ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
Asecond testrunundertheseconditions showed asimilareffectthatoccurred evenfaster: thefrictionon theentireunlubricated disksidewaslowered afterfivecycles. Thisisexactly thetypeofbehavior that wouldbeexpected iflubricant werebeinggradually transferred fromthecoatedsideofthedisktothe uncoated sidebytheballmoving aroundthesurface ofthedisk.Theperiodofrelatively highfriction grewshorterwitheachrevolution asthelubricant wasspreadfartheraroundthetrackwitheach revolution ofthesample. Underthesetestconditions, therateoflubricant transfer wasintherangeof0.2 to0.4cm/revolution, although suchnumbers aredependent onloadandgeometrical considerations. Surface analyses wereperformed onthetrackandballsurfaces tolookforevidence oftheMoS2 lubricant. Figure11presents theXPSdatafromatestwherethediskhadbeenrotatedapproximately 150timesincontact withtheballunderaconstant loadof3N.Theelemental compositions obtained fromthesuperalloy diskinclude sulfurandexcessive carbonandmolybdenum. Thisisstrongevidence forthetransfer oflubricant because thereareMoandSpeaksthatindicate approximately 6%MoS2. Spectra werealsocollected atapointfurtheralongtheweartrack,approximately 2mmbeforetheball crossed overfromthebaremetaltothelubricated sideofthedisk.Theconcentration ofMoS2inthis areawasapproximately 3%.(Someofthedetected Moineachanalysis resultsfromthesubstrate.) The amount ofMoS2detected relative totheCsignalwasmuchgreater intheweartrack(MoS2:C =6:45; 3:49forthetwodatapoints)thanonthefullycoatedsample (3:85).Thisindicates thepreferential transfer oftheMoS2lubricant inthewearareas,actingtoreducethefrictionmoreeffectively thanwould transfer ofthephenolic resin. Further evidence ofthetransfer oflubricant wasfoundbyanalyzing thecontact areaoftheball,which wasusedwiththehalf-solid-lube sample duringthetestdescribed previously. Thesurface ofthecontact areacontained approximately 3%MoS2withinthevolume probedbyXPS.Afterthedetection ofanMoS2 transfer filmonthissurface, theballwassubjected tothesurface preparation protocol thatwasapplied to thelatchsurfaces: multiple wipeswithaclean-room wipesaturated withethylacetate. Thecontact surface wasagaininspected withXPS.Still,wefoundthepresence ofatransfer filmofMoS2 representing 2%-3% ofthesurface material. Therelative fraction ofMoS2wasverysmall,butverylittle MoS2isnecessary toreducethecoefficient offriction. Itisevident thatthrough continued contact with thelubricant, atenacious filmofMoS2wasburnished ontothe440Csurface oftheball.Itisexpected thatthisfilmwouldreducethefrictionbetween theballandsuperalloy surface, asthelevelsoffilmwere comparable tothelevelsfoundonthediskweartrack. 09 <v .... |,,,,|,,,,I,,,.t.... I., 11001000900800700600500400300200100 0 Binding Energy (eV) Figure11.XPSdataobtained fromtheweartrackontheinitially unlubricated sideofahalf-solidlube-coated diskaftertestundervacuum. Thisshowsthesignature ofthetransfer ofMoSz. 326
Similartestswereperformed inairtodetermine ifatmospheric gaseschangethelubricant transfer phenomenon observed undervacuum. TheresultsofonesuchtestareshowninFigure12.These resultsshowthesamefundamental behavior occurring overapproximately thesametimescale:the frictionisgradually loweredontheunlubricated portionofthediskwithinthefirst5-10revolutions ofthe testdisk.Following testseitherinairorinvacuum, debriswereevidentvisuallyinandaroundthetrack ontheunlubricated diskside.Inaddition, thewearonthesolidlubricant coatingseemed muchgreater thanintestsofthefullylubricated disks.Bothoftheseobservations canlikelybeexplained bythe transferofthelubricant fromthelubricated sidetotheunlubricated sideofthedisk. Oneinteresting difference onsamples runinaircompared tothoserunundervacuum isthatoncethe lubricant wascompletely distributed acrossthesample,thedifference inthefrictioncoefficient between thelubricated andinitiallyunlubricated