Trajectory optimization procedures for rotorcraft vehicles, their software implementation and applicability to models of varying complexity

This paper describes numerical procedures for the solution of trajectory optimization problems in rotorcraft flight mechanics. We specifically consider procedures which can be easily interfaced with black-box flight simulators, with minimal assumptions on the functionalities of such third-party software components, and which can cater to a wide range of vehicle models of varying complexity. At first we identify in the direct approach to the solution of maneuver optimal control problems the method of choice for this class of problems. Next, we formulate the direct transcription and the direct multiple shooting approaches, we discuss their characteristics and identify their respective optimal application areas. Finally, we describe the functionality and architecture of a general purpose code implementing both methods. The capabilities of the proposed procedures are demonstrated with the help of practical examples of industrial relevance, regarding both helicopters and tilt-rotors.