Optimal and Suboptimal Control Synthesis for Minimum Time VTOL Transition

Optimal open-loop and suboptimal closed-loop controls for a VTOL aircraft in a minimum climb-to-cruise time transition are presented in this paper. The optimal open-loop controls are synthesized by a proposed gradient technique which provides for the selection of desired changes in physically meaningful parameters during each iteration step. The suboptimal closed-loop controls are synthesized as integral mean-square approximations to the optimal open-loop controls over the minimum time-to- climb interval. Piecewiseconstant feedback gains and switching times are synthesized for multidimensional control vectors which are linear combinations of observable states. Several computational results are presented for optimal and suboptimal minimum time controls with constrained and unconstrained terminal flight-path angles.