Rotor system with pitch flap coupling
AssigneeSikorsky Aircraft Corporation
InventorsDavid N. Schmaling, Pedro L. Cabrera
Life of this patent
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Abstract
An articulated rotor system with a servo-flap rotor control system locates the focal point of a blade retention spherical elastomeric bearing inboard of a joint in the servo-flap pitch control tube which separates the flap hinge and supports the servo-flap pitch control tube on a single pivot bearing within a blade retention spindle. Rotor blade flapping produces relative movements between the servo-flap pitch control tube and the blade retention spindle which is converted through a servo-flap drive linkage into servo-flap pitch motions to provide flap/pitch coupling which reduces steady and transient blade flapping.
Claims24
A rotor blade assembly comprising:
- a rotor blade bearing housing;
- a blade pitch control coupling mounted within said rotor blade bearing housing for rotation about a blade hub axis;
- an elastomeric bearing mounted to said rotor blade bearing housing;
- a blade spindle mounted to said elastomeric bearing to define a blade spindle flapping focal point;
- a spherical bearing mounted within said blade spindle;
- and
- a servo-flap pitch control tube mounted within said spherical bearing for rotation about a servo-flap pitch control tube axis, said servo-flap pitch control tube mounted to said blade pitch control coupling at a joint which defines a servo-flap pitch control tube pivot point, said servo-flap pitch control tube pivot point offset from said blade spindle flapping focal point, said servo-flap pitch control tube drives a servo-flap assembly relative a rotor blade.
A servo-flap rotor blade assembly comprising:
- a rotor blade bearing housing;
- an elastomeric bearing mounted to said rotor blade bearing housing;
- a blade spindle mounted to said elastomeric bearing to define a blade spindle flapping focal point;
- a blade cuff mounted to said blade spindle;
- a rotor blade mountable to said blade cuff;
- a spherical bearing mounted within said blade spindle;
- a servo-flap pitch control tube mounted within said spherical bearing for rotation about a servo-flap pitch control tube axis, said servo-flap pitch control tube mounted at a joint which defines a servo-flap pitch control tube pivot point, said servo-flap pitch control tube pivot point offset from said blade spindle flapping focal point;
- and
- a servo-flap pitchable relative to said rotor blade in response to rotation of said servo-flap pitch control tube.
A method of pitch/flap coupling for a rotor blade assembly of a rotary-wing aircraft comprising the steps of:
- (A) flapping a rotor blade spindle about a blade spindle flapping focal point;
- (B) flapping a servo-flap pitch control tube about a servo-flap pitch control tube pivot point offset from the blade spindle flapping focal point;
- and
- (C) tilting the servo-flap pitch control tube relative the blade spindle in response to said step (B) to pitch a servo-flap relative a rotor blade.
A rotor blade assembly comprising:
- a rotor blade;
- a servo-flap movable relative to said rotor blade;
- a blade spindle mounted to said rotor blade, said blade spindle defines a blade spindle flapping focal point;
- and
- a servo-flap pitch control tube mounted at least partially through said blade spindle, said servo-flap pitch control tube defines a servo-flap pitch control tube pivot point offset from said blade spindle flapping focal point, said servo-flap pitch control tube free to tilt about said servo-flap pitch control tube pivot point relative to said blade spindle as said rotor blade flaps about said blade spindle flapping focal point such that said servo-flap pitch control tube pitches said servo-flap relative to said rotor blade to generate a stabilizing pitch-flap coupling.
Dependencies are inferred from the claim text.