surfaces wasquitesmallfortheairtests;also,therangeoffriction levelsmeasured throughout theduration oftheteststayedmuchlowerthanlevelsobserved inthe vacuumtests,asshowninFigure10.Recallthatthedifference inthefrictionmeasured between the cleanandunlubricated partsinairwaslessthanthatobserved undervacuum(seeTable1),andthe transferexperiment maybeaffectedbythisdifference. However, thiseffectalonecannotexplainthe observations inFigure12.Thiseffectmayalsoindicatethatthelubricant transferprocessisaffected by thepresence ofairorsurfaceoxidesinamannerthatmakestransfermoreuniformduringtestsinair,as described previously 6.Furtherstudywouldberequired tounderstand thiseffectmorecompletely. 0.1 (0.0) (0.1/- (0.2)- 8(0.3)- (o.4)- (o.5)- (0.6) i = i t = 2 3 4 5 6 Time(s)-3 2 q 1 Figure12.PlotoftheCOFandloadatthestartofatestofahalf-solid-lube-coated superalloy diskagainst a440Cballinair.Thediskbeganrotating nearthe2.4smark,as indicated bythefrictionmeasurement. Dependence onLoad Twotestswereconducted undervacuumwithloadsintherangeof0.2to0.5N.Thefirsttestwas performed withahalf-solid-lube sample,andthesecondwasperformed withacleansuperalloy sample. 327
1.00 c 0.750.50 t0.25 u_0.00 (0.25)-3 -2 -1 0 0123456789Z 00 O..J Time(s) Figure13.COFandloadvs.timeduringtheInitialsliding contact between 440C andsuperalloy witha15nmfilmofBray880. 1.00 E0.75G) _0.50 O o  ,o.25  o.oo (0.25) I I I I I I I I 0123456789 Time(s)-3 -2"-"Zv "0 0 ._1 -1 0 Figure14.COFandloadvs.timeduringtheinitialslidingcontact between 440C andsuperalloy witha60nmfilmofBray880. 329
appliedtothemiddlebearingthroughacylinderattached tothetestersquirrelcage.Axialloadsare appliedbychanging theinternalpressures eitherinthetopcavityorinthethrustpistonlocatedatthe bottomofthetestrig.Liquidhydrogen isroutedinseriesthroughthetopbearing, throughthemiddle bearing, andoutoftherig.Thehydrostatic bearinghasahydrogen supplyofitsown.Gaseous heliumis routedthruthebuffersealtokeeptheliquidhydrogen andgaseous nitrogen separated. Figure1.CrossSection OfBearing TestRig Ball/Roller configuration onleft,Ball/Ball configuration onright, flowpathsasindicated instrumentation isprovided formonitoring theoperation ofthetestrigandfacility.Pressures, flowrates, andtemperatures arerecorded fortheruntank,alongtheinletpiping,inthetester,andintheexitlines. Axialload,radialtoad,andspeedarealsorecorded. Duringthetesting,criticalmeasurements are watched onmonitors inthecontrolroom.Redlinecutsaresetonmaximum andminimum limitsofcertain parameters. Because ofthehazardous natureofhydrogen, nopersonnel areallowedontheteststand oncetestingstarts.Alltestsarevideotapedandafiresuppression systemisonlineincaseofan incident. TheBearings Thebearings (Figure2)thatarerunintherigarethesamebearings thatareusedinthedevelopmental andcertification turbopumps. Forthisbuild,thetopbearing, calledthereactionbearing, isaballbearing withCronidur 30rings,Armalon cagewithSaloxinserts,andsiliconnitrideballs.Themiddlebearing calledtheloadbearing, isarollerbearingwithCronidur 30rings,Armalon cage,andsiliconnitriderollers. Thereaction bearingis60mm(2.36inch)bore,130mm(5.12inch)outsidediameter, andhaseleven 20.6mm(0.81inch)balls.Theloadbearingis72.9mm(2.87inch)bore,133mm(5.23inch)outside diameter, andhasfourteen 17mm(0.667inch)diameter rollers. Thereaction bearingcamefromahot-fired enginetestandhad3,861seconds oftimeonit.Theload bearingcamefromanengineandalsohadtesttimeonitforatotalof1,824seconds. Avisualinspection 332
andvideotapingofthecomponents document thepretestconditions ofthebearings. Highprecision dimensional andsurfacetexturemeasurements aremadebeforeandafterthetestseries.Typical measurements arediameter, roundness, surfacetexture,crossracecurvatures, andwear.Aftertesting, thecomponents areinspected againandnotedfeatures canberelocated andinspected asecondtimeto lookfordegradation. Figure2TypicalBallBearing (top)andTypicalRollerBearing (bottom) usedinTestRig. Therollingelements ofbothbearings haddegradation intheformofrivermarksandothersurface anomalies thatwerenotedbeforeinstallation intothetestrig.Thesewereformedinthehot-fired engine testing. Objectives Therewasaninterestindocumenting theperformance ofhybridrollerbearings runningathighspeedsin liquidhydrogen environments. Also,thesurfaceanomaly thathasbeencalled"rivermarks"existson 333
