Position and control system for helicopter blade actuation

Abstract

A helicopter blade position and control mechanism including a hollow rotor shaft for mounting a plurality of rotor blades with provision for pitch adjustment. A control shaft is disposed within the rotor shaft and is rotatable relative thereto and is associated with actuators for the blades such that the pitch of the blades is changed when the control shaft rotates relative to the rotor shaft. A planetary gear assembly interconnects the control shaft and a source of power fixed to the helicopter fuselage and is such that when an input to the planetary gear assembly is quiescent, the control shaft will rotate in the same direction and at the same rate as the rotor shaft to maintain a desired blade pitch. Conversely, when an input is placed on the planetary gear system, relative rotation between the control shaft and the rotor shaft will occur to provide the desired adjustment in blade pitch. The system allows accurate blade position feedback signals to be taken from a feedback device stationarily mounted on the fuselage.