Design and Evaluation of a Dynamic Inversion Control Law for X-31A

Abstract

The Enhanced Fighter Maneuverability of the thrust-vectored X-31A aircraft has already been proven in the German-American (EFM) program in the early nineties . Recently its characteristics with reduced vertical tail were investigated as one of the key research objectives within the German-American VECTOR program. To fulfill this aim the principle of Nonlinear Dynamic Inversion (NDI) has been applied for the primary control law design. NDI is based on the inversion of model equations, so that control laws are easily adapted to varying aircraft configurations and may be generated automatically with the help of advanced modeling tools. The control laws were implemented in the VECTOR fixed-base flight simulator facility. Six experienced pilots assessed and compared flying qualities (for conven-tional as well as post-stall flight conditions) for full and 50% vertical tail configurations.