Airplane Longitudinal Equilibrium

14.2.3.1 Global Coefficients

The airplane has the following lift and moment coefficients in terms of the geometric angle of attack a (rd) and tail setting angle tt (rd):

CL(a, tt) = 3.88a + 0.5 + 0.481ft
Cm,0(a, tt) = -1.31a — 0.124 — 0.452tt

Find the location ^ of the aerodynamic center.

Find the location of the center of gravity, given a 4% static margin of stability.

Give the definition of the aerodynamic center.

Derive the expression for the moment about the aerodynamic center, CM, ac{tt) as a function of the tail setting angle.

14.2.3.2 Take-Off Conditions

Using the transfer of moment formula, derive the moment about the center of gravity,

CM, cg {a, tt).

Find the equilibrium conditions, aeq{tt) and CLeq{tt) for the airplane.

If the airplane take-off lift coefficient is {CL )t-o = 1 -44, find the tail setting angle that will be needed, and the corresponding value of {aeq )t-o.

14.2 Problem 3

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