARDS SHAN CHOCI':, TOWING, FTC. • FRAMES", 5, AND 6 (LOWER) nST _ f lECTAICAl CASlf RACEWA'fS • [)()wNlOCK AND BACKUI" STRUCTURF _GUPHt'ALE TUBE _ STR INGERS AND SHEL L PLA, INli • SiJ:lLiT tOil rwf'RATtONS _SHEAR STAAKE • BOW THRUSTER FOUNDATION Figure 18. Production PHM • FACTORY TESTS ICONTINUE) _ HARPOON fOUNDATIONS • ANOOfS Assembly Sequence '--______....J / '. ~ '"'f;~, <,,' " FWD DECKHOUSE INSTL DECKHOUSE~ ASSY AFT DECKH'OUSE INSTL 14 MAST ASSY FORWARD LOWER HULL ASSY LOWER HULL ASSY SYSTEM I NSTL HYDROFOIL INSTALLATION LAUNCH SIDE FRAMES AND SHELL PLATING FORWARD HYDROFOIL ASSY Figure 19. PHM Production Assembly Schedule 18 LAUNCH 5.7 HYDROFOIL PAINT INSTALLATION TIE WELD CENTER OML MACHINE SECTION EB WELD OML MACHINE EB WELD OML MACHINE SR FOIL TIPS PORT ANDSTARBOARDr---~~~~----~ FOI LIN BOAR D SPANS 'r---T-r------rI 64 PORT AND STARBOARD'------'-'-===---.J...J Abbreviations: WELD I inspect SR stress relieve HT heat treat SF surface finish Figure 20. PHM 3 Aft Strut and Foll Production Assembly Schedule 19 Learning standard used in estimating is called the "learning curve." The learning curve states One of the major advantages to the modular that each time the production quantity concept of fabrication is that it gives the doubles (i.e., 1, 2, 4, 8, 16, etc.), the man workman a chance to improve his capabili hour expenditure per unit will be a given ties to perform a job. The shop orders fraction (or percentage) of the manhours mentioned earlier define the jobs to be done needed to produce a unit in the preceeding and the sequence in which they are to be quantity. As an example, it was originally done. They do not tell the workm an specifi estimated that the manufacture of the cally how to do the job. The workman will lower hull, Tool 4, would follow a 75 percent initially produce a fully acceptable part but learning curve, figure 21. During definition not necessarily in an efficient manner. of the work sequence, the Methods group in After a few repetitions he will have Industr ial Engineering predicted the learning "learned" the job procedure, will have the rate would be 75 percent to build Unit 2, but right tools in hand, and wlll perform the job would then improve to a 70 percent rate. In in the most efficient manner. This learning fact, the actual "learning curve" experi process of repeating a job or performing enced between units 1 thru 4 in Tool 4 has similar jobs reduces the manhour expendi been much better than the initial prediction. ture, shortens the second and subsequent These data are shown on figure 21. unit schedule and results in reduced cost. A 100 4~ ...... 90 l ~~ ///""15% ;::: 80 z UJ u ~~~~ ~ 0:: 70 w / ...... ~ ...... 1/--70% ~ 75%~ ~ w '- ...... / I 20 L. I 1 2 3 4 5 6 7 8 9 10 UNIT NUMBER Figure 21. Tool Number 4 Learning Curve 20 Learning standard used in estimating is called the ITlearning curve." The learning curve states One of the major advantages to the modular that each time the production quantity concept of fabrication is that it gives the dou bles (i.e., I, 2, 4, 8, 16, etc.), the man workman a chance to improve his capabili hour expenditure per unit will be a given ties to perform a job. The shop orders fraction (or percentage) of the manhours mentioned earlier define the jobs to be done needed to produce a unit in the preceeding and the sequence in which they are to be quantity. As an example, it was originally done. They do not tell the workman specifi estimated that the manufacture of the cally how to do the job. The workman will lower hull, Tool 4, would follow a 75 percent initially produce a fully acceptable part but learning curve, figure 21. During definition not necessar ily in an efficient manner. of the work sequence, the Methods group in After a few repetitions he will have Industrial Engineering predicted the learning ITlearnedlT the job procedure, will have the rate would be 75 percent to build Unit 2, but right tools in hand, and will perform the job would then improve to a 70 percent rate. In in the most efficient manner. This learning fact, the actual "learning curve" experi process of repeating a job or performing enced between units 1 thru 4 in Tool 4 has similar jobs reduces the manhour expendi been much better than the initial prediction. ture, shortens the second and subsequent These data are shown on figure 21. unit schedule and results in reduced cost. A 100 90 ~-- .. 75% // 80 ~~ ;:: ---- Z LJ.J y~:~ ~/ U 70 a: / LJ.J / ~ 15%- ~ ...... ~--...... 1/-10% UJ I- / 20 1 2 3 4 5 6 1 8 9 10 UNIT NUMBER Figure 21. Tool Number 4 Learning Curve 20 Figure 22. Boeing Marine Systems Hydrofoil Production Facility SUMMARY REFERENCES PHM is a well developed and tested ship 1. Rolf Boehe, "The Patrol Hydrofoil system. Lessons learned from both con Missile (PHM), NATO's Advanced War struction and operation of the lead ship, ship Project," International Defense USS Pegasus, have been incorporated into Review, June 1973. the production ship design. Many elements of the ship have been specifically designed 2. CDR Karl M. Duff, "The NATO Patrol to facilitate production. Detail manufac Missile Hydrofoil (PHM)," AIAA/ turing planning, tooling, and production SNAME/USN Advanced Marine Vehi management systems consistent with effi cles Meeting, AIAA Paper No. cient rate production have been completed. 72-596, July 1972. Progression of four ship sets through the major tool positions has demonstrated the 3. CDR Karl M. Duff, LCDR Henry effectiveness of the production design and Schmidt, and LCDR Michael R. Terry, process, and production learning has been "The NATO PHM Ship and Weapons achieved. Figure 22 shows the factory floor System Technical Evaluation Pro with assemblies at all stages of completion. gram," AIAA/SNAME Advanced Marine Vehicles Conference, AIAA While this document does not address speci Paper No. 76-848, Arlington, Virginia, fic roles and missions for PHM, operational September 20-22, 1976. experience to date verifies it is a highly effective surface warfare ship. Studies 4. J. T. Drewry and O. P. Jons, "Modu show the role of PHM can be extended to larity: Maximizing the Return on the include ASW and mine countermeasures by Navy's Investment," Naval Engineers adapting equipment presently available or in Journal, Apr il 1975. development and taking advantage of the growth potential included in the ship design. 5. CDR J. L. Simmons, USN, "Design for Change - The Impact of Changing The attributes of PHM as an operational Threats and Missions on System Design unit combined with the quality, cost and Philosophy," Naval Engineers Journal, near-term availability resulting from the April 1975. ser ies production approach described here provide an effective fighting ship capable of meeting the many needs of the world's navies. 21