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AIAA95-1830

ExperimentalAerodynamicCharacteristicsof

thePegasusAir-LaunchedBoosterand

ComparisonswithPredictedandFlight

Results

M.N.RhodeandW.C.Engelund

NASALangleyResearchCenter

Hampton,VA

M.R.Mendenhall

NielsenEngineering&Research,Inc.

MountainView,CA

AIAA13thAppliedAerodynamics

Conference

June19-22,1995/SanDiego,CA

Forpermissiontocopyorrepublish,contacttheAmericanInstituteofAeronauticsandAstronautics

370L'EnfantPromenade,S.W.,Washington,D.C.20024

ExperimentalAerodynamicCharacteristicsofthe

PegasusAir-LaunchedBoosterandComparisonswith

PredictedandFlightResults

MatthewN.Rhode*andWalterC.Engelundt

NASALangleyResearchCenter,Hampton,VA23681

MichaelR.Mendenhall_

NielsenEngineering_Research,Inc.,MountainView,CA94043 Experimentallongitudinalandlateral-directionalaerodynamiccharacteristicswereobtainedforthePega- susandPegasusXLconfigurationsoveraMachnumberrangefrom1.6to6andanglesofattackfrom-4to +24degrees.Angleofsideslipwasvariedfrom-6to-{-6degrees,andcontrolsurfacesweredeflectedtoobtain
elevon,aileron,andruddereffectiveness.ExperimentaldataforthePegasusconfigurationarecomparedwith engineeringcodepredictionsperformedbyNielsenEngineeringg_Research,Inc.(NEAR)intheaerodynamic designofthePegasusvehicle,andwithresultsfromtheAerodynamicPreliminaryAnalysisSystem(APAS) code.ComparisonsofexperimentalresultsarealsomadewithlongitudinalflightdatafromFlight_2ofthe Pegasusvehicle.ResultsshowthatthelongitudinalaerodynamiccharacteristicsofthePegasusandPega- susXLconfigurationsaresimilar,havingthesamelift-curveslopeanddraglevelsacrosstheMachnumber range.Bothconfigurationsarelongitudinallystable,withstabilitydecreasingtowardsneutrallevelsasMach numberincreases.Directionalstabilityisnegativeatmoderatetohighanglesofattackduetoseparatedflow overtheverticaltail.Dihedraleffectispositiveforbothconfigurations,butisreduced30-50percentforthe PegasusXLconfigurationbecauseofthehorizontaltailanhedral.Predictedlongitudinalcharacteristicsand bothlongitudinalandlateral-directionalcontroleffectivenessaregenerallyingoodagreementwithexperi- ment.Duetothecomplexleesidefiowfield,lateral-directionalcharacteristicsarenotaswellpredictedbythe engineeringcodes.ExperimentandflightdataareingoodagreementacrosstheMachnumberrange. AR b CA Co CL

CLoNomenclature

Wingaspectratio,b2/S

Wingspan,in

Referencelength,in

Axialforcecoefficient,{axialforce}/q_S

Dragcoefficient,{drag}/qooS

Liftcoefficient,{lift}/qooS

Lift-curveslope,(gCL/COOtatcr=0°CLue

Ci C/_ CIs_ C._ *AerospaceTechnologist,AerothermodynamicsBranch,Gas

DynamicsDivision.MemberAIAA.

tAerospaceTechnologist,VehicleAnalysisBranch,SpaceSys- temsandConceptsDivision.MemberAIAA.Cn$ tVicePresident.AIAAAssociateFellow.Cn6.Copyright_)1995bytheAmericanInstituteofAeronautics andAstronautics,/nc.NocopyrightisassertedintheUnitedCns_ StatesunderTitle17,U.S.Code.TheU.S.GovernmenthasCy aroyalty-freelicensetoexerciseallrightsunderthecopyrightCyB claimedhereinforgovernmentpurposes.Allotherrightsarere-L servedbythecopyrightowner.C_

C.Elevonlifteffectiveness,ACL/A6_

Rollingmomentcoefficient,

{rollingmoment}/qooSb

Effectivedihedralparameter,ACL/A13

Aileronrolleffectiveness,ACdA6a

Rudderrolleffectiveness,ACdA6r

Pitchingmomentcoefficient,

{pitchingmoment}/qooS_

Elevonpitcheffectiveness,ACm/A6,

Normalforcecoefficient,{normalforce}/qooS

Yawingmomentcoefficient,

{yawingmoment}/qooSb

Directionalstabilityparameter,ACn/At3

Aileronyaweffectiveness,ACn/A6a

Rudderyaweffectiveness,ACn/A6r

Sideforcecoefficient,{sideforce}/qooS

Sideforceparameter,ACy/fl

Modellength,in

L/D M P q Re S T X Y Z ot _e $r ['tail

ALELift-to-dragratio

Machnumber

Pressure,lb/in_

Dynamicpressure,lb/in2

UnitReynoldsnumber,1/ft

Referencearea,in2

Temperature,°R

Longitudinalmodelbodyaxis

Lateralmodelbodyaxis

Verticalmodelbodyaxis

Angleofattack,deg

Angleofsideslip,deg

Ailerondeflectionangle,_Se,t-6e,,-,deg

Elevondeflectionangle,(_,t+6_,_)/2,deg

Rudderdeflectionangle,deg

Horizontaltaildihedralangle,deg

Wingleadingedgesweepangle,deg

Wingtaperratio

Subscripts:

cpCenterofpressure maxMaximum tReserviorconditions

0Zero-lift

c¢Freestreamstaticconditions

Introduction

Withthegrowingemergenceofmicro-satellitesin

thecommerciallaunchmarket,therehasbeenincreasing interestinsmall-payload-to-orbitvehicles(SPOV)capa- bleofdelivering1000-2000lbpayloadstoLEOatre- ducedcost)SeveralconceptsforSPOVshaveemerged, includingbothexpendableandpartiallyreusablevehi- cles,launchedfromthegroundorair-launchedfroma carrieraircraft.Thelatterconceptisreceivingcon- siderableattentionduetothemanyadvantagesofair- bornelaunch.Forexample,boosterperformanceisen- hancedbythekineticenergyimpartedbythecarrierair- craft,andstructuralweightcanbereducedduetothe lowerdynamicpressuresandresultingreducedstructural stressesencounteredatlaunchaltitude.2Additionally, airbornelaunchallowstheabilitytolaunchintoanyor- bitalinclinationorintotrajectoriessuitableforava- rietyofhypersonictestbedmissions.3,4Inthecurrent

X-34programtodevelopasmalldemonstrationlaunch

vehicle,anair-launchedconfigurationwaschosenfrom severalconcepts.5

Theviabilityofanair-launchedboosterconcepthas

beendemonstratedwiththePegasusvehicle.Pegasusis athree-stage,solid-rocket-propelled,wingedboosterca- pableofdelivering900lbofpayloadtoLEO.Developed jointlybyOrbitalSciencesCorporation(OSC)andHer- culesAerospaceCompany,PegasusfirstflewinApril,1991,andhassinceflownseveralmissions.Thevehicle iscarriedaloftbyaB-52carrieraircraftanddropped ataprescribedaltitudeandvelocity.Aphotographof thePegasus/B-52launchsystemisshowninFigure1.

