Bell Helicopter Textron Inc.

Textron Corporation

Cecil E Covington

David E Snyder

Ajay Sehgal

Frank B Stamps

Patrick R Tisdale

Ernst C Schellhase

William D Neathery

Madison K Robinson

Joseph J Zierer

James L Braswell

Nolan B Phillips

Charles Eric Covington

David Popelka

Bryan W Marshall

Glenn Alan Shimek

James Braswell, Jr

Eric Charles Boyle

Mithat Yuce

David Allen Haynie

Timothy Kent Ledbetter

Willem Broekhuizen

Robert M Wohlfeld

Peter A Reyes

Wesley L Cresap

Ronnie Lee Martin

Charles L Baskin

Walter G Sonneborn

Ernest A Powell

Robert W Metzger

David A Popelka

Vas H Brogdon

Joe J Zierer

Reggie J Tomerlin

Richard E Wheelis

Dan Anastas, Deceased

Paul E Keefer

By Peggy Anastas, Executrix

Thomas B Settle, Jr

Richard L Bennett

Michael R Smith

Thomas B Settle

A multi-bladed tail rotor assembly is disclosed that provides higher aerodynamic performance, damage tolerant design with 10,000-hour life expectancy, and which requires low maintenance through the use of composites and elastomerics. The tail rotor hub assembly includes two stacked yoke assemblies having multi-bladed teetering rotors, each mounted on a single drive mast. Each yoke assembly includes a yoke hub having a transverse bore therethrough, a bearing assembly disposed within the bore, and retention means for aligning and securing the bearing assembly within the bore. Each bearing assembly includes a trunnion portion having trunnion arms that extend outwardly from a trunnion body portion, and an elastomeric bearing disposed about each trunnion arm. The tail rotor assembly utilizes a composite twist strap flexure to accommodate collective pitch control integral with each rotor blade.

Multi-bladed tail rotor hub design for coriolis relief

The subject tiltrotor aircraft has three modes of operation: airplane mode, helicopter mode, and transition mode. A tilting mast, which transitions the aircraft between airplane mode and helicopter mode, is controlled by systems that allow selective movement of the rotor blades between the flight modes. A hub couples the rotor blades to the tilting mast such that torque and thrust are transferred, while allowing rotor thrust vector tilting. A main swash plate controls rotor thrust vector direction. Pitch horns are coupled to the rotor blades and the main swash plate via pitch links such that swash plate inputs are communicated to the rotor blades. The pitch links are coupled at &ldquo;delta-3&rdquo; values that are not optimum. A feedback swash plate and feedback links receive disk tilting inputs from the rotor blades, and supply inputs to the main swash plate, which compensates for the less than optimum delta-3 coupling.

Coupled aircraft rotor system

Rotor blade stowing system for stowing rotor blades that conserves storage space without adding significant weight or cost to the aircraft. The system includes a rotary actuator disposed on a blade grip member. A rotor blade is pivotally connected to the blade grip member. The rotary actuator is operably coupled to a blade pivoting cam and a locking cam. The system includes a cam follower linkage which has a first end which includes a blade pivoting cam follower and a locking cam follower and a second end. The blade pivoting cam follower follows the blade pivoting cam. The locking cam follower follows the locking cam. The second end of the cam follower linkage is coupled to the blade grip member. The system includes a shaft rotatably coupled to the blade grip member, a locking linkage bell crank operably coupled to the shaft, a delay cam coupled to the blade grip member, and a locking linkage idler operably coupled to the locking linkage bell crank. The locking linkage idler includes a delay cam follower that follows the delay cam. The system includes a locking linkage which has a first end coupled to the locking cam and a second end coupled to the locking linkage idler.

Rotor blade stowing system

A vibration absorber having a mass member which when static is supported by in-plane springs spaced apart from a base plate, top plate and spring retaining structures. The mass member has a bumper surface for contacting a motion limiter in the base plate. The mass member, base plate and top plate can have a passageway through the axis. The vibration absorber can be tuned by proper selection of the springs, degree of precompression and the variation of the amount of mass by the addition or removal of mass tuning weights.

Rotor system vibration absorber

An improved feathering flexure for a helicopter rotor system yoke includes, in transverse cross section, a relatively thin central web and six relatively thin flanges. Three flanges extend from each of the web's two edges, and the flanges lie in planes which are approximately radial relative to the neutral feathering axis of the feathering flexure. The feathering flexure is constructed of fiberglass material embedded in a polymer matrix. The web's fiberglass material in the web is bias material, that is, material whose glass fibers are oriented at plus or minus 45 degrees relative to the yoke's spanwise axis. In transverse cross section, each of the flanges includes two unidirectional belts disposed on either side of a bias pack. The glass fibers in the unidirectional belts are oriented parallel to the yoke's spanwise axis. The fiberglass material in the bias packs is bias material. Each flange's unidirectional belts taper inwardly toward its bias pack adjacent to web, thereby decreasing the thickness of the flange adjacent to the web. In addition, the portion of each flange adjacent to the web is configured to minimize torsional rigidity and shear stress resulting from twisting the feathering flexure.

