Mechanical Design of the LMDE.pdf - Heroicrelics

More documents

Recommendations

Info

during lunar descent, in addition to the shock and vibration environment oflaunch and boost and engine firing, revealed the need to make some changesto the bearing design. Those changes were accomplished before tests of afull gimbal frame was scheduled to start.When a complete gimbal assembly was available for further testing,an engine assembly still could not be used; therefore, it was planned touse an engine mass simulator. This unit simulated the mass properties inthe Y and Z axes but not in the X axis (the centerline of the engine thrust) .The gimbal was first subjected to the environments of salt fog,sand and dust and a limit load test to several of the critical loads. Abreakaway torque test on the bearings while subjected to a thrust load of10 , 500 lbs was used as one criteria for acceptance of the gimbal after eachtest. Alignment of the thrust axis was another criteria.Shock tests of the gimbal with the engine mass simulator wereconducted about all three axes . A shock impulse of 15 g peak with a6 millisecond rise time was applied three times along each axis. Duringthe shock test the gimbal was rigidly attached to the shock test equipment.No unexpected responses were noted.Vibration tests of the gimbal frame were next performed. Forthis test the gimbal trunnions were mounted to a structure which simulatedthe influence coefficients of the Lunar Module support structure. SeeFigures 6 and 7. During the first sinusoidal vibration sweep along theY axis an unexpected torsional mode was observed at 18 cps. Strain gageswere installed on the gimbal frame to measure bending stresses due to thetorsion and the survey repeated . As a result of the data obtained, itbecame apparent that it was necessary to correctly simulate the moment ofinertia of the engine mass simulator about the X axis. The first simulationof I was 34 , 000 lb-in 2 while the calculated engine inertia wasxx66,000 lb-in 2 . The change in inertia was made and the vibration test completed.These tests pointed out a minor structural weakness which wouldhave delayed the qualification tests if not discovered at this time. Thebolt which attached the bearing to the gimbal frame was restrained againstrotation by means of two cotter pins. These pins failed in shear permittingthe bolt to rotate during vibration. Retention of the bolt waschanged to the heat treated, machined lock ring shown in Figure 8.This specimen was then subjected to mechanical cycling of ± 6 0for 500 cycles about each of the rotational axes while subjected to10,500 lbs of thrust load.Upon completion of the mechanical cycling test, a static test toultimate loads was performed for the most critical load conditions. Thenload was applied until failure for the most critical condition with thrustapplied at 6 0 in both directions from center . Failure occurred at39,800 lbs which is 1.92 times the ultimate load taking account for gimballedangle, thermal degradation and other structural loads. SeeFigure 9.- 5 -
Figure 6.Engine Mass SimulatorMounted in GimbalFrame on VibrationTest FixtureFigure 7.View of Simulationof Lunar ModuleSupport StructureFigure 8 .Redesigned Bearing BoltRetention on Gimbal Frame- 6 -
Page 1 and 2: MECHANICALDESIGNDFTHE LUNARMODULEDE
Page 3 and 4: Engine DescriptionCOMffNSAT1NGSPIti
Page 5: Engine GimbalThe gimbal assembly is
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 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

Mechanical Design of the LMDE.pdf - Heroicrelics

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?