Westland Aircraft Limited

Westland Plc

Stephen P King

Alan H Vincent

Christopher I Hughes

This invention relates to a method and apparatus for reducing vibration of a helicopter fuselage. The apparatus comprises a plurality of actuators interconnecting parts of the helicopter structure capable of relative motion at an exciting frequency, means to continuously oscillate the actuators at a frequency corresponding to the exciting frequency, a plurality of accelerometers attached to the fuselage for generating signals representative of fuselage dynamic accelerations, and processing means for processing said signals and providing output signals for controlling the phase and magnitude of operation of the actuators. In a described embodiment, one of the relatively movable parts comprises a raft structure carrying the gearbox and engines and attached to the fuselage by a resilient attachment adjacent each of its four corners.

Method and apparatus for reducing vibration of a helicopter fuselage

A vibration absorber for a helicopter rotor includes a hub portion, a mass portion encircling the hub portion and a plurality of resilient arms extending in a spaced-apart spiral pattern between the hub and the mass. In operation, the hub portion of the vibration absorber is mounted on a helicopter rotor so as to be rotated with the rotor about an axis of rotation of the rotor, the resilient arms ensuring that the mass is capable of equal resilient deflection in any direction within its plane of rotation whereby the vibration absorber simultaneously reduces in-plane vibration forces of different frequencies.

Vibration absorber for helicopter

A vibration absorber includes a hub arranged for rotation during operation about an aixs, a mass encircling the hub and a plurality of resilient arms extending in a spaced-apart spiral pattern between the hub and the mass so that the mass rotates with the hub in a plane of rotation perpendicular to the axis and is capable of equal resilient deflection in any direction within its plane of rotation. In operation the absorber operates as a spring mass device and finds particular application in damping vibrations in a helicopter rotor due to the facility to simultaneously cancel vibration forces of different frequencies.

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Stoke-sub-Hamdon, United Kingdom

Stephen P King