Investigation on Helicopter Vibration Reduction by Means of Multicyclic Rotor Control with the Use of Flight Simulator

This paper describes a preliminary phase of the program is being launched by Mil Design Bureau (MDB) on the development of multicyclic control system for the production Mi-8 helicopter. The investigation of multicyclic Mi-8 rotor control according to the IBC concept was made with the use of MDB flight simulator with comprehensive mathematical model of the rotor and helicopter dynamics. This model was used to determine high frequency response of hub shears and moments to the multicyclic input signals. The influence on 4/rev, 5/rev, and 6/rev multicyclic harmonics on the dominating 5/rev content of hub shears and moments was evaluated. Multicyclic amplitudes were imposed in the form of equivalent pitch angle of each rotor blade.The data obtained are pertinent to evaluate the applicability of the rotor/helicopter model for multicyclic control investigations, and evaluate by the first approximation the influence of various input harmonics on the 5/rev hub shears and moments content.