Introduction to Aircraft Structural Analysis (Elsevier Aerospace Engineering)

Problems 399

or

VC>108m/s

Thus,forcivilaircraftofthistypehavingcruisingspeedsinexcessof108m/s,thegustcaseisthemost
critical.Thiswould,infact,applytomostmoderncivilairliners.
Although,thesamecombinationofVandnintheflightandgustenvelopeswillproducethesame
totalliftonanaircraft,theindividualwingandtailplaneloadswillbedifferent,asshownpreviously
(seethederivationofEq.(13.33)).ThissituationcanbeimportantforaircraftsuchastheAirbus,which
hasalargetailplaneandaCGforwardoftheaerodynamiccenter.Intheflightenvelopecase,thetail
loadisdownward,whereasinthegustcaseitisupward;clearlytherewillbeasignificantdifferencein
wingload.
The transference of maneuver and gust loads into bending, shear and torsional loads on wings,
fuselage,andtailplaneshasbeendiscussedinSection11.1.Furtherloadsarisefromaileronapplica-
tion,inundercarriagesduringlanding,onenginemountings,andduringcrashlandings.Analysisand
discussionofthesemaybefoundinRef.[6].

References

[1] Zbrozek, J.K., Atmospheric gusts—present state of the art and further research,J.Roy.Aero.Soc., January
1965.
[2] Cox,R.A.,Acomparativestudyofaircraftgustanalysisprocedures,J.Roy.Aero.Soc.,October1970.
[3] Bisplinghoff,R.L.,Ashley,H.,andHalfman,R.L.,Aeroelasticity,Addison-Wesley,1955.
[4] Babister,A.W.,AircraftStabilityandControl,PergamonPress,1961.
[5] Zbrozek,J.K.,GustAlleviationFactor,R.andM.No.2970,May1953.
[6]HandbookofAeronauticsNo.1—StructuralPrinciplesandData,4thedition,TheRoyalAeronauticalSociety,
1952.

Problems..............................................................................................

P.13.1 TheaircraftshowninFig.P.13.1(a)weighs135kNandhaslandedsuchthatattheinstantofimpactthe
groundreactiononeachmainundercarriagewheelis200kNanditsverticalvelocityis3.5m/s.

Fig. P.13.1