Introduction to Aeronautics: A Design Perspective Second Edition StevenA.Brandt U.S.AirForceAcademy ColoradoSprings,Colorado RandallJ.Stiles ColoradoCollege ColoradoSprings,Colorado JohnJ.Bertin U.S.AirForceAcademy ColoradoSprings,Colorado RayWhitford RoyalMilitaryCollegeofScience andtheCranfieldInstituteofTechnology UnitedKingdom EDUCATIONSERIES JosephA.Schetz SeriesEditor-in-Chief VirginiaPolytechnicInstituteandStateUniversity Blacksburg,Virginia Publishedby AmericanInstituteofAeronauticsandAstronautics,Inc. 1801AlexanderBellDrive,Reston,VA20191-4344 AmericanInstituteofAeronauticsandAstronautics,Inc.,Reston,Virginia 1 2 3 4 5 LibraryofCongressCataloging-in-PublicationData Introductiontoaeronautics:adesignperspective/StevenA.Brandt...[etal.].–2nded. p. cm. – (Educationseries) Includesbibliographicalreferencesandindex. ISBN1-56347-701-7(alk.paper) 1.Airplanes–Designandconstruction. 2.Aeronautics. I.Brandt,StevenA.,1953- II.Title. III.Series:AIAAeducationseries. TL671.2.I64 2004 629.134(cid:1)1–dc22 2004005844 Copyright (cid:2)c 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rightsreserved.ThisworkwascreatedintheperformanceofaCooperativeResearchand DevelopmentAgreementwiththeDepartmentoftheAirForce.TheGovernmentofthe UnitedStateshascertainrightstousethiswork.PrintedintheUnitedStatesofAmerica. Nopartofthispublicationmaybereproduced,distributed,ortransmitted,inanyformorby anymeans,orstoredinadatabaseorretrievalsystem,withoutthepriorwrittenpermission ofthepublisher. Dataandinformationappearinginthisbookareforinformationalpurposesonly.AIAAis notresponsibleforanyinjuryordamageresultingfromuseorreliance,nordoesAIAA warrantthatuseorreliancewillbefreefromprivatelyownedrights. Nomenclature A =streamtubecross-sectionalarea =aspectratio,b2/S √ a =speedofsoundinair, λRT;linearacceleration,dV/dt b =wingspan C =finitewingorwholeaircraft(three-dimensional)dragcoefficient, D/qS D C =finitewingorwholeaircraft(three-dimensional)induced(duetolift) Di dragcoefficient C =wholeaircraft(three-dimensional)zero-liftdragcoefficient CD0 =equivalentskin-frictioncoefficient Cfe =finitewingorwholeaircraft(three-dimensional)liftcoefficient, L/qS L C =finitewingorwholeaircraftpitchingmomentcoefficient, M/qSc M c =wingorairfoilchord;specificfuelconsumptionusedfor reciprocatingengines c¯ =wingmeanaerodynamicchord c =airfoil(two-dimensional)dragcoefficient,d/qS d c =airfoil(two-dimensional)liftcoefficient,l/qS l c =airfoilpitchingmomentcoefficient,m/qSc m c =thrust-specificfuelconsumptionusedprimarilyforturbineengines t c =wingrootchord root c =wingtipchord tip D =wingoraircrafttotaldrag D =wingoraircraftinduceddragordragduetolift i D =wingoraircraftzero-liftdrag 0 d =airfoildrag E =wavedragefficiencyparameter,comparesactualtoidealwavedrag WD e =wingspanefficiencyfactor e =aircraftOswald’sefficiencyfactor O F =force f =airspeedcompressibilitycorrectionfactor h =altitude i =incidenceangle k,k =induceddragtermcoefficient,1/(πe ) 1 k =camberinfluencecoefficientininduceddragterm 2 L =finitewingorwholeaircraft(three-dimensional)lift l =airfoillift;overalllength,especiallyofthefuselageortheentireaircraft L =wholeaircraftrollingmoment M =wingorwholeaircraftpitchingmoment;Machnumber,V/a m =airfoilpitchingmoment N =normalforce,yawingmoment xix n =loadfactor P =staticpressure;power,TV P =poweravailable avail P =powerrequired req P =specificexcesspower,V(T −D)/W S q =dynamicpressure, 1ρV2 2 R =range;idealgaslawproportionalityconstant(P =ρRT) Re =Reynoldsnumber,ρVx/µ r =turnradius S =referenceplanformarea,usuallytheareaofthewingplanform S =canardplanformarea c S =horizontaltailplanformarea t s =distancealongapath T =thrust;temperature T =thrustavailable avail T =thrustrequired, D req t =time u =x-axiscomponentofvelocity V =velocity(magnitude) V =horizontaltailvolumeratio,Sl /Sc H t t V∞ =freestreamvelocityvector v = y-axiscomponentofvelocity w =z-axiscomponentofvelocity X =forcecomponentalongthex axis x =axisofcoordinatesystem,whichisfrequentlyalignedwiththeaircraft’s longitudinalaxis Y =forcecomponentalongthe y axis y =axisofcoordinatesystem,whichisfrequentlyalignedpositiveoutthe aircraft’srightwing Z =forcecomponentalongthezaxis z =axisofcoordinatesystem,whichisfrequentlyalignedpositivedown Greek α =angleofattack;thrustlapse,T/T SL αa =absoluteangleofattack,α−αL=0 αl=0 =airfoilzero-liftangleofattack