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8/3/2019 Development and Whirl Tower Test of the Smart Active Flap Rotor
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DevelopmentandwhirltowertestoftheSMARTactiveflaprotor
FriedrichK.Straub,DennisK.Kennedy,AlanD.Stemple,V.R.Anand,andTerryS.Birchette
TheBoeingCompany,Mesa,Az85215
ABSTRACT
AfullscaleSmartMaterialActuatedRotorTechnology(SMART)systemwithpiezoelectricactuatedbladeflaps
wasdevelopedandwhirltowertested.Thedevelopmenteffortincludeddesign,fabrication,andcomponenttesting
ofrotorblades,trailingedgeflaps,piezoelectricactuators,switchingpoweramplifiers,andthedata/powersystem.
Simulationsandmodelscalewindtunneltestshaveshownthatthissystemcanprovide80%vibrationreduction,
10dBnoisereductionforahelicopterpassingoverhead,andsubstantialaerodynamicperformancegains.Whirl
towertestingofthe34-footdiameterrotordemonstratedthefunctionality,robustness,andrequiredauthorityofthe
activeflapsystem.
Theprograminvolvedextensivedevelopmentworkandriskreductiontestswhichresultedinarobust,high
performanceactuatorandatightlyintegratedactuator,flap,andbladesystem.Theactuatordemonstratedexcellent
performanceduringbenchtestingandhasaccumulatedover60millioncyclesunderaspectrumofloading
conditions.TheflightworthyactiveflaprotorbladeswerebasedonamodifieddesignoftheFAAcertifiedMD900
Explorerproductionrotorblade.Whirltowertestingwasconductedwithfullrotorinstrumentationanda5-
componentbalance.Therotorwastestedfor13hoursunderarangeofconditions,including7hoursofflap
operation.Flapinputsincludedopenloopstaticanddynamiccommands.Theflapsshowedexcellentauthority
withoscillatorythrustgreaterthan10%ofthesteadybaselinethrust.Variousflapactuationfrequencysweepswere
runtoinvestigatethedynamicsoftherotorandtheflapsystem.Limitedclosedlooptestsusedhubaccelerations
andhubloadsforfeedback.
Provingtheintegration,robustoperation,andauthorityoftheflapsystemwerethekeyobjectivesmetbythewhirl
towertest.Thissuccessdependedontailoringthepiezoelectricmaterialsandactuatortotheapplicationand
meetingactuator/bladeintegrationrequirements.Testresultsdemonstratethefeasibilityandpracticalityofapplying
smartmaterialsforlimitedauthority,activecontrolonahelicopterrotor.Follow-onforwardflightdemonstrations
areneededtoquantifytheexpectedsignificantimprovementsinvibrations,noise,andaerodynamicperformance.Extensionsofthistechnologyareaprimecandidateforon-bladeflightcontrol,i.e.eliminationoftheswashplate.
ThisprogramwasperformedaspartofDARPAsSmartMaterialsandStructuresDemonstrations.Fundingwas
providedbyDARPA,TheBoeingCompany,NASA,andtheU.S.Army.Additionalcostsharefundswereprovided
bytheUniversityofMaryland,MIT,andUCLA.
Keywords:Smartmaterials,piezoelectric,actuator,helicopter,blade,flap,vibrationcontrol,noisecontrol
1.INTRODUCTION
Vibration,noise,andaerodynamicdesigncompromisescontinueasbarrierstofurtherimprovementsineffectivenessandpublicacceptanceofthehelicopter.Bladetrailingedgeflapsactuatedbyin-bladesmartmaterialactuatorshave
emergedasprimarycandidatetodynamicallyalterthebladestructureandapplylimitedauthorityactivecontrolto
achievesignificantimprovementsinrotorcraftperformanceandmissioncapability[1-5].Simulationsandmodel
scalewindtunneltestshaveshownthatthissystemcanprovidemorethan80%vibrationreduction,10dBnoise
reductionforahelicopterpassingoverhead,andsubstantialaerodynamicperformancegains.Resultingbenefits
includeajetsmoothride,improvedcommunityacceptance,aswellassignificantlyimprovedlifecyclecost,
productivity,andfleetreadiness.
PresentedatSPIEsIntl.SymposiumonSmartStructuresandMaterials,SanDiego,CA,March14-18,2004.
