空氣動(dòng)力學(xué)講義課件

Chapter3AerodynamicsThischapterestablishesthebasicknowledgeelementsofaerodynamics.Chapter3AerodynamicsThischaSectionsALiftanddragBStabilityCFlightcontrolsDHigh-liftdevicesETurnFVmcGHighspeedflightSectionsALiftanddragSectionALiftandDragTheFirstLawofThermodynamics:Energycannotbecreatedordestroyed,Energycanbeconvertedfromoneformintoanother.SectionALiftandDragTheFiBernoulli’sPrinciple

“Inthestreamlineflowofanidealfluid,thesumofallenergieswillremainconstant”

AnexampleofBernoulli’sTheoremcanbeseeninaVenturi.Bernoulli’sPrinciple

“InthStaticPressure+DynamicPressure=Total(Constant)TheVenturiStaticPressure+DynamicPresBernoull’sEquation:Bernoull’sEquation:A1,v1A2,v2Bernoull’sEquation:Bernoull’sDynamicPressure

StaticPressure

TotalPressureDynamicPressure

StaticPressuPerformanceTheairflowingovertheuppercamberedsurfaceflowfasterthantheairovertheoppositesurfacetoreachthetrailing.Thusthepressureontheupperwingsurfaceislowerthanthatonthelowersurfaceandliftisproduced.PerformanceTheairflowingoveAirfoilsAnairfoilisanysurface,suchasawing,whichprovidesaerodynamicforcewhenitinteractswith（相互作用）amovingstreamofair.AirfoilsAirfoilsLeadingedge:thepartofairfoilmeetstheairflowfirst.Trailingedge:wheretheairflowovertheuppersurfacerejoinsthelowersurfaceairflow.

Chordline：animaginarystraightlinedrawnthroughanairfoilfromtheleadingedgetothetrailingedge.AirfoilsLeadingedge:thepartAirfoilsCamber:thecharacteristiccurveofitsupperandlowersurfaces.Theuppercamberismorepronounced,whilethelowercamberiscomparativelyflat.Thiscausesthevelocityoftheairflowimmediatelyabovethewingtobemuchhigherthanthatbelowthewing.Relativewind:isparalleltoandoppositetheflightpathoftheairplane.AirfoilsCamber:thecharacteriAirfoils-DefinitionsAirfoils-DefinitionsAngleofattack

Theanglebetweenthechordlineofthewing,andtherelativewind.

Notbeconfusedwithanairplane’sattitudeinrelationtotheearth’ssurface,orwith“angleofincidence”（安裝角）Angleofattack

TheanglebetFourforcesLiftDragWeightThrustFourforcesLiftDragWeightThrusWeightWeightistheforceofgravitywhichactsverticallydownwardsthroughthecentreofgravity(CG)towardsthecentreoftheearth.WWeightWeightistheforceofgLiftfromanAerofoil垂直的LiftfromanAerofoil垂直的TheLiftFormulaLIFT=CL.?V2.S

CListheCoefficientofLift

?V2

istheIndicatedAirspeed

S

istheWingArea

TheLiftFormulaLIFT=CL.?Co-efficientofLiftAComponentofTotalLift.Dependson:AngleofAttackWingDesignIfyouincreaseCL,youincreaseLiftCo-efficientofLiftAComponenCoefficientofLift-CLCoefficientofLift-CLSimplifiedLiftFormulaLiftAirspeedAngleofAttackSimplifiedLiftFormulaLiftAirAngleofattackandindicatedairspeeddeterminethetotallift.Tomaintainthesametotallift,whenanindicatedairspeedisdecreased,theangleofattackmustbeincreasedtocompensate補(bǔ)償forthelossoflift.Iftheangleofattackdoesnotchange,theairspeeddoubles,theliftwillincreasebyfourtime.AngleofattackandindicatedThrustThrustistheforward-actingforcewhichopposesdragandpropelstheairplane.Inmostgeneralaviationaircraft,thisforceisprovidedwhentheengineturnsthepropellerTThrustThrustistheforward-acDragDragisacomponentofthetotalaerodynamicreactionwhichactsinthesamedirectionastherelativeairflow.Itisaforceintheoppositedirectiontoflight.DDragcanbeclassifiedinto2broadtypes:Parasite(寄生蟲(chóng)）InducedDragDragisacomponentoftheParasiteDragParasiteDragiscausedbyanyaircraftsurfacewhichdeflectsorinterfereswiththesmoothairflowaroundtheairplane.ThreeTypesFormDragInterferenceDragSkinFrictionParasiteDragParasiteDragisFormDrag壓差阻力 Resultsfromtheturbulentwakecausedbytheseparationofairflowfromthesurfaceofastructure.TheamountofdragisrelatedtotheSIZE

andSHAPE

oftheobject.FormDrag壓差阻力FormDragFormDragcanbedecreasedby‘streamlining’FormDragFormDragcanbedecrInterferenceDrag干擾阻力InterferenceDragoccurswhenvariedcurrentsofairoveranairplanemeetandinteract.AnexampleofInterferenceDragisthemixingofairoverlandinggearstruts（支柱）.Fairings（整流罩）andblendingofshapeshelpreduceinterferencedrag.InterferenceDrag干擾阻力InterfereSkinFrictionSkinFrictioniscausedbytheroughnessofalltheairplanessurfaces.

Alayerofairclings(sticks)tothesesurfaces,creatingsmalleddieswhichcontributetodrag.Smoothingofaircraftcomponents,andlaminarsurfaceshelptoreduceskinfrictiondrag.SkinFrictionSkinFrictionisAsairspeedisincreased,parasitedragincreasesatthesquareofthespeedParasiteDragAsairspeedisincreased,paraInducedDragWheneverweproduceLift,wewillproduceInducedDrag.InducedDragWheneverweproducInducedDragBecauseofthepressuredifferentialbetweentheupperandlowersurfacesofawing,thereisatendencyfortheairto‘leak’aroundthewingtip翼尖(airwantstomovefromareasofhighpressuretoareasoflowerpressure).Astheairplaneistravellingforward,thispressuredifferentialcreates‘wing-tipvortices渦流’whichcomedownbehindthewing.InducedDragBecauseofthepreInducedDrag

LL’DInducedDragLL’DAsairspeedisincreasedtheamountofInducedDragisdecreasedInducedDragAsairspeedisincreasedtheaTotalDragCurveAthigherairspeeds,totaldragincreasesbecauseofincreasingparasitedrag.Atlowerairspeeds,induceddragincreaseswhichincreasesthetotaldragTotalDragCurveAthigherairsL/DRATIO升阻比是相同迎角下，升力系數(shù)與阻力系數(shù)之比，用K表示。升阻比的大小主要隨迎角變化而變化。

升阻比越大，飛機(jī)的空氣動(dòng)力性能越好。L/DRATIO升阻比是相同迎角下，升力系數(shù)與阻力系數(shù)之比Performance4012.Whichistrueregardingtheforcesactingonanaircraftinasteady-statedescent?A.ThesumofallupwardforcesislessthanthesumofalldownwardforcesB.ThesumofallrewardforcesisgreaterthanthesumofallforcesC.Thesumofallforwardforcesisequaltothesumofallrearwardforces4013.WhatperformanceischaracteristicofflightatmaximumL/Dinapropeller-drivenairplane?A.MaximumrangeanddistanceglideB.BestangleofclimbC.MaximumendurancePerformance4012.WhichistruePerformance4014.WhatistheeffectontotaldragofanaircraftiftheairspeeddecreasesinlevelflightbelowthatspeedformaximumL/D?A.DragincreasesbecauseofincreasedinduceddragB.DragincreasesbecauseofincreasedparasitedragC.Dragdecreasesbecauseoflowerinduceddrag4015.Whatistherelationshipbetweeninducedandparasitedragwhenthegrossweightisincreased?A.parasitedragincreasesmorethaninduceddragB.induceddragincreasesmorethanparasitedragC.bothparasiteandinduceddragareequallyincreasedPerformance4014.WhatistheePerformance4016.Whattrueairspeedandangleofattackshouldbeusedtogeneratethesameamountofliftasaltitudeisincreased?A.ThesametrueairspeedandangleofattackB.AhighertrueairspeedforanygivenangleofattackC.Alowertrueairspeedandhigherangleofattack4017.Whatwillbetheratiobetweenairspeedandliftiftheangleofattackandotherfactorsremainconstantandairspeedisdoubled?LiftwillbeA.ThesameB.TwotimesgreaterC.FourtimesgreaterPerformance4016.WhattrueairPerformanceSTALLThereisaspeedbelowwhichwecannotfly.PerformanceSTALLThereisaspeThreeAxesofFlight

CanYouDescribeAllThree?

VerticalLongitudinalLateralThreeAxesofFlight

CanYouDAllthreeaxesintersectattheCenterOfGravityAnaircraftwillalwaysmaneuveraboutitsCGAllthreeaxesintersectatthThreeAxesofFlight:LateralAxisLateralAxisPitchDownChordLineIncreasedLiftElevatorRelativeWindIncreasedAngleofAttackHORIZONTALSTABILIZERThreeAxesofFlight:Lateral空氣動(dòng)力學(xué)講義課件ThreeAxesofFlight:LongitudinalAxis

ChordLineIncreasedLiftAileronRelativeWindIncreasedAngleofAttackChordLineRightWingLeftWingRollLeftLongitudinalAxisDecreasedLiftDecreasedAngleofAttackRelativeWindAileronThreeAxesofFlight:Longitud空氣動(dòng)力學(xué)講義課件ThreeAxesofFlight:VerticalAxisVerticalAxisYawLeftChordLineIncreasedLiftRudderRelativeWindIncreasedAngleofAttackTOPVIEWOFVERTICALSTABILIZERThreeAxesofFlight:Vertical空氣動(dòng)力學(xué)講義課件SectionBSTABILITYSectionBSTABILITYStabilityStaticStability靜穩(wěn)定性DynamicStability動(dòng)穩(wěn)定性LongitudinalStability縱向穩(wěn)定性LateralStability橫向穩(wěn)定性DirectionalStability方向穩(wěn)定性StabilityStaticStability靜穩(wěn)定性StaticStabilityStaticStabilityreferstotheaircraft'sinitialresponsetoadisturbanceMostairplaneshavepositivestaticstabilityinpitchandyaw,andareclosetoneutrallystableinroll.StaticStabilityStaticStabiliDynamicStabilityDynamicStabilitycanonlyoccuriftheobjectfirstlydisplaysstaticStabilityItisthesubsequentmotionofthedisturbedbody,oncethestaticstabilityreactionhastakenplaceDynamicStabilityDynamicStabiLongitudinal(pitch)StabilityBalanceCentreofGravitypositionCofGtoofarForwardCofGtoofarAftHorizontalStabilizerPowerEffectsLongitudinal(pitch)StabilityLongitudinalStabilityLongitudinalStabilityreferstoanaircraftsstabilityaboutitsLateralAxisCofGCentreofPressureLongitudinalStabilityLongitudHorizontalStabilizerTheHorizontalStabilizerprovidesabalancingforceinmostflightconditionsBalancingForceHorizontalStabilizerTheHorizHorizontalStabilizerTheeffectivenessofthehorizontalstabilizerdependson;SizeDistancefromtheCofGAirspeedHorizontalStabilizerTheeffecLateralStabilityLateralStabilityreferstostabilityaboutanaircraft’sLongitudinalAxisIfanaircraftmeetsadisturbanceandisrolled,itwillslipinthedirectionoftheroll.ItisthisslipwhichprovidestheLateralStabilityLateralStabilityLateralStabiLateralStability(Jep.3-31)DihedralSweepbackLateralStability(Jep.3-31)DDihedralDihedralDihedralSlipDihedralSlipSweepback(Jep.3-34)SweepbackisfoundmostlyonlargeaircraftandthemainpurposeistoimproveLateralStability.Refertofig.3-41Sweepback(Jep.3-34)SweepbackDirectionalStabilityDirectionalStabilityisstabilityabouttheverticalaxis.Theverticaltailactsmuchlikeaweathervane,pivotingaroundtheaircraftCG.DirectionalStabilityDirectionPerformance4006.DescribedynamiclongitudinalstabilityA.MotionaboutthelongitudinalB.MotionaboutthelateralaxisC.Motionabouttheverticalaxis4007.IdentifythetypestabilityiftheaircraftattituderemainsinnewpositionafterthecontrolshavebeenneutralizedA.NegativelongitudinalstaticstabilityB.NeutrallongitudinaldynamicstabilityC.Neutrallongitudinalstaticstability4008.IndentifythetypestabilityiftheaircraftattitudetendstomovefartherfromitsoriginalpositionafterthecontrolshavebeenneutralizedA.NegativestaticstabilityB.PositivestaticstabilityC.NegativedynamicstabilityPerformance4006.DescribedynaPerformance4009.IndentifythetypestabilityiftheaircraftattitudetendstoreturntoitsoriginalafterthecontrolshavebeenneutralizedA.PositivedynamicstabilityB.PositivestaticstabilityC.Neutraldynamicstability4010.Whatisacharacteristicoflongitudinalinstability?A.PitchoscillationsbecomingprogressivelygreaterB.BankoscillationsbecomingprogressivelygreaterC.Aircraftconstantlytriestopitchdown4011.Iftheaircraftattituderemainsinanewpositionaftertheelevatorcontrolispressedforwardandreleased,theairplanedisplaysA.neutrallongitudinalstaticstabilityB.positivelongitudinalstaticstabilityC.neutrallongitudinaldynamicstabilityPerformance4009.IndentifytheCenterofGravityPosition(Jep.3-27)TheCGisbydefinationthepointaboutwhichallgravitationalmomentsadduptozero.CenterofGravityPosition(JepCofGtoofarForwardLowNoseAttitudeAbilitytoreducespeedisaffectedApproachwithasmuchpowerinuseaspossibleHardertomaneuverCofGtoofarForwardLowNoseCofGtoofarAftHighnoseattitudeForwardvisibilitypoorStallrecoveryverydifficultStallspeeddecreasedCofGtoofarAftHighnoseatPerformanceGroundEffectWhenanaircraftfliedingroundeffect,thegroundinterfereswiththetipvotex.Thisreducestheinduceddragandincreaseslift.Asanairplanefliesoutofgroundeffectontake-off,theincreasedinduceddragwillrequireahigherangleofattack.飛機(jī)脫離地面效應(yīng)區(qū)飛機(jī)處于地面效應(yīng)區(qū)PerformanceGroundEffectWhenaPerformanceSectionCFlightControlsFlightcontrolsareusuallymovedbyhydraulicactuatorsanddividedintoprimaryflightcontrolsandsecondaryflightcontrols.PerformanceSectionCFlightCoPerformanceRollControlItisprovidedbytheaileronsandflightspoilers.PerformanceRollControlItispPerformanceAileronManyaircrafthavetwosetsofailerons---inboardandoutboard.Inboardaileronsoperateinallflightregimes---bothlowspeedandhighspeedflight.Outboardaileronsworkonlywhenthewingflapsareextendedandareautomaticallylockedoutwhenflapsareretracted---preventexcessiverollandwingbending(twist)athighspeeds.PerformanceAileronManyaircrafPerformanceSpoilersIfraisedononlyonewing,theyaidrollcontrolbycausingtheliftofthatwingdrop.Ifthespoilersraisesymmetrically(對(duì)稱(chēng)地)inflight,theaircraftcaneitherbeslowedinlevelflightorcandescendrapidlywithoutanincreaseinairspeed.Oftenaircrafthavebothflightandgroundspoilers.whenspoilersdeployontheground,theydecrease\reduceliftandmakethebrakemoreeffective.PerformanceSpoilersIfraisedoPerformanceVortexGeneratorsItisdesignedtopreventflowseparationandtheattendantpressuredrag.Thepurposeofwing-mountedvortexgeneratorsreducesthedragcausedbysupersonicflowoverportionsofthewing.PerformanceVortexGeneratorsItPerformanceTabsAnotherwayofchangingtheamountofforcethepilotmustapplytothecontrolcolumnisthroughservoandanti-servotabs.Servotabsareonthetrailingedgeofthecontrolsurfaceandlinkedtomoveoppositethedirectionofthesurface.(Thepurposeistoreducethecontrolforce)Anti-servotabsmoveinthesamedirectionastheprimarycontrolsurface.Thishelpto

preventthecontrolsurfacefrommovingtoafulldeflection.PerformanceTabsAnotherwayofPerformance(elevator)Trimtabsisonemethodofrelievingaerodynamicloadbymeansofasecondarycontrolsurfaceattachedtotheendoftheprimarysurface.

(Modifythedownwardtailloadforvariousairspeedsinflight，eliminatingflight-controlpressures.)Theymustbemovedintheoppositedirectiontothatoftheprimarycontrolsurface.Thecontroltabisusedonlyduringmanualreversion,thatis,withthelossofhydraulicpressure.Theyworkthesameasaservotabbutonlyinmanualmode.Performance(elevator)TrimtabsPerformanceQ1.Howcananairplaneproducethesameliftingroundeffectsaswhenoutofgroundeffect?A.ThesameangleofattackB.AlowerangelofattackC.AhigherangleofattackQ2.Whatisapurposeofflightspoilers?A.IncreasethecamberofthewingB.ReduceliftwithoutincreasingairspeedC.DirectairflowoverthetopofthewingathighanglesofattackQ3.Whichisapurposeofgroundspoilers? A．Reducethewingsliftuponlanding? B．Aidinrollinganairplaneintoturn.? C．Increasetherateofdescentwithoutgainingairspeed.PerformanceQ1.HowcananairpPerformanceQ4.Whatisthepurposeofacontroltab?A．Movetheflightcontrolsintheeventofmanualreversion.B．Reducecontrolforcesbydeflectingintheproperdirectiontomoveaprimaryflightcontrol.C．Preventacontrolsurfacefrommovingtoafull-deflectionpositionduetoaerodynamicforces.Q5.Whichisapurposeofwing-mountedvortexgenerators?A．ReducethedragcausedbysupersonicflowoverportionsofthewingB．IncreasetheonsetofdragdivergenceandaidinaileroneffectivenessathighspeedC．BreaktheairflowoverthewingsothestallwillprogressfromtherootouttothetipofthewingPerformanceQ4.WhatisthepurpPerformanceQ6.Whatisthepurposeofaservotab？A．Movetheflightcontrolsintheeventofmanualreversion.B．Reducecontrolforcesbydeflectingintheproperdirectiontomoveaprimaryflightcontrol.C．Preventacontrolsurfacefrommovingtoafull-deflectionpositionduetoaerodynamicforces.Q7.Whatisthepurposeofanelevatortrimtab?A．Providehorizontalbalanceasairspeedisincreasedtoallowhands-offflight.B．Adjustthespeedtailloadfordifferentairspeedsinflightallowingneutralcontrolforces.C．Modifythedownwardtailloadforvariousairspeedsinflighteliminatingflight-controlpressures.PerformanceQ6.WhatisthepurpPerformanceQ8.Whichdirectionfromtheprimarycontrolsurfacedoesaservotabmove？A.SamedirectionB.OppositedirectionC.RemainsfixedforallpositionsQ9.Whichdirectionfromtheprimarycontrolsurfacedoesananti-servotabmove?A.SamedirectionB.OppositedirectionC.RemainsfixedforallpositionsQ10.Whichdirectionfromtheprimarycontrolsurfacedoesanelevatoradjustabletrimtabmovewhenthecontrolsurfaceismoved?A.SamedirectionB.OppositedirectionC.RemainsfixedforallpositionsPerformanceQ8.WhichdirectionPerformanceQ11.Whenareoutboardaileronsnormallyused?A.Low-speedflightonlyB.High-speedflightonlyC.Low-speedandhigh-speedflightQ12.Whenareinboardaileronsnormallyused?A.Low-speedflightonlyB.High-speedflightonlyC.Low-speedandhigh-speedflightPerformanceQ11.WhenareoutboPerformanceSectionDHigh-liftDevicesLeadingedgedevicesPerformanceSectionDHigh-liftPerformance分裂襟翼（TheSplitFlap）簡(jiǎn)單襟翼

（ThePlainFlap）Performance分裂襟翼（TheSplitFlapPerformance開(kāi)縫襟翼

（TheSlottedFlap）后退襟翼（TheFowlerFlap）Performance開(kāi)縫襟翼（TheSlottedFPerformanceQ1.Whichisapurposeoftheleading-edgeflaps?A.IncreasethecamberofthewingB.ReduceliftwithoutincreasingairspeedC.DirectairspeedoverthetopofthewingathighanglesofattackQ2.TheKruegerflapextendsfromtheleadingedgeofthewing,increasingitsA.angleofattackB.camberC.energyPerformanceQ1.WhichisapurpPerformanceQ3.Whichisapurposeofleading-edgeslatsonhigh-performancewings?A.DirectairfromthelowpressureareaundertheleadingedgealongthetopofthewingB.ImproveaileroncontrolduringlowanglesofattackC.IncreaseliftatrelativeslowspeedsQ4.Whateffectdoestheleadingslotinthewinghaveonperformance?A.DecreaseprofiledragB.ChangesthestallingangleofattacktoahigherangleC.DeceleratestheuppersurfaceboundarylayerairPerformanceQ3.WhichisapurpPerformanceQ5.Whatistheprimaryfunctionoftheleadingedgeflapsinlandingconfigurationduringtheflarebeforetouchdown?A.preventflowseparationB.decreaserateofsinkC.increaseprofiledragPerformanceQ5.WhatistheprimPerformanceSectionETurnWhenanairplaneisinalevelturnitisinastateofacceleration.Whenthepilotrollstheairplaneintoaturn,hemustincreasethetotalliftofthewingsothattheverticalcomponentisequaltotheairplane'sweightbyincreasingtheangleofattack.PerformanceSectionETurnWPerformanceLoadFactorLoadfactoristheratiooftheweightsupportedbythewingstotheactualweightoftheaircraft.Onthegroundorinunacceleratedflighttheloadfactorisone.Conditionswhichcanincreasetheloadfactorareverticalgustsandlevelturns.Inalevelturn,theloadfactorisdependentonlyontheangleofbank.PerformanceLoadFactorLoadfacPerformance結(jié)論：Thetimetoturnisproportionaltovelocityandinverselyproportionaltoangleofbank.盤(pán)旋時(shí)間與速度成正比，與坡度正切成反比。結(jié)論：Ittakeslongertimetoturnatahighspeed,butlesstimetoturnatalargeangleofbank.保持坡度，增大速度就減小了轉(zhuǎn)彎角速度。

Rateofturnisthenumberofdegreespersecondatwhichtheaircraftturns.Performance結(jié)論：ThetimetoturnPerformance結(jié)論：Radiusofturndependsonvelocitysquaredandisinverselyproportionaltothetangentoftheangleofbank.盤(pán)旋半徑與速度平飛成正比，與坡度正切成反比。Performance結(jié)論：RadiusofturndPerformanceQ1.Howcanthepilotincreasetherateofturnanddecreasetheradiusatthesametime?A.SteepenthebankandincreaseairspeedB.SteepenthebankanddecreaseairspeedC.ShallowthebankandincreaseairspeedQ2.Howcanturbulenceaircauseanincreaseinstallingspeedofanairfoil?A.AnabruptchangeinrelativewindB.AdecreaseinangleofattackC.SuddendecreaseinloadfactorQ3.Whatistherelationshipoftherateofturnwiththeradiusofturnwithaconstantangleofbankbutincreasingairspeed?A.RatewilldecreaseandradiuswillincreaseB.RatewilldecreaseandradiuswilldecreaseC.RateandradiuswillincreasePerformanceQ1.HowcanthepilPerformanceSectionFVMCP-factorThedowngoingbladewillbeatagreaterangleofattackandthereforewillproducemorethrust.PerformanceSectionFVMCP-factPerformanceCriticalEngineOneoftheenginehasitsthrustlineclosertotheaircraftcenterline.Thelossofthisenginewouldmoreadverselyaffecttheperformanceandhandlingoftheaircraft,thisistheCriticalEngine.Forunsuperchargedengine,VMCdecreaseasaltitudeisincreases.Stallshouldneverbepracticedwithoneengineinoperativebecauseofthepotentialforlossofcontrol.Theblueradiallineontheairspeedindicatorofalight,twinengineairplanerepresentmaximumsingle-enginerateofclimb.PerformanceCriticalEngineOnePerformanceSectionGHighSpeedFlightMachnumber:istheratioofTASandthespeedofsound.Withrespecttomachcruisecontrol,flightspeedcanbedividedintothreeregimes:--subsonic--transonic--supersonicPerformanceSectionGHighSpeePerformanceCriticalmachnumber:Thespeedatwhichairflowoverthewingfirstreachesbutdoesnotexceed,thespeedofsound.MCRITtheremaybesonicbutnosupersonicflow.TwowaysofincreasingMCRIT:givethewingalowcamberandincreasewingsweep.PerformanceCriticalmachnumbePerformanceMachtuckSweepwingaircraftDuchrollPerformanceMachtuckPerformanceQ1.WhichofthefollowingisnotthewayofincreasingMCRITinjettransportdesigns?A.GivethewingalowercamberB.IncreasewingsweepC.AddslatsQ2.WithinwhatMachrangedoestransonicflightregimesusuallyoccur?A.0.50to0.75MachB.0.75to1.20MachC.1.20to2.50MachQ3.AtwhatMachrangedoesthesubsonicflightrangenormallyoccur?A.Below.75MachB.From.75to1.20MachC.From1.20to2.50MachPerformanceQ1.WhichofthefoPerformanceQ4.WhatisthefreestreamMachnumberwhichproducefirstoflocalsonicflow?A.supersonicMachnumberB.transonicMachnumberC.criticalMachnumberQ5.Whatisthehighestspeedpossiblewithoutsupersonicflowoverthewing?A.criticalMachnumberB.initialbuffetspeedC.transonicindexPerformanceQ4.WhatisthefrePerformanceQ6.Whatismovementofthecenterpressurewhenthewingtipsofasweptwingairplaneareshock-stalledfirst?A.inwardandaftB.inwardandforwardC.outwardandforwardQ7.Whatisonedisadvantageofasweptwingdesign?A.ThewingrootstallspriortothewingtipsectionB.ThewingtipsectionstallspriortothewingrootC.SeverepitchdownmomentwhenthecenterofpressureshiftsforwardPerformanceQ6.WhatismovemenPerformanceQ8.Whatistheconditionknownaswhengustscauseasweptwing-typeairplanetorollinonedirectionwhileyawingintheother?A.PorpoiseB.WingoverC.DutchrollQ9.Whatistheprincipaladvantageofasweepbackdesignwingoverastraightwingdesign?A.ThecriticalMachnumberwillincreasesignificantlyB.SweepbackwillincreasechangesinthemagnitudeofforcecoefficientsduetocompressibilityC.SweepbackwillacceleratetheonsetofcompressibilityeffectPerformanceQ8.WhatistheconPerformanceQ10.Whatistheresultofashock-inducedseparationofairflowoccurringsymmetricallynearthewingrootofasweptwingaircraft?A.Ahigh-speedstallandsuddenpitchupB.Aseveremomentor“tuckunder”C.SevereporpoisingPerformanceQ10.WhatisthereSpiralInstabilityCausesRemediesSpiralInstabilitySpiralInstability

Causes&RemedyIfanaeroplanehasstrongDirectionalStabilityrelativetoitsLateralStability,itmaydisplaySpiralInstability.Whenabumporagustproducesasideslipinanaeroplanewithspiralinstability,itspowerfuldirectionalstabilitytendstoyawtheaircraftbackintoalignmentwiththerelativewind.Astheouterwingtravelsfasteritgeneratesmorelift,tendingtorolltheaeroplaneinthedirectionofyaw.Thisrollingforceovercomesthecomparativelyweakdihedraleffectallowingtherolltoprogress.Astheverticalcomponentofliftdecreases,therelativewindhasanupwardcomponent,astheairplaneswingsintoalignment,thenosebeginstodrop.Thisresultsinagradualtighteningofthespiraldive.Spiralinstabilityisnormallyeasilyovercomebythepilot.Remedy.Poweroff.Levelwings,easeoutofdive.ReintroducePower.SpiralInstability

Causes&RDutchRollCausesRemediesDutchRollDutchRollCauses&RemediesDutchRoll,oroscillatorylateralinstability,isusuallyaconsequenceoftwomuchdihedraleffect,fromthecombinationofactualdihedral,sweepback,ahighwingconfiguration,relativelysmallverticaltail,andorotherfactors.Indutchroll,theaeroplanemakesacontinuousbackandforthrollingandyawingmotionwiththerolloutofphasewiththeyaw.Dutchrollisusuallydynamicallystable,thatis,theoscillationstendtodecreaseinamplitude.Iftheoscillationisweaklydampeneditmaycontinueforalongtime.Dutchrollcanbeaggravatedbythepilotsattempttocorrectit.RemedyItisbetterfortheaircrafttobestrongerinthedirectionstabilityandacceptspiralinstabilitythantohaveanaircraftthatDutchrolls.Acertaindegreeofspiralinstabilityisconsideracceptable,sodesignersusuallytrytominimis