Recently,OSChasdevelopedthePegasusXLvehicle,

alengthenedversionofPegasuswithincreasedperfor- manceandpayloadcapacity,designedtolaunchfroma

L-1011aircraft.

ThePegasusvehiclewasdesignedsolelyusingengi-

neeringcodes,supportedbylimitedcomputationalfluid dynamic(CFD)predictions,thuswithoutthebenefit ofwindtunneldata.s,rTotieinexperimentalground testdatawithexistingpredictionsandflighttestre- suits,aseriesofwindtunneltestswereperformedby theAerothermodynamicsBranchoftheNASALangley

ResearchCenteronthePegasus,andlater,PegasusXL

configurations.Thesynergisticcombinationofwindtun- nel,computational,andflightresultswillprovideacom- prehensivedatabaseforcalibrationandimprovementof theanalyticaltoolsthatwillbeusedinthedesignof futureair-launchedSPOVs.

Three-percent-scalemodelsofthePegasusand

PegasusXLconfigurationsweretestedintheNASA

LangleyResearchCenterUnitaryPlanWindTunnel

(UPWT)andthe20-InchMach6Tunneltoobtainlongi- tudinalandlateral/directionalaerodynamiccharacteris- ticsoveraMachnumberrangefrom1.6to6.Thispaper presentssomeresultsofthatexperimentalstudy,show- ingeffectsofMachnumber,attitude,andcontrolsur- facedeflectionontheaerodynamicperformance,stabil- ity,control,andtrimcharacteristicsofthePegasusand

PegasusXLconfiguration.Alsopresentedarecompar-

isonsoftheexperimentalresultswithpredictionsfrom theLangleyAerodynamicPreliminaryAnalysisSystem (APAS)andengineeringcodesusedbyNielsenEngineer- ingandResearch,Inc.(NEAR)inthedesignofthe

Pegasusvehicle,andwithflightdata.

ExperimentalMethod

Models

Testswereperformedusing3-percent-scale,ma-

chined,stainless-steelmodelsofthePegasusandPega- susXLconfigurations.Sketchesandphotographsofthe modelsareshowninFigures2through4.ThePega- susconfigurationhasacylindricalfuselagewithablunt nose.Aclippeddeltawingismountedonalargefillet ontopofthefuselage.Inboard,thewinghasadouble- wedgeairfoilsection,transitioningtoadiamondsection towardsthewingtip.Theall-moveablehorizontaland verticaltailsareidenticalinsizeandshape.Onthe model,thetailsurfacescanbedeflected-t-20degrees in5-degreeincrements.Racewaysforeandaftofthe wing/fuselagefilletareremovableandcanbereplaced

withflushinserts.Themodelissting-mountedthroughthebase,withtheinsidebasesurfacecontouredtosim-ulatetherocketnozzle.Thestingwasaffixedtothetunnelsupportmechanismmorethantenstingdiame-tersdownstreamofthemodelbasetominimizesupportinterferenceeffects.Thetriangularflatregionontheup-persurfaceofthewingwasusedtolevelthemodelinbothpitchandroll.ThePegasusXLmodelisformedbyreplacingfor-wardandaftsectionsofthemodeltolengthenthefuse-lageandplacethehorizontaltailsatananhedralangleof23degrees.Themiddlefuselagesection,wing,andtailsurfacesarecommontobothmodels.AsummaryofdimensionalinformationforbothmodelsisfoundinTable1.

Facilities

TheLangleyUPWTisasupersonicclosed-circuit

pressuretunnelwithtwotestlegs.Theflowinthelow- speedleg(TestSection#1)canbevariedfromaMach numberof1.5to2.86.Thehigh-speedleg(TestSec- tion#2)producesflowMachnumbersfrom2.36to4.63. Bothlegshavetestsectionsof4×4×7feetinsizeand utilizetwo-dimensional,asymmetricsliding-blocktype nozzlestoprovidecontinuousvariationinMachnumber.

Themodelsupportmechanismsallowremotecontrolof

angleofattack,sideslip,androll,aswellasaxialposi- tioninthetestsections.Amorecompletedescriptionof thisfacilitycanbefoundinReference8.

TheLangley20-InchMach6Tunnelisablowdown

windtunnelutilizingdryairasthetestgas.Theair isheatedtoamaximumtemperatureof1000°Rusing anelectricalresistanceheater,withamaximumreser- voirpressureof525psia,beforeexpandingthrougha fixed,two-dimensional,contourednozzleintoa20-inch- squaretestsection.Aninjectionsystemisusedtomove themodelintotheflowfromashelteredpositionfollow- ingtunnelstartandestablishmentofthedesiredflow conditions.Thisinjectionprocessisrequiredtoprotect themodelandstrain-gaugebalancefromtunnelstart- uploadsandtominimizeheatingtothebalance.Run timesaretypicallyfrom2to10minutesdependingon thereservoirpressureandvacuumlevels.Thisfacilityis discussedinmoredetailinReference9.

TestConditions

Forthepresentinvestigation,testswereperformed

inthelow-speedlegoftheUPWTatMachnumbers of1.60and2.00,andinthehigh-speedlegatMach numbersof2.50,2.96,3.95,and4.63.Inbothlegs,the freestreamunitReynoldsnumberatallMachnumbers wasmaintainedat2×10sperfoot.Flowconditions weredeterminedfromreservoirconditionsandthecur- rentcalibrationofthetunnel.IntheUPWT,angleofattackwasvariedinapitch-pausemodefrom-4degrees toamaximumof20degreesforthePegasusmodeland

24degreesforthePegasusXLmodelatanglesofsideslip

of0and2degrees.Angleofsideslipwasvariedfrom -6to+6degreesatfixedanglesofattack.Anattempt wasmadetokeepthemodelangleofattackrangeclose totheflightvehicletrajectorytolimitthetestmatrix, therebyshorteningtunneloccupancytime.

Inthe20-InchMach6Tunnel,runswereperformed

overarangeoffreestreamunitReynoldsnumberfrom

1x106perfootto3×l0sperfoot.Flowconditionswere

determinedfromreservoirconditionsandthestagnation pressuremeasuredviaapitotprobeinthetestsection.

Angleofattackwasvariedinapitch-pausemodefrom

-2to+8degreesatanglesofsideslipof0and2degrees.

Atfixedanglesofattack,angleofsideslipwasvaried

from-3to+3degrees.

Asummaryofflowconditionsforbothfacilitiesmay

befoundinTable2.

InstrumentationandSetup

Aerodynamicforcesandmomentsactingonthe

modelweremeasuredwithinternally-mounted,six- component,strain-gaugebalancesaffixedtoastraight sting.Thebalanceusedinthe20-InchMach6Tun- nelwaswater-cooledtominimizemeasurementerrors inducedbythermalstresses.Pressuretransducersexter- naltothemodelwereusedtomeasurechamberpressure inthebalancecavitybywayofthintubingroutedupthe sidesofthesting.Anelectricalfoulingstripwasplaced onthestingatthemodelexittosignalanyfoulingon themodelsupport.

