Externally referenced rotary wing cyclic pitch control

The control system uses a terrestrially stationary field to reference the cyclic pitch control for a rotary winged aircraft. Suitable fields include the earth's magnetic field or a stationary radio beacon 8. The control surfaces 3 are varied in a cyclic fashion which is a function of the angle between the surfaces and the reference field. The phase of this function controls the direction relative to the reference field of the axis about which the attitude of the aircraft varies. This in turn controls the direction relative to the reference field of the aircraft's movement. A motor 5 drives a lift propeller 6. Control surfaces 3 on rods 2 extending radially of a ring 1 are actuated cyclically. A direction sensor 7 senses the stationary field.