Device for automatically stabilizing the yaw motion of a helicopter

A device for stabilizing the yaw motion of a helicopter having a main rotor with a main axis, a power source for driving a tail rotor, and a tail boom with a longitudinal axis, the device comprising

• a tail rotor supported for rotation about a transverse rotor axis, the tail rotor including a hollow rotor shaft operably connectable to be driven by the power source and including a plurality of rotor blades extending radially from said rotor shaft along respective pitch axes, the collective pitch of the rotor blades being variable,
• pitch varying means extending through the shaft for permitting the pilot of the helicopter to manually vary the magnitude of the collective pitch, the pitch varying means including a push-pull rod coupled to the rotor blades, and
• gyroscopic means for automatically varying the collective pitch of the rotor blades in response and opposition to yaw motions, the gyroscopic means including a gyro rotor and means for pivotably mounting the gyro rotor to the push-pull rod so that the gyro rotor pivots relative to the push-pull rod to vary the collective pitch of the rotor blades to supplement any pitch variance caused by concurrent operation of the pitch varying means.

A device for automatically stabilizing the yaw motion of a helicopter having a tail boom, a tail rotor including rotor blades, and pitch varying means for varying the pitch of the rotor blades, the device comprising

• pilot means for providing a primary input to the pitch varying means to vary the pitch of the rotor blades and thereby change the magnitude of thrust force generated by the tail rotor, the pilot means including a primary linkage connected to the pitch varying means and means for moving the primary linkage to actuate the pitch varying means, and
• gyroscopic means for providing a supplemental input to the pitch varying means to adjust continuously the pitch of the rotor blades established by the pilot means to counter any intermittent changes in yaw caused by external forces applied to the helicopter during flight without varying the primary input provided by the pilot means, the gyroscopic means including a gyro rotor, means for mounting the gyro rotor for pivotable movement relative to the tail rotor in response to application of external forces to the helicopter in flight, and a secondary linkage interconnecting the pivotable gyro rotor and the pitch varying means and moving independently of the primary linkage to adjust the pitch of the rotor blades established by the pilot means.

A device sensitive to angular displacement, the device comprising

• a plurality of blades extending from a rotatable hollow shaft,
• a push-pull rod extending through the hollow shaft and operably connected to the blades to collectively control the pitch of the blades, and
• a gyroscopic assembly including a gyro rotor mounted to rotate with the hollow shaft, to pivot about a pivot axis located at or near the end of the push-pull rod, and to automatically vary the collective pitch of the blades in response to angular displacement of the device.

In a helicopter having a tail rotor with a plurality of rotor blades extending radially from a hollow rotor shaft which is mounted for rotation about a transverse rotor axis, and having a rod extending through the hollow shaft and operably connected to the blades to manually vary the collective pitch of the blades, a device for automatically stabilizing the yaw motion of the helicopter comprising

• a gyroscopic assembly including a gyro rotor mounted to rotate with the tail rotor, to pivot about a substantially longitudinal pivot axis at the outboard end of the rod and to automatically vary the collective pitch of the blades in response to yaw motion.