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Publication numberUS2322632 A
Publication typeGrant
Publication dateJun 22, 1943
Filing dateFeb 13, 1940
Priority dateFeb 13, 1940
Publication numberUS 2322632 A, US 2322632A, US-A-2322632, US2322632 A, US2322632A
InventorsJr William Harper
Original AssigneeJr William Harper
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Covering for airfoil surfaces
US 2322632 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

June 22, 1943. w. HARPER, JR

COVERING FOR AIRFOIL SURFACES Filed Feb. 13, 1940 ,Illl lll'.

INVENTOR Wzz/A/y 4/45/29?) (/5? ATTORNEY Patented June 22, 1943 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to a covering for an airfoil surface, and aims to reduce skin friction and turbulence.

As a result of experiments and investigation I have discovered that the so-called skin friction of an airfoil surface, which is really the effect of turbulence between the boundary layer and the air beyond, may be reduced by providing the airfoil surface with a nap whose filaments may be bent down in the direction of air flow along the surface.

My invention is applicable to all the surfaces of an airplane along which the air flows and is of especial value on the wing surfaces. It may also be applied to the surfaces of the propeller blades. It is of especial value in airplanes designed for very high speeds, and is, so far as I am aware, the only type of airfoil surface which will avoid turbulence at speeds above six-tenths of the velocity of sound.

An airfoil covering embodying my invention consists of a tegument provided with a nap of closely spaced, normally upstanding, fine filaments which are flexible and slightly resilient so that, when the airfoil surface is in motion, the filaments of the nap are bent down by the air flow along the airfoil surface in the direction of the air flow. In this position, they effectively prevent turbulence at high speeds.

The covering may consist of an ordinary fabric provided with a nap, such as velvet.

An important feature of my invention consists in making the filaments of the nap of glass so that they are durable and not affected by moisture. In order to provide the requisite flexibility, I use glass filaments of less than 0.004 inch in diameter. This preferred form is illustrated in the accompanyiny drawing in which Fig. 1 is a cross-section of an airfoil surface showing the position of the nap when the airfoil is stationary, and Fig. 2 is a similar view showing the position of the nap when the airfoil surface is moving rapidly through th air.

In the drawing, A represents glass fibres of less than 0.004 inch in diameter and preferably about inch in length. B represents a tegument in which the inner ends of the filaments are held.

As appears from Fig. 1, the glass filaments A of the nap when in their normal or upstanding position when the airfoil is stationary are inclined rearwardly at an angle of about 45 to the airfoil surface. When the airfoil is moving rapid- 1y through the air, the filaments of the forward part of the surface are bent down more nearly in line with the surface while those at the rear part of the surface remain substantially in their normal position, both the depressed and upstanding fibres being inclined in the direction of the air flow along the surface.

What I claim is:

l. A covering for an airfoil surface, comprising a nap of flexible glass filaments normally inclined outwardly relative to the airfoil surface in the direction of the airflow along said surface.

2. A covering for an airfoil surface, comprising a nap of glass filaments less than 0.004 inch in diameter normally inclined outwardly relative to the airfoil surface in the direction of the airfiow along said surface.

3. A covering for an airfoil surface, comprising a tegument and a multiplicity of fibres set in said tegument at an acute angle so that they extend upwardly therefrom in the direction of air flow along the surface, the fibres being sufficiently flexible to be bent down in the direction of air flow by flow of air along the surface.

WILLIAM HARPER, J R.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2426334 *Oct 15, 1943Aug 26, 1947Jr Thomas A BanningWing for airplanes and the like
US4650138 *Sep 30, 1985Mar 17, 1987Internorth, Inc.Cascaded micro-groove aerodynamic drag reducer
US4759516 *Sep 30, 1985Jul 26, 1988Ronald D. GroseCascaded turbulence generation inhibitor
US4867503 *Nov 9, 1984Sep 19, 1989Rockwell-Golde GmbhWind deflector for sliding roofs of automobiles
US5402964 *Oct 25, 1993Apr 4, 1995Wygnanski; Israel J.Interference with vortex formation and control of fluid flow to reduce noise and change flow stability
US6789769 *Nov 22, 2002Sep 14, 2004Airbus Deutschland GmbhFlexible airflow separator to reduce aerodynamic noise generated by a leading edge slat of an aircraft wing
US7059662 *Dec 6, 2004Jun 13, 2006Drews Hilbert F PPost pressurizing material treatment for bodies moving through fluid
US7156032 *Aug 27, 2003Jan 2, 2007Lucent Technologies Inc.Method and apparatus for controlling friction between a fluid and a body
US7357442Apr 3, 2006Apr 15, 2008Drews Hilbert F PPost pressurizing material treatment for bodies moving through fluid
US7455021