Atsupersonicconditions,transitionstripswereap-

pliedtotheforebodynoseandleadingedgesofthewing andtailsurfacestoensureboundary-layertransitionto turbulentflow.1°ForMachnumbersof1.60and2.00,

No.60sandwassprinkledina1/8-inch-widestrip,1.2

inchesstreamwisefromthestagnationpointonthenose, and0.4inchesstreamwisefromthewingandtailsurface leadingedges.AtthehigherMachnumbers,individual grainsofNo.35gritwereplacedinthesamepositions relativetothenoseandleadingedges.Gritspacing wasdependentonthelocalleadingedgesweepangle, hencevaryingamongthenose,wing,andtailsurfaces.

Noattemptwasmadetotriptheflowinthe20-Inch

Mach6Tunnel.

DataReductionandUncertainty

Conventionsforthecoordinatesystem,forces,mo-

ments,andattitudeanglesareshowninFigure5.The forceandmomentdatawerereducedtocoefficientform usingthereferencedimensionsgiveninTable1anda momentreferencecenterofapproximately59percentof thebodylengthforthePegasusmodeland58percent

forthePegasusXLmodel.Thecoefficientdataarecor-rectedforchamberpressureinthemodel,andanglesofattackandsidesliparecorrectedforflowangularityanddeflectionsofthestingandbalanceunderaerody-namicload.Lateral-directionalderivativeswerecalcu-

latedfrombody-axisdataatfixedanglesofsideslipof0and2degrees.EstimateduncertaintiesinthestaticaerodynamiccoefficientsaregiveninTable3forthevarioustestMachnumbers.Forthe20-InchMach6Tunnel,the

listeduncertaintiesareforaconditioncorrespondingtoaunitReynoldsnumberof2x106perfoot.Theun- certaintyanalysiswasbasedonthemethodofpropaga- tionoferrorsandtookintoaccountuncertaintyinthe strain-gaugebalancemeasurements;uncertaintyinan- glesofattackandsideslip;anduncertaintyindynamic pressure.ll-13Balancemeasurementuncertaintieswere basedonstatistically-derivedvaluesfromthehundreds ofloadingsperformedduringthebalancecalibration.14

Uncertaintyinanglesofattackandsideslipwasesti-

matedtobe0.10degrees,includingsting/balancede- flectionandflowangularity.Whiletheuncertaintyin themeasurementofdynamicpressureisverysmall,the variationindynamicpressureacrossthetestsections ofthetwofacilitiesisapproximately2percent.Repeat pointstakenattheendofeverypitchsweepandfrom separaterunsshowthedatarepeatabilitytobewithin theuncertaintiesgiveninTable3.

FlowVisualization

Flowvisualizationdataintheformofschlierenand

vaporscreenphotographswereobtainedintheUPWT.

Shockwavepatternswereobservedusingasingle-pass

schlierensystemwiththeknifeedgeinahorizontalori- entation.Thevaporscreenphotographsweretakenwith astillcameramountedinsidethetunnelandaboveand behindthemodel.Watervaporwasintroducedintothe flow,andalaserlightsheetwasprojectedacrossthetest sectiontoilluminateacrosssectionoftheflowfield.The modelwastraversedthroughthelightsheettoobserve theflowfieldatvariousmodelstations.Inthevapor screenphotographs,theenvelopesoftheshockwaves areseenaslight-coloredregions.Dark-coloredregions denotelow-pressurezones,suchasvortices.Schlieren andoil-flowphotographswereobtainedinthe20-Inch

Mach6Tunnel,butarenotpresentedhere.

PredictionMethods

APAS

TheAerodynamicPreliminaryAnalysisSystem,or

APAS,isaninteractivecomputerprogramthatwasde-

velopedtoestimatetheaerodynamiccharacteristicsof aerospacevehicles.15Asthenameimplies,itsintentisapreliminaryevaluationtoolusedtoobtainquickesti- mationsofconfigurationaerodynamics,includinglon- gitudinalandlateral-directionalstatic,dynamic,and controleffectivenesscharacteristicsofarbitrarythree- dimensionalconfigurationsthroughoutthespeedregime.

Inthesubsonicandlowsupersonicspeedregimes,

APASutilizesacombinationofslenderbodytheory,

linearizedchordplanesourceandvortexpaneldistribu- tions,andempiricalviscousandwavedragestimation techniques.Inthesupersonicthroughhypersonicflight regimeanon-interferencefiniteelementmodelofthe vehicleisanalyzedusingavarietyoftheoreticaland empiricalimpactpressuremethodsalongwithvarious approximateboundarylayerrelations.16Thesuper- sonic/hypersonicanalysismoduleusedinAPASisessen- tiallyanenhancedversionoftheHypersonicArbitrary

BodyProgramMarkIll(HABP).17Inthisparticular

study,alloftheAPASsolutionsatMachnumbersbelow threewerecomputedusingtheslenderbody/linearpanel codemethods.AthigherMachnumbers,thehypersonic impactmethodswereused.AlloftheAPASsolutions includedinthisstudywerecomputedforwindtunnel conditions.

NEARAerodynamicPredictions

TheNEARpredictionswereperformedusinga

varietyofengineeringcodesandpanelmethods.5At

Machnumbersbelow4.0,MISL3andMissileDATCOM

wereusedinparalleltopredictlongitudinalandlateral- directionalaerodynamics.Theseindependentcodesem- ployacombinationoftheoreticalmethodsandempirical databaseswhichinherentlyaccountforviscouseffects, non-linearhigh-angle-of-attackaerodynamics,andcon- trolsurfaceinterference.AthigherMachnumbers,im- pactmethodcodessuchasS/HABPandMADMwere usedforaerodynamicpredictions.Subsonicandsuper- sonicpanelmethodcodeswereusedforaerodynamic calculations,particularlyathighanglesofattackwhere forebodyvortexeffectshadtobeincluded.Theaero- dynamicdatabasewasassembledbasedonexperienceof theindividualstrengthsandweaknessesofeachcode.

Higher-ordermethodssuchasEulerandNavier-Stokes

solutionswereusedtocheckimportantpointsonthe trajectory.TheresultsfromtheNEARpredictionsin- cludedinthispaperwereallcomputedpriortothewind tunneltestsatflightconditionsbasedonanominalflight trajectory.

FlightData

Experimentalandpredictedlongitudinalaerody-

namiccharacteristicsarecomparedwithlimitedflight datafromthesecondflightofthePegasusvehicle.To lessentheimpactonthepayloadcapacityduringthis operationalflight,onlyalimitedamountofadditionalinstrumentationwascarriedonboard.Detailsofthe

flighttestanddatareductiontechniquesarefoundinReferences18and19.Becauseofpropellentlossduetotheburningrocketmotor,thecenterofgravitymovesforwardduringflight.Inthispaper,theflightpitchingmomentcoefficientdataarereferencedtothecenterof

gravitypositionatagivenpointintime,ortheinstan-taneouscenterofgravity.

ResultsandDiscussion

PegasusandPegasusXLAerodynamics

LongitudinalaerodynamiccharacteristicsofthePe-

gasusandPegasusXLconfigurationsareshowninFig- ures7and8.AtallMachnumbers,aerodynamicper- formanceandlongitudinalstabilityofthetwoconfigu- rationsaresimilar,withthePegasusXLhavingslightly moreliftandnose-downpitchingmomentathigheran- glesofattack.AtthelowerMachnumbers,theliftcurve remainsnearlylinearthroughanangleofattackof24de- grees.AthigherMachnumbers,theeffectofvortices sheddingofftheforebodyandwingrootoccursatlower anglesofattackandtheliftcurvebecomesnon-linear. Overall,thelift-curveslopedecreasesbyoverafactorof threefromavalueofapproximately0.06perdegreeata

Machnumberof1.6to0.015perdegreeataMachnum-

berof6.WhileincreasingMathnumberdecreasesCDo by28percent,thelargelossofliftresultsina38per- centreductionin(L/D),narfrom2.7atMach1.6to1.65 atM=6.However,forbothconfigurations(L/D)mar occursatanangleofattackofapproximately12de- greesthroughouttheMachnumberrange.Bothconfig- urationsarelongitudinallystable,withnegligiblevalues ofCmoatallMachnumbers.Stabilitylevelsdecrease withincreasingMachnumber,tendingtowardneutral stabilityasthecenterofpressuremovesforward.Atthe lowerMachnumbers,adistinct"break"inthepitching momentcurveisevidentaroundanangleofattackof

8-10degrees.Thisdecreaseinstabilityoccurswhena

combinationofincreasingforebodyvortexstrengthand downwashinterferenceonthehorizontaltailscausesa forwardshiftinthecenterofpressure.Thesevortices maybeobservedinflowvisualizationphotographsin

Figure9.

Lateral-directionalaerodynamiccharacteristicsof

thePegasusandPegasusXLconfigurationsarepre- sentedinFigure10.AtthelowerMathnumbers,both configurationsshowpositivedirectionalstabilityatlow anglesofattack,becomingincreasinglyunstableasan- gleofattackincreasesandtheverticaltailisshadowed bythewingandfuselage.Theincreasedstabilityofthe

PegasusXLconfigurationatlowanglesofattackisa

resultoftheeffectiveincreaseinverticalareaduetothehorizontaltailanhedral.Thedirectionalstabilityof bothconfigurationstendstowardneutralvalueswithin- creasingMachnumber.Inaddition,thereducedvertical stabilizereffectivenessathigherMachnumbersresults indirectionalinstabilityatlowanglesofattackandless changeinstabilitylevelswithangleofattack.Dihedral effectispositiveatallconditions,withstabilitygenerally decreasingwithincreasingMachnumber.Atthelower

Machnumbers,dihedraleffectdecreasesathigherangles

ofattackasflowseparatesfromtheuppersurfaceofthe wing.ThistrenddiminishesathigherMachnumbers wherethewindwardflowsupportsagreaterpercentage ofthelift.Theanhedralofthehorizontalstabilizerson thePegasusXLresultsina30-50percentreductionin rollstabilityduetotheprojectedsideareaofthetails belowthecenterofgravity.

Controleffectivenessforbothconfigurationsis

showninFigures11and12foraMachnumberof2.0. ElevoneffectivenessisnoticeablygreaterforthePegasus

XLconfigurationatallanglesofattackduetothelonger

momentarmandtailanhedralanglewhichreducesfuse- lageinterferenceandplacesthesurfacesfurtherfrom thewingdownwash.PitcheffectivenessforthePegasus

XLincreasesby50percentwithangleofattackand,at

highanglesofattack,is37percenthigherthanforthe Pegasusconfiguration.Aileron(differentialtaildeflec- tion)andrudderrolleffectivenessvarylittlebetweenthe twoconfigurationsandarenearlyconstantwithangleof attack.Thereisanoticeableeffectofailerondeflection onyawingmomentforthePegasusXLduetotheside forcecomponentproducedwhentheanhedraitailsare deflected.Forbothconfigurations,Ca6,increaseswith angleofattackasthelift,andhencethedragduetolift, decreasesonthedownward-deflected(port)horizontal stabilizerandincreasesontheupward-deflected(star- board)stabilizer.Thedifferenceindragbetweenthe portandstarboardtailsresultsinapositiveyawingmo- mentincrement.Ruddereffectivenessisgreaterforthe

PegasusXLduetothelongermomentarmoftheverti-

caltail.Theruddereffectivenessforbothconfigurations, andthedifferenceineffectivenessbetweenthetwo,de- creasewithangleofattackastheverticaltailbecomes shadowedbythefuselage.

ComparisonofExperimentandPrediction

ComparisonsoftheexperimentaldatawithAPAS

predictionsbasedonwindtunnelflowconditionsand

NEARpredictionsforflightconditionsarepresentedin

Figures13through17forthePegasusconfiguration.

Sincethepredictionsandexperimentwerenotallcon-

ductedatthesameMachnumbers,comparisonsaregen- erallypresentedonlyforcaseswheretheMachnumbers areidentical.However,atthehighendoftheMach numberrange,experimentaldataatMath6arecom- paredwithNEARpredictionsataMachnumberof5.0.

Experimentalandpredictedlongitudinalaerody-namiccharacteristicsofthePegasusconfigurationareshowninFigures13and14.Ascomparedtotheex-perimentalresults,theNEARdatabasegenerallygivesabetteroverallpredictionofthelongitudinalaerody-

namicsthantheAPAScode.Lift-curveslopeisoverpre- dictedbyAPASduetotheinabilityofthecodetohan- dleseparatedflowregions.Thepredictionimprovesat higherMachnumberswheretheleesideflowhaslesscon- tributiontotheoveralllift.Lift-curveslopedatafrom theNEARcodes,whichemployempiricaldatabasesand leesidevortexmodels,comparewellwiththeexperimen- taldatathroughouttheMachnumberrange.Atlow

Machnumbers,bothcodespredictlesslongitudinalsta-

bilitythantheexperimentalresults.Thecomparison improveswithMachnumberasliftbecomesdominated bythewindwardflowandthecodesarebetterableto predicttheoverallpressuredistributionandhencethe locationofthecenterofpressure.TheNEARresults giveabetterpredictionofdragcoefficientandlift-to- dragratio,particularlyathighanglesofattackwhere APASoverpredictslift.Zero-liftdragcoefficientresults fromtheAPAScodecomparewellwithexperimental dataexceptatlowerMachnumbers,whereAPASpre- dictsa26percenthighervalueofCDo.AtMachnumbers above1.6,theNEARpredictionsyieldvaluesofCooup to15percenthigherthanexperiment.Thisisaresultof theattemptbyNEARtofactorinincreaseddragdueto protuberancesandsurfaceroughnessontheflightvehicle thatarenotmodelledinthewindtunnel.

TheflowfieldaboutthePegasusvehicleisquitecom-

plex,particularlyatsideslip,withlargeareasofflow separationandvorticesaboveandbelowthewing.(See againFigure9.)Consequently,thepredictedlateral- directionalaerodynamiccharacteristicsdonotcompare asfavorablywiththeexperimentaldata,asisevidentin

Figure15.OvertheMachnumberrange,theNEARre-

sultsgenerallyprovideabetterpredictionofdirectional stabilitythanAPAS.BecauseAPASdoesnotmodelsep- aratedflowregions,thewakeflowovertheverticaltail andsubsequentlossofdirectionalstabilityathighangles ofattackarenotpredicted.Rather,theAPASresults showpositivedirectionalstabilitythroughtheangleof attackrange,tendingtowardneutralstabilitywithin- creasingMachnumber.AtlowerMachnumbers,di- rectionalstabilitypredictionsfromNEARcomparewell withexperimentalresultsthroughanangleofattack rangeof12degrees.Athigherangles,thepredictions showlessdirectionalinstabilitythantheexperimental data.ThecomparisonisnotasfavorableathigherMach numbers,wheretheNEARcodespredicthigherlevelsof directionalinstability.TheAPAScodeyieldsabetter predictionofsideforceandthegenerallevelofdihedraleffect,althoughneitherpredictionmodelsthereduction inrollstabilityathighanglesofattackthatresultsfrom flowseparationonthewing.

