Mechanical Design of the LMDE.pdf - Heroicrelics

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Table 1 presents the qualification sinusoidal and random vibrationtest levels applied to the attachment interface on the gimbal frame.The configuration of the final engine vibration test specimen is shown inFigure 26. It was necessary to mount the engine upside- down in order tokeep the mass of the supporting fixture low, since the mass of the fixtureplus the engine approached the maximum limits of the shaker . The supportingstructure is the same as used for the gimbal test shown in Figures 6and 7.TABLE 1VIBRATION LEVELS FOR QUALIFICATIONTEST (LAUNCH AND BOOST)SINUSOIDAL VIBRATIONFlightEnvironmentFrequencyInput LevelSweep RateLaunch andBoost5-1616-1000.2 inches d.a.2.5 g vector3 oct/min upand downRANDOM VIBRATIONPhaseFrequency Band(cps)Power SpectralDensityTime perTest AxisLaunch 10-23 12 db/octave rise23-80 0.025 g2/cpsand 80-100 12 db/~ctave rise100-1000 0 . 06 g /cpsBoost 1000-12000 12 db/octave fall1200-2000 0.025 g2/cps5 minutesof randomvibrationTable 2 presents a comparison of the calculated and measured frequenciesand loads. It is seen that the final mathematical model permitsaccurate estimation of the dynamic characteristics of the engine.The analytical model has been used primarily to determine theeffects of design changes . For example, following vibration of the gimbalwith a mass simulated engine during design verification testing, the stiffnessesof the support trusses that mount the engine in the Lunar Modulewere decreased to save weight. The mathematical model was used to determinethe effects of the softer mounting system on engine dynamic response. Othersimilar analyses include the effects of changing the gimbal actuator stiffness,effects of changing the engine c . g . location, and an evaluation of thevibration test fixture.In addition, the dynamic loads on the gimbal nozzle extension andthrottle control system have been computed for use in associated stressanalyses of these components. The loads computed for the throttle control- 19 -
Figure 26.Vibration Test of LMDEsystem, verified by the results of the engine mass simulator vibration testresults, allowed simplification of the structure mounting the throttlecontrol system on the engine.TABLE 2COMPARISON OF ANALYTICAL WITH TESTDYNAMIC RESPONSE OF ENGINEANALYSISMODALFREQUENCIES(cps)(All Axes)11.212.627.533.137.9QUAL LEVELTEST RESONANTFREQUENCIES(cps)AxisX Y ZMAXIMUM GIMBAL LOADSLOAD TEST ANALYSIS11.4 11.6Mx12.7 12.728170 in-lbs 31330 in-lbs28.4 29.2 1:'y 5580 lbs 5220 lbs30.8 34.1 34.3 Px 7105 lbs 7520 lbs39.0 38.7 Pz 6723 lbs 6275 lbs- 20 -
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 and 16: (a)Cross BeamFlexure(b)Injector Dri
Page 17 and 18: Figure 21.Figure 22.Section of Two-
Page 19: out of the first two analyses on th
Page 23: designers and builders of the Lunar

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