A HYBRID PERIODIC-SHOOTING, AUTO-PILOT METHOD FOR ROTORCRAFT TRIM ANALYSIS

A discrete auto-pilot method is developed and applied to various helicopter trim models. The results show that the method solves the stable and unstable system trim problem successfully. A unified trim algorithm is also developed and applied to various helicopter trim models. This algorithm combines the advantages of the periodic shooting method, the auto-pilot method and the discrete auto-pilot method. Therefore it overcomes the inefficiency of the periodic shooting (when the system is very large) and the instability of the auto-pilot when the system is neutrally stable (such as in free-flight) or unstable. The results show that such a unified method is very efficient and robust to solve the rotorcraft trim problem.