Westland Aircraft Limited

Westland Plc

Kenneth Watson

James E Saunders

Richard G Buswell

Diametrically opposed rotor blades of a helicopter rotor are interconnected by a strap member which is flexible in torsion and in a plane perpendicular to a plane of rotation and has a plan profile extending between leading and trailing edges. Each rotor blade is provided with inwardly extending lever means adapted for attachment to drive means externally of the strap plan profile and adjacent one of its edges and to pitch control means externally of the plan profile and adjacent the other of its edges. In one embodiment, the lever means comprise individual levers formed integral with a connecting member rotationally fixed to the rotor blade and in a further embodiment the lever means comprise an inwardly extending torque sleeve. The drive means attachments of opposed blades lie along a common axis parallel to the plane of rotation and intersecting the axis of rotation at approximately 45 degrees to a longitudinal axis of the strap member.

Helicopter rotors

A helicopter rotor (10, 29) includes a rotor hub (11, 30) supporting a plurality of rotor blades, and a pitch control means comprising a universal joint (21, 45) adapted to permit both tilting and axial vertical movements of the control means to change the pitch of the rotor blades both cyclically and collectively. The universal joint has three radially extending pins (22) each supporting a radially slidable and rotatable bearing (23) having a spherical external surface (25), the bearings being located in generally axially extending tracks (26) having a circular cross-sectional shape for rolling engagement by the bearings. Axial movements are permitted by rolling of the bearings along the tracks and tilting movements by a combination of rolling and a sliding movement of the bearings along the pins. Several embodiments are described and illustrated.

Helicopter rotor

A freewheel device for connecting a power input to a selected one of a plurality of outputs so as to transmit rotary motion in one direction of rotation and to over-run when the speed of the selected one of the outputs exceeds that of the input, includes a neutral condition in which the input is rotationally disengaged from any of the outputs. In a described embodiment, the freewheel device comprises a plurality of rollers retained circumferentially adjacent one end of an axially movable shaft in operative association with a plurality of wedge-shaped portions formed on the shaft, axial movement of the shaft serving to engage the rollers between the wedge-shaped portions and, selectively axially spaced-apart internal, cylindrical surfaces formed on each of the outputs and on a rotatable support. The freewheel device finds particular application in the transmission system of multi-engined helicopters.

Freewheel devices

A helicopter rotor includes a powered blade fold mechanism adapted to move a rotor blade between a spread operational position and a folded position and at least one lock pin (17) to lock the blade in its spread position. The mechanism includes a rotary power source (21) and a mechanical linkage (23, 25) having an over-center position and adapted so that energization of the power source in one direction moves the linkage through the over-center position to withdraw the lock pin and fold the blade, and energization in the other direction moves the blade to the spread position and re-inserts the lock pin automatically as the linkage moves back through its over-center position. Lock means may be provided to lock the blade in pitch and, in one embodiment particularly adapted for use in an articulated rotor, the lock means includes pitch, flap and lag locks.

A helicopter rotor has at least one pair of diametrically opposed rotor blades interconnected by a strap member flexible in torsion and in a plane perpendicular to a plane of rotation and stiff in a plane coincident with the plane of rotation. A torsionally flexible tie-bar having a tensile elastic modulus greater than that of the strap member is extended between pivotal attachments adjacent opposed ends of the interconnecting strap member. In operation, a major portion of centrifugal loads caused by the rotating blades is carried by the tie-bar.

This invention is concerned with helicopter rotor control systems which hitherto have tended to comprise complex assemblies which are costly to manufacture and maintain and which are vulnerable to external damage. A helicopter rotor is disclosed in which each of a plurality of radially extending rotor blades is attached to the outer end of an individual spindle 19 having its inner end protruding into the interior of a hollow rotor hub structure 12 and supported by bearing means 21 arranged to permit rotational movement of the spindle 19 about its axis. A pitch control lever 22 is attached to the inner end of each spindle 19 and is articulated, through a universal joint, to the upper end of an individual connecting rod 38, 39, 40 and 41, the lower ends of the connecting rods being attached to a common housing 42 having independently rotatable means for connection to helicopter flying controls.

This invention relates to helicopter rotors in which the rotor blades are supported by flexure members and resilient means to permit flap and lead/lag movements. Hitherto such support means have been subjected to centrifugal forces thus complicating their design and requiring compromises such that optimum properties in flap and lead/lag planes have been unattainable. In this invention, each blade is attached by an individual spindle 19 supported in an elastomeric bearing 21 secured in a hollow rotor hub 12. Arms 26, flexible in a flapping plane, extend from the rotor hub 12 and a bearing 46 at the outer end of each spindle is attached to its associated arms through resilient means 30 to permit lead/lag movement of the spindle 19 relative the arms 26. In operation, centrifugal loads are transmitted to the hub 12 so that the arms 26 and resilient means 30 can be designed to provide optimum properties in the flap and lead/lag planes. Furthermore, bending of the spindles 19 due to such blade movements significantly reduces corresponding deflections of the elastomeric bearing 21.

Helicopter rotor and blade connection

A helicopter rotor includes, for each of a plurality of rotor blades, a generally radially extending flexure member to accommodate blade flap movements, a feathering hinge for pitch change movements and an elastic shear mounting located within the feathering hinge to accommodate rotor blade lead and lag movements. Spaced-apart elastomeric bearings are utilized in the feathering hinge, and the elastic shear mounting is associated with the outer elastomeric bearing and is arranged to be substantially equally resilient in both the lead/lag and flap planes. The arrangement facilitates the incorporation of automatic damping in the lead/lag plane by selection of suitable material for the elastic shear mounting.

This invention relates to freewheels comprising a plurality of rollers interposed between inner and outer races formed on driving and driven members respectively, one of said races having a plurality of wedge-shaped portions equal in number to the number of rollers. The invention is particularly concerned with cageless freewheels of this construction, and discloses a means for moving said rollers between a first position in which the rollers assume an engaged position to transmit rotation to the driven member, and a second position in which the rollers are retained in a disengaged position. This is accomplished by at least one actuating lever interposed in the rollers, and being capable of limited circumferential movement between said first and second positions. In one embodiment the actuating lever has parallel side portions for engagement with adjacent rollers, and in a second embodiment the actuating lever includes a circular section spindle portion rotatably mounted in an axial bore in one of the rollers.

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.

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.

Rotor for rotary wing aircraft

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.

Semi-rigid rotors for rotary wing aircraft

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. Internal gear teeth are provided adjacent the other end of the drive member to mesh with external teeth on a gear rotationally fixed to the other drive shaft part to transmit torque between the drive member and the other drive shaft part when the components are drivingly connected. A plurality of flyweights are arranged in the retaining member so that at least part of each flyweight is automatically extended on rotation of the coupling so that movement of the retaining member through the aperture is prevented thereby to prevent separation of the coupling components during rotation.

Disconnect coupling for drive shafts

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.

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Yeovil, United Kingdom

Kenneth Watson