Mechanical Design of the LMDE.pdf - Heroicrelics

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Figure 19.Deflection Test ofThrottle Linkagethrottle actuator and the injectorsleeve were observed and recordedunder the influence of variousfluid pressures and chamberpressures.Bellows AssembliesBoth the flow controlvalves and the injector driveassembly contain a moving elementused to control propellant flowrates while containing the propellantunder pressure . Bellows areused as dynamic seals, permittingdirect external actuation of internalmetering surfaces . The configurationselected to accomplishthis was a thin wall (0.006 to0.010 inch) stainless steel weldedbellows. Figure 20 shows thelocation of the bellows in theflow control valve. A similarapplication of bellows is used inthe injector drive . In 1963 atest program to verify the str engthand life of these bellows was instituted.Ten thousand cycles (33mission duty cycles) was selectedas a minimum life requirement . The original configuration did not survivethe tests. Fatigue cracks occurred in the single ply convolution at theweld joints. The final configuration (Figure 21) a two-ply design with0 . 004 inch convolutions successfully passed all of the tests which consistedPINTLEBEARINGINLETDIFFUSERFLOW SPLITTERVENTURI THROATFigure 20.LMDE Flow Control Valve- 15 -
Figure 21.Figure 22.Section of Two-PlyBellowsComponent Test ofInlet Lines , FlowControl Valve andShutoff Valveof cycles of surge pressure, andextension and compression cyclesunder static pressure, followedby burst tests in excess of tentimes the design pressure.Here again, early testingof a component revealed a designdeficiency which was correctedwithout affecting the engine developmentschedule. The final configuration(two-ply bellows) hadan additional advantage of havinga lower spring rate than the singleply bellows originally proposed.Testing of the bellowscontinued when they were combinedinto assemblies. A componentdesign verification test of theflow control valve included longterm exposure to propellants, shockand vibration tests representinglaunch aud boost and engine firing,and 33 mission duty cycles of pressurizationand actuation. Uponcompletion of these exposures, thecomponents were required to passtheir acceptance criteria.Figure 22 shows the arrangementfor testing the flow control valve,shutoff valve and inlet line asa subassembly.Engine TestsAs the next step in thetest program, an assembly of thehead end - composed of injectormanifold, injector drive, ducting,shutoff valves, flow control valves,throttle actuator, and throttlelinkage - was subjected to the completequalification level of vibrationenvironment (Figure 23). Inorder to establish the margin ofstrength built into the head endassembly, upon completion of acceptancetests following the qualificationtests, it was tested to 125% ofthe qual levels, then again to 150%in an attempt to find out whenfailure would occur. Finallyfailure did occur at 175% of- 16 -
Page 1 and 2: MECHANICALDESIGNDFTHE LUNARMODULEDE
Page 3 and 4: Engine DescriptionCOMffNSAT1NGSPIti
Page 5 and 6: Engine GimbalThe gimbal assembly is
Page 7 and 8: Figure 6.Engine Mass SimulatorMount
Page 9 and 10: Figure 10.Combustion Chamber Assemb
Page 11 and 12: Nozzle ExtensionThe radiation coole
Page 13 and 14: Figure 15.Nozzle Extension in Crush
Page 15: (a)Cross BeamFlexure(b)Injector Dri
Page 19 and 20: out of the first two analyses on th
Page 21 and 22: Figure 26.Vibration Test of LMDEsys
Page 23: designers and builders of the Lunar

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