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1、AircraftConceptualDesignUsingVehicleSketchPad13WilliamJ.Fredericks,KevinR.Antcliff,2GuillermoCosta,NachiketDeshpande,47MarkD.Moore,5EdricA.SanMiguel,6AlisonN.SnyderNASALangleyResearchCenter,Hampton,VA,23681VehicleSketchPad(VSP)isaparametricgeometrymodelingtoolthatisintendedforus
2、eintheconceptualdesignofaircraft.TheintentofthissoftwareistorapidlymodelaircraftconfigurationswithoutexpendingtheexpertiseandtimethatistypicallyrequiredformodelingwithtraditionalComputerAidedDesign(CAD)packages.VSPaccomplishesthisbyusingparametricallydefinedcomponents,suchasawin
3、gthatisdefinedbyspan,area,sweep,taperratio,thicknesstocord,andsoon.Duringthisphaseoffrequentdesignbuilds,changestothemodelcanberapidlyvisualizedalongwiththeinternalvolumetriclayout.Usingthisgeometry-basedapproach,parameterssuchaswettedareasandcordlengthscanbeeasilyextractedforra
4、pidexternalperformanceanalyses,suchasaparasitedragbuildup.Atthecompletionoftheconceptualdesignphase,VSPcanexportitsgeometrytohigherfidelitytools.ThisgeometrytoolwasdevelopedbyNASAandisfreelyavailabletoU.S.companiesanduniversities.IthasbecomeintegraltoconceptualdesignintheAeronau
5、ticsSystemsAnalysisBranch(ASAB)hereatNASALangleyResearchCenterandiscurrentlybeingusedatover100universities,aerospacecompanies,andothergovernmentagencies.ThispaperfocusesontheuseofVSPinrecentNASAconceptualdesignstudiestofacilitategeometry-centereddesignmethodology.Suchaprocessiss
6、howntopromotegreaterlevelsofcreativity,morerapidassessmentofcriticaldesignissues,andimprovedabilitytoquicklyinteractwithhigherorderanalyses.AnumberofVSPvehiclemodelexamplesarecomparedtoCAD-basedconceptualdesign,fromadesignerperspective;comparisonsarealsomadeofthetimeandexpertise
7、requiredtobuildthegeometryrepresentationsaswell.NomenclatureCd=LocaldragcoefficientCDo=ParasiticdragcoefficientCf=SkinfrictioncoefficientCf-L=LaminarskinfrictioncoefficientCf-T=TurbulentskinfrictioncoefficientCf-A=WeightedaverageskinfrictioncoefficientCL=LiftcoefficientCl=Locall
8、iftcoefficientCP=PressurecoefficientI.Introduct