Nonlinear aeroelasticity and flight dynamics of high-altitude long-endurance aircraft

High-altitude long-endurance (HALE) aircraft have wings with high aspect ratios. During operations of these aircraft, the wings can undergo large static deflections. These large static deflections can change the natural frequencies of the wing, which, in turn, can produce significant changes in its aeroelastic behavior. This behavior can be accounted for only by using a rigorous nonlinear aeroelastic analysis. Results are obtained from such an analysis for aeroelastic behavior as well as overall flight dynamic characteristics of a complete aircraft model representative of HALE aircraft. When the nonlinear flexibility effects are taken into account in the calculation of trim and flight dynamics characteristics, the predicted aeroelastic behavior of the complete aircraft turns out to be very different from what it would be without such effects.