Optimization of critical trajectories for rotorcraft vehicles

This paper focuses on the development of computational procedures for the trajectory management of maneuvering rotorcraft vehicles. The flight mechanics models are based on classic blade element theory, and are applicable to both helicopters and tilt-rotor aircrafts. The computation of an optimal maneuver is viewed here as an optimal control problem, where the solution minimizes an appropriate cost function subjected to constraints that translate the flight envelope limitations of the aircraft and all the necessary safety and operational requirements. A finite element based transcription process is used for discretizing the problem, obtaining a finite dimensional parameter optimization problem. Ad hoc procedures are proposed for ensuring flyable and realistic computed control time histories, that are compatible with the hidden (unmodelled) actuator dynamics. The methodology is used for developing and studying various models of the take-off of helicopters and tilt-rotors in the one-engine failure case under Category-A certification requirements.