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Theoverallprogramobjectivewastodevelopthetechnologyanddemonstratethatsmartmaterialactuatedflapsare
feasibleandpracticalforhighbandwidth,limitedauthorityactivecontrolofahelicoptermainrotor.TheMD900
Explorertwinengine,lightutilityhelicopterwasselectedasdemonstrationvehicle.Itsstate-of-the-art5-bladed
composite,bearinglessmainrotorsystemwasmodifiedtoincludein-bladepiezoelectricactuatorsandtrailingedge
flaps,Figure1.
ConceptdevelopmentanddesignsupporttestswereconductedduringPhaseIofthisprogram[6].Thecurrent
PhaseIIeffortincludeddesign,fabrication,andcomponenttestingofflightworthyhardwareandwhirltowertesting
oftheintegratedsystem.Primarycomponentsofthesystemincludetheblades,flaps,piezoelectricstacksand
actuators,switchingpoweramplifiers,anddata/powersystem.Theirdevelopmentandresultsofthewhirltowertest
arepresentedhere.AdditionaldetailsoftheworkperformedunderPhaseIIcanbefoundinReferences7-17.
2.ROTORBLADEANDFLAPDEVELOPMENT
ThebasiccharacteristicsoftheSMARTrotorareshowninTable1.Primarydesignobjectivesforthemodified
bladeandtheflapweretominimizeactuationrequirements,matchthebaselinebladedynamics,andminimize
weight.Akeyconstraintwastousetheproductionbladetoolingwithonlyminormodifications.Secondarydesign
objectivesweresimplicity,modularity,andtheflexibilityofthebladetoserveasatestbedforalternateactuators.
Thebladedesignwasmodifiedtocarrytheactuatorinsidethesparcavityandtoaddprovisionsformountingtheflap.Ashortlinkconnectstheactuatorandflap.Detailsoftheblade,flap,andactuatorintegrationareshownin
Figures2-4.TheoveralllayoutofthehardwarecomponentsisshowninFigure5.Severalchangesweremadeto
thebladeconstruction,includingreplacementofthreeglassplyswithtwographiteplysinthespar,eliminationof
theouterveilply,anduseoflightweighthoneycombcoreinthemid-sectionoftheblade.Reinforcementswere
addedtoprovideattachmentsfortheactuatorcavityaccesscover,Figure6,theactuatormounts,andtheflap
supports,Figure7.Leadingedgeweightwasaddedtomaintainchordwisebalance,Figure8.Bladeinternalwiring
wasprovidedforactuatordataandpower.
Theflapparameters,Table2,werechosentominimizeactuationrequirements.Becauseoftheflaplength,three
intermediateflapsupportsarerequiredtocarrytheflaploads.Theflapisaerodynamicallybalancedinorderto
lowertheaerodynamichingemomentandthustheactuatorforcerequired.Theflapisalsomassbalanced.For
maximumtorsionalstiffnesstheflapisconstructedusing45deggraphiteplys.Theradiallocationwaschosento
providebothvibrationandnoisereduction.Centrifugalloadsaretransmittedtothebladeusingatension-torsionrod.Aflexiblelinkandarodendbearingtransmittheactuatoroutputtotheflaphorn.Aseriesoftestswere
conductedontheflap,flaplink,andtension-torsionrodtoconfirmpropertiesandtoprovidequalificationdata.
Aprototypeblade,flap,andactuatorwerefabricatedandusedtoconfirmfitandfunction.Integratedtestingofthe
assemblytogetherwithaswitchingamplifierprototypeestablishedthevalidityofthedesign.Actuator/flap
performanceunderarangeofbladedeformationsshowednodegradation.Bladestiffnessandfree-freefrequency
testsconfirmedthatthecompletebladeassembly,includingflapandactuator,closelymatchedthebaselineblade.
3.PIEZOELECTRICACTUATORANDAMPLIFIERDEVELOPMENT
Actuatordesignconsiderationsincludeahighenergydensity,highbandwidthsmartmaterialtomeetactuation
requirements,anefficientmechanismtoprovidestrokeamplificationandminimizelosses,andlowvolume.Inparticulartheactuatorheightmustbesmalltofitinsidethebladespar.Furthermore,theactuatormustberobustand
withstandthebladeelasticdeformationsanddynamicloadingof650gsteadyand30gcyclic.Modelscalerotor
testswereconductedandestablishedthefeasibilityandbenefitsofusingpiezoelectricactuatedbladeflaps[7,8].
Aeroelasticsimulationsshowedthat2degflapdeflectionaresufficientforvibrationreductionathighspeedandfor
noisereduction[6,9,10].Thiscorrespondstoanactuatoroutputof43lband0.032in,includingsomeallowance
forlosses.Fordesignpurposesanominalflapdeflectionof4degwithanactuatoroutputof63lband0.062in
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wereused.Maximumoperatingfrequencywaschosenastherotor(N+1)/rev,i.e.6/revor40Hzforthis5-bladed
rotor,asrequiredforvibrationreduction.
Piezoelectricstackactuatorswereselectedasthedrivingelement.Severallowandhighvoltagestacksweretested
[11-15].Thelatterprovidedbetterperformanceandmoreflexibilitywithrespecttofabricationofdifferent
geometries.Acustommade,highvoltagestackwasselected.Anumberofthesestackswereextensivelytested
underarangeofelectrical,mechanical,andthermalconditions.Bothperformanceandfatiguetestsupto150
millioncycleswereconducted.Fatiguetestswererunatelevatedfieldlevels(2.9kV/mm)andmechanicalpreloads
(6ksi)withoutputs75%largerthancommerciallyavailable.Thesetestsdemonstratedthatdomainwallmovement
withinthepiezoelectricceramicscanbeusedwithoutanysignificantdegradationover150millioncyclesof
operation.
Theactuatormechanismwasbasedonthex-frameconcept[7]withtwoactuatorsworkinginparallel,thusthe2x-
frameactuator.Thetwox-framesareactuated180degout-of-phaseinapush-pullmode.Theactuatorstructure
providesstrokeamplification,ameansforpreloadingthepiezo-ceramicstacks,andprovisionsformountinginthe
blade.Threeprototypeswerefabricatedandtestedtooptimizeperformanceanddurability.Thefirstprototypeused
lowvoltagestacksandvalidatedtheconcept[17].Ithadmarginalperformancebutshowedexcellentrobustness
duringspintesting.Thesecondprototypewasscaledupby15%andusedcustomhighvoltagestacks,Figure9.
Severalfeatureswereaddedtofacilitateassembly,enhancewearcharacteristics,andimprovemountingintheblade.
Athirdprototypewithimprovedstructuralcharacteristicswasdeveloped,Figure10.Itdemonstratedexcellent
performanceduringbenchtesting,Table3,andaccumulated66millioncyclesunderrepresentativeelectricalandmechanicalloadconditions.Thiscorrespondsto560hoursofoperationat5/rev.Theactuatorandbenchtestrigare
showninFigure11.
Aswitchingpoweramplifierwasdevelopedtodrivethepiezoelectricactuator.IGBT(Insulated-GateBipolar
Transistor)switchingat20kHzandcapacitiveenergystorage[18]providedtheefficiencyrequiredtomeetthe
volumeandweightconstraintsforflighttesting.Intermsofpowerdensityitrepresentsafour-foldincrease
comparedtopreviousmodels.Theamplifiermaximumoutputwas-300/+1200Vand3Aforcapacitiveloadsof
4 F.Aprototypeamplifierwasdevelopedandusedtodrivetheflapsystem.Basedontestresults,thedesignwas
enhancedbyaddingnoisesuppressionfilters,providingbetterthermalprotectionforflighttestingonhotdays,and
improvingmodularity.
4.FLIGHTHARDWAREFABRICATIONANDTESTING
Acompletesetof5flightworthyblades,flaps,actuators,andamplifierswasfabricatedforwhirltesting.Inaddition
aspareactuatorandasparebladeforfuturepressureinstrumentationwerefabricated.Fiveactuatorsweretestedon
thebenchtoestablishperformance,stiffness,andnaturalfrequencies.Inadditiontheywererunforonehourtoseat
thecomponents,letthepreloadsettle,andbreakintheflaplinkrodendbearing.Afterinstallationintheblade,the
actuator/flapsystemwasruntoestablishbaselineperformance,naturalfrequencies,andtobreakintheflapbearing
surfaces.Thebladeinstalledactuator/flapsystemnaturalfrequencywas98Hz.Thepitchinertiasofallflapsand
thefree-freefrequenciesandpitchinertiasofthemassbalancedbladeassemblieswerealsodetermined.Theoverall
bladeweightincreasedby5lb,anincreaseof9%inweightand15%inspanwisemomentcomparedtothebaseline
blade.ThechordwiseCGremainedunchangedat27.4%.ThecompletedbladeassemblyisshowninFigure12.
