Patent FR1285569A successfully refreshed from Google Patents.
US4714409A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Helicopter rotor
Assignee: Westland Group PLC
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Filing: 1986-10-02
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Granted: 1987-12-22
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Expires: 2006-10-02
Abstract
Abstract A helicopter rotor includes a plurality of rotor blades attached to a rotor hub by flexure members adapted during operation to permit pitch changes and flap and lag movements of the rotor blades. Each flexure member comprises a plurality of longitudinally extending reinforcing plates which in cross section extend generally radially from a geometric center of the flexure member and are enclosed in a resilient matrix material.
Inventors
- 👤 Samuel J. M. Denison
- 👤 David P. Bashford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:12
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/32; B64C27/33
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
83 words
A helicopter rotor including a rotor hub for rotation about an axis and a plurality of radially extending rotor blades each attached to the hub by an elongated flexure member to permit pitch changes and flap and lag movements of the attached rotor blade, wherein each flexure member includes a plurality of longitudinally extending reinforcing plates which in cross section extend generally radially for 360° around a geometric centre of the flexure member, said reinforcing plates being enclosed in a resilient matrix material.
Claim 2
Dependent Claim
83 words
A helicopter rotor including a rotor hub for rotation about an axis and a plurality of radially extending rotor blades each attached to the hub by an elongated flexure member to permit pitch changes and flap and lag movements of the attached rotor blade, wherein each flexure member includes a plurality of longitudinally extending reinforcing plates which in cross section extend generally radially for 360° around a geometric centre of the flexure member, said reinforcing plates being enclosed in a resilient matrix material.
Claim 3
Dependent Claim
17 words
A rotor as claimed in claim 1, wherein said reinforcing plates are arranged in diametrically opposed pairs.
Claim 4
Dependent Claim
18 words
A rotor as claimed in claim 1, wherein said reinforcing plates are distributed uniformly around said geometric centre.
Claim 5
Dependent Claim
28 words
A rotor as claimed in claim 1, wherein reinforcing plate comprises a pre-cured fibre reinforced laminate including a plurality of pre-impregnated fibre layers embedded in a matrix material.
Claim 6
Dependent Claim
17 words
A rotor as claimed in claim 4, wherein the fibres of the fibre layers are unidirectional fibres.
Claim 7
Dependent Claim
39 words
A motor as claimed in claim 5, wherein the fibres of some layers extend generally parallel to the longitudinal axis of the reinforcing plate and the fibres of other layers extend at ±45 degrees to the longitudinally extending fibres.
Claim 8
Dependent Claim
18 words
A rotor as claimed in claim 4 wherein the reinforcing plate matrix material is a thermo-setting epoxy resin.
Claim 9
Dependent Claim
19 words
A rotor as claimed in claim 1, wherein each reinforcing plate tapers downwardly in thickness from an outer edge.
Claim 10
Dependent Claim
15 words
A rotor as claimed in claim 1, wherein the resilient matrix material comprises an elastomer.
Claim 11
Dependent Claim
33 words
A rotor as claimed in claim 1, wherein the flexure member is elliptical in cross section and arranged with the minor axis aligned with the direction of flap movement of the rotor blade.
Claim 12
Dependent Claim
31 words
A rotor as claimed in claim 10, wherein the flexure member is tapered with both the minor and major axes reducing dimensionally with increasing radial distance from the axis of rotation.
Claim 13
Dependent Claim
18 words
A rotor as claimed in claim 1, wherein the flexure member is formed integral with the rotor hub.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-21 | 1991-06-22 | 1991-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-21 | 1995-06-22 | 1995-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-21 | 1999-06-22 | 1999-12-22 | $7700.00 | Window Closed / Lapsed |