Yoke for helicopter rotor systems

A composite rotor blade comprising an outboard portion defining an airfoil surface, an inboard portion defining an end tang having a mounting section and an extension lug section. The mounting section of the end tang having at least one mounting aperture with an axis parallel to the chordline of the airfoil for mounting of the blade, and the extension lug section having at least one extension lug extending inboard of the mounting aperture to provide a lever surface for interaction with suitable mounting mechanisms.

Rotor blade

Folding and folding locking apparatus for rotor blades that includes a power actuator for rotating the blades and locking means for securing the blade in the deployed position and securing the blades against rotation of the pitch angle during and when the blades are folded. The apparatus also provides for the complete fairing of the blades at their connections with the rotary drive hub and provides a powered door in the fairing that can be opened and closed to permit the quick and easy folding and redeployment of the blades.

Apparatus and method for folding and locking rotor blades

This invention relates to helicopter rotors and more particularly to rotor mounting involving a composite fiber-reinforced unitary yoke with resilient inplane restraints.

Soft inplane bearingless helicopter rotor

A helicopter tail rotor structure includes a thin, flat, tension-bearing strap of fibers extending spanwise, and is to be centrally secured by a hub to a helicopter tail mast. Flex sections are formed inboard of substantially equally divided portions of said fibers which extend as top and bottom blade spars from the outboard margins of the flex sections. Preferably, the planes of the flex sections and the planes of the spars are oriented at predetermined nose-up twist angles, one relative to the other.

Bearingless tail rotor for helicopters

A tail rotor blade for a helicopter has a core 22 whose shape defines the trailing portions of the blade. Core 22 is adhered to upper 20 and lower 21 metallic skins which extend within and are adhered to the inner surfaces at the trailing edge of a metallic nose spar 10. A pair of straps 30, 31 of unidirectional fiberglass strands extend spanwise and are adhered to the inner surface of the leading edges of the skins 20, 21 and the outer leading surfaces of the core 22 as to span chordwise the regions of the joints between nose spar 10 and skins 20, 21.

Tail rotor blade

A helicopter rotor hub assembly (10) in which a blade grip (30) extends inboard of a yoke (14) and transfers centrifugal forces to the yoke (14) through a spherical elastomeric bearing (38). Pitch change of the grip (30) and blade (32) is accommodated by the spherical elastomeric bearing (38) which also acts as the pivot point for lead-lag motion of the blade (32) and grip (30). A lead-lag damper (22) is located inboard of the elastomeric bearing (38) and is connected between one end of the grip (30) spaced away from the lead-lag pivot and the yoke (14) for damping the lead-lag motion between the grip (30) and yoke (14).

Soft inplane helicopter rotor

An apparatus is disclosed for folding a helicopter rotor blade (16) for storage. The blade (16) is secured to a grip (12) by blade bolts (18, 20) which are locked in place by a latch plate (22). Each bolt (18, 20) has an annular groove (30, 31) in which is mated a corresponding aperture (42, 46) in the latch plate (22). To fold the blade (16) the latch plate (22) is translated against the tension of spring (24) to expose a blade bolt (18) to an enlarged aperture (40). This bolt (18) can then be removed to permit pivoting of the blade (16) about the remaining bolt (20). To further secure the latch plate (22), a cap (54) is provided to lock the latch plate (22) to the blade bolt (18).

Helicopter blade folding system

A helicopter main rotor blade having a metallic nose spar extending the length of the leading edge of the blade and a trailing edge skin attached to the nose spar. A closure channel fixed within the nose spar extends the length thereof with unidirectional fiberglass material fixed to and extending along the length of the closure channel. A bushing on the inboard end of the blade preferably is attached both to the nose spar and the fiberglass bands for transfer of centrifugal forces in the blade to a grip.

Helicopter blade structure

A composite rotor blade has a nose spar of fiber reinforced plastic with the fibers extending spanwise the length of the spar and at the root encircling a transverse hub attachment structure with the spar provided with a tubular inner liner of cross ply filament wound fiberglass forming a closure for the nose spar with a blad afterbody structure including skins for integrating the afterbody with the nose spar and liner. Preferably the spar has an inner liner and an outer liner both of cross ply filament wound fiberglass in multi layers. The blade afterbody structure includes honeycomb filler having cells extending in the direction of blade thickness.

Composite rotor blade

A grip-yoke assembly for attaching a helicopter blade to the mast of the helicopter rotor having a conventional primary coupling to carry the centrifugal loads and a redundant path operative should the primary coupling fail to insure continued operability of the blade. In one embodiment, the redundant load path has a bearing surface formed on the inboard end of the grip and a corresponding thrust bearing mounted on an inboard yoke fitting for engagement with the bearing surface upon failure of the coupling. In an alternative embodiment, a bearing surface is formed on an outboard grip fitting and a corresponding thrust bearing is supported on the yoke outboard of the grip fitting.

Growing community of inventors

Hurst, TX, United States of America

Cecil E Covington