somesiliconnitrideballsandrollersandtheireffectonlifeneeded tobestudied. Rivermarks(Figure 3) areseenonthesurface ofsiliconnitrideballsandrollersinbearings running inhighload,cryogenic fluid applications. Theyarecharacterized bylargewidthtodepthratiosandrunonthesurface oftheballor rollerwithsmalltributaries leavingthemainline.Thewallsoredgesofthemarkscanbesteep.Typical widthanddepthvaluesseenare0.14mmand0.005mm,respectively. Fracture ofthematerial hasbeen aconcern, however nofractures haveoccurred inanytestingtodate. Figure3."RiverMark"asseenonSilicon Nitride BallsandRollers Run inCryogenic Environments Toachieve theobjective, thebearings installed inthetestrighadrivermarking ontheballsandrollers. Theregions weredocumented forabeforeandaftertestingcomparison. Previous testing1withhybrid ballbeadngs hasshownthatrivermarkstendtogrowinlengthbutnotseverity. Thetestprogram was startedwiththegoalofaccumulating 31,000seconds ofruntimeathighspeed. TestProcedure Atestconsistofchillingthetesterdowntocryogenic temperature, flowing hydrogen through thebearings, spinning thetester,conducting anytransient loadcycles,andstopping thetestrig.Runtimeislimitedby a5000gallontankthatprovides theliquidhydrogen. Testtimesaverage 800to1000seconds, requiring 31to40teststocomplete aseries. Testing rollerbearings presents auniquesituation whereasrollerbearings donottakethrustloads.To holdtheshaftinplaceandapplypreload totheballbearing, pressure mustbebalanced between thetop cavityandthebottomthrustpistoninthetestrig.Automatic controls weresetuptoeffectively controlthe valvesthatapplythispressure. Aprevious testseriesfailedduetotheshaftseizingtothethrustpiston surface. Noautomatic controlwasusedinthisseries. Pressure changes happen sorapidlythatmanual controls cannotbeused Anormaltestsequence afterthetesterischilledistoapplypressure inthethrustpistonlocated atthe bottomoftheshafttolifttheshaftandapplyapreload of3113newtons (700Ib)ontheballbearing. Instrumented straingagesonthepreload springgivearealtimereadoutofthisvalue.Therigisbrought uptoarunpressure of8.4MPa(1225psi).Rotation isstartedwithatargetspeedof35,000rpmdesired. Duringthespeedramp,radialloadsareapplied instepsupto4.4kN(1000Ib).Theautopressure controlkeepsthepressure differential between thetopcavityofthetesterandthrustpistonconstant so asnottoallowtheshafttodropandrubthetopofthethrustpiston. Thetemperature ofthecoolant is normally inthe28K(-410°F) range.Theflowrateintothebearings is0.25kg/sec(0.5Ib/sec)with0.45 334
Figure4.Installed TestRig. Testermounted onstand,inletandoutletpipingisabovetoallowaccesstoportsandinstrumentation. Fire suppression systemisoverhead. Hydrogen burnoffstacksareinbackground. Allpipingandvalvesareinsulated beforetestseriesbeginstoconserve hydrogen. Conclusions Afterexaminations ofthehardware andtestdatareviews werecomplete, therigwasreassembled. No obvious reasonforthespeedfluctuation wasfound.Theactionofrivermarkgrowthhascontinued inthis testseriesjustasithasinotherbearing testingatMarshall 2.Nodefinite mechanism forrivermark formation hasbeendetermined. Thedegradation ofthesurface hasnotcaused anypremature failures in thebearings todate.Thetestingwillcontinue withthegoalofaccumulating theneeded 20,000seconds thatwillcomplete thisprogram. Acknowledgements Theprimary authorwouldliketothankChipMooreofMSFCforthemetrology measurements andtest support, Dr.RobertThomofMSFCforthedetermination ininvestigating thesafetyofhybridbearings, JimMooreofSRSTechnologies andPhillipBenefield ofUSAforthetestsupport anddatareviews, Steve AllumsofMSFCforconducting thetest,andthetechnicians ofLB&Bforcontinuing teststandsupport. References 1.Moore,Chip,Howard Gibson, andDr.RobertThom,"LiquidHydrogen Testing ofSiliconNitride • ,,, . noA Bearings forUseInHighSpeedTurbomachmery, Proceedings fromthe32e_paceMechanisms Symposium, May1998 336
