U.S. Patent Specifications

In a helicopter, a bladed lifting rotor, a non‐rotative mounting therefor, said rotor incorporating a tiltable and rotatable hub and a plurality of sustaining blades mounted with freedom for flapping movement about axes offset from the hub axis whereby the plane of rotation of the blade tips may assume various inclinations with reference to the body of the aircraft and whereby the axis of rotation of the tiltable hub tends to remain coincident with the axis of the cone generated by the radial axes of the blades in normal flight, the sustaining blades further being mounted for variation of pitch angle and the rotor incorporating mechanism for cyclically varying the blade pitch angle, said mechanism being automatically operative upon deviation of the blade tip path from a given plane to vary the pitch in a sense tending to restore the blade tip path to said given plane, and in combination therewith rotor driving means including jet reaction devices mounted on or incorporated in the lifting blades of the rotor and means for supplying the jet reaction devices with a stream of reactive fluid, whereby no torque reaction is transmitted from the rotor to its non‐rotative mounting.