Bell Helicopter Textron Inc.

Ajay Sehgal

Eric Charles Boyle

Cecil E Covington

Bryan W Marshall

Ernest A Powell

Frank B Stamps

Michael Reaugh Smith

Patrick R Tisdale

Glenn Alan Shimek

Robert Shawn Thompson

Mithat Yuce

David Allen Haynie

Timothy Kent Ledbetter

Joseph J Zierer

Madison K Robinson

Norman Kuhns

Christopher Finch

Peggy Covington, Legal Representative

Glen A Shimek

Michael R Smith

Christopher O Finch

A rotor system vibration absorber for use with a helicopter of other rotorcraft is disclosed in which spring forces are provided by a plurality of elongated rods arranged in a selected pattern. The rods are coupled at one end to a fixed base that is coupled to a rotor hub, and at the other end to a tuning weight.

Rotor system vibration absorber

A helicopter main rotor blade balance weight retention system and assembly having a base plate (), at least one support post () integral with the base plate and extending out perpendicularly from the base plate, a plurality of balance weights (), a retaining nut plate (), and one or more fastening bolts () for securing the balance weights to the base plate, and the base plate to the rotor blade. The balance weights () include apertures () through which the support posts and the fastening bolts pass. The apertures through which the support posts pass are dimensioned such that the a snug fit is formed between the support posts and the balance weight; but the apertures through which the fastening bolts pass are dimensioned such that the threaded portions of the fastening bolts are not subjected to any shear loads from the balance weights due to the centrifugal force generated by the rotating rotor blades. The weight retention assembly is installed into pockets in the blade tip.

Helicopter main rotor blade balance weight retention assembly

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 present invention comprises a rotor blade and method of manufacture thereof. The rotor blade of the present invention incorporates a number of novel features in order to increase its reliability and strength while reducing its weight. In certain embodiments, the rotor blade of the present invention incorporates a flexural strap in place of traditional pitch bearings. In certain embodiments, the rotor blade of the present invention is manufactured using a unique fiber placement layup technique to reduce failure modes and maximize the fatigue strength of the part.

Composite rotor blade and method of manufacture

The present invention comprises an apparatus for mounting two or more tail rotor hubs to a tail rotor mast. The apparatus comprises a mast having an externally-splined inboard section shaped and sized to mate with an internal spline on an inboard trunnion. The inboard trunnion is mechanically fixed to the one or more outboard hubs via a torsionally-rigid connection. The outboard portion of the mast is designed to have reduced torsional stiffness, so that torque is transmitted to the outboard trunnions through the inboard trunnion rather than through the mast.

Dual trunnion hub-to-mast assembly

Tail rotor yoke assembly

Pitch change adapter for a helicopter main rotor 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.

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

Growing community of inventors

Leonardtown, MD, United States of America

Ajay Sehgal