2.Gibson, Howard, andS.Fears,"Bearing Testing Performed inLiquidOxygen", Proceedings fromthe Advanced EarthToOrbitPropulsion Technology Conference, MSFC, 1992 SiliconNitrideBallWithRiverMarkOnLeft AndSurface Anomaly InMiddleCloseUpOfRiverMarkOnBall Surface Anomaly InMiddleOfBall CloseUpOfMarkAfter10,894Seconds Surface Anomaly After10,894Seconds Figure5.BallNumber 1FromTestRig 337
XProfile 0.002040.6081013 Title:Build5,Ball7vm YProfile Note:Pre-test examination, TSN-03NH XProfile 1i_i_¸:°i::_:,,if. YProfile O002030.50.608 10 Title:Build5A,Ball7v 0- -lao.oo•,..........o,_..o............ ...jo Note:Midtimeexamination, TSN-03NH Figure 9.WYKO NT-2000 Surface Inspection 341
Og 05 04 O? O0 O00204OB0.81012XProfile -2_o T-  ........................!! oi oi .iYProfile v Title:Build5,Ball1 Note:Pre-test examination, TSN-03NH XProfile 09 0.6 04 02 00 0.0020406081012 Title:Build5A,Ball1aloJ0ov o.h o_....,u YProfile V m -,--11--.k!_,....!......... t..... -----_--_-_-_-: _ ......................;..... a=j i--'.-_-;................;;; 4= , _] , ........ | ..................... ].................... _............... _.................... _............... Note:Midtimeexamination, TSN-03NH! Figure10.WYKONT-2000 Surface Inspection 342
commercial high-pressure pneumatic cylinders (Figure5).Onecylinderofeachpairisspringretracted (extension cylinder) andthesecondisspringextended (compression cylinder). Together, theyprovide thespringcentering capability required forthestruts.Spherical rodendsallowforendrotationandstrut lengthadjustment. Internalsealfriction,airflowthroughtheventports,andintegralcushions providea limiteddegreeofdamping. Thecounterbalancing capability iscreatedbyapplying equalpneumatic pressure totherodendsofbothcylinders. Attheproperpressure setting,thestrutssupporttheweightof thepanelwhilethespringsprovidethebiasforcenecessary toovercome sealfrictionandcenterthe strut.Thepressure isremoved fromthestrutsafterthevehicleisrotatedtovertical. Itshouldbenoted thatthestrutsystemis"over-constrained;" thatis,onlythreeofthelateralstrutassemblies arerequired forstability. Thefourthstrutassembly wasaddedtoeliminate moments induced intothepanelassembly bylateralaccelerations andpreventunwanted rotationoftheplatefollowing disconnect. Compression CylinderNitrogen Supply (Counterbalanced Strut Only) Piston Extension CylinderSpring II Figure5.Compliance Mechanism LateralStrutAssembly PanelAlignment Mechanism Thepanelalignment mechanism guidesthegroundpanelintoalignment withtheflightpanelformating. Afteraligningthepanels,themechanism matesalloftheumbilical connectors byguidingthepanels together whilemaintaining alignment andparallelism. Thealignment mechanism consists ofaretractable pinsystemonthegroundpanelandmatingreceptacles ontheflightpanel. PaneiAli_nment Mecharl|sm Requirements Someofthesignificant designrequirements forthepanelalignment mechanism were: •Correctforsixdegree-of-freedom initialmisalignment ofpanels •Eliminate possibility ofbindingduringalignment ordisconnect •Alignpanelswithin+_0.015mm •Maintain panelsparaiielwithin_+0.03mmthroughout matingoperation •Operatewithcordless drillormanually •Providenominallateralalignment forceof1kN,failsafeat8kN •Providemaximum axialloadcapacity of18kN •Accommodate maximum initiallateralmisalignment of2cm •Accommodate initialangularmisalignment withinlimffsoflateralmisalignment •Providematingstroke(parallel motion)of5cm 348
