Development of a flight envelope protection system for a helicopter in autorotation

In this thesis, a flight envelope protection system was developed for a helicopter in autorotation to prevent main rotor speed limit exceedance. A rotor speed estimation model was developed using a neural network based algorithm for a helicopter at autorotation. Using the lead estimate, the collective input margin and pitch angle margin are calculated. Two flight envelope protection methodologies were proposed using these margins. The envelope protection strategies were shown through simulations to be successful in preventing the rotor speed limit exceedance.