US3874820A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hingeless in-plane rotor blade design
Assignee: RTX Corp
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Filing: 1974-04-08
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Granted: 1975-04-01
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Expires: 1994-04-08
Abstract
Abstract A hingeless rotor wing system having a relatively stiff in-plane blade which has a one-piece spar of substantially rectangular cross section which is untwisted at the mean blade angle and airfoil defining structure surrounding the spar, the blade angle of the structure relative to the spar being preset to the mean operating angle of the blade in order to reduce the variation of the in-plane natural frequency during operation.
Inventors
- 👤 Ronald Raymond Fenaughty
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:57
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/32; B64C27/33; B64C27/46; B64C27/473; Y; Y10; Y10S; Y10S416/00; Y10S416/02
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
100 words
A hingeless rotor wing system including at least one rotor blade having an operating angle range extending from a minimum angle to a maximum angle, said blade having a spar extending over a majority of the blade span, controlling the primary blade vibration frequencies, said spar having a major axis, structural means surrounding said spar and defining an airfoil shape for said rotor blade, said structural means also having a major axis, the angular relationship of said spar major axis and said structural means major axis being substantially equivalent to the mean blade angle of said blade operating angle range.
Claim 2
Dependent Claim
100 words
A hingeless rotor wing system including at least one rotor blade having an operating angle range extending from a minimum angle to a maximum angle, said blade having a spar extending over a majority of the blade span, controlling the primary blade vibration frequencies, said spar having a major axis, structural means surrounding said spar and defining an airfoil shape for said rotor blade, said structural means also having a major axis, the angular relationship of said spar major axis and said structural means major axis being substantially equivalent to the mean blade angle of said blade operating angle range.
Claim 3
Dependent Claim
24 words
A rotor blade for a hingeless rotor wing system in accordance with claim 1 in which the spar is essentially of rectangular cross section.
Claim 4
Dependent Claim
32 words
A rotor blade for a hingeless rotor wing system in accordance with claim 2 in which upper and lower surfaces of the rectangular spar are bevelled to accommodate the surrounding structural means.
Claim 5
Dependent Claim
33 words
A rotor blade for a hingeless rotor wing system in accordance with claim 1 in which the blade is relatively stiff in-plane and relatively flexible in a plane perpendicular to the in-plane plane.
Claim 6
Dependent Claim
114 words
A rotor blade for a hingeless rotor wing system, said blade being relatively stiff about an axis perpendicular to the blade rotational plane and having an angular range of operation extending from a minimum angle to a maximum angle with respect to said rotational plane, a spar for said rotor having a major axis essentially parallel to the blade rotational plane, blade structural means surrounding said spar and defining an airfoil shape for said blade, said structural means also having a major axis, said structural means having an angular relationship with respect to said spar at at least one spanwise location along said blade equal to the mean angle of the range of operation.
Claim 7
Dependent Claim
114 words
A rotor blade for a hingeless rotor wing system, said blade being relatively stiff about an axis perpendicular to the blade rotational plane and having an angular range of operation extending from a minimum angle to a maximum angle with respect to said rotational plane, a spar for said rotor having a major axis essentially parallel to the blade rotational plane, blade structural means surrounding said spar and defining an airfoil shape for said blade, said structural means also having a major axis, said structural means having an angular relationship with respect to said spar at at least one spanwise location along said blade equal to the mean angle of the range of operation.
Claim 8
Dependent Claim
36 words
A rotor blade in accordance with claim 5 in which the angular relationship of the structural means to the spar is equal to the mean angle of the range of operation along the full blade span.
Claim 9
Dependent Claim
31 words
A rotor blade in accordance with claim 5 in which the blade structural means has an inboard edge to which means is connected for varying the operational angle of said blade.
References Cited (Backward Citations)
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Cited
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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) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |