United Technologies Corporation

US Government As Represented by the Secretary of the Army

USA As Represented by Secretary of the Navy

Donald L Ferris

Peter C Ogle

Francis E Byrnes

William L Noehren

Eric G Olsen

Edward S Hibyan

David G Matuska

Robert C Rybicki

Robert L Faiz

Michael J Marchitto

Thomas G Campbell

Charles F Niebanck

Elliot F Olster

Lawrence Nicholas Varholak, Jr

Johnny P Gendreau

Herbert Heise

George A Smith

Alexander Korzun

A major design consideration in helicopters is that of compensating for ssses on blades resulting from air forces during blade revolutions. Spinning rotor blades are severely stressed. To some degree conventional articulated helicopter rotor hubs overcome vibration difficulties, but high maintenance is a problem. Hingeless helicopter rotor assemblies, generally employing composite materials, were developed to overcome these obstacles. Such hingeless helicopter rotor assemblies usually include a rigid central hub member, and radial flexbeams rigidly attached to the hub member. Flexbeam rotors do not completely eliminate the dynamic instability difficulty. Even using these designs energy must be absorbed by damping means. The shear principle of damping is utilized in this invention.

Apparatus for damping helicopter rotor blade oscillations

A helicopter composite swashplate ring that has a triaxial braided tubular ring that withstands both forces in-plane and normal to the plane of the swashplate. The triaxial braided tubular ring comprises substantially circumferential fibers interwoven with angled fibers oriented at a predetermined angle to the circumferential fibers. The tubular ring contains a composite circumferential spacer ring that comprises an upper ring plate connected to a lower ring plate by a plurality of first tubular support members. The upper ring plate and lower ring plate are adjacent the inside upper and insider lower surfaces of the tubular ring, respectively. The upper and lower plates have openings in alignment with the first tubular support members. The ring plates have a plurality of sections extending radially outward. The sections have lug openings that are in alignment with a plurality of second vertical support members to form channels therethrough for accepting servo or control rod lugs.

Composite helicopter swashplate

A fiber reinforced braided composite main helicopter rotor hub retention plate whose fiber orientation withstands forces both in the plane of the retention plate and normal to the plane. The retention plate comprises a fiber reinforced resin braided tubular ring having substantially circumferential fibers interwoven with angled fibers disposed about a central core. Arms extend inward from the braided ring for attachment to a driveshaft.

Composite helicopter rotor hub

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

Links (48-50) tangential to the rotorshaft (30) and connected to the inner swashplate ring (38) center the swashplate and restrain it from rotating (in the case of a stationary inner ring) by attachment to gearbox lugs (34-36), or drive it in unison with the rotorshaft (in the case of a rotating inner ring) by attachment to rotorshaft flanges. Spherical (rod-end) bearings (52-54, 56-58) so that the links can accommodate collective and cyclic swashplate attitude changes by moving out of plane. Links (70-72) tangential to the outer swashplate ring (64) and connected thereto and to the airframe (74) perform a similar function in restraining, centering and allowing for collective/cyclic movement of a stationary outer swashplate ring.

Tangential link swashplate centering member

The tiltwise stiffness of an axially-lobed, nearly-spherical elastomeric joint is made uniform at all azimuths by contouring the axial height of the elastomer or by reducing the thickness or durometer of the elastomer at azimuths where the joint otherwise would be tiltwise stiffer, such as at the lobes. The improvement is useful in the application of the joint to a gimbal-like rotor system.

Tailoring tilt in an elastomeric high torque, constant velocity joint

A threadless retention apparatus holds a spindle (2) against a bearing (22) in a helicopter hub and has a split ring (10) mating with an annular spindle groove (4) and a loading hoop (32) holding the ring (10) within the groove (4), the loading hoop (32) locating the ring (10) and spindle (2) in relation to the bearing (10) as a unit.

Helicopter rotor spindle retention assembly

Apparatus for damping blade lead/lag motion on a hingeless helicopter rotor assembly, including a hub, blades and flexbeam(s) interposed between the root end of the blades and the hub. Rigid, radial links extend the length of the flexbeams for attachment to the outboard ends thereof. Lead/lag motion at the outboard end of the flexbeam causes flexbeam bending, which is converted to radial translation of the links. This radial translation of the links and likewise the blade lead/lag motion is damped by damper means connected between the inboard ends of the links and the hub.

Tension/compression rod arrangement for damping helicopter rotor blade

Centering and stabilizing against rotation of a helicopter swashplate stationary ring are provided by spokes that are attached between the airframe and the stationary ring. When the swashplate tilts for cyclic control, the spokes bend and twist. When the swashplate translates for collective control, the spokes are required to lengthen and skew with respect to the swashplate. An elastomeric bearing having a cylindrical component to allow for skew and a shear pad to allow for lengthening attaches each spoke to the swashplate. The invention eliminates the need for the ball joint, standpipe and scissors associated with traditional swashplate centering techniques.

Flexible swashplate centering member

The axial load-carrying ability of an axially-lobed, nearly-spherical elastomeric joint is enhanced by offsetting the elastomer layers so that there is more elastomer to react the load in compression. The improvement is useful in the application of the joint to a gimbal-like rotor system.

Accommodating axial load in an elastomeric high torque, constant

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 helicopter rotor blade to hub arm attachment configured to react centrifugal loads from the blade through a blade cuff, spindle, and elastomeric bearings utilizes a bolt in the bore of the spindle for secondary load path operation and a spindle integrity monitoring indicator to provide a visual showing of a deviation from the normal load path.

Rotor blade shaft integrity monitoring system

A helicopter rotor blade to hub arm attachment configured to react centrifugal loads from the blade through a blade cuff, spindle, and elastomeric bearings utilizes a pre-loaded bolt through the spindle for load sharing therewith and a spindle integrity monitoring indicator to provide a visual showing of a deviation from the normal load sharing proportion.

An improved droop stop for a fully articulated helicopter rotor is provided herein curved mating surfaces are employed between the spindle pad and the centrifugal droop stop static support arm to provide surface rather than line contact therebetween during centrifugal operation. The centers of the curved surfaces are coincident at the pivot point of the droop stop centrifugal arm to force the downward load of the blade to pass through this pivot point.

Droop stop for fully articulated rotor

A helicopter rotor having an even number of articulated blades wherein opposing blades are interconnected by a common spar passing across the rotor axis. Pitch change is introduced to the blade at the spar-blade attachment joint through a torque member connected at its outboard end to the blade joint and including a control horn at its inner end to receive pitch inputs. Drive for the rotor and support for each blade is provided by a spherical bearing directly connecting the torque member to the blade associated hub arm.

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Newtown, CT, United States of America

Donald L Ferris