PanelAli.qnment Mechanism Description Thealignment mechanism usesfourretractable taperedpinslocatedatthecornersofthegroundpanel. Fourmatingreceptacles arelocatedatthecornersoftheflightpanel.Thetaperedpinsandreceptacles, inconjunction withthecompliance mechanism, alignthepanelstothedesiredaccuracy. Afterthepanels arealigned,thefourpinsareretracted inunisontomaintain parallelism astheconnectors engage. Thetaperedpinassemblies (Figure6)arecomprised ofahousing, acommercial jackassembly, the taperedpin,andsupportbearings. Thefourpinassemblies areinstalled onthegroundpanelandlinked withasystemofshaftsandgeardrivesforparalleloperation (Figure7).Thetaperedpinhasa10-degree half-angle coneandaflatend(Figure8).Theflatendprevents bindingandaccommodates thermal distortions andmanufacturing tolerances (seenextparagraph). Thehousingisaluminum, thebearings areplainbronze,andthepinis15-5PHstainless. Themachine screwjackassembly isinternally keyed topreventscrewrotation, theratedcapacity is4.5kNandtheleadis.127mm/turn. SScrewJack _Alignment Pin /Housing -_ /  FlightReceptacl_ __.,.\...\.,,\.,_.__._._._1 i' Figure6.Alignment PinandReceptacle 349
PinAssembly _ fl...  I1! F-_'T"iIJ_ i_,,_'_ ShaftBearing ---_ _ __ \,11!!i i" ii R i ,J_,,4Ground PanelAssembly DriveShaft Alignment Pin Figure7.Alignment pinAssembly L Electrical Connectors [__ PininTight __ _t_O°O0 01_0 0 Receptacle o@o (Clearance Exaggerated) © o0_,0o0[] S/' # " LooseReceptacle (3) FlightPanelAssembly Figure8.Alignment PinReceptacle Details 35O
attaching thehousing totheboltforsecondary release. Allcomponents, exceptfortheshearpin,are fabricated fromA286stainless steel,andtheconicalsleeveisdry-film lubricated. Thedesignshear-out loadforthe17-7PHstainless drawnwirepinis24.5kN(totalindoubleshear),whichis150%ofthe designstaticloadonthelock.Thepinstock(allfromasinglelot)wasordered slightlyoversize andpull testedtoobtainashearstrength. Thefinalpindiameter wasdetermined fromthesheartests.Theflight pins,testpins,andspareswerethengroundtofinalsize.Fivepinsweresheared foracceptance testing. Allofthetestpinssheared within50Nofthedesigntarget.Therewassomeconcern aboutwedging the receptacle together andincreasing theshear-out force.Toeliminate thispossibility, anassembly tool wasusedtocontroltheaxialforceapplied tothetapered connection duringmatchdrillingandpinning. Thelockmechanism ismated(locked) byinserting thecolletintotheconicalsleeveuntilthesliding sleeveisfirmlyseatedagainst theflightpanel.Pneumatic pressure isapplied tothecylinder todrivethe pinintothecolletandexpand thefingers. Thetapersinthesleeveandonthecolletfingersgenerate the desired jointpreload. Pininsertion pressure isusedtoverifyproperpreload generation. Figure11shows themechanism inthelockedconfiguration. Foraprimary release ofthemechanism, thelanyard pullcauses thecamstorotateandreactbetween thetrunnion andthesleeverollerstoretractthepinandcollapse thecolletfingers(Figure 12).Additional pullonthelanyard drivesthesleeveforward onthehousing toprovide akick-off forceforseparation. 1 NPinShears Sleeve Extends Collet Collapses CamDrives Sleeve Out CamDrives PinBack Primary Release Secondary Release Figure12.LockMechanism Release Modes Thelockmechanism cantolerate several different failures oftheprimary operation. Ifthecambearings weretoseizeandprevent rotation, thepinwillstillbepulled(withalossofthemechanical advantage of thecam)torelease thejoint.Thekick-off forcewillnotbeapplied inthiscase.Intheeventthatthepin doesnotretract,thecamsimmediately forcethesleeveforward toseparate thejointbybreaking the 355
