Bifurcation Analysis of the Generic Transport Model with a view to Upset Recovery

Abstract

There is a trend developing in research focusing on commercial aircraft safety, especially with respect to upset recovery and loss-of-control. In seeking to address the upset recovery problem from a control perspective and owing to the fact that upsets involve ight outside the regular ight envelope, the requirement for a wide-envelope non-linear model arises, along with the requirement for non-linear analysis techniques. These needs are addressed by NASA’s Generic Transport Model (GTM) and bifurcation theory respectively, with the latter having been used extensively in the analysis of non-linear ight dynamics of military aircraft operating in broad ight envelopes. This paper focuses on the application of bifurcation theory to the GTM and includes an analysis of the initial results thereof. It covers the diculties involved in combining the two tools, especially the changes that need to be made to the GTM simulation in order to make it compatible with the mathematics performed in bifurcation analysis. Bifurcation theory is applied primarily to the longitudinal dynamics of the aircraft to investigate the eects of the aircraft elevator and throttle on the aircraft behaviour. The results agree with other research that suggests the classical role these controls play in established upset recovery doctrine is eective, but often not correctly executed. The paper also investigates the coupling between the longitudinal and lateral dynamics of the aircraft, highlighting how aerodynamic stall negatively aects the lateral dynamics.