Patent US3774867A successfully refreshed from Google Patents.
US3774867A
Expired / Lapsed
US
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Acoustic wing stall delaying device
Assignee: United States Department of the Air Force
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Filing: 1972-06-27
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Granted: 1973-11-27
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Expires: 1992-06-27
Abstract
Abstract An apparatus for delaying the onset of wing stall in an aircraft having a plurality of acoustic resonators positioned in the forward portion of the upper surface of the wing with a movable panel to close the resonator cavities during normal flight. The movable panels partially expose the resonator cavities to provide orifices which generate the desired acoustic signal of approximately the same frequency as in the flow field.
Inventors
- 👤 B Quinn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:52
CPC Classifications
B; B64; B64C; B64C21/00; B64C21/02; B64C2230/00; B64C2230/02; B64C2230/04; Y; Y02; Y02T; Y02T50/00; Y02T50/10
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
110 words
An airfoil for an aircraft, adapted to be moved through the air to provide an air flow over the surface of the airfoil, wherein the air stream, under stall conditions, forms a pocket of dead air adjacent the airfoil and wherein the interface between the dead air region and the freely flowing air stream oscillates at a frequency determined by the air flow and the size and shape of the airfoil, comprising: means for bathing the upper surface of the airfoil with an acoustic signal of a predetermined frequency corresponding to the frequency within said interface and means for selectively discontinuing the acoustic signal during normal flight of the aircraft.
Claim 2
Dependent Claim
110 words
An airfoil for an aircraft, adapted to be moved through the air to provide an air flow over the surface of the airfoil, wherein the air stream, under stall conditions, forms a pocket of dead air adjacent the airfoil and wherein the interface between the dead air region and the freely flowing air stream oscillates at a frequency determined by the air flow and the size and shape of the airfoil, comprising: means for bathing the upper surface of the airfoil with an acoustic signal of a predetermined frequency corresponding to the frequency within said interface and means for selectively discontinuing the acoustic signal during normal flight of the aircraft.
Claim 3
Dependent Claim
97 words
The device as recited in claim 1 wherein said means for bathing the upper surface of the airfoil with an acoustic signal of a predetermined frequency, comprises: a plurality of cavity resonator elements positioned in the upper surface of the airfoil forward of the point of maximum thickness; means for providing a predetermined orifice for said cavity resonator elements; said means for selectively discontinuing the acoustic signal, including the means for providing a predetermined orifice for the cavity resonator elements and for selectively closing the cavity resonator elements to provide a smooth upper surface for the airfoil.
Claim 4
Dependent Claim
44 words
The device as recited in claim 2 wherein the means for providing a predetermined orifice for the resonators includes a panel which is movable from a closed position completely covering the resonator to an open position which uncovers a predetermined portion of the resonator.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |