Tail rotor integrated damper attachment

Patent metadata

Field	Value
Publication number	US-10689104-B2
Application number	US-201715590736-A
Country	US
Kind code	B2
Filing date	May 9, 2017
Priority date	May 9, 2017
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

A system and method for attaching a damper to a tail rotor blade includes a cuff that is integral with the rotor blade. The cuff has upper and lower lugs formed by extending a skin over a blade core of the rotor blade. The skin extends past the blade core to the root end of the rotor blade. The rod end of the damper is inserted into an opening between the lugs. The rod end of the damper is coupled to the blade with a bolt through aligned holes in the lugs. The cuff also couples the rotor blade to the grip inside the cuff. The cuff includes a same material as that forming the skin. Sacrificial buffer pads are applied to interior faces of the lugs. The buffer pads permit a distance between the lugs to be machined within a tolerance without removing skin from the cuff.

First claim

What is claimed is:

1. A device comprising:
a rotor blade comprising:
a blade core having a root end and a tip end opposite the root end, the blade core having an upper surface and a lower surface opposite the upper surface, the upper surface and the lower surface extending between the root end and the tip end; and
a material covering the upper surface and the lower surface, the material extending outwards away from the blade core past the root end, wherein the material covering the upper surface of the blade core comprises an upper skin, and the material covering the lower surface of the blade core comprises a lower skin;
wherein the material extending outwards away from the blade core forms a cuff that is integral with the upper surface and the lower surface, wherein the cuff has an upper side and a lower side, and wherein the cuff further has an opening between the upper side and the lower side, and wherein the upper side of the cuff has an upper lug disposed beyond the root end of the blade core, wherein the lower side of the cuff has a lower lug disposed beyond the root end of the blade core, wherein the upper lug is formed from an extension of the upper skin beyond the root end of the blade core, and wherein the lower lug is formed from an extension of the lower skin beyond the root end of the blade core;

wherein the cuff is configured to receive a first end of a damper inside the cuff between the upper lug and the lower lug, and wherein the opening has a width configured to accept the first end of the damper;
wherein the upper lug has a first hole extending therethrough to the opening, and wherein the lower lug has a second hole extending therethrough to the opening, wherein the first hole is disposed across the opening from, and is aligned with, second hole, and wherein the first hole and the second hole have substantially same diameters; and
wherein the cuff is configured to accept attachment of the first end of the damper between the upper lug and the lower lug by a bolt disposed in the cuff through the first hole and the second hole and extending through the first hole, through a third hole in the first end of the damper and through the second hole, and wherein the first end of the damper is an outboard rod end of the damper, the damper having the third hole through the outboard rod end.

2. The device of claim 1 , wherein the rotor blade is configured to be installed in a tail rotor assembly of a rotorcraft, and the tail rotor assembly comprises an articulated tail rotor hub and the rotor blade, wherein the cuff is further configured to connect the rotor blade to the articulated tail rotor hub.

3. The device of claim 1 , wherein the cuff provides a fail-safe failure mode for operating the damper with the rotor blade, the fail-safe failure mode is configured to provide visible indications of fatigue, stress, or wear on the cuff prior to the material experiencing a structural failure.

4. The device of claim 3 , wherein the material is a composite material comprising at least one of fiberglass and carbon fiber, and the visible indications of fatigue, stress, or wear include delamination of the composite material from an outer surface portion of the cuff.

5. The device of claim 1 , wherein the upper lug includes a flange bushing bonded to an interior of the first hole, and the lower lug includes a flange bushing bonded to an interior of the second hole.

6. The device of claim 1 , wherein the rotor blade further comprises:
an upper outer buffer pad bonded to an upper surface of the upper lug;
an upper inner buffer pad bonded to a lower surface of the upper lug, the upper inner buffer pad positioned opposite the upper outer buffer pad across the periphery of the upper lug;
a lower inner buffer pad bonded to an upper surface of the lower lug, the upper surface of the lower lug facing the lower surface of the upper lug across the opening; and
a lower outer buffer pad bonded to a lower surface of the lower lug, the lower outer buffer pad positioned opposite the lower inner buffer pad across the periphery of the lower lug,
wherein the upper outer buffer pad and the upper inner buffer pad are positioned in an area of the upper skin forming the upper lug, for forming the first hole through the upper outer buffer pad, the periphery of the upper lug, and the upper inner buffer pad,
wherein the lower outer buffer pad and the lower inner buffer pad are positioned in an area of the lower skin forming the lower lug, for forming the second hole through the lower inner buffer pad, the periphery of the lower lug, and the lower outer buffer pad,
wherein the upper outer buffer pad, the upper inner buffer pad, the lower inner buffer pad and the lower outer buffer pad comprise a sacrificial fiberglass material that is at least partially removed from at least one of the upper outer buffer pad, the upper inner buffer pad, the lower inner buffer pad and the lower outer buffer pad, by at least one of a machining an outer surface of the cuff within a first tolerance and machining a distance across the opening with a second tolerance, and
wherein the distance across the opening is machined within a second tolerance suitable for disposing the first end of the damper in the cuff.

7. The device of claim 1 , wherein the third hole is offset from an axis extending from the first hole through the second hole.

8. The device of claim 1 , wherein the damper is a lead-lag damper.

9. A rotor assembly comprising:
a mast having a principal axis, the mast being configured to rotate around the principal axis;
a yoke splined to the mast, the yoke being configured to rotate with a rotation of the mast;
a rotor blade configured to rotate with the yoke around the principal axis, the rotor blade having a tip end distally disposed from the yoke and a root end proximate the yoke;
a grip coupling the rotor blade to the yoke at a root end of the rotor blade;
a damper coupled to the yoke and the rotor blade; and
a first bolt and a second bolt;
wherein the rotor blade includes a blade core and a sleeve, the sleeve including a first portion surrounding the blade core, and the sleeve including a second portion extending past the blade core toward the root end of the rotor blade, the second portion forming a cuff that is integral with the rotor blade, and
wherein the cuff includes an upper tape lug and a lower tape lug, and wherein the cuff has an opening disposed between the upper tape lug and lower tape lug;
wherein flange bushings are disposed at the upper tape lug and the lower tape lug, and wherein the second bolt extends through the flange bushings;
wherein a first end of the grip extends into the opening and the first bolt extends between the upper tape lug and the lower tape lug and attaches the first end of the grip to the rotor blade; and
wherein an end of the damper extends into the opening and the second bolt extends between the upper tape lug and the lower tape lug and attaches the end of the damper to the rotor blade.

10. The rotor assembly of claim 9 , wherein the bushings are affixed, with an adhesive, to interior surfaces of holes in the upper tape lug and lower tape lug.

11. The rotor assembly of claim 9 , wherein the end of the damper that extends into the opening is an outboard rod end of the damper.

12. The rotor assembly of claim 9 , wherein the damper is a lead-lag damper.

13. A method comprising:
bonding an upper skin of a rotor blade onto an upper surface of a blade core of the rotor blade, the upper skin comprising a first composite material, a first portion of the upper skin extending away from a root end of the blade core, the first portion forming an up

Assignees

• Textron Innovations Inc

Inventors

• Shimek Glenn Alan
• Green Nathan Patrick
• Self Robert Alan
• Wiinikka Mark Adam

Classifications

• B64C27/48

  Root attachment to rotor head · CPC title

• B64C2027/4736

  from composite materials · CPC title

• B64C27/473

  Constructional features · CPC title

• B29L2031/082

  Blades, e.g. for helicopters · CPC title

• B64C27/54

  Mechanisms for controlling blade adjustment or movement relative to rotor head, e.g. lag-lead movement · CPC title