/a(z){l - cos A(z - Sl)} -SmA(\ Jl)sin Az Wl v n cos Aj

where cos A(z — = 0 when z <s\ The spanwise variation of total local wing lift coefficient is given by strip theory as where 0 is known from Eq. (13.29) and a is the steady flight wing incidence.

The aileron effectiveness is often measured in terms of the wing-tip helix angle (psj V) per unit aileron displacement during a steady roll. In this condition the rolling moments due to a given aileron deflection, wing twist and aerodynamic damping are in equilibrium so that from Fig. 13.6(a) and Eq. (13.23) and noting that ailerons on opposite wings both contribute to the rolling, we have zdz = 0

from which

Substituting for 0 from Eq. (13.29) into Eq. (13.32) gives v dc\ / Ps sin Az 1 / dc\ 1 dcm 0

",•/ w, w m sinA(.v — S|) . ./;,(-){' - cos A(z-.?,)}--:-sin Ar cos A.v

~^Â{z)rà: = y ya(r){l -cosA(r-.v,)} s dci sinAz sin A(.v - .v,) .

-sin Ar cos A.v dr n da A.v cos A.v Therefore, aileron effectiveness [ps/V)/^ is given by ft \ + f'tl + L dCm0

cos A.v dc\ sinAz

Integration of the right-hand side of the above equation gives

0 0

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