Yaw control and stabilization system for helicopters

Abstract

A device for stabilizing yaw motion is provided for use on a helicopter having a main rotor rotatable about a main rotor axis, a power source, and a tail rotor boom with a longitudinal axis. The device includes a tail rotor and a gyroscopic mechanism. The tail rotor is mounted to the tail boom of a helicopter and is rotated about a tail rotor axis by the power source to generate a thrust force transverse to the tail boom and offset from the main rotor axis. The gyroscopic mechanism automatically varies the thrust force generated by the tail rotor to oppose yaw motions. The gyroscopic mechanism includes first and second variable pitch gyro arms extending along first and second gyro arm pitch axes, respectively, a support mechanism, and a pitch adjustor linkage. The support mechanism is configured to support the variable pitch gyro arms for pivotable movement about a gyro pivot axis between a nominal orientation and a tilted orientation so that the variable pitch gyro arms pivot about the gyro pivot axis from the nominal orientation toward the tilted orientation in response to yaw motion encountered by the gyro arms during flight to vary the thrust generated by the tail rotor. The pitch adjustor linkage is appended to the first gyro arm to adjust the pitch of the first gyro arm about the first gyro arm pitch axis.