1、PRINCIPLESOFFLIGHTObjectivesAirfoildesigncharacteristicsFourforcesinflightWingtipvorticesandprecautionstobetakenLoadfactorsinairplanedesignAirplanestabilityandcontrollabilityAirfoildesigncharacteristicsWingisalowdragdeviceshapedtogetapositivepressureliftingactionfrombelowandanegativepressureliftinga
2、ctionfromaboveDragonahandorcarAirfoildesigncharacteristicsAirmoleculesarestationaryandweremovingthroughitTwoneighbormoleculeswanttoendupnexttoeachotheratthetrailingedgeofthewingTheongoingoverthetophastomovefasterBernoullisprincipleWhenafluidsvelocityincreases,pressuredecreasesWingisbasicallyhalfofav
3、enturiLowpressureabovethewing,highpressurebelowAirfoildesigncharacteristicsChordlinerunsfromtheleadingedgetothetrailingedgeAngleofattackCamberisthecurvatureofthewingGenerally,theupperhalfismorecurvedthanthelowerCamberlineiswherealldistancesoneithersideofthelineareequalFourforcesinflightThrustLiftDra
4、gWeightThesumofallupwardforcesequalsthesumofalldownwardforcesThesumofallforwardforcesequalsthesumofallrearwardforcesThrustForwardforceproducedbythepowerplantandpropellerThrustmustbeexertedinorderfortheairplanetomoveThrustTomaintainaconstantairspeed,thrustanddragmustbeequalIfinlevelflight,theenginepo
5、werisreduced,thrustdecreasesandtheairplaneslowsdownIfthrustislessthandragtheairplanewilldecelerateuntilitsairspeedisinsufficienttosupportitThrustIfinlevelflight,theenginepowerisincreasedthenthrustincreasesandairspeedincreasesAslongasthrustisgreaterthandrag,theairplanewillaccelerateThrustandAOAStraig
6、htandlevelflightcanbesustainedatspeedsfromveryfasttoveryslowMustcoordinateangleofattackandthrustinordertoholdlevelWhenairspeedislow,whatmustwedowithourangleofattacktomaintainlevelflight?IncreaseangleofattackWhy?ThrustandAOAWhenairspeedislow,AOAmustberelativelyhightoincreaseliftIfthrustdecreasesandai
7、rspeeddecreases,liftbecomeslessthanweightandtheairplanedescendsDuringstraightandlevelflight,ifthrustisincreased,whatmustwedotoourAOA?DecreaseitIfweincreasethrustwithoutdecreasingAOA,theairplanewillclimbMustdecreaseAOAtokeepliftequaltoweightWeightThecombinedloadoftheairplaneitself,thecrew,fuel,andcar
8、goorbaggageWeightpullstheaircraftdownwardbecauseofgravityOpposesliftandactsverticallydownwardthroughtheairplanescenterofgravityWeightIfinstabilizedlevelflight,whenliftisequaltoweight,theairplanewontgainorlosealtitudeIfliftbecomeslessthanweight,theairplanelosesaltitudeIfliftisgreaterthanweight,theair
9、planegainsaltitudeLiftProducedbytheeffectoftheairactingonthewingOpposesthedownwardforceofweightL=1/2V2CLSWhichofthesevariablescanwechange?AngleofattackAirspeedLiftAnytimeyoumovethecontrolcolumnforeoraft,theangleofattackchangesAsangleofattackincreases,liftincreaseswithallotherfactorsbeingequalProport
10、ionaltothesquareoftheairplanesspeedAnairplanetravelingat200knotshas4timestheliftasthesameairplanegoing100knotsiftheangleofattackandotherfactorsremainconstantLiftPlanecantstayataconstantaltitudeandkeepthesameangleofattackifspeedisincreasedLiftwouldincreaseandtheplanewouldclimbTomaintainthebalanceofli
11、ftandweightifspeedisincreased,whatmustwedo?DecreaseangleofattackForeveryangleofattack,theresacorrespondingindicatedairspeedrequiredtomaintainunacceleratedflightDragArearwardforcecausedbydisruptionofairflowbythewing,fuselage,andotherprotrudingobjectsOpposesthrustWhatkindsofdragdowehave?InducedParasit
12、eTotaldrag=induceddrag+parasitedragParasitedragFormdragBasedonthesizeandshapeoftheplane,howwellstreamlinedandamountoffrontalareaParasitedragSkinfrictiondragCausedbyfrictionbetweenafluidandthebodyofthesurfacemovingthroughitParasitedragInterferencedragWhenairflowarounddifferentpartsoftheplaneinteractw
13、itheachotherInduceddragResultofcreatingliftWingtipvorticeswashoverthewingeffectivelybendstheliftvectorbackwardsInduceddragDecreaseswithairspeedThelowertheairspeed,thehigherAOAneededtoproduceliftHighAOAmeanslotsofliftBigpressuredifferentialBigwingtipvorticesLotsofdragWingtipvorticesSpanwiseflowHighpr
14、essureairhitsthebottomofthewingandmovesouttothetipLowerpressureattherootduetohighAOAAirgoesfromhigherlowpressuretolowerlowpressureHighpressuretriestogotolowwhichresultsinwingtipvorticesandthepathofleastresistanceisthewingtipInordertocreatelowerpressureandliftontopofthewing,itneedstobeatahigherangleo
15、fattackCausesagreaterpressuredifferentialandstrongerwingtipvorticesPlanehastheworstwingtipvorticeswhenitsheavy,clean,andslowWhendoesthisoccur?Whyheavy,clean,andslow?AvoidingwingtipvorticesTakeoffbeforetheplaneinfrontofyouandclimboutonasteeperpathLandaftertheplaneinfrontofyouandcomeinonahigherglidepa
16、thVorticessinksoavoidthemAlightquarteringtailwindwillkeepvorticesonarunwaysobecarefulifthisconditionexistsWhatelsecanwedotoreducewingtipvortices?WingletsInterruptwingtipvorticesCanincreasefuelefficiencyathighspeedsby16-26%InduceddragGroundeffectReduceddownwashmeanslessinduceddragCanflyatalowerAOAbec
17、auseverticalcomponentofliftmovesforwardLiftincreasesGroundeffectWhentheairplaneisneartheground,wegetwhatiscalled“groundeffect”Grounddisruptswingtipvortices whichreducesdownwashGroundeffectFeelslikeacushionofairYoullnoticegroundeffectwhentheairplaneiswithinonewingspanofthegroundLoadfactorsinairplaned
18、esignLoadfactoristheratioofthetotalloadactionontheairplanetothegrossweightoftheairplaneAloadfactorof3meansthetotalloadontheplanesstructureisthreetimesitsgrossweightManeuveringspeedMaximumspeedwherefull,abruptcontrolmovementinthepitchaxiswillresultinanaerodynamicstalloftheaircraftpriortoexceedingthed
19、esignloadlimitVA2=VAW2/W1VA2=Maneuveringspeed(atthisweight)At2550lbs,VAis105knotsWhatisVAat2300lbs?99knotsLoadfactorincreaseswithbankangleAsweturn,liftgetssplitinto2components:verticalandhorizontalInordertomaintainaltitude,wemustkeeptheverticalcomponentofliftthesameasitwasinstraightandlevelflightHow
20、dowedothis?EqualandoppositereactionLoadfactorincreaseswithbankangleAirplanestabilityandcontrollabilityControllabilityThecapabilityofanairplanetorespondtothepilotsinputStabilityTheinherentqualityofanairplanetocorrectforconditionsthatdisturbitsequilibriumThetendencytoreturntoequilibrium2kindsofstabili
21、tyStaticDynamicStaticstabilityTheinitialtendencytheairplanedisplaysafteritsequilibriumisdisturbedStaticstabilityPositivestaticstabilityThetendencytoreturntotheoriginalstateofequilibriumNeutralstaticstabilityThetendencytocontinueinthenewconditionafterbeingdisturbedNegativestaticstabilityThetendencyto
22、continueawayfromequilibriumafterbeingdisturbedDynamicstabilityTheoveralltendencyofanairplaneafterbeingtakenoutofequilibriumAssumeallexampleshavepositivestaticstabilityPlanewillattempttoreturntoequilibriumDynamicstabilityPositivedynamicstabilitywillcausetheplanetopitchupthendowninanattempttoreturntoequilibriumwithsteadilydecreasingoscillationsNeutraldynamicstabilitywillcausetheplanetopitchupanddowntoattempttoreturntoequilibriumbutoscillationswillneverchangeNegativedynamicstabilityiswhenthesizeoftheoscillationsincreasesandtheplanemovesfartherfromequilibriumQuestions?
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