Abstract: This invention relates to helicopter rotors having three or more blades and of the type having a hollow rotor drive shaft and a control column positioned within the hollow shaft arranged to support a spider assembly at its upper end through which control movements are transmitted to the rotor. In the present invention, the inner ends of at least two of the arms of the spider are retained in fixed relationship and the outer end of each arm is connected to its respective feathering hinge through a vertical pivot located on an axis at an operational radius not greater than a radius of a point about which blade lead/lag movements occur. This arrangement serves to establish a virtual floating fulcrum about which the control column is tilted during operation to impart control movements, and thereby eliminates the complicated mechanical support means that are a feature of prior rotors of this type.

Abstract: This invention provides a rotor hub for a rotary wing aircraft in which elastomeric bearing means are utilized to transmit centrifugal loads and blade pitch, flap and lead lag movements, and in which the blades are foldable about a pivot located outboard of the elastomeric bearing means between extended and folded positions. Locking means are provided to ensure that no deflection of the elastomeric bearing means occurs during the folding operation.

Abstract: This invention relates to a semi-rigid rotor of the type in which each rotor blade is attached to a hub through a flexure member comprising an inner part which accommodates flapping movements and an outer part which accommodates lead/lag movements. In the arrangement of the present invention the outer part of each flexure member comprises a spindle extending from the inner part and an arm extending from a housing rotationally mounted on the spindle, the arm extending outwardly to an outer end arranged for connection to a rotor blade and spaced-apart radially from an outer end of the spindle. A tie-bar interconnects the outer end of the arm and the spindle, and means are provided to rotate the housing to effect pitch changes of the rotor blade during operation.

Abstract: This invention relates to a disconnect coupling for drivingly connecting separate parts of a drive shaft, and finds particular application in helicopter tail rotor drive shafts. The coupling comprises components fixed respectively to the shaft parts and being separable in a generally axial direction to enable the drive shaft parts to be disconnected, and includes retaining means automatically operative to prevent axial separation of the separable components during rotation. In one embodiment a cylindrical drive member is coupled to one drive shaft part and includes adjacent one end a radially inwardly extending flange having a central aperture for co-operation with a retaining member secured on the other drive shaft part, the retaining member being arranged to protrude through the aperture when the coupling components are drivingly connected.

Abstract: This invention relates to power transmission systems for helicopters having two or more engines, the transmission system comprising for each engine, drive shafting and gearing including a final drive gear for transmitting torque from each engine to a common output gear for connection to the rotor system, and an idler gear interconnecting the respective gearings to distribute available torque amongst the full complement of final drive gears. A particular embodiment is shown and described for a twin-engined helicopter in which an additional final drive gear is meshed with the output gear and driven from the idler gear so that, even in the event of an engine failure the available torque from the remaining engine is transmitted through all three final drive gears to the rotor system. In the particular embodiment the drive to the additional final drive gear is also arranged for connection to a tail rotor.