VSTOL autonomous takeoff flight control

Abstract

An autonomous takeoff mode for a VSTOL aircraft flight control system is developed. In low-speed situations, such as takeoff, landing, and hover, aerodynamic forces are negligible compared with the reaction control forces produced by engine thrust. This fact is applied in an approximately optimal real-time controller that guides the vehicle from a stationary starting position to a prescribed final altitude, flight path angle, and velocity in minimum time. This flight control scheme is formulated as an optimal control problem whose solution is expanded using regular perturbation methods. The first two terms of this expansion have shown close agreement with the optimal solution on many related problems. In this work, the inertial forces are considered to dominate the motion, and the aerodynamic, forces are included in the first-order correction. The zeroth-order problem is characterized by being analytically integrable where the value of certain parameters are obtained through iteration. The firstorder corrections require numerical quadrature integration, but no iteration. To ensure dominance of the zeroth-order term, the expansion is augmented with state jumps associated with the aerodynamic forces distributed judiciously over the flight path.