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US4354648A
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Airstream modification device for airfoils
Assignee: LearJet Inc
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Filing: 1980-02-06
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Granted: 1982-10-19
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Expires: 2000-02-06
Abstract
Abstract An airfoil modification device that helps maintain airstream attachment to either upper or lower airfoil surfaces, the device in the form of a plurality of spaced, low profile rods arranged generally end-to-end and attached to the airfoil and generally normal to the airstream to define a serrated edge that induces multi-directional airstream turbulence.
Inventors
- 👤 Karl M. Schenk
- 👤 Peter T. Reynolds
- 👤 M. H. Abla
- 👤 Robert K. Wattson, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 03:51
CPC Classifications
B; B64; B64C; B64C3/00; B64C3/58; B64C21/00; B64C21/10; B64C23/00; B64C23/06; Y; Y02; Y02T; Y02T50/00; Y02T50/10
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
137 words
In an airstream flow modification device of the type secured to and extending beyond a normaly smooth contour surface of an aircraft airfoil to project into an airstream boundary layer and delay the onset of airstream flow separation from the airfoil while operating at higher aircraft speeds at Mach numbers of about 0.6 to about 0.9 when the airstream near the airfoil accelerates to supersonic speeds, the improvement comprising: a plurality of spaced, generally rod shaped elements arranged generally end to end in at least one row and extending from said airfoil surface, each element having a height less than the boundary layer thickness formed at said aircraft speeds and a length oriented generally normal to the airstream flow within a range of about -30 degrees to about +30 degrees from a normal to the airstream flow.
Claim 2
Dependent Claim
137 words
In an airstream flow modification device of the type secured to and extending beyond a normaly smooth contour surface of an aircraft airfoil to project into an airstream boundary layer and delay the onset of airstream flow separation from the airfoil while operating at higher aircraft speeds at Mach numbers of about 0.6 to about 0.9 when the airstream near the airfoil accelerates to supersonic speeds, the improvement comprising: a plurality of spaced, generally rod shaped elements arranged generally end to end in at least one row and extending from said airfoil surface, each element having a height less than the boundary layer thickness formed at said aircraft speeds and a length oriented generally normal to the airstream flow within a range of about -30 degrees to about +30 degrees from a normal to the airstream flow.
Claim 3
Dependent Claim
25 words
The airfoil as claimed in claim 1 wherein the length of each element is oriented substantially at a constant percentage of a local airfoil chord.
Claim 4
Dependent Claim
26 words
The airfoil as claimed in claim 1 wherein the spacing between elements in a row is from about 0.2 to about 0.7 of the element length.
Claim 5
Dependent Claim
20 words
The airfoil as claimed in claim 1 wherein the elements of a row are staggered in relation to each other.
Claim 6
Dependent Claim
19 words
The airfoil as claimed in claim 1 wherein the elements extend from an upper contour surface of the airfoil.
Claim 7
Dependent Claim
29 words
The airfoil as claimed in claim 1 wherein there are at least two rows of elements where the elements in each row are substantially in alignment with each other.
Claim 8
Dependent Claim
23 words
The airfoil as claimed in claim 1 wherein the element height is from about 0.1 to about 0.5 of the boundary layer thickness.
Claim 9
Dependent Claim
16 words
The airfoil as claimed in claim 1 wherein the elements have generally a triangular cross section.
Claim 10
Dependent Claim
15 words
The airfoil as claimed in claim 1 wherein the elements have substantially squared end portions.
Claim 11
Dependent Claim
16 words
The airfoil as claimed in claim 1 wherein the top surface of each element is rounded.
Claim 12
Dependent Claim
41 words
The airfoil as claimed in claim 1 wherein the elements have a height from about 3 mm to about 4 mm and are spaced in end-to-end fashion from each other at a spacing from about 25 mm to about 50 mm.
Claim 13
Dependent Claim
21 words
The airfoil as claimed in claim 1 wherein there are from about 4 to about 16 elements per meter per row.
Claim 14
Dependent Claim
26 words
The airstream modification device as claimed in claim 1 where the spacing between adjacent rod members is less than the individual length of the rod members.
Claim 15
Dependent Claim
18 words
The airstream modification device as claimed in claim 1 wherein the rod members are of substantially equal length.
Claim 16
Dependent Claim
21 words
The airstream modification device as claimed in claim 1 wherein the rod members are linearly aligned and are substantially equally spaced.
Claim 17
Dependent Claim
26 words
The airstream modification device as claimed in claim 1 wherein the rod members have an aspect ratio of length to thickness of at least about 8:1.
Claim 18
Dependent Claim
17 words
The airstream modification device as claimed in claim 1 wherein the rod end portions have abrupt edges.
References Cited (Backward Citations)
GB101442A
Cited
US1864803A
Cited
US1815489A
Cited
US2453403A
Cited
US2739770A
Cited
US2852209A
Cited
CH349958A
Cited
US3578264A
Cited
US3578264B1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-18 | 1986-04-19 | 1986-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-18 | 1990-04-19 | 1990-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-18 | 1994-04-19 | 1994-10-19 | $7700.00 | Window Closed / Lapsed |