Comparisonsofcontroleffectivenessfromprediction

andexperimentaldataareshowninFigures16and17. LongitudinalcontroleffectivenessresultsfromNEARare ingoodagreementwithexperiment,exceptatMach6, whereboththeNEARandAPASpredictionsshowtwice theliftandpitchingmomenteffectiveness.Thisdiscrep- ancyisunexpectedconsideringthegoodagreementat lowerMachnumbers,andnoplausibleexpanationcan begivenatthistime.AcrosstheMachnumberrange (exceptforMach6),APASoverpredictselevoneffective- nessatlowtomoderateanglesofattackbyabout12and

28percent,respectively,forliftandpitchingmoment.

ResultsfromtheNEARpredictionsforrollingmoment

duetobothaileronandrudderdeflectioncomparewell withexperimentaldatainallcases.Similarresultsfrom

APASshow25percentgreatereffectivenessatlowsu-

personicMachnumbers,withimprovingagreementat higherMachnumbers.Ruddereffectivenessisgenerally notaswellpredicted.APAScompareswellataMach numberof1.6,butshowsincreasinglylesseffectiveness thanexperiment,upto30percent,asMachnumberin- creasesto2.96.AgreementatMach6isexcellent.Data fromNEARshowareductioninruddereffectivenessat anglesofattackabove12degreesformostoftheMach numberrange.Thisdecrease,asmuchas36percentat aMachnumberof2.0,isnotborneoutbyexperimental results.

ComparisonsofExperimentalandFlightData

Inthecomparisonofexperimentalandflightdata,

theflightdatawereusedasthebaselinecondition.Ex- perimentaldatawereinterpolatedtotheflightangleof attackandcorrectedforelevondeflectionbeforebeing referencedtotheinstantaneouscenterofgravity.Flight angleofattackandelevondeflectionhistoriesareshown inFigure18,andcomparisonsofthelongitudinaldata arepresentedinFigure19.Theagreementbetweenex- perimentandflightmeasuredvaluesofliftcoefficientis verygoodacrosstheMachnumberrange.Windtunnel datacapturethetrendindragcoefficientbutareap- proximately15percentlowerthanflightvalues.These lowerdragcoefficientnumbersaccountfortheincreased valuesoflift-to-dragratioatthelowerMachnumbers.

Thehigherdragcoefficientvaluesforflightmaybethe

resultofprotuberancesontheflightvehicle(antennae, hatches,etc)whicharenotrepresentedonthewindtun- nelmodel,andalsoincreasedskinfrictionduetothesur- faceroughnessofthethermalprotectionsystem.Flight andexperimentalpitchingmomentdataforatrimmed configurationareinexcellentagreementexceptatthe lowerMachnumbers.AtaMachnumberof1.6,thedif-

terenceinpitchingmomentcoefficientisequivalenttoaforwardshiftincenterofgravityorrearwardshiftincenterofpressureof0.59feet,or1.2percentofthebodylength.Thisdiscrepancyisnotunexpectedgiventhecomplexnatureoftheflowfieldathighanglesofattack.

ConcludingRemarks

Experimentallongitudinalandlateral-directional

aerodynamiccharacteristicsforthePegasusandPega- susXLconfigurationswereobtainedforarangeofMach numberfrom1.6to6andanglesofattackfrom-4de- greesto24degrees.ExperimentaldataforthePegasus configurationarecomparedwiththoseforthePegasus

XLconfiguration;withpredictionsfromNEARandthe

APAScode;andwithflightdata.Longitudinal,lateral-

directional,andcontroleffectivenessdataarepresented.

Resultsindicatethatthelongitudinalaerodynamic

characteristicsforthePegasusandPegasusXLconfigu- rationsareverysimilar.Bothvehiclesarelongitudinally stableovertheangleofattackrange,withatrendtoward neutralstabilityathigherMachnumbersasthecenterof pressuremovesforward.Atmoderatetohighanglesof attack,bothconfigurationsbecomedirectionallyunsta- bleastheverticaltailbecomesshadowedbythefuselage andwing.DihedraleffectispositiveatallMachnum- bers,tendingtowardneutralvaluesathighanglesofat- tack.TheanhedralonthehorizontaltailsofthePegasus

XLreducetherollstabilityby30-50percent.Longitudi-

nalandlateral-directionalcontroleffectivenessdecrease withincreasingMachnumber.ThePegasusXLshows slightlygreaterelevoneffectivenessandaaileronyawing momentincrementduetothehorizontaltailanhedral.

PredictionsfromNEARandtheAPAScodeyield

goodassessmentsoflongitudinalaerodynamicsandboth longitudinalandlateral-directionalcontroleffectiveness.

Duetotheinabilitytomodelseparatedflow,theAPAS

codeoverpredictsthelift-curveslopeatlowerMachnum- bers.Calculationsforlateral-directionalaerodynamic characteristicswerenotingoodagreementwithexperi- ment.PredictionsfromNEARoverestimatedirectional stabilityathigherMachnumbersandunderestimateroll stabilityandsideforceatmostconditions.Exceptat highMachnumbers,theAPAScodeyieldspoorpredic- tionsofdirectionalstability.Estimationsofsideforce anddihedraleffect,however,aregenerallybetterthan thosefromNEARforthePegasusconfiguration.

Experimentallongitudinalaerodynamicdatacom-

parefairlywellwithflightdataacrosstheMachnum- berrange.Experimentally-measuredvaluesofdragco- efficientareapproximately15percentlowerthanflight values.AtlowsupersonicMachnumbers,experimental resultsforatrimmedflightconditionshowaslightneg- ativepitchingmoment,equivalenttoarearwardshiftincenterofpressureof1.2percentofthebodylength.

Abetterunderstandingofthecapabilitiesofpre-

liminaryaerodynamicanalysistoolswillimprovethe efficiencyandaccuracyofsuchanalysesinthedesign cycleoffutureair-launchedSPOVs.Currentpredic- tionmethodologiessuchasthoseusedinthedesignof thePegasusvehicleprovidereasonablygoodassessments oflongitudinalaerodynamicandcontroleffectiveness characteristics;however,forconfigurationswithcom- plex,vortex-dominatedflowfields,windtunnelstudies arerequiredtoprovidecrediblelateral-directionalaero- dynamiccharacteristics.

Acknowledgments

TheauthorwouldliketothankMr.RobertCurryof

NASADrydenFlightResearchCenterandMr.Bryan

MoultonofPRC,Inc.,Edwards,California,whopro-

videdtheflightdatapresentedinthispaper.

