Patent US3776170A successfully refreshed from Google Patents.
US3776170A
Expired / Lapsed
US
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Air foil with vortex generators
Assignee: Individual
•
Filing: 1973-02-23
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Granted: 1973-12-04
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Expires: 1993-02-23
Abstract
Abstract A sail is provided with short rows of closely spaced holes, with the axes of the rows converging and being inclined at an acute angle to the path of the free air past the sail. The converging ends of individual rows are relatively widely spaced and the rows are arranged in an array from the head to the foot of the sail. The angle between the axis of each row of holes and the direction of the free air flow path is alternated along the array from a positive to negative angle. The rows of holes, in turn, produce a row of discrete air jets on the convex, low pressure side of the sail, forming angled aerodynamic ''''fences.'''' These fences present a partial obstruction to the flow of the free air past the sail, causing the air to form twisted streams when spilling over the aerodynamic fences. These streams form continuous, helical trailing vortices that mix the free air stream with the slower moving boundary layer of air next to convex surface of the sail. The resulting mixing action continually re-energizes the boundary layer of air, thus preventing stall and improving the driving force of the sail. The principle is also useful in the control of parachutes and other thin air foils.
Inventors
- 👤 A Slemmons
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:11
CPC Classifications
B; B63; B63H; B63H9/00; B63H9/04; B63H9/06; B63H9/067; B64; B64D; B64D17/00; B64D17/40; B64D17/52
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
137 words
A thin air foil such as a sail or the like of the type having apertures thereon to improve its aerodynamic effectiveness; the improvement wherein said apertures are formed in discrete rows of three or more apertures with each row providing an aerodynamic fence of small air Jets that produces a trailing vortex, said rows of apertures being formed in an elongated array the axis of the array being generally normal to the free air stream flowing along the foil, the axes of said rows being at acute angles to the free air stream, said rows of apertures being spaced along the array axis by a distance sufficient to present a gap to the air stream that is not substantially less than the extent of one of said rows as measured along the axis of the array.
Claim 2
Dependent Claim
137 words
A thin air foil such as a sail or the like of the type having apertures thereon to improve its aerodynamic effectiveness; the improvement wherein said apertures are formed in discrete rows of three or more apertures with each row providing an aerodynamic fence of small air Jets that produces a trailing vortex, said rows of apertures being formed in an elongated array the axis of the array being generally normal to the free air stream flowing along the foil, the axes of said rows being at acute angles to the free air stream, said rows of apertures being spaced along the array axis by a distance sufficient to present a gap to the air stream that is not substantially less than the extent of one of said rows as measured along the axis of the array.
Claim 3
Dependent Claim
19 words
The air foil of claim 1, wherein the rows of apertures in said array are disposed in zig-zag fashion.
Claim 4
Dependent Claim
16 words
The air foil of claim 1, whereby there are at least four apertures in each row.
Claim 5
Dependent Claim
59 words
The air foil of claim 1, wherein the angle of inclination of the rows of apertures to the array axis and the angle of inclination of the array axis to the air stream are selected so that during normal operation of the air foil the angle of inclination of the rows to the air stream is about 20 degrees.
Claim 6
Dependent Claim
20 words
The air foil of claim 4, wherein said rows of apertures are arranged in zig-zag formation along the array axis.
Claim 7
Dependent Claim
27 words
The airfoil of claim 5, wherein the air foil is a fore and aft sailboat sail, and the array axis extends along the luff of the sail.
Claim 8
Dependent Claim
20 words
The sail of claim 6, wherein the array axis is inclined from the mast axis at a positive acute angle.
Claim 9
Dependent Claim
15 words
The sail of claim 7, wherein said positive acute angle of inclination is about 10*.
Claim 10
Dependent Claim
26 words
The sail of claim 6, wherein the diameter of the holes is about 1/2 to 1 inch, the diameter increasing with the height of the sail.
Claim 11
Dependent Claim
28 words
The air foil of claim 2, wherein said air foil is a parachute, and the zig-zag array of holes extends circumferentially adjacent the lower edge of the parachute.
Claim 12
Dependent Claim
138 words
A fore and aft sail boat sail of the type having apertures thereon to improve its aerodynamic effectiveness; the improvement wherein said apertures are formed in discrete rows of three or more apertures with each row providing an aerodynamic fence of small air jets that produces a trailing vortex, said rows of apertures being formed in a zig-zag array near the luff of the sail, the axes of the individual rows of holes being at acute angles to the array axis, the rearwardly converging ends of said rows of apertures being spaced along the array axis by a distance such that the rearwardly converging ends of the rows of holes present a gap to the air stream that is not substantially less than the extent of one of said rows as measured along the axis of the array.
Claim 13
Dependent Claim
138 words
A fore and aft sail boat sail of the type having apertures thereon to improve its aerodynamic effectiveness; the improvement wherein said apertures are formed in discrete rows of three or more apertures with each row providing an aerodynamic fence of small air jets that produces a trailing vortex, said rows of apertures being formed in a zig-zag array near the luff of the sail, the axes of the individual rows of holes being at acute angles to the array axis, the rearwardly converging ends of said rows of apertures being spaced along the array axis by a distance such that the rearwardly converging ends of the rows of holes present a gap to the air stream that is not substantially less than the extent of one of said rows as measured along the axis of the array.
Claim 14
Dependent Claim
16 words
The air foil of claim 11, whereby there are at least four apertures in each row.
Claim 15
Dependent Claim
58 words
The sail of claim 11, wherein the angle of inclination of the rows of apertures to the array axis and the angle of inclination of the array axis to the air stream are selected so that during normal operation of the air foil the angle of inclination of the rows to the free air stream is about 20*.
Claim 16
Dependent Claim
31 words
The sail of claim 13, wherein the axis of the array is inclined to that of the mast at a small positive acute angle of compensate for heeling of the boat.
Claim 17
Dependent Claim
29 words
The sail of claim 11, wherein the gap between the rearwardly converging ends of the rows of holes is about equal to the axial length of an individual row.
Claim 18
Dependent Claim
24 words
The sail of claim 11, wherein the diameter of each hole is about 1/2 to 1 inch, depending on the height of the sail.
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) | 1976-12-03 | 1977-06-04 | 1977-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-03 | 1981-06-04 | 1981-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-03 | 1985-06-04 | 1985-12-04 | $7700.00 | Window Closed / Lapsed |