Rotor Dynamics and Helicopter Stability

Development of a Unified Mathematical Theory of the Steady and Disturbed Motion of a Helicopter with Particular Emphasis on the Dynamical Aspects of the Problem. The basic features of the disturbed motion of a helicopter are first discussed, and the question of the separation of longitudinal and lateral modes is examined. This is followed by a detailed account of the entire family of helicopter stability derivatives. Particular attention is paid to derivatives involving cross‐coupling between the lateral and longitudinal modes because of the vital part they play in modifying the longitudinal stability behaviour. A full treatment is given of the flapping and downwash derivatives which play an integral part in the calculation of the main‐rotor derivatives. A method is then developed of calculating the tail‐rotor parameters to trim, and the values of the tail rotor derivatives are deduced. The contribution of the fuselage is also examined, and full expressions are finally presented for all thirty‐six derivatives of the complete helicopter.