Nonlinear Aeroelasticity and Flight Dynamics of High-Altitude Long-Endurance Aircraft

TLDR

High‑altitude long‑endurance aircraft have high‑aspect‑ratio wings that can experience large deflections, altering their natural frequencies and thus their aeroelastic behavior. The study aims to account for these nonlinear aeroelastic effects by employing a rigorous nonlinear aeroelastic analysis. Using this analysis, the authors compute aeroelastic responses and overall flight‑dynamic characteristics for a representative HALE aircraft model. The analysis shows that incorporating wing flexibility markedly changes the predicted aeroelastic behavior and flight dynamics, including trim, short‑period, and phugoid modes.

Abstract

High-Altitude Long-Endurance (HALE) aircraft have wings with high aspect ratios. During operations of these aircraft, the wings can undergo large de∞ections. These large de∞ections can change the natural frequencies of the wing which, in turn, can produce noticeable 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 ∞ight dynamic characteristics of a complete aircraft model representative of HALE aircraft. When the nonlinear ∞exibility efiects are taken into account in the calculation of trim and ∞ight dynamics characteristics, the predicted aeroelastic behavior of the complete aircraft turns out to be very difierent from what it would be without such efiects. The overall ∞ight dynamic characteristics of the aircraft also change due to wing ∞exibility. For example, the results show that the trim solution as well as the short-period and phugoid modes are afiected by wing ∞exibility.