Westland Aircraft Limited

Westland Plc

Alfred C Martin

Alan Waddington

A helicopter rotor having a rotor hub and a plurality of rotor blades includes for each blade a blade fold mechanism comprising a reversible rotary power source and a rack and pinion mechanism adapted to operate one or more lock pins and to fold the blades between an operational spread position and a folded position. Two embodiments of the invention are described and illustrated.

Helicopter rotors

A helicopter rotor includes a rotor head arranged to support a plurality of rotor blades for rotation about an axis. The rotor head comprises a generally hollow structure, and each rotor blade is supported by an elastomeric bearing arranged to permit blade flap, lead/lag and feathering movements. A resilient support means is housed within the structure and is operatively associated with each rotor blade so as to provide controlled restraint of rotor blade movements in the blade flap plane. In the illustrated embodiment, the support means comprises interconnected inner and outer elastomeric assemblies, the outer assembly being connected to each rotor blade through a common elastomeric lead/lag damper unit which provides inter-blade damping of blade lead/lag movements. The outer elastomeric assembly also provides an automatic blade droop stop.

A helicopter rotor includes a rotor head having, for each of a plurality of rotor blades, an elastomeric bearing and a damper that is arranged to provide controlled restraint of rotor blade movement in both the flap and lead/lag planes. The damper can be arranged to exhibit either substantially equal stiffness in both operational planes or any desired stiffness ratio. In a preferred embodiment of the latter arrangement, the desired stiffness in the respective planes are provided by separate components incorporated in the single damper. The damper may be situated either inboard or outboard of the elastomeric bearing.

Damper means for helicopter rotors

A helicopter rotor includes a rotor hub and a plurality of rotor blades, the rotor hub comprising, for each rotor blade, a flexure member extending generally radially from the hub and being flexible in a blade flap plane. A feathering hinge is located at an outer end of the flexure member and includes a cylindrical portion mounted on an extension of the flexure member and resilient means arranged to permit blade lead and lag movements of the cylindrical portion during operation. In a described embodiment, the cylindrical portion is mounted on axially spaced apart bearings comprising an inner part spherical bearing having a geometrical center and an outer parallel bearing, and a resilient elastomer ring is interposed between the outer bearing and the cylindrical portion so as to permit pivotal movement of the cylindrical portion about the geometrical center of the inner bearing.

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Shepton Mallet, United Kingdom

Alfred C Martin