5.WHIRLTOWERTEST
WhirltestswereconductedatMesainawhirlcageusingtheLargeRotorTestStand(LRTS).TheLRTSincludesa
1500HPmotor,transmission,strutassembly,a5-componentrotorbalance,andtherotorflightcontrols,Figure13.
Thisteststandhasbeenusedinanumberofwhirltowerandwindtunneltestsofseveraldifferentrotors.
Testsetupstartedwithinstallationoftheteststand,motor,rotorbalance,androtorhubinthewhirlcage.Forthe
SMARTrotortestahubmounteddataacquisitionandmultiplexingsystem,Figure14,andaslipringforrotordata
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normalforceresults,Figure22,showthatwithharmonicflapinputstherotoractsasafilterandonly5/revbalance
loadsareseen.Applying450Vat5Presultsina5Pnormalforceof550lb,orabout10%ofthenominalsteady
thrust.Thislevelofauthorityatamediumvalueofdrivingvoltageexceedsrequirementsandindicatesthattheflap
systemshouldbeabletoprovidetheexpectedvibration,noise,andaerodynamicimprovementsinforwardflight.
Oneadvantageoftheflapsystemisthatitiscompletelyindependentoftheprimarycontrolsystemandisnotflight
safetycritical.Varioustestswereruntoinvestigatethesystembehaviorwithoneflapinoperativeoratfullstatic
deflection(hardover)withtheotherflapsoperatingnormally.Noproblemswereobserved,butairframevibration
levelswouldcertainlyincreaseshouldsuchaneventoccuronanaircraft.Tofurtherdemonstraterobustness,the
flapsystemwasruncontinuouslyforovertwohourswithoutanyissuesandnodegradationinperformance.After
completionofthewhirltesttheflapsystemwasbenchtested,disassembled,andinspected.Performancematched
datatakenbeforethewhirltestandnosignsofanyinterferenceorunduewearwerefound.
6.SUMMARY
Afullscalerotorsystemwithpiezoelectricactuatedbladeflapswasdevelopedandwhirltowertested.The
developmenteffortincludeddesign,fabrication,andcomponenttestingofrotorblades,trailingedgeflaps,
piezoelectricactuators,switchingpoweramplifiers,andthedata/powersystem.Whirltowertestingofthe34-foot
diameterrotordemonstratedthefunctionality,robustness,andrequiredauthorityoftheflapsystem.
Provingtheintegration,robustoperation,andauthorityoftheflapsystemwerethekeyobjectivesmetbythewhirl
towertest.Thissuccessdependedontailoringthepiezoelectricmaterialsandactuatortotheapplicationand
meetingactuator/bladeintegrationrequirements.Testresultsdemonstratethefeasibilityandpracticalityofapplying
smartmaterialsforlimitedauthority,activecontrolonahelicopterrotor.Follow-onforwardflightdemonstrations
areneededtoquantifytheexpectedsignificantimprovementsinvibrations,noise,andaerodynamicperformance.
Extensionsofthistechnologyareaprimecandidateforon-bladeflightcontrol,i.e.eliminationoftheswashplate.
Specificconclusionsare:
1. Modelscalerotortestsdemonstratedthefeasibilityandbenefitsofpiezoelectricactuatedtrailingedgeflaps.2. Highvoltagecustompiezostackscanbedrivenathighfieldlevelsandmechanicalpreloadwithoutputs75%
largerthancommerciallyavailablewithoutaffectingdurability.
3. Ahighenergy,compactpiezoelectricactuatorforoperationintheruggedrotorbladeenvironmentwas
developed.Performanceanddurabilityweredemonstratedinextensivebenchtests.4. Ahighefficiencyswitchingpoweramplifierwasdeveloped.Powerdensitywasincreasedfour-foldcompared
topreviousmodels.
