United Technologies Corporation

USA as Represented by Secretary of the Navy

Edward S Hibyan

Francis E Byrnes

Peter C Ogle

William L Noehren

Thomas J Toner

Donald L Ferris

George J Wehnert

Robert L Faiz

Albert T Krauss

An articulated helicopter rotor wherein the blade-to-hub connection consists of a spherical elastomeric bearing connected to the hub and a composite yoke connected thereto in series and consisting of a plurality of unidirectional high strength fibers bonded together to form a continuous strap which passes through a central opening in the elastomeric bearing and is pin-wrap connected to the hub at a single station and to the blade at two spaced stations produces a construction which is light in weight, easy to manufacture, ballistrically tolerant, redundant, and readily visually inspectable for structural integrity.

Articulated helicopter rotor within an improved blade-to-hub connection

A swashplate configuration for helicopter which eliminates the need for scissors linkages through the use of a centering member capable of tilt and axial translation while driving torque to the rotating swashplate member through the use of elastomeric bearing assemblies each consisting of a first stack of flat laminates and a second stack of spherical laminates.

Elastomeric swashplate configuration for helicopters

A tail rotor flapping hinge elastomeric bearing in which the inner and outer races are split and the races have ramped surfaces with the higher slope of the inner races being toward the outer edge of the bearing. The races have a plurality of slope angles and each inner race having a groove therein to facilitate a method of preloading.

Preloaded tunable elastomeric flapping hinge bearing and method of

The lag-torsion flexure portion (16) of a flexbeam (10) having segregated lag-torsion flexure portions (16) and flap flexure portions has multiple longitudinal lobes (98A-98G, 100A-100G) formed by multiple grooves (90A-90F, 92A-92F) extending from the upper (94) and lower (96) surfaces of the lag-torsion flexure portion to a central planar portion (102) thereof. The bases of the grooves are radiused (r) for favorable stress distribution while allowing for torsional and lead/lag softness in the lag-torsion flexure portion. The preferred number of grooves is an even number, such as six, resulting in an odd number of lobes. The lobes may decrease in height from the central lobe to the edgemost lobes (FIG. 12A). The lobes may be radiused at the upper and lower surfaces of the lag-torsion flexure portions (FIG. 12B). The lobes may be formed of alternate layers of unidirectional longitudinal fiber (32) extending the length of the flexbeam and elastomeric material (112) (FIG. 12D). Furthermore, the central planar portion (102) of the lag-torsion flexure portion may include layers (110) of fibers laid up at an angle to the unidirectional longitudinal fibers (FIG. 12C).

Lobed composite flexbeam

A nearly spherical laminated elastomeric bearing has a non-circular latitudinal cross-section to accommodate high torque loads in elastomer bending rather than in shear. The nearly spherical profile of the bearing accommodates tilt primarily in shear. Both inwardly and outwardly extending lobes, or splines, are disclosed. The nearly spherical, lobed bearing is useful for a constant velocity joint.

Elastomeric high torque, constant velocity joint

A composite helicopter hub yoke is described. The yoke is made up of glass fibers unidirectionally oriented in the direction of principle stress, i.e. along the length of the yoke. The yoke also has clevis sections on either end and the clevis sections additionally contain multiaxially oriented multiple plies of unidirectionally oriented continuous graphite fibers interleaved with the unidirectionally oriented continuous glass fibers to produce crack resistance, damage tolerance, and integrity inspectability.

Fiber reinforced/epoxy matrix composite helicopter rotor yoke

A composite helicopter rotor hub is described having a composite retention plate, yokes and torque tubes. The retention plate is made up of graphite and glass fiber reinforced epoxy resin. The graphite fiber reinforcement is in-plane isotropically laid continuous graphite fibers and the glass fiber reinforcement comprises segments of fiberglass continuously and circumferentially wound around the areas of retention. The yoke is made up of glass fibers unidirectionally oriented in the direction of principle stress, i.e., along the length of the yoke. The yoke also has clevis sections on either end and the clevis sections additionally contain multiaxially oriented multiple plies of unidirectionally oriented continuous graphite fibers interleaved with the unidirectionally oriented continuous glass fibers. The torque tube contains upper and lower load bearing surfaces connected by two sidewall portions. Both the sidewall and load bearing portions contain filament wound glass fiber reinforced epoxy resin such fibers having a .+-.45.degree. orientation. The upper and lower load bearing portions additionally contain multiaxially oriented multiple plies of unidirectionally oriented continuous graphite fibers interleaved with the glass fibers. The particular materials selected combined in the unique manner described provide the individual components as well as the entire hub assembly with crack resistance, damage tolerance, light weight, strength and integrity inspectability.

Composite helicopter rotor hub

A composite torque tube for a helicopter rotor hub is described. The torque tube contains upper and lower load bearing surfaces connected by two sidewall portions. Both the sidewall and load bearing portions contain filament wound glass fiber reinforced epoxy resin such fibers having a .+-.45.degree. orientation. The upper and lower load bearing portions additionally contain a plurality of multiaxially oriented plies of continuous unidirectionally oriented graphite fibers interleaved with the glass fibers so as to produce a torque tube with crack resistance, damage tolerance, light weight, strength and integrity inspectability.

Fiber reinforced/epoxy matrix composite helicopter rotor torque tube

Apparatus for supporting the rotor blades of a helicopter is disclosed. Support in droop under both statically and dynamically loaded conditions is discussed. The droop stop mechanism 34 has low susceptibility to the deleterious effects of snow/ice or dirt contamination. The droop stop seat 42 is mounted for rotation in a corresponding receptacle 50 at the base of the rotor blade assembly 14 and is slidable between static stop and dynamic stop positions along the pitch axis of the blade to be supported.

Helicopter blade droop stop with slidable droop stop seat

An aerodynamic rotor having a flexible blade comprising a plurality of planar layers and an anvil having configured bearing areas engagable with the flexed blade is presented. The plurality of layers are slidably movable in a shearing motion with respect to other layers. The blade is secured by the anvil with the configured bearing areas being engagable with an adjacent portion of the blade when the blade is flexed by forces created by the driven rotory motion of the anvil about an axis of rotation. Such a rotor with a laminated blade exhibits reduced head moment forces and reduced stress/strain forces within the blade thereby permitting improved reliability and maintenance.

Anvil-strap rotor

A helicopter rotor having one or more blades mounted for rotation with the rotor hub and each supported therefrom by an elastomeric bearing, and having a lead-lag damper connected to the blade and the hub and extending substantially parallel to the blade axis, and including the improvement of apparatus for preventing tension loading of the elastomeric bearing as the blade moves radially inwardly as a result of rotor braking.

Elastomeric helicopter rotor load reaction system

A cross-beam helicopter rotor wherein the pitch actuator shaft passes through an elliptically shaped hole in the unidirectional, composite helicopter spar, each of selected dimension so that the stress concentration factor across the spar at the hole is minimized when the spar is carrying balanced centrifugal blade loads. The shaft also passes through a centering pin which is supported in the spar hole by an elliptically shaped plug of selected dimension so that when supported from the spar hole by elastomer of selected shape factor, durometer and dimension, the plug and pin are load isolated from the spar and the stress concentration factor across the spar at the hole is substantially unchanged from that of the unplugged hole both during balanced and unbalanced centrifugal blade load operation of the spar, and so that the elastomer transmits unbalanced centrifugal blade loads therethrough from the spar to the plug and pin for centering the rotor.

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Trumbull, CT, United States of America

Edward S Hibyan