Question 29.3: Calculate the aileron reversal speed for the wing of P.29.2 ......
Calculate the aileron reversal speed for the wing of P.29.2 if the rate of change of lift coefficient with aileron angle is 0.15 and the rate of change of pitching moment coefficient with aileron angle is –0.3. What is the aileron effectiveness at an aircraft speed of 160 m/s?
Answer: 224.4 m/s. 76%.
The wing area, S=2.8\times8.0=22.4\,{\mathrm{m}}^{2}. Then, from Eq. (29.18),
V_{r}=\sqrt{\frac{-K(\partial C_{L}/\partial \xi )}{\frac{1}{2}\rho Sc(\partial C_{M,0}/\partial \xi )(\partial C_{L}/\partial \alpha ) } } (29.18)
i.e.,
V_{\mathrm{r}}=224.4\,\mathrm{m}/sTherefore, from Eq. (29.22),
Aileron effectiveness = \frac{1-V^{2}/V_{r}^{2}}{1-V^{2}/V_{d}^{2}} (29.22)
Aileron effectiveness = \left(1-160^{2}/224.4^{2}\right)/\left(1-160^{2}/269.2^{2}\right)=0.76
The aileron is therefore 76% effective.