5. Aeroelasticsimulationmodelsfortheflapsystemweredeveloped.Resultsshowedthat2degreesofflapdeflectionaresufficientforvibrationreductionathighspeed.
6. Theactuator/flapintegrationintothebladewasoptimizedforperformance,weight,matchingbaselinebladedynamics,andusingproductionbladetooling.Fabricationmethodsweredevelopedtoembedactuatorandflap
supportingstructuresaswellasdata/powerwiringintheblade.
7. Therobustnessandcontrolauthorityoftheflapsystemwasdemonstratedinwhirltowertests.Therotorwasfullyinstrumentedandanextensivedatasetofactuatorperformanceandrotorloadswasobtained.
8. Actuatorauthorityexceededrequirements.Flapinducedoscillatoryrotorthrustwasgreaterthan10%ofbaselinethrust.
9. TheSMARTrotorsystemisreadyforforwardflightdemonstrations.
ACKNOWLEDGEMENTS
Drs.EphrahimGarciaandTerryWeisshaar,DARPA,providedthemotivationandfundingfortheeffort.Dr.Gary
Anderson,ARO,providedtechnicaloversightwithsupportfromotherresearchersatU.S.Armylaboratories.Dr.
JanetSater,IDA,providedguidance.Drs.WilliamWarmbrodt(NASA)andCheeTung(U.S.Army)provided
fundingandtechnicaloversight.AtBoeingthefollowingengineers,staff,andsubcontractorsprovidedsupport:
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LouSilverthorn,MikeNothaft,JeffHughes,MikeGamble,DaveDomzalski,JosephJette,andmanyothers.Atthe
UniversityofMaryland,Prof.InderjitChopra,assistedbyJinweiShen,TaeohLee,AndreasBernhard,andNikhil
Koratkarsupportedrotoraeroelasticanalysesandflapactuatorspintesting,andconductedmodelrotorwindtunnel
tests.AtUCLA,Prof.GregoryCarman,assistedbyMilanMitrovichandPaulChaplya,testedPEmaterials.At
MIT,Prof.StevenHall,assistedbyEricPrechtlandDoraTzianetopoulou,conductedmodelrotorspintestsand
supporteddesignofthedoublex-frameactuator.
REFERENCES
1. ChopraI.,StatusofApplicationofSmartStructuresTechnologytoRotorcraftSystems",RAEConference"InnovationinRotorcraftTechnology,London,UK,June1997(republishedinJournaloftheAHSSociety,
Vol.45(4),pp228-252,October2000).
2. FriedmannP.,ThePromiseofAdaptativeMaterialsforAlleviatingAeroelasticProblemsandSomeConcerns,RAEConference"InnovationinRotorcraftTechnology",London,UK,June1997.
3. Straub,F.K.andKing,R.J.,Applicationofsmartmaterialstocontrolofahelicopterrotor,Proc.SPIESymposiumonSmartStructuresandMaterials,SanDiego,March1996.
4. HasegawaY.,KatayamaN.,KobikiN.,NakasatoE.,YamakawaE.,OkawaH.,ExperimentalandAnalyticalResultsofWhirlTowerTestofATICFullScaleRotorSystem,57thAnnualForum,Washington,DC,May9-
11,2001.5. Enenkl,B.,Klppel,V.,Preiler,D.,andJnker,P.,FullScaleRotorwithPiezoelectricActuatedBlade
Flaps,Proc.28thEuropeanRotorcraftForum,Paper89,Bristol,UK,Sept.2002.
6. Straub,F.K.etal.,SmartMaterialActuatedRotorTechnologySMART,Proc.AIAASDMConference,AIAA-2000-1715,Atlanta,GA,April2000.
7. Prechtl,E.,andHall,S.R.,Closed-LoopVibrationControlExperimentsonaRotorwithBladeMountedActuation,Proc.41
stAIAASDMConference,AIAA-2000-1714,Atlanta,GA,April2000.
8. Koratkar,N.A.,andChopra,I.,WindTunnelTestingofaMach-ScaledRotorModelwithTrailingEdgeFlaps,Proc.57
thAHSAnnualForum,Alexandria,VA,2001,pp.1069-1099.
9. Shen,J.andChopra,I.,AeroelasticModelingofTrailing-EdgeFlapswithSmartMaterialActuators,Proc.41stAIAASDMConference,AIAA-2000-1622,Atlanta,GA,April2000.
10. Shen,J.andChopra,I.,AeroelasticStabilityofSmartTrailing-EdgeFlapHelicopterRotors,Proc.42ndAIAASDMConference,AIAA-2001-1675,Seattle,WA,April2001.
11. Mitrovic,M.,G.P.Carman,andF.K.Straub,Electro-MechanicalCharacterizationofPiezoelectricStackActuators,Proc.SPIEConferenceonSmartStructuresandMaterials,SPIEVol.3668,NewportBeach,CA,
March1999,pp.586-601.
12. Mitrovic,M.,GregP.Carman,G.P.andStraub,F.K,DurabilityCharacterizationofPiezoelectricStackActuatorsunderCombinedElectro-MechanicalLoading,Proc.AIAASDMConference,AIAA-2000-1500,
Atlanta,April2000.
13. Mitrovic,M.,G.P.Carman,andF.K.Straub,DurabilityofPiezoelectricStackActuatorsunderCombinedElectro-Mechanical-ThermalLoading,Proc.SPIEConferenceonSmartStructuresandMaterials,Paper4333-
04,NewportBeach,CA,March2001,pp.586-601.
14. Chaplya,P.M.andCarman,G.P.,TheEffectofMechanicalPrestressonDielectricandPiezoelectricResponseofPZT-5HatHighElectricFields,AdaptiveStructuresandMaterialSystems,Orlando,FL,Nov.
2000,pp.327-334.
15. Chaplya,P.andCarman,G.P.,DielectricandPiezoelectricResponseofLeadZirconateTitanateatHigh
ElectricandMechanicalLoadsinTermsofNon-180DomainWallMotion,JournalofAppliedPhysics,November2001,V90Issue10,pp.5278-5286.
16. Hall,S.R.,Tzianetopoulou,T.,Straub,F.K.,andNgo,H.,DesignandTestingofaDoubleX-FramePiezoelectricActuator,Proc.SPIEConferenceonSmartStructuresandMaterials,NewportBeach,CA,
March2000.
17. Clingman,D.J.,andGamble,M.HighPowerPiezoDriveAmplifierforLargeStackandPFCApplications,Proc.SPIEConferenceonSmartStructuresandMaterials,NewportBeach,CA,March2001.
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Table1:Rotorcharacteristics
Rotorblade modifiedMD900
Hubtype bearingless
No.ofblades 5
Radius 203.1in
RotorSpeed 392rpm
Chord 10in
Airfoil HH-10,HH-06
Twist 10deg
Torsionfrequency 5.7/rev
Table2:Flapdata
Radialstation 150186in
Length 36in
Chord 3.5in
Hingelocation 75%ofchord
Hornlength 0.75in
Max.flapangle 6deg
Table3:2x-Frameactuatorcharacteristics
Blockedforce 113lb
Freestroke 0.081in
Maximumwork 2.28in-lb
Voltage 475725V
Weight 2.16lb
Specificwork 1.1in-lb/lb
Actuator
Flap
Blade
Actuator
Flap
Blade
Figure1:MD900bladewithembeddedpiezoelectric
actuatorandtrailingedgeflap
AccessPlateFrame/Balbar
ActuatorMounts
FlapRention Strap
Tension/TorsionRod
Flextural RodEndLinkage
Flap
FlapHinges
FlapFrame
SMARTActuators
A
A
ElectricalConnectors
Outbd FlapSupportw/FlapStop
Inbd FlapSupportw/IntegratedLinkEgressTunnel
Figure2:Blade,flap,actuatordesignintegration
ArcPathofFlapHornSpar
CrossSection
FlapLinkAssembly
Tension-TorsionRod
2-XFrameActuator
ArcPathofFlapHornSpar
CrossSection
FlapLinkAssembly
Tension-TorsionRod
2-XFrameActuator
Figure3:Actuator,flaplink,tension-torsionrod
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ActuatorStacks
Flap
Balbar
FlexturalLinkage
AccessPlateFrame
LinkageTunnel
FoamCore
X-Frames BladeSpar
RodEndBearing
AccessPlate
Figure4:Blade,flap,actuatorcross-section(A-A)
Actuator
Flaps
Access
Cover
TipWeights
Actuator
Flaps
Access
Cover
TipWeights
Figure5:Flapsystemcomponents
SparInnerTorqueWrap
AccessPlateFrame
SparOuterTorqueWrap
LeadingEdge
Weights
SparInnerTorqueWrap
AccessPlateFrame
SparOuterTorqueWrap
LeadingEdge
Weights
Figure6:Bladesparfabrication
SparDetail
HingeAxisAlignmentTool
Inbd FlapSupport
Outbd FlapSupport
Strap
SparDetail
HingeAxisAlignmentTool
Inbd FlapSupport
Outbd FlapSupport
Strap
Figure7:Bladesparandflapsupportdetaillayup
BalanceWeight
AccessPlate
OffsetTool
LeadingEdgeWrap
BalanceWeight
AccessPlate
OffsetTool
LeadingEdgeWrap
Figure8:Leadingedgewrapclosureandbalance
weight
Lowerviewshown
PiezoStackColumn
InboardX-FrameActuator,Assembled
LoadLink
X-FrameActuator,Frames
OutboardX-FrameActuator,Disassembled
FlexureMount
Figure9:2x-frameactuator
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FixedFrame
MovingFrame
Figure10:2x-frameactuatordetails
BenchTestRig
FlapLinkTorsionBar
Spring
InboardX-FrameOutboardX-Frame
BenchTestRig
FlapLinkTorsionBar
Spring
InboardX-FrameOutboardX-Frame
Figure11:Actuatoronbenchtestrig
10in
chord
13Ft13Ft
3Ft
Actuator
Access
Cover
Flap
Figure12:Smartrotorbladeassembly
GearBox
RotorBalance
StrutAssy
1500HP
Motor
Figure13:Largerotorteststand(LRTS)
Figure14:Rotorhubwithdata/powertransferunit
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Figure15:Smartrotorbladeonwhirltower
Figure16:Smartrotoronwhirltower
-4
-3
-2
-1
0
1
2
3
4
0 20 40 60 80 100
RotorSpeed,%NR;Collective*10,deg
FlapDeflection-Average,
Relative
,deg
test11 test12 test18
te st1 1 te st 18
vsRotorSpeed
vsCollective
vsRotorSpeed
vsCollective
Figure17:Flapdeflectionversusrotorspeed(0deg
collective)andcollectivepitch(100%Rpm)withno
powerapplied.
-60
-40
-20
0
20
40
60
-600 -400 -200 0 200 400 600
ActuatorVoltage,V
ActuatorDisplacement,mil
8degcollective
0degcollective
1.5deg
Figure18:Staticactuatordeflectionversusapplied
voltage,at100%Rpm
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-2000
-1500
-1000
-500
0
500
-4 -3 -2 -1 0 1 2 3 4
FlapDeflection,deg
BladeTorsionMoment,in-lb
T51 T71 T130 T165
Figure19:Bladetorsionmomentatfourstations
versusstaticflapdeflection(8degcoll.,100%Rpm)
0
0.5
1
1.5
2
2.5
3
3.5
4
0 1 2 3 4 5 6 7
RotorSpeedMultiple
CyclicFlapDisplacement(Avgof5),deg
300V
400V
450V
Figure20:Flapdeflectionversusexcitation
frequencyforthreevoltagelevels(100%Rpm,8deg
collective,1P=6.53Hz)
0
100
200
300
400
500
600
700
0 1 2 3 4 5 6 7
RotorSpeedMultiple
TorsionMomentSta71,
in-
lb
300V
400V
450V
0V
Figure21:Bladetorsionmomentharmonicsat
station71inattheexcitationfrequencyforthree
voltagelevels(100%Rpm,8degcollective,1P=
6.53Hz)
0
100
200
300
400
500
600
0 1 2 3 4 5 6 7
RotorSpeedMultiple
BalanceNormal,lb
300V
400V
450V
0V
Figure22:Balancenormalforce(thrust)harmonics
attheexcitationfrequencyforthreevoltagelevels
(100%Rpm,8degcollective,1P=6.53Hz)