Reduced-order nonlinear analysis of aircraft dynamics

Abstract

Results from nonlinear dynamical systems theory are used in understanding flight dynamics at large angles of attack and sideslip. For flight in this regime traditional methods of stability analysis based on linear systems theory are of limited use. This is especially so in the identification of postcritical behavior. Instabilities encountered at large angles of attack and sideslip such as pitch-up, nose-slice, and wing-rock are readily examined within the context of bifurcation theory. Examples of nonlinear analysis using reduced-order models and a combined symbolic/numerical computational approach are discussed and the robustness of the bifurcations to unmodeled dynamics is examined.