The NASA STI Program Office provides(7)

Since its founding, NASA has been dedicated to the advancement of aeronautics and space

2.Angle-of-attack,,

3.Pitchrate,,

4.Eulerangle,

5.Altitude,,

6.Rollrate,,

7.Yawrate,,

8.Bankangle,

9.Sidslipangle,

10.Eulerangle,

http://www.77cn.com.cntitude,and12.Longitude.

Linearizationofthetrimmedaircraftproducesa12by12statematrix,.Thelongitudinal

eigenvaluesarefoundbytakingtheeigenvaluesofthesub-matrixofconsistingofthe rst5rowsandcolumnsof.Thelateraleigenvaluesarefoundbytakingtheeigenvaluesofthesub-matrixofconsistingofrowsandcolumns6–9of.

TrimResults

TrimvaluesoftrimvariablesareshowninFigs.5–10.Fig.5showsthat,withtheX-CG

heldtoitsnominalposition,trimcanbeestablishedthroughoutthereferencemissionpro lewithstabilizerde ectionsofnomorethanabout(withcoupledelevatorde ectionsofuptoabout

).Fig.6showsthenominalX-CGschedule(circles)andtheX-CGpositionneededtotrimintheabsenceofstabilatorde ection(x’s).Thehorizontaldash-dotlinesshowtheforward(48%)andaft(54%)X-CGlimitsasgivenin[2,PageB-8].ThenominalX-CGscheduletakesitoutsidetheselimitsduringpartofthesupersoniccruisesegment(Seg.2).ThetrimpositionoftheX-CG,however,exceedstheaftX-CGlimitbothmoreoftenandbyagreateramountthanthenominal.Theelapsedtimeto yfrom ightcondition8to15(thelastconditionbeforetheX-CGexceedsitsaftlimituntilthe rstconditionwheretheX-CGhasreturnedtoitslimit)is10minutes22seconds.Besidesthequestionofwhetheronewouldwanttoexceedthelimitbysomuch,thereisthequestionofwhetheronewouldwanttoincludehighenoughcapacityfuelpumpingsystemstomovetheX-CGthatrapidly.TheX-CGtrimpositionthroughouttheentiredescentandsubsoniccruisephase(Segs.3–5)fallsoutsidetheaftlimit,theexcessbecomingasmuchas6%ofmeanaerodynamicchord.

ThevalueoftrimvariabletotrimtheaircraftisshowninFig.7.Itseemstobequite

insensitivetowhethertheaircraftistrimmedbystabilatorde ectionorX-CGpositioning.Thevaluesoftrimvariablesand,showninFigs.8and9,showonlyslightlymoresensitivitytothetrimmode.

Inthecruisesegments,thepowerleversettingisusedasanadditionaltrimvariable,sup-plementedbyaddingtheconstraintthatthetotalaccelerationshouldbezero().Fig.10

4

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