Abstract: A variable pitch multi-blade propeller suitable for use on a helicopter is constructed of a foam preform joined with a fibrous spar enclosed in resin-impregnated foils and fitted with a metal leading edge. Various components are assembled in a mold and the resins, then cured. The structure may further include a reinforcing yoke of carbon fiber fabrics preimpregnated with a polymerizable synthetic resin. The process may further include a heat treating step to effect polymerization.

Abstract: Each blade is fixed to the hub by the root part of the spar, arranged in the form of a loop surrounding a connection element bolted on the hub, with the interposition of rigid rings by a pin simultaneously fixing the hub on a drive sleeve transmitting thereto the driving torque of the central shaft. The hub comprises two coaxial cylindrical walls in each of which is pierced, for each blade, a circular opening in which the member for controlling the angle of attach which is fast with the blade root is mounted to rotate via self-lubricating rings. The invention is particularly applicable to helicopters.

Abstract: Each blade is fixed to the hub by the root part of the spar, arranged in the form of a loop surrounding a connection element bolted on the hub, with the interposition of rigid rings by a pin simultaneously fixing the hub on a drive sleeve transmitting thereto the driving torque of the central shaft. The hub comprises two coaxial cylindrical walls in each of which is pierced, for each blade, a circular opening in which the member for controlling the angle of attack which is fast with the blade root is mounted to rotate via self-lubricating rings. The invention is particularly applicable to helicopters.

Abstract: This invention concerns devices for limiting the flapping movements of the blades of a rotary-wing aircraft main rotor. The device described has a well known reciprocal ring lower abutment common to all the blades. The disadvantages of this well known arrangement is obviated by the use of separate upper abutment devices for each blade. Each upper abutment device comprises a bent lever a first arm of which forms an abutment part and a second arm supports a weight. The lever can oscillate on a pivot and is acted upon by a spring which holds it in a stop position when the rotor stops so that the first arm of the lever extends almost parallel to the axial plane of symmetry of the associated blade. When the rotor rotates at sufficient speed centrifugal force pivots the lever away from the blade root.