Patent US3885887A successfully refreshed from Google Patents.
US3885887A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flexure for bearingless rotor
Assignee: Boeing Co
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Filing: 1973-12-05
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Granted: 1975-05-27
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Expires: 1993-12-05
Abstract
Abstract A flexure is provided for bearingless rotors wherein the effective hinge about which rotor blade flapping and lead lap motion occurs may be located at a point less than eight percent of the rotor radius. The flexure is made of three tubular stages connected in series and in an overlapping manner. The first stage is connected to the rotor hub, the second stage is cantilevered inward towards the center of the rotor hub and is connected to the outboard end of the first stage. The third stage is cantilevered outward from the inboard end of the second stage. The rotor blade forms a part of, or is rigidly connected to, the outboard end of the third stage. Each stage bears a concentric relationship to the other stages. The flexure provides a high degree of flexibility compared to other means for connecting a rotor blade to a hub.
Inventors
- 👤 Rene A Desjardins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:59
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/32; B64C27/33; B64C27/37; B64C27/45
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
170 words
In a rotor for a rotor craft having a rotor hub with a rotor blade mounted thereto, a flexure for mounting the rotor blade to the rotor hub so as to permit flapping, lead lag and pitch, which comprises: a tubular first stage having one end thereof rigidly connected to the rotor hub extending radially therefrom; a tubular second stage having one end thereof rigidly connected to the remaining end of said first stage, oriented concentrically about said first stage and extending radially toward the hub; a tubular third stage having one end thereof mounted to the remaining end of said second stage so that axial movement therebetween may take place, said third stage mounted concentrically about said second stage, the remaining end of said third stage rigidly connected to the rotor blade; and a tension-torsion strap mounted concentrically within said first stage connected at one end to the rotor hub and connected at the other end to the rotor blade for restraining axial movement and bearing tension loads therebetween.
Claim 2
Dependent Claim
170 words
In a rotor for a rotor craft having a rotor hub with a rotor blade mounted thereto, a flexure for mounting the rotor blade to the rotor hub so as to permit flapping, lead lag and pitch, which comprises: a tubular first stage having one end thereof rigidly connected to the rotor hub extending radially therefrom; a tubular second stage having one end thereof rigidly connected to the remaining end of said first stage, oriented concentrically about said first stage and extending radially toward the hub; a tubular third stage having one end thereof mounted to the remaining end of said second stage so that axial movement therebetween may take place, said third stage mounted concentrically about said second stage, the remaining end of said third stage rigidly connected to the rotor blade; and a tension-torsion strap mounted concentrically within said first stage connected at one end to the rotor hub and connected at the other end to the rotor blade for restraining axial movement and bearing tension loads therebetween.
Claim 3
Dependent Claim
28 words
The flexure of claim 1 which further includes an elastomeric bearing connected to said second stage and to said third stage so as to permit axial movement therebetween.
Claim 4
Dependent Claim
41 words
The flexure of claim 1 which further includes a viscous fluid interposed in the chambers formed within said first stage, between said first stage and said second stage, and between said second stage and said third stage whereby damping is provided.
Claim 5
Dependent Claim
26 words
The flexure of claim 1 which further includes a bearing assembly interposed between said second stage and said third stage so as to permit rotation therebetween.
Claim 6
Dependent Claim
174 words
In a rotor for a rotor craft having a rotor hub with a rotor blade mounted thereto, a flexure for mounting the rotor blade to the rotor hub so as to permit flapping, lead lag and pitch, which comprises: a tubular third stage having one end thereof rigidly connected to the rotor blade extending radially therefrom; a tubular second stage having one end thereof rigidly connected to the remaining end of said third stage so that axial movement therebetween may take place, said second stage mounted concentrically about said third stage and extending radially away from the hub; a tubular first stage having one end thereof mounted to the remaining end of said second stage said first stage mounted concentrically about said second stage, the remaining end of said first stage rigidly connected to the rotor hub; and a tension-torsion strap mounted concentrically within said third stage connected at one end to the rotor hub and connected at the other end to the rotor bladE for restraining axial movement and bearing tension loads therebetween.
Claim 7
Dependent Claim
174 words
In a rotor for a rotor craft having a rotor hub with a rotor blade mounted thereto, a flexure for mounting the rotor blade to the rotor hub so as to permit flapping, lead lag and pitch, which comprises: a tubular third stage having one end thereof rigidly connected to the rotor blade extending radially therefrom; a tubular second stage having one end thereof rigidly connected to the remaining end of said third stage so that axial movement therebetween may take place, said second stage mounted concentrically about said third stage and extending radially away from the hub; a tubular first stage having one end thereof mounted to the remaining end of said second stage said first stage mounted concentrically about said second stage, the remaining end of said first stage rigidly connected to the rotor hub; and a tension-torsion strap mounted concentrically within said third stage connected at one end to the rotor hub and connected at the other end to the rotor bladE for restraining axial movement and bearing tension loads therebetween.
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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) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |