Page 566 - Aircraft Stuctures for Engineering Student

13.2 Control effectiveness and reversal 547

L + AL

Spring stiffness K

V
____t

t-

Fig. Aileron effectiveness and reversal speed (two-dimensional tax,.

these in turn cause an elastic twist, 8, of the wing. Thus

(13.12)

where aCL/aa has been previously defined and aCL/a( is the rate of change of lift
coefficient with aileron angle. Also

in which aCM,o/at is the rate of change of wing pitching moment coefficient with
aileron deflection. The moment produced by these increments in lift and pitching
moment is equilibrated by an increment of torque AT about the flexural axis. Hence

Isolating e from Eq. (13.14) gives
e= pv2sc[(acL/at)e f acM,O/ad< (13.15)
K - $pv2Sce(aCL/aa)
Substituting for B in Eq. (13.12) we have

ifv2sc{(acL/at)e f acM,O/%) acL I acL] E
K - 3 p V2Sce ( dCL/da) aa at

which simplifies to