US3831886A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Airfoil with extendible and retractable leading edge
Assignee: Lockheed Martin Corp
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Filing: 1973-01-26
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Granted: 1974-08-27
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Expires: 1993-01-26
Abstract
Abstract A leading edge device (referred to as a foreflap) is formed by passing a curved parting line through an airfoil in such a manner as to allow the front part of the airfoil to rotate about a pivot which is close to the wing external contour. When the foreflap is thus extended, the resulting airfoil contour has a large bulbous nose which is formed mainly by the parting line. The exact contour of the resulting nose may be shaped to optimum aerodynamic contour for high lift operation without adversely affecting high speed performance, since the parting surface is inside of the clean airfoil when the foreflap is retracted. The foreflap may be operated by any conventional means, e.g., a simple hinge located at the pivot outside of the airfoil contour.
Inventors
- 👤 K Burdges
- 👤 A Robertson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 09:30
CPC Classifications
B; B64; B64C; B64C9/00; B64C9/14; B64C9/22; B64C9/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
201 words
An airfoil comprising an extendible and retractable leading edge flap defined by a surface configured by an arc subStantially tangent to the adjacent airfoil upper surface at each position throughout movement of said flap during its extension and retraction, said arc intersecting the adjacent airfoil lower surface at a point located a predetermined percentage of the airfoil chord length, whereby said leading edge flap provides an external upper contour which forms an unbroken continuation on the adjacent airfoil surface with a smooth aerodynamic pressure distribution at all times during its extension and retraction, and a hinge fitting formed by a rigid link fixedly attached at one of its ends to said flap to extend therefrom and pivotally connected at its other end to a hinge point secured to and projecting from said airfoil lower surface establishing a pivot for said flap at substantially the point where a line connecting the centers of curvature for successive points on said airfoil upper surface intersects the perpendicular bisector of a line between one of said points proximate the tangency point of said arc with said airfoil upper surface when said flap is fully retracted and the predetermined point on the airfoil lower surface aforesaid.
Claim 2
Dependent Claim
201 words
An airfoil comprising an extendible and retractable leading edge flap defined by a surface configured by an arc subStantially tangent to the adjacent airfoil upper surface at each position throughout movement of said flap during its extension and retraction, said arc intersecting the adjacent airfoil lower surface at a point located a predetermined percentage of the airfoil chord length, whereby said leading edge flap provides an external upper contour which forms an unbroken continuation on the adjacent airfoil surface with a smooth aerodynamic pressure distribution at all times during its extension and retraction, and a hinge fitting formed by a rigid link fixedly attached at one of its ends to said flap to extend therefrom and pivotally connected at its other end to a hinge point secured to and projecting from said airfoil lower surface establishing a pivot for said flap at substantially the point where a line connecting the centers of curvature for successive points on said airfoil upper surface intersects the perpendicular bisector of a line between one of said points proximate the tangency point of said arc with said airfoil upper surface when said flap is fully retracted and the predetermined point on the airfoil lower surface aforesaid.
Claim 3
Dependent Claim
33 words
The airfoil of claim 1 wherein the intersection of the arc with the lower surface as aforesaid is located at a point on the order of 15 percent of the airfoil chord length.
Claim 4
Dependent Claim
70 words
The airfoil of claim 1 including a spanwise duct within said leading edge flap, nozzles at discrete intervals in the length of said duct opening outwardly of said arc in an aftward direction and so located as to be disposed upstream of said adjacent airfoil upper surface when said leading edge is in the extended position, and a source of air under pressure communicating with the interior of said duct.
Claim 5
Dependent Claim
22 words
The airfoil of claim 3 wherein said spanwise duct includes a flexible duct between it and said source of air under pressure.
Claim 6
Dependent Claim
40 words
The airfoil of claim 3 in combination with an aircraft powered by at least one engine and further including a duct operatively connected between the interior of each said engine and said spanwise duct constituting the source of air aforesaid.
Claim 7
Dependent Claim
21 words
The airfoil of claim 5 wherein the aforesaid duct between said engine and said spanwise duct is flexible adjacent one end.
Claim 8
Dependent Claim
67 words
The airfoil of claim 1 wherein said leading edge flap is formed by multiple interconnected segments disposed end to end and at least one hinge fitting is connected as aforesaid to each segment, and including a drive linkage pivotally connected at opposite ends to said airfoil and to said flap and a torque tube common to all of said drive linkages for the actuation thereof in unison.
References Cited (Backward Citations)
US2496565A
Cited
US2774555A
Cited
US2886264A
Cited
US3047257A
Cited
US3093350A
Cited
US3612444A
Cited
US3743220A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-26 | 1978-02-25 | 1978-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-26 | 1982-02-25 | 1982-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-26 | 1986-02-25 | 1986-08-27 | $7700.00 | Window Closed / Lapsed |