Mechanical Design of the LMDE.pdf - Heroicrelics

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 -