αL=0 =wingzero-liftangleofattack β =sideslipangle;weightfraction,W/W TO (cid:6) =dihedralangle γ =flight-pathangle;ratioofspecificheats,1.4forair δ =controlsurfacedeflectionangle ε =downwashangle η =mechanicalefficiency (cid:11) =wingsweepangle λ =wingtaperratio µ =airviscosity;rollingfrictioncoefficient ρ =airdensity τ =shearstress φ =bankangle ω =angularvelocity,rateofrotation Math ∞ =largestpossiblenumber,usedasasubscripttodenoteagreat distanceaway (cid:5) =parallelto ⊥ =perpendicularto Preface ThistextbookandtheaccompanyingAeroDYNAMICsoftwarewerecreatedfor useasresourcesforteachingbasicdesignmethodsinconjunctionwithanintro- ductory course in aeronautics. That these two topics can coexist and reinforce eachotherinanintroductory-levelcoursehasbeenprovenby11yearsofexpe- rience with a course taught to the entire student body of the United States Air ForceAcademy(USAFA).Thebookwaswrittenforuseinteachingstudentsin theirfirstthreeyearsofpost-secondaryeducation,sounderstandingofthederiva- tionsandanalysismethodsisfacilitatedbypriorknowledgeofcalculus,classical physics,andengineeringmechanics.However,thematerialispresentedatalevel thatshouldbeunderstandablebyadvancedhighschoolstudents. The text begins with an entire chapter devoted to the motivation, methods, andhistoryofengineeringdesigningeneralandaircraftdesigninparticular.The designmethodsdescribedarecommonlyusedthroughoutindustry,butmostofthe examples given are specific to aircraft design. The reasoning behind placing the designchapterfirstisidenticaltothereasoningthatmotivatesteachingdesignin conjuction with basic aeronautical engineering concepts. Typically, engineering students spend their first two or three years learning basic math, science, and engineeringanalysismethodswithouthavingmuchopportunitytoseewhereall thisknowledgefitsintheworkthatengineersdo.Mostengineeringstudentshave chosen engineering as their major because they want to learn how to design. ExperienceatUSAFAhasshownthatlearningaboutdesignfirstmotivatesstudents tolearnthetheoryandanalysismethodsthattheyneedinordertodesign.Chapter1 does not describe any analysis methods in detail, but simply describes where analysisfitsinthedesignprocess.Subsequentchaptersintroduceanalysismethods anddescribewhytheyarenecessarytoolsoftheaircraftdesigner.Inotherwords, Chapter1establishesaframeworkoroutlineoftheaircraftdesignprocess,then Chapters2–8fillintheanalysismethodsneededineachdesignstep. Chapter 2 introduces analysis methods, which apply to static fluids, and de- scribeshowthesemethodscanbeusedintheconstructionofpressuremeasurement devicesandamodeloftheatmospherethatengineersuseasastandardreference. Chapter3teachesanalysisofmovingfluidsandshowshowthesemethodsareused topredicttheliftanddragexertedbyfluidsonbodiesmovingthroughthem.Chap- ter 4 expands the lift and drag prediction methods to include three-dimensional effects of finite wings and whole aircraft, and gives an example of how these methodsareusedtopredicttheaerodynamiccharacteristicsofamodernjetfighter aircraft. In Chapter 5 the reader learns how knowledge of an aircraft’s aerody- namics, engine thrust capabilities, and the laws of physics are used to predict its performance capabilities, or in other words the ability of the aircraft to meet a customer’s needs. Chapter 5 also discusses constraint analysis, a method used tochooseaircraftcharacteristicssuchthattheaircraftcanmeetcustomerneeds. xv Chapter 6 introduces stability and control concepts, and further describes static longitudinalstabilityanalysisasasimpleexampleofhowthestaticanddynamic stability of an aircraft in all six degrees of freedom is analyzed. Chapter 7 dis- cusses the fundamentals of structural design and analysis and presents a simple structuralsizingexample.Chapter8dealswithsizing,determininghowlargean aircraftneedstobeinordertoflyaparticularmissionwithaspecifiedpayload. Thisdiscussionincludesanintroductiontomissionanalysismethodsthatareused todeterminetheamountoffuelrequiredbyanaircrafttoflyamission.Chapter8 alsodiscussesasimplemethodforpredictingaircraftpurchaseandoperatingcosts. Oncestudentshavemasteredthebasicaeronauticalengineeringmethodspre- sented in Chapters 1–8, they are adequately equipped to tackle simple aircraft designproblems.Chapter9explainshowallofthemethodsareusedinthecon- ceptualaircraftdesignprocess.TheAeroDYNAMICsoftwarethatcomplements