无人机专业英语 第二版 课件 4.1 Flight Dynamics of UAV-fixed-wing

EnglishforUnmannedaerialvehicle无人机专业英语Project4:FlightDynamicsofUAV-------Fixed-wingdroneAerodynamicforcesControlsurfacesAileronsElevatorsRudderFlapsswivel [ˈswɪvl]vt.（使）旋转;在枢轴上转动perpendicular[ˌpɜ:pənˈdɪkjələ(r)]adj.垂直的，成直角的sideslip['saɪdslɪp]n.侧滑profile [ˈprəʊfaɪl]n.侧面;外形，轮廓airfoil [ˈeəfɔɪl]n.翼面deflect [dɪˈflekt]vt.使弯曲;偏转camber [ˈkæmbə(r)]n.拱形versatile[ˈvɜ:sətaɪl]adj.多功能的;多用途的hinge[hɪndʒ]n.铰链NewWordsswash[swɒʃ]platen.倾斜盘gearbox [ˈgɪəbɒks]n.变速箱;齿轮箱;变速器collectivepitch[kəˈlektivpitʃ]n.总距rod[rɒd]n.杆，拉杆cyclicpitch[ˈsaɪklɪkpitʃ]n.周期桨距bearing [ˈbeərɪŋ]n.轴承NewWordsFlightdynamicsofUAVreferstothestudyoftheperformance,stability,andcontrolofunmannedaerialvehicles.Itisconcernedwithhowforcesactingonthevehicleinfluenceitsspeedandattitudewithrespecttotime.无人机飞行动力学研究的是无人机的性能、稳定性和控制。它关心的是作用在无人机上的力如何影响其速度和姿态。Part0----WhatisFlightDynamicsThethreecriticalflightdynamicsparametersoffixed-wingdronearetheanglesofrotationinthreedimensionsaboutthevehicle‘scenterofmass,knownaspitch,rollandyaw.固定翼无人机三个关键的飞行动力参数是以飞机重心为坐标原点的三维坐标系下的旋转角，即我们熟知的俯仰角、横滚角和偏航角。Themostcommonaeronauticalconventiondefinestherollasactingaboutthelongitudinalaxis,positivewiththestarboard(right)wingdown.Theyawisabouttheverticalbodyaxis,positivewiththenosetostarboard.Pitchisaboutanaxisperpendiculartothelongitudinalplaneofsymmetry,positivenoseup.最通常的航空惯例定义横滚轴为飞机的纵轴，向右滚转为正方向；偏航轴为飞机立轴，向右偏航为正；俯仰轴垂直于飞机纵向对称面，飞机抬头为正。Part1----Fixed-wingdroneAfixed-wingdroneincreasesordecreasestheliftgeneratedbythewingswhenitpitchesnoseupordownbyincreasingordecreasingtheangleofattack(AOA).Therollangleisalsoknownasbankangleonafixed-wingaircraft,whichusually"banks"tochangethehorizontaldirectionofflight.Anaircraftisusuallystreamlinedfromnosetotailtoreducedragmakingittypicallyadvantageoustokeepthesideslipanglenearzero.当飞机俯仰时，其攻角会增加或者减少，带来的是通过机翼产生的升力的增加或者减少。横滚角也叫倾斜角，一般是通过倾斜来改变飞行的水平方向。飞机从机头到机尾通常呈流线型，这样可以减少阻力，通常有利于保持侧滑角接近于零。Part1----Fixed-wingdroneEssentiallythereare4aerodynamicforcesthatactonanairplaneinflight;thesearelift,drag,thrustandweight.飞机在飞行中主要受到4个力：升力、阻力、推理和重力。Part2----AerodynamicforcesInsimpleterms,dragistheresistanceofairmoleculeshittingtheairplane(thebackwardforce),thrustisthepoweroftheairplane'sengine(theforwardforce),liftistheupwardforceandweightisthedownwardforce.So,forairplanestoflyandstayairborne,thethrustmustbegreaterthanthedragandtheliftmustbegreaterthantheweight.简单来说，阻力是空气分子撞击飞机产生的阻滞力；推力是飞机发动机的动力；升力是向上的力；重力是向下的力。因此，飞机要飞起来并维持飞行状态，推力必须大于阻力，并且升力必须大于重力。