SUPPRESSION OF TRANSMITTED HARMONIC ROTOR LOADS BY BLADE PITCH CONTROL

Abstract : A method is developed for computing the pitch angle inputs required to eliminate the transmission of harmonic vertical forces from a helicopter rotor to its driving shaft. The inertia and aerodynamic forces due to dynamic blade motions are taken into account in the computations. In finding the aerodynamic loads, a realistic model is used which represents the wake vorticity by a mesh of segmented vortex filaments. Results of computations for three flight conditions are presented for a rotor which is approximately the same as the UH-1A configuration except for assumed differences in pitch control.