this text provides user-friendly aircraft geometry modeling and design analysis tools that greatly facilitate the working of such problems. Chapter 10 is offered tosupportstudents’firstdesignexperiencesbypresentingcasestudiesofthede- velopmentofthreewell-knownaircraftdesignsandadiscussionoffutureaircraft designpossibilities.Thesediscussionsfocusontheimpactoftechnology,politics, andtheeconomyoneachaircraft’sdesignprocess. The material in this textbook and the AeroDYNAMIC software is sufficient to support a university-level course of three to six semester hours. At USAFA, Chapters1–6areusedinathree-semester-hourcoursetaughttotheentirestudent body. The material in Chapters 7–10 is taught at USAFA in later courses taken onlybyaeronauticalengineeringmajors. StevenA.Brandt May2004 Table of Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix Chapter1. DesignThinking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 DesignMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.3 DesignExample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.4 DesignandAeronautics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1.5 BriefHistoryofAircraftDesign . . . . . . . . . . . . . . . . . . . . . . . . . 15 1.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1.7 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1.8 MoreDetails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Chapter2. OperatingEnvironment . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.1 DesignMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.2 CharacteristicsoftheAtmosphere . . . . . . . . . . . . . . . . . . . . . . . 42 2.3 PressureMeasurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 2.4 StandardAtmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 2.5 CommonUsesoftheStandardAtmosphere . . . . . . . . . . . . . . . . . 51 2.6 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 2.7 MoreDetails—MolecularCollisionsandAerodynamics . . . . . . . . 54 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Chapter3. AerodynamicsandAirfoils . . . . . . . . . . . . . . . . . . . . . . . 61 3.1 DesignMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 3.2 BasicAerodynamics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 3.3 BasicAerodynamicsApplications . . . . . . . . . . . . . . . . . . . . . . . 66 3.4 ViscousFlow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 3.5 AirfoilCharacteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 3.6 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 3.7 MoreDetails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 xi Chapter4. WingsandAirplanes. . . . . . . . . . . . . . . . . . . . . . . . . . . 113 4.1 DesignMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 4.2 Wings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 4.3 High-LiftDevices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 4.4 WholeAircraftLift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 4.5 WholeAircraftDragandDragPolar . . . . . . . . . . . . . . . . . . . . . 128 4.6 Mach-NumberEffects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 4.7 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 4.8 MoreDetails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 4.9 WholeAircraftAnalysisExample . . . . . . . . . . . . . . . . . . . . . . 162 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 Chapter5. Performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 5.1 DesignMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 5.2 EquationsofMotion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 5.3 Propulsion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 5.4 DragCurves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 5.5 Lift-to-DragRatio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 5.6 PowerCurves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 5.7 CurveShifts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 5.8 Glides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 5.9 Climbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 5.10 RangeandEndurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 5.11 TakeoffandLanding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 5.12 Turns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 5.13 V–nDiagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 5.14 EnergyHeightandSpecificExcessPower . . . . . . . . . . . . . . . . . 