United Technologies Corporation

The United States of America As Represented by the Administrator of the

Thomas G Campbell

Eric G Olsen

Donald L Ferris

Charles F Niebanck

An improved helicopter rotor flexbeam (20) comprises a pair of generally parallel outwardly open, cross-sectionally C-shaped beams (25) of a geometry which defines therein a first inboard region (A) of enhanced out-of-plane flexibility and a second outboard region (B) of enhanced in-plane and torsional flexibility.

Helicopter rotor flexbeam

Hub moment and driving torque is provided for a helicopter gimbal rotor by two-part flat springs that are in-plane with the rotor tilt point (P). The inboard end of an outward part of each spring is connected to the rotorshaft and the inboard end of an inward part of the spring is connected to the tiltable hub member. The outboard ends of the two spring parts are journaled together by an eccentric elastomeric joint that allows for spring foreshortening that accompanies rotor tilt.

Helicopter gimbal rotor

A structure (10) for reducing vibratory airloading in a rotor blade (12) with a leading edge (14) and a trailing edge (16) includes a cut-out portion (18) at the trailing edge. A substantially wedge shaped cross-section, inertially deflectable tab (20), also having a leading edge (22) and a trailing edge (24) is pivotally mounted in the cut-out portion. The trailing edge (24) of the tab (20) may move above and below the rotor blade (12). A torsion strap (26 or 64) applies force against the tab (20) when the trailing edge (24) of the tab (20) is above and below the rotor blade (12). A restraining member (92) is slidably movable along the torsion strap (64) to vary torsional biasing force supplied by the torsion bar (64) to the tab (20). A plurality of movable weights (82) positioned between plates (84) and (86) vary a center of gravity of the tab (20). Skin (74) of the tab (20) is formed from unidirectional graphite and fiberglass layers. Sliders (54 and 56), coupled with a pinned degree of freedom at rod (58) eliminate bending of tab (20) under edgewise blade deflection.

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Cheshire, CT, United States of America

Thomas G Campbell