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Abstract
AcomparisonismadebetweentheresultsoftrimmingaHighSpeedCivilTransport(H-SCT)conceptalongareferencemissionpro leusingtwotrimmodes.Onemodeusesthestabilator.Theothermodeusesforeandaftplacementofthecenterofgravity.Acomparisonismadeofthethrottlesettings(cruisesegments)orthetotalacceleration(ascentanddescentsegments)andofthedragcoef cient.Thecomparativestabilityoftrimmingusingthetwomodesisalsoassessedbycomparingthestabilitymarginsandtheplacementofthelateralandlongitudinaleigenvalues.
Introduction
ThestudyreportedinthisdocumentisafollowonstudytotheworkreportedbyChowdhry
andButtrillintheirmemorandum[1].Inthatreport,theydocumented“astudyperformedtoassessthebareairframestabilitycharacteristicsofaHSCTcon gurationandtoinvestigatethebene ts,ifany,ofusinganactivefuelmanagementsystemtoreducetrimdrag.”Thestudyconsistsoftrimmingtheaircraftateachpointalongareferencemissionpro le(1)holdingthex-cgatitsnominalpositionandusingthestabilatorand(2)holdingthestabilatoratzerode ectionandmovingthex-cgtotrim.Stabilityandperformancemeasuresoftheaircraftarecomparedatthetwotrimconditionsateachpointofthereferencemissionpro le.
Ref.[1]studiedtheReferenceH,cycle1HSCTconcept.Thepresentstudyusesthe
ReferenceHCycle3airplane(Ref.H-3)[2].
ReferenceMissionPro le
Thereferencemissionpro lewastakenfromaTCACon gurationDescriptionDocument
[3,pp.A32–A43].Itisdescribedbyasampleof79 ightconditionsdividedinto vesegments:Seg.1Climb,30 ightconditions(numbers1–30).
Seg.2Supersoniccruise,13 ightconditions(numbers31–43).Seg.3Supersonicdescent,16 ightconditions(numbers44–59).Seg.4Subsoniccruise,13 ightconditions(numbers60–72).Seg.5Subsonicdescent,7 ightconditions(numbers73–79).
Thismissionpro lewasdesignedfortheTechnologyConceptAirplane(TCA)whichis
heavierthanRef.H-3.Tocorrectforthisweightdifferential,theaircraftweightsfromtheTCAmissionpro lehavebeenmultipliedbythefactor649914/740600whichistheratioofthemaxi-mumtaxiweightofRef.H-3tothatofTCA.Each ightconditionofthereferencemissionpro leisthende nedbyitsMachnumber,itsaltitude,its(scaled)weight,anditsrateofclimb.TheseareshowninFigs.1–4.
ModelingandAnalysisSoftware
ThemodelofRef.H-3andmuchoftheanalysissoftwarewascontainedinanintegrated
MATLAB/SIMULINKHSCTsimulation[4].Thesoftwaremodulerefhsim3
FLAGandtheAUTOWT