Composite flexure for tiltrotor rotor system

• US 9,499,262 B2
• Filed: 08/02/2013
• Issued: 11/22/2016
• Est. Priority Date: 08/02/2013
• Status: Active Grant

• Current Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Original Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Inventors: Foskey, Christopher, Stamps, Frank B., McIntyre, Joel, Miller, Gary
• Primary Examiner(s): Sanderson, Joseph W
• Application Number:
  US13/958,192
• Publication Number:
  US 20150034772A1
• Time in Patent Office: 1,208 Days
• US Class Current: 1/1
• CPC Class Codes: B64C 27/33 having flexing arms
• CPC Class Codes: B64C 27/48 Root attachment to rotor head
• CPC Class Codes: B64C 29/0033 the propellers being tiltable relative to the fuselage

Abstract

A composite flexure that secures a rotor blade to a gimbaled yoke in a tiltrotor rotor system. The composite flexure includes a composite flexure member, a first end, and a second end. The first end of the composite flexure couples the composite flexure to the gimbaled yoke, and the second end of the composite flexure couples the composite flexure to the rotor blade. The composite flexure is twisted when the composite flexure is not subject to torsional loads in order to accommodate various forces imparted on the rotor system.

Claims

1. A tiltrotor aircraft, comprising:

a body;

a wing member;

a power train coupled to the body and comprising a power source and a drive shaft in mechanical communication with the power source; and

a rotor system coupled to the wing member and in mechanical communication with the drive shaft, at least part of the rotor system being tiltable between a helicopter mode position and an airplane mode position, the rotor system comprising;

a gimbaled yoke in mechanical communication with the drive shaft;

a rotor blade having a single, uninterrupted blade body extending from a root end to a tip end and having a hollow cavity therein, the hollow cavity having an open end and a closed end opposite the open end, the rotor blade comprising the root end and an attachment location disposed within the hollow cavity and located outboard of the root end, the rotor blade being twisted such that an angular difference exists between the chord of the rotor blade at the root end and the chord of the rotor blade at the attachment location; and

a composite flexure comprising a composite member disposed completely within the hollow cavity of the rotor blade, the composite flexure coupled to the gimbaled yoke at a first end and coupled to the rotor blade at a second end, wherein a first attachment plane associated with the first end is angled relative to a second attachment plane associated with the second end such that the composite member is twisted at a composite-flexure twist angle between the first end and the second end when the composite flexure is not subject to torsional loads, the composite-flexure twist angle between the first end and the second end corresponding to the angular difference between the chord of the rotor blade at the root end and the chord of the rotor blade at the attachment location.

2. The tiltrotor aircraft of claim 1, the composite flexure comprising a matrix material and a reinforcement material.

3. The tiltrotor aircraft of claim 2, wherein the reinforcement material comprises at least one layer of reinforcement material providing axial stiffness to the composite flexure.

4. The tiltrotor aircraft of claim 2, wherein the reinforcement material comprises a plurality of reinforcement layers configured to provide torsional flexibility to the composite flexure such that at least part of the composite flexure may twist in response to feathering of the rotor blade.

5. The tiltrotor aircraft of claim 2, wherein the reinforcement material comprises a plurality of reinforcement layers configured to provide bending flexibility to the composite flexure such that at least part of the composite flexure may bend in response to coning or flapping of the rotor blade.

6. The tiltrotor aircraft of claim 2, wherein the reinforcement material comprises a plurality of reinforcement layers configured to provide bending flexibility to the composite flexure such that at least part of the composite flexure may bend in response to leading or lagging of the rotor blade.

7. The tiltrotor aircraft of claim 1, wherein the composite flexure comprises first and second composite flexure members, each composite flexure member coupled to the gimbaled yoke at respective first ends and coupled to the rotor blade at respective second ends.

8. The tiltrotor aircraft of claim 7, wherein both the first and second composite flexure members feature respective twisted body portions.

9. The tiltrotor aircraft of claim 1, wherein the gimbaled yoke and the composite flexure are of the same integral composite structure.

10. The tiltrotor aircraft of claim 1, wherein the rotor blade and the composite flexure are of the same integral composite structure.

11. The tiltrotor aircraft of claim 1, wherein the composite flexure is coupled to the rotor blade at a position in an interior portion of the rotor blade.

12. The tiltrotor aircraft of claim 11, wherein the position is a location in the rotor blade designed to have the lowest chordwise loads.

13. The tiltrotor aircraft of claim 1, wherein the rotor system further comprises:

a second rotor blade;

a second composite flexure coupled to the gimbaled yoke at a first end and coupled to the second rotor blade at a second end;

a third rotor blade;

a third composite flexure coupled to the gimbaled yoke at a first end and coupled to the third rotor blade at a second end;

a fourth rotor blade; and

a fourth composite flexure coupled to the gimbaled yoke at a first end and coupled to the fourth rotor blade at a second end.

14. The tiltrotor aircraft of claim 1, wherein the composite flexure is removably coupled to the gimbaled yoke.