shearpinintheflightreceptacle (Figure12).Notethattheforcetoshearthepinisreactedinternally in thelockandtheonlyexternal forceappliedtothevehicleisthelanyardload.Thesystemmechanical advantage reducesthelanyardloadtoapproximately 33%oftheshear-out load.Similarly, ifthepinis retracted buticeordebrisprevents thecolletfromcollapsing, thesleevewillstillsheartheflightpinas notedabove.Finally,iftheentiremechanism orthelanyardweretofail,theweaklinkinthesystemis stilltheshearpin.Thiscasewould,however, transfertheentireshear-out force(24.5kN)tothevehicle. Verification Testing Averification testprogram wasperformed todemonstrate properoperation oftheX-33umbilicals in processing andlaunchmodes.Testingwasdividedintotwophasesforeachumbilical. Thefirstphase testswereperformed withtheumbilical inthehorizontal processing configuration. Thesecondtestphase wasperformed withtheumbilical intheverticallaunchconfiguration. Rotation testingwasperformed at thelaunchsite. Thehorizontal testsverifiedumbilical mating(connection), de-mating, andleaktightness. Thecounterbalanced strutsinthecompliance mechanism workedwell.Thegroundpanelwasheldcentered but couldbeeasilydeflected byatechnician. Thereturntocenterwassomewhat sluggish. Thesealfriction onthepistonandrodincreased significantly whenthecylinderwaspressurized. Aslightlyhigherforcein thereturnspringswouldhavehelpedeliminate thisproblem. Eachumbilical wasmatedwithnine different initialalignment offsets.Thecompliance mechanism andalignment systemaccurately mated thepanels.Thequick-release locks(collets)consistently generated thedesiredpreload. Withthe exception ofasealthatwasdamaged duringshipping, therewerenoout-of-specification leaksdetected. Figure13showsanumbilical duringhorizontal testingandgivesagoodideaofthesizeofthesystems. Theumbilical matetimewasreduced tolessthanonehourfrommorethaneighthoursrequired forthe SpaceShuttle. Mostofthetimeisusedforcleaning, inspection, andverification. Theactualmate processonlytakesafewminutes. Figu_-e13.Horizontal TestSetup 356
Development ofaFlywheel forEnergy Storage andAttitude Control ofanExoatmospheric Interceptor DougHavenhill', FrankNimblett", SteveNichols" andJohnYoung'* Abstract SatCon Technology Corporation isdeveloping auniquesubsystem thatcontrols theattitude and trajectory ofanexoatmospheric kineticweapon (KW)whilesupplying powertotheweapon's subsystems. TheMissileIntegrated PowerandRollControl System (MiPARS) usesSatCon-developed flywheels and controlelectronics inconjunction withamultiple ignition solidfuelgasgenerator toprovide rotational and translational controloftheKW.Energy storedintherotating flywheels isusedtosupplypowertotheKW throughout itsflight. Introduction Kineticweapons aredesigned tointercept anddestroy incoming missiles. Withclosing velocities approaching 5km/s,translational andattitude controlplayakeyroleinasuccessful intercept. Current KWsystems usecontinuously burning, solidpropellant, gasgenerators withdivertthrusters for translational control, offsetthrusters forattitude control, andthermal batteries forpower. Drawbacks inherent withthisapproach include Shortflighttimesduetolimitedfuelcapacity Structural excitation duetobang-bang thruster control Preflight testingofthepowersourceisimpossible Obscuration ofsensorbyburntfuel SatCon, undercontract fromtheU.S.Navy,wastaskedwithdeveloping aninnovative approach tothe divertandattitude controlsystem (DACS) foraKW.Ourapproach usesthreeflywheels asattitude controltorqueactuators andpowersources andamultiple-ignition solid-propellant gasgenerator to provide divertthrustandtospinuptheflywheels. Ourspecific goalswereto 1) 2) 3) 4)Enablea300-second KWflight Improve KWaccuracy Reduce DACScost Improve KWreliability TheMIPARS isrequired toperform threemajorfunctions: SupplypowertotheKWsystems duringflight Provide KWattitude controltorque Provide KWdivertthrustfortranslational control Underourcurrentcontract weestablished requirements, performed aconceptual designofaDACS system, anddesigned, built,andtestedbenchmodel(proofofconcept) flywheels. Figure1illustrates the MIPARS conceptual design. *SatCon Technology Corporation, Peoria,AZ ""SatCon Technology Corporation, Cambridge, MA Proceedings ofthe34thAerospace Mechanisms Symposium, Goddard SpaceFlightCenter,May10-12,2000 359