Introduction to Aircraft Structural Analysis (Elsevier Aerospace Engineering)

Problems 401

CalculatethemaneuverloadfactorbothattheCGandatthetailplaneCP,theforwardinertiacoefficient,andthe

taillift.

Ans. n=3.78(CG),n=5.19atTP,f=−0.370,P=18925N.

P.13.5 Anaircraftfliesatsealevelinacorrectlybankedturnofradius610mataspeedof168m/s.FigureP.13.5

showstherelativepositionsoftheCG,aerodynamiccenterofthecompleteaircraftlesstailplaneandthetailplane

centerofpressurefortheaircraftatzeroliftincidence.

Fig. P.13.5

Calculatethetailloadnecessaryforequilibriumintheturn.Thenecessarydataaregivenintheusualnotation

asfollows:

WeightW=133500N dCL/dα=4.5/rad

WingareaS=46.5m^2 CD=0.01+0.05CL^2

Wingmeanchord ̄c=3.0m CM,0=−0.03

Ans. 73,160N.

P.13.6 TheaircraftforwhichthestallingspeedVsinlevelflightis46.5m/shasamaximumallowablemaneuver

load factorn 1 of 4.0. In assessing gyroscopic effects on the engine mounting, the following two cases are to be

considered:

(a) Pull-out at maximum permissible rate from a dive in symmetric flight, the angle of the flight path to the
horizontalbeinglimitedto60◦forthisaircraft.
(b) Steady,correctlybankedturnatthemaximumpermissiblerateinhorizontalflight.

Findthecorrespondingmaximumangularvelocitiesinyawandpitch.

Ans. (a)Pitch,0.37rad/s,(b)Pitch,0.41rad/s,Yaw,0.103rad/s.

P.13.7 A tail-first supersonic airliner, whose essential geometry is shown in Fig. P.13.7, flies at 610m/s true

airspeedatanaltitudeof18300m.Assumingthatthrustanddragforcesactinthesamestraightline,calculatethe

tailliftinsteadystraightandlevelflight.

If,atthesamealtitude,theaircraftencountersasharp-edgedverticalup-gustof18m/strueairspeed,calculate

thechangesintheliftandtailloadandalsotheresultantloadfactorn.

Therelevantdataintheusualnotationareasfollows:

Wing:S=280m^2 , ∂CL/∂α=1.5

Tail:ST=28m^2 , ∂CL,T/∂α=2.0

WeightW=1600000N

CM,0=−0.01

Meanchordc ̄=22.8m