233 5.15 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 5.16 MoreDetails—ManeuverabilityDiagramsand ConstraintAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 5.17 PerformanceAnalysisExample . . . . . . . . . . . . . . . . . . . . . . . . 253 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 Chapter6. StabilityandControl . . . . . . . . . . . . . . . . . . . . . . . . . . 267 6.1 DesignMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 6.2 Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 6.3 LongitudinalControlAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . 275 6.4 LongitudinalStability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278 6.5 DynamicLongitudinalStability . . . . . . . . . . . . . . . . . . . . . . . . 285 6.6 Lateral-DirectionalStability . . . . . . . . . . . . . . . . . . . . . . . . . . 287 6.7 DynamicLateral-DirectionalStability . . . . . . . . . . . . . . . . . . . . 293 6.8 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 6.9 MoreDetails—CalculatingStabilityParameters . . . . . . . . . . . . . 300 6.10 StabilityandControlAnalysisExample:F-16AandF-16C . . . . . 305 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 Chapter7. Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315 7.1 DesignMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315 7.2 SolidMechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315 7.3 TypesofStress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321 7.4 Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323 7.5 StructuralLayout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328 7.6 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331 7.7 ComponentSizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 7.8 StructuralSizingExample . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339 7.9 WeightEstimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340 7.10 FiniteElementAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340 7.11 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 Chapter8. Sizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345 8.1 DesignMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345 8.2 InternalLayout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346 8.3 StructuresandWeight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347 8.4 GeometryConstraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350 8.5 MissionAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354 8.6 SizingEquation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362 8.7 WeightFractionMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364 8.8 WeightandBalance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365 8.9 MissionAnalysisandSizingExample. . . . . . . . . . . . . . . . . . . . 367 8.10 AeroDYNAMIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373 8.11 Cost. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373 8.12 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378 Chapter9. PuttingItAllTogether:ConceptualAircraftDesign . . . . 379 9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379 9.2 Overviewofthe12Activities. . . . . . . . . . . . . . . . . . . . . . . . . . 380 9.3 CustomerFocus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381 9.4 DesignSynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382 9.5 GeometryModelingandEngineeringDrawing . . . . . . . . . . . . . . 383 9.6 AerodynamicAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383 9.7 PropulsionAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386 9.8 ConstraintAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387 9.9 MissionAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 9.10 WeightAnalysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390 9.11 Sizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391 9.12 CostAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 9.13 Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 9.14 PerformanceReporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393 9.15 PuttingItAllTogether . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395
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