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

High-altitude long-endurance (HALE) aircraft have wings with high aspect ra tios. During operations of these aircraft, the wings can undergo large stat ic deflections. These large static deflections can change the natural frequ encies of the wing, which, in turn, can produce significant changes in its aeroelastic behavior. This behavior can be accounted for only by using a ri gorous nonlinear aeroelastic analysis. Results are obtained from such an an alysis for aeroelastic behavior as well as overall flight dynamic character istics of a complete aircraft model representative of HALE aircraft. When t he nonlinear flexibility effects are taken into account in the calculation of trim and flight dynamics characteristics, the predicted aeroelastic beha vior of the complete aircraft turns out to be very different from what it w ould be without such effects.