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"AerodynamicFlightResearchUsingthePegasusAir-

LaunchedBooster."AIAAPaper92-3990,July1992.

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AIAAPaper92-4104,August1994.

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namicDesignofPegasus--ConcepttoFlightwith

CFD."AGARDSymposiumonMissileAerodynamics,

Friedrichshafen,Germany,April1990.

7.Mendenhall,M.R.;Lesieutre,D.J.;Whittaker,C.H.;

Curry,R.E.;andMoulton,B.:"AerodynamicAnalysis

ofPegasus--ComputationsvsReality."AIAAPaper

93-0520,January1993.

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PlanWindTunnel.NASATP1905,1981.

9.Miller,C.G.:"LangleyHypersonicAero-

dynamic/AerothermodynamicTestingCapabilities--

PresentandFuture."AIAAPaper90-1376,June1990.

10.Braslow,A.L.;Hicks,R.M.;andHarris,R.V.,

Jr.:UseofGrit-TypeBoundaryLayerTransitionTrips

onWindTunnelModels.NASATND-3579,1966.

11.Kiine,S.J.andMcClintock,F.A.:"DescribingUn-

certaintiesinSingle-SampleExperiments."Mechanical

Engineering,Vol.75,No.1,pp3-9,January1953.

12.Coleman,H.W.andSteele,W.G.,Jr.:Ezperimenta-

lionandUncertaintyAnalysisforEngineers,JohnWiley &Sons,1989.

13.Bathill,S.P.:EzperimentalUncertaintyandDrag

MeasurementsintheNationalTransonicFacility,NASA

CR4600,1994.

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surementUncertaintyofMulti-ComponentWindTunnel

Balances."AIAAPaper94-2589,June1994.

15.Cruz,C.I.andWilhite,A.W.:"PredictionofHigh-

SpeedAerodynamicCharacteristicsUsingtheAerody-

namicPreliminaryAnalysisSystem(APAS)."AIAAPa- per89-2173,July1989.

16.Engelund,W.C.andWare,G.M.:"Aerodynamic

PredictionsandExperimentalResultsforanAdvanced

MannedLaunchSystemOrbiterConfiguration."AIAA

Paper93-1020,February1993.

17.Gentry,A:HypersonicArbitrary-BodyAerodynamic

ComputerProgram(MarkIIIVersion},1/ol.H:Pro-

gramFormulationandListings.DouglasReportDAC

61552,April1968.

18.Curry,R.E.;Mendenhall,M.R.;andMoulton,B.:

In-FlightEvaluationofAerodynammicPredictionsofan

Air-LaunchedSpaceBooster.NASATM104246,1992.

19.Noffz,G.K.;Curry,R.E.;Haering,E.A.,Jr.;

andKolodziej,P.:AerothermalTestResultsFromthe

FirstFlightofthePegasusAir-LaunchedSpaceBooster.

NASATM4330,1991.

Table1.Modelgeometriccharacteristics.(alldimensionsininchesorinches2).

Dimension

Modellength,L

Wingspan,b

Referencelength,

Referencearea,S

Wingaspectratio,AR

Wingtaperratio,;L

Wingleadingedgesweep,ALE

Horizontaltaildihedralangle,FtailPegasus

17.774

7.920 2.934

18.912

3.333 0.092

45°

0oPegasusXL

19.974

7.920 2.934

18.912

3.333 0.092

45°

-23o

FacilityM_Table2.Flowconditions.

Pt,psiaTt,°RPoo,psia

UPWT1.607.495851.762

UPWT2.008.705851.113

UPWT2.5011.15850.650

UPWT2.9614.25850.409

UPWT3.9525.16100.177

UPW'r4.6334.36100.101

20-InchMach6Tunnel5.92608850.042

20-InchMach6Tunnel5.981259100.083

20-InchMach6Tunnel6.001959350.124OR

387
325
260
213
148
115
110
112

114qoo,psia

3.16 3.11 2.85 2.51 1.93 1.52 1.03 2.05

3.13Rex10"6/ft

2.0 2.0 2.0 2.0 2.0 2.0 1.0 2.0 3.0 Table3.Uncertaintiesinbody-axisaerodynamiccoefficients.

ACy1.60

.00642.00 .00522.50 .0043MachNumber 2.96 .00383.95 .00324.63 .00335.98 .0021 .0026ACN

ACA.0005.0005.0006.0007.0009.0011.0008

ACm.0036.0027.0021.0020.0017.0022.0004

ACt.0004.0003.0003.0003.0003.0004.0002

ACn.0014.0012.0006.0004.0005.0006.0002

.0025.0024.0026.0026.0028.0018

NIU_"l'g4,Wl

Figure1.PegasusvehicleonB-52carrieraircraft.,10.438 17.77 (a)Pegasus<_'C__:_-'+_i473 t,__f__k11.557_-,.__

19.97,[

(b)PegasusXL

Figure2.SketchesofPegasusandPegasusXLmodels.

Alldimensionsaregivenininches.Figure4.PhotographofPegasusXLmodelinUPWT. Y

Sirleforce__Rollingmoment4

Rowdirection__

Z

Figure5.Coordinatesystem.

Figure3.PhotographofPegasusmodelin

20-InchMach6Tunnel[.

Figure6.Pegasuspaneled-bodymodel

usedinAPASpredictions. 10

©Pegasus©Pegasus

[]PegasusXL[]PegasusXL CL Cm1.2 1.0 .8 .6 .4 .2 -.21 -.4CD.8 .7 .6 .5 .4 -3 .2 .I 0,i, .8"!_4.6"3 .42 .21 0L/D0 -.2-1 -.4-2 -.6"3 -.$.,-4 -8-404812162024rd :J ,L,.,.i.L.L.I.,-.4-.20.2.4.6.81.01.21.2 1.0 .8 .6 CL.4 .2 0 -,2 -.4 Cm.6 .6 .4 .2 0 -.2 -.4J o.6 -.6.,....i_b.J.L., -8-404812162024 _,degCL_,degCD.6 .7 .6 .5 .4 .3 .2 .I 0,L, (a)Moo=1.6

Figure7.Longitudinalaerodynamiccharacteristicsof

PegasusandPegasusXLconfigurations.4

3 2fI LID0 -I -2- -3- -.4-.20.2.4.6.81.01.2 CL (c)Moo=2.96

Figure7.Continued.

©Pegasus

[]PegasusXL0Pegasus []PegasusXL 1.2 1.0 .6 .6 CL.4 .2 0 -.2 o.4

CmCD.6

.7 .6 .5 ,4 .3 .2 0_. .6- .4 .2 0 -.2 -.4 -.6 -.6,i -8-404812162024 (x,deg4 3 2 I -1 -3- -4•,• -.4-.2 (b)Moo=2.0

Figure7.Continued..h.i.i.,.,.J

•

2.4.6.81.01.2

CL1.2 1.0 .6 .6 CL.4 .2 0 -.2 -.4 Cm,l, .8 .6 .4 .2 0_. -.2 *.4 -.6 *.8.,• -8.4.6- .7- .6" .6" Co.4- .3- 0,i, .,.i.i.,.i.,

4612162024

_,deg4 3 2 1

L/D0-1

-2- -3- -.4-.2 (d)Moo=4.63

Figure7.Continued.f

.i,,.b.,.i., .2.4.6.81.01.2 CL 11

©Pegasus

CL Cm1.2 1.0 .8 .6 .4 .2 0 -.2 -.4C_.8 .7 .6 .5 CD.4 .3 .2 .1(1 .6 .6 .4 .2

0^,-_;C,O@@_

-.2 -.4 -.5 -8-404812162024 a,dogL/D i-2t Y .i..,.J.i.J.,,j -.4-.2O,2.4.6.81.01.2 CL (e)Moo=6.0

Figure7.Concluded.(a)Schlieren

Figure9.Flowvisualizationresultsat

Moo=2.5anda=12°.

0Pegasus

[]PegasusXL .O8 .07 ,06 .05

CLa.04

.03 .02 .01 0 .14 .13 .12 .11

CDo.10

.09 .08 .07 .063.0 2.6 Q2.6 02.4

I"I[]Q[]0(LiD)max2.02"21.61.81.4

•J.i.i.Lii,L,iiiD n_ 0 .i*L.l.,.,,i,i,I D [] _o

12345678

M_Xc_-.60

.75 .70 ,ss_ .__HA_oc.g. .S5 .45

01234S$78

M_

Figure8.Summaryoflongitudinalaerodynamic

characteristicsofPegasusandPegasusXL configurations.(b)Vaporscreen

Figure9.Concluded.

12

0Pegasus©Pegasus

DPegasusXL[]PegasusXL

.012"

°°.i2.11114

0.

Cnp-.11114

o._8 -.012 -.010 -.020.... .O03 .002 .001 0 c=_-.ooi:_. -.002:""0,. -.003- -.004- -.005.I+ .8,4.03Stable.02To,0 _Cyp-.01*.02' -.04 .t+L.,.i.,.+-._i ._+i+i.i+i.i

4812102024

c_,deg (a)Moo=1.6-8-404012162024 a,deg Figure10.Lateral-directionalaerodynamiccharacteristics ofPegasusandPegasusXLconfigurations.Cnp

Clp.012-

.008 .004 0 -.004 -.008 -.012 -.016 -.020 .003 .002 .001 0 -.001 -.002 -._ -.0_4 -.005•,i -8-4+L•J.,•L•L•J

4812162024

c_deg (c)Moo=2.96.02 .01 0

Cyp-.01

-.02 -.03 "04"[-.05......,.,....,= -8-404812162024 (x,deg

Figure10.Continued.

0Pegasus

[]PegasusXL©Pegasus []PegasusXL .012 .008 .004_I) 0_

Cnp-.004

-.008 -.012 -.016 -.020.,•J•J+i+i+i+J.03 .02 .01 0

Cyp-.01

-.02 -.03 -.04 -.05.,• -8-4 .003- .002 .001- 0 -.004- -.005,L,I............-8-404812162024 a,dog (b)Moo=2.0

Figure10.Continued.I

4812102024

a,degCnp

CIp.012

.00_" .004" o-.004- -.008- -.012 -.016 -.020, .003 .002 .001

°L-.002I-

o._r- ::f.,+.03 .02 .01 0

Cyp-.01-

-.02 o.03 -.04 *.05,L, -8-4 -8-404012162024 a,dog (d)Moo=4.63

Figure10.Continued.,t,,.,.,•...

4812162024

a,deg 13

©Pegasus©Pegasus

[]PegasusXL Cnp

CIp.012

.008 .004 0 -.004 -.008 -.012 -.016 -.020.03 .02 .01 0

Cyp-.01

-.02 -.O3 -.04 -.0_ .003- .002- .O31- 0 -,001-GQ -,002- -.003 -,004- ".005,I,'I'J"n,IiInI -8-404812162024d_g (e)Moo=6.0

Figure10.Concluded.cnoo_o_o

-8.404812162024¢leg.O3,1 .003 .002 .001 Cn_.0 -.001 -.002 -.003 -.004 .O04 .003 .002 .001 Cl_e0 -.001 -.002 -.003I -.004.,•I............ -8-404812162024.002 .001 0 -.001

Cn_-.002k

-.003_i

°,l_S-

.11114 .002 .001-_ Cl_r0 -.001 -.002 %003 -.004._. -8-44812162024 c(,deg(x,deg Figure12.Lateral-directionalcontroleffectivnessfor

PegasusandPegasusXLconfigurationsatMoo=2.0.

©Experiment

APAS

©Pegasus

[]PegasusXLCL1.2 1.0 .8 .6 .4 .2 0 -.2 -.4/°_0o o o° CD.8 .7 .0 .5 .4 .3 .2 0,i.o

CLse.016

.014 .012 .010 .008 .006 .004 .002 0 -80-.0C5 -.010 -.015

Cmse-.020

-.025 -.030

I-.035

-404812162024-8-404812162024 c_,deg(x,deg Figure11.LongitudinalcontroleffectivenessforPegasus andPegasusXLconfigurationsatMoo=2.0.Cm.8 .6 .4 .2 0 -.2 -,4

°.S

-.S -8-4I./D4 3 2 1 O -1 -2 -3 -4, -.4-.2"O

4812162024.2.4.6.S1.01.2

(_,degCL (a)M_:I.6

Figure13.Comparisonofexperimentalandpredicted

longitudinalaerodynamiccharacteristics forPegasusconfiguration. 14 CL.

CmOExperiment

APAS ........NEARDatabase 1.2 1.0 .8 .6 .4 .2 0

°.2

-.4/•iL.L,L,L,J.8 .7 -5 .5 CD.4 .3 .2 .1 0 .6 .4 .2 0 -.4 -.8 -.8.i. -8-404812182024 =,degI.JD4 3 2 1 0 -1"_ -2- -3- -.4-.20.2.4.6.81.81.2 CL (b)M_=2.0

Figure13.Continued.CL

Cm©Experiment

APAS ........NEARDatabase,M_:5.0 1.2- 1.0- .8"t.8 .7 .6 .5 CD.4 !Lt/ .8 .6 .4 .2 0_'_ *.4- -.8" %8.i._i.I.i,L,i,I -8404812182024 (x,deg4 3 2 1 L/Do -1 -2" -3- -4.i.I.,.i..,i,_,I -.4-.20.2.4.8.81.01.2 CL (d)Mo_=6.0

Figure13.Concluded.

CL. Cm1.2 1.8 .8 .6 .4 .2 0 -.2 -.4 .8 .6 .4 .2 0 -.2 -.4 -.8 *.8 -8©Experiment APAS ........NEARDatabase .8¸ .7 •8.¸ CD._

L•/

/ -404812162024 _,degL/D4 3 2 1 0 -1 -2 -3 -4 -.4.,.....,.,k,,i.p -.20.2.4.6.81.01.2 CL (c)Moo=2.96

Figure13.Continued..O8

.07 .06 .85

CLa.04

.03 .02 .01 0 .14 .13 .12 .11

CDo.18

.09 .08 .07 .06©Experiment APAS ........NEARDatabase o\

O\(LJD)max

o .iJ.ii.[:1:[i]4.4 4.0 3.6 3.2 2.8 2.4 2.0 1.8

1.2O.80.75

.70 c_-....85 _0"--Xcp/L".80 .55 "'°_..°.50 .45 .'.'-'-'-''J,I.40

12345678

M_O0 .L•,,,.,.,.,.,..

12345878

M.

Figure14.Summaryofexperimentalandpredicted

longitudinalaerodynamiccharacteristicsfor

Pegasusconfiguration.

15 .012 .008 .004 0

Cn_-.004

-.008 -.012 -.016 -.020 .003 .002 .001 0

Cl_,-.001

-.002 -.003©Experiment APAS

Stab4o

0 o o o oCy_.02 .01 0 -.01 -.02 -.03- -.04- -.05.h,l.*._,,.,,i,i -8-404812102024 %deg io L_ -.004 -.005.L• -8-4oStable

4012102024

ct,deg (a)Moo=1.6

Figure15.Comparisonofexperimentalandpredicted

lateral-directionalaerodynamiccharacteristics forPegasusconfiguration.Cnp

Clp©Experiment

APAS ........NEARDatabase .012 .008 .004 0 *.004 -.(X_ -.012 -.o10 -.020I........ .003" .002- .001 -.001 *.002•-__. -.003i -.004-.006.L_].,.,.i.,,_,, -8-404012102024 c(,dog (c)M_=2.96.02 .01 0 -.01 -.02 -.03- -.04- -.rJ6.....,.,.,J.J,, -8-404012102024 _,deg

Figure15.Continued.

©Experiment

APAS ........NEARDatabase .012-^_.o(_- .oo4• o

C.p-.oo4i.qgoo.......

-.008[Ooo-.012 -.016[•.020J.•,•,-4,t,I,ICyp .OO3 .002 .001 0

CIp-.001

-.002"_ -.003 -.004 o.0(_.,, -8-4o •i.,.,.i.J.b

4012162024

ct,deg (b)Moo=2.0.03- .02-_".01- 0 -.01 -.02"_"-- -.03- -.04- -8.404812102024 _,deg

Figure15.Continued.Cnp

CI_0Experiment

APAS ........NEARDatabase,M.=5.0 .o12 .oo4 o -.oo4 -.o06 -.o12 -.OLO ..020.03 .o2 .Olo.-..........Cy_-.01 i-.02 -.03 -.04 .i..I.,.,.,.,.,-.05 "0°3I.002!i .001,-.001J -.002------" -8-404812162024 (x,dog (d)Moo=6.0Q] -8-44012162024 (_,dog

Figure15.Concluded.

16

©Experiment

APAS©Experiment

APAS ........NEARDatabase .010 .o14 .o12 ,OlO

CLoe.008

.006 .004 .002 0.L. -8-4oO4uO .J._.J.i.J.J

4012162024

_,deg0• -.005 -.010 -.015

Cm_-.020•

-.02So(3( -.030 -.035 -.040,,, -8000000000 ,,.,.,.,L,,,

404012162024

_,deg (a)Moo=1.6

Figure16.Comparisonofexperimentalandpredicted

longitudinalcontroleffectiveness forPegasusconfiguration..016" .014- .012" .010"

CL_.008"

.oos-__o___,___:)o.____:-:__.....004. .002-

0•,•.,.,.i.i.t.,

• .8-404812102024 a,deg (c)Moo=2.96..030-

°.03S-

-.040.,. -8-4O- -.010 -.015

Cm_-.020

04012162O24

co,deg

Figure16.Continued.

0Experiment

APAS ........NEARDatabase0Experiment APAS ........NEARDatabase,M.=5.0

CL6e.016

.014 .012 .010 .OOe .006 .004 .002

0•,•

-8-40 -.005 -.010 -.015 _...Cmbe-.020 -.025 -.030 -.035 .............,040

4812162024-8

(_,deg (b)Moo=2.0_7_'O0"O_f_O_.... -404812162024 _,deg

Figure16.Continued.CL_.016

.014 .012 .010 .008 .004_--._.,. .002OC

0•,•

.8.40" -.010"-- -.015""-.

Cmoe-.020

--"-.025--.030--.035-

4812162024-8-404812162024

cx,degoc,deg (d)M_=6.0

Figure16.Concluded.

17

©Experiment

APAS .004- .003- .002• .001

Cn_0_--(

-.001- -.002- -.003• -.004,._OO.002F O' -.001

Cn_--,002_

-.003_ -,004- -.oos-o-,00_,I,oo0o°

Clam.004-.004-

.003.003- .002'.002- .001•.001-o

0Cl_,o

-.001._)ooooo__-.001 -.002•-.002 -.003-.003 -,004.................004._. •8.404812162024-8-4 (x,deg(x,deg (a)M_=l.6

Figure17.Comparisonofexperimentalandpredicted

lateral.directionalcontroleffectiveness forPegasusconfiguration.uOO0o .,._.J.,.,,,

481216_24CnGa

Cl_0Experiment

APAS ........NEARDatabase .004- .003- .002- .001" 0-C_: -.001- %002- -.003- -.004.+.Cn).002 .001 0 -.001 -.002-0 -.003 -.O(Oi -.005 -.006.,. .004- .001

0,"-,ri_._____.+___-.001

-.002- -.003- -.004+i+.k+_,J,i.,., -8,,404812162024 (_,deg.oo4 .003 .oo2 .001 0 -.001- -.002- -.003- -.004.,._-c--c_-_Cl& -8 (c)Moo=2.96-404812162024 a,dog

Figure17.Continued.

.004 .003 .002 .001 Cn_0 -.001 -.002 -.003 -.0040Experiment APAS ........NEARDatabase

Cn6r.002

.001 0 -.001 -.002 -.003 -.004 -.005 -.00(i0+-_'-o-'ooo.004¸ .003 .002 .001 Cn_0 -.001 %002 -.003 -.0040Experiment APAS ........NEARDatabase,M.=5.0 Cn_. .O04 .003 .002 .001 Cl_0 -.001o -.002 -.003 -.004.,+ -8-4(,-_r_-e---@--G-0---

4812162024

(_,deg.004- .003- .002- .001-_j, Cl_o -.001 -.002 -.003 -.004.t. -8.4 (b)Moo=2.0

Figure17.Continued.'+-+_'--+:_---_-.O+-D___

4812162024

a,dogCl_.004 .003 .002 .001 0 -.001 -.002 -.003 -.0041., -8.44812162024 c{,degCl_.004- .003- .002- .001- 0 -.001- -.002- -.003-I -.004.,•,+,.,-,,,_.+ -6-404812162024 _,deg (d)Moo=6.0

Figure17.Concluded.

18 --Flight (z,deg28 24
20 18 12 8 4 0 -44 0 -4"6e-12 -16 -20 -24 -,-,-,-,-i,L,i,_-28

012345878

U_/12345678

M_ Figure18.Angleofattackandelevondeflectionhistories forPegasusFlight#2.

CL12I1.0

vC -.41......Experiment

Flight

.8 .7 .6 .5 CD.4 .3 .2 .1 0

Cm---cc_ccc

oo.2O .15 .10 .05 0 -.05 -.10 -.15 -.20................

012345878

M.30[2.5

2.0°°

1.0 -1.0[................

812345878

M_

Figure19.Comparisonofexperimentalandflight

longitudinalaerodynamicdataforFlight#2of thePegasusvehicle. 19

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