Flight dynamic modeling of bearingless helicopters

Flight Dynamic equations of the helicopter including the rotor and inflow degrees of freedom are developed. A six degree of freedom, rigid helicopter airframe model is coupled with the elastic rotor and dynamic inflow models. The rotor is represented by the generalized blade equations based on the rotating elastic modes, while a first harmonic model is used for the inflow perturbation dynamics. Floquet Theory is applied to the periodic flight dynamic stability problem in forward flight. Results are presented in the form of eigenvalues and eigenvectors. Quasi-Static rotor assumption is investigated in Multiblade Coordinates and is found to be unsatisfactory. Time invariant analysis is found to be acceptable in near hover flight conditions but not at high forward speeds. Effects of rotor inertial loads are found to be significant.