Acrosssectionofatypicalairplanewingshowthetopsurfacetobemorecurvedthanthebottomsurface.Thisshapedprofileiscalledan'airfoil'andtheshapeexistsbecauseit'slongbeenproven(sincethedawnofflight)thatanairfoilgeneratessignificantlymoreliftthanopposingdrag.典型飞机机翼的横截面是上表面比底部更弯曲。这种形状的翼型称作一种翼面，而且已经证明了这种形状的机翼产生的升力比飞行阻力要多得多。Part2----AerodynamicforcesDuringflight,airnaturallyflowsoverandbeneaththewingandisdeflectedupwardsoverthetopsurfaceanddownwardsbeneaththelowersurface.Anydifferenceindeflectioncausesadifferenceinairpressure('pressuregradient')andbecauseoftheairfoilshapethepressureofthedeflectedairislowerabovetheairfoilthanbelowit.Asaresult,thewingis'pushed'upwardsbythehigherpressurebeneath.在飞行中，空气自然地流过机翼上下表面，并且沿着上下表面弯曲。弯曲上的任何改变会引起空气压力的改变，并且由于翼面形状特性，翼面上表面空气压力比下表面低。结果是，机翼被下表面高压空气向上托起。Part2----AerodynamicforcesLocatedonthetrailingedge(rear)ofthewing,theaileronscontroltheairplane‘srollaboutitslongitudinalaxis.Eachaileronmovesatthesametimebutinoppositedirectionsi.e.whentheleftaileronmovesup,therightaileronmovesdownandviceversa.位于机翼的后缘，副翼控制飞机沿飞机纵轴滚转的动作。每一个同时动作，但是转动方向相反，例如，当左副翼朝上，则右副翼朝下，反之亦然。Part3----AileronsThismovementcausesaslightdecreaseinliftonthewingtipwiththeupwardmovingaileron,whiletheoppositewingtipexperiencesaslightincreaseinlift.Becauseofthesesubtlechangesinlift,theairplaneisforcedtorollintheappropriatedirectioni.e.whentheoperatormovesthecontrolsticktotheleftonthetransmitter,theleftaileronwillriseandtheairplanewillrollleftinresponsetothechangeinliftoneachwing.向上的副翼会引起翼梢上升力的轻微减少，与之相对的翼梢上的升力则略微增加。由于升力的轻微改变，飞机就能朝合适的方向进行滚转。当操控者操控遥控器上的控制杆向左，左副翼向上，飞机上机翼的升力将会改变，飞机将向左滚转。Part3----AileronsTheelevatorsarelocatedontherearhalfofthetailplane,orhorizontalstabiliser.Thejobofthetailplaneistogenerateadownwardforcetocounteractthenaturalnose-divingtendencyofplanes,whichhappensasaresultofthenaturalforcesthataregeneratedaboutaplane'sCentreofGravityandCentreofLift.升降舵位于尾翼（水平安定面）的后半部分。尾翼的作用是产生一个下洗力来对抗飞机自然地抬头趋势，这些自然力作用在飞机上的结果是形成了重心和压力中心。Part4----ElevatorsTheruddermakesuptherearportionoftheverticalstabiliser,orfin.Whentheoperatormovestheruddersticktotheleftonthetransmitter,theruddermovestotheleft,whiledepressingtheruddersticktotherightdeflectstheruddertotheright.方向舵位于垂直安定面的后部。当操控者在遥控器上向左打方向杆，方向舵朝左偏，而向右压方向杆，方向舵会朝右偏转。Part4----RudderEssentially,youcanthinkofafinasaverticalwing.Theairflowingoveritandtherudderactsinexactlythesamewayasitdoesflowingoverawingandaileron-excepttheforcesareverticalandnothorizontal.本质上，你可以把垂直尾翼看做是垂直的机翼。流过它的空气和方向舵作用的方式和副翼及机翼与空气作用的方式是一样的，只不过现在的空气动力是垂直的而不是水平的。Deflectingtheruddertotheleftincreasestheairpressureontheleftsideofthefinandrudder,andsothewholebackendoftheplaneispushedacrosstotheright,thusyawingthenosetotheleft.方向舵向左偏转使得垂直尾翼左侧空气压力增加，所以飞机的整个尾部被推向右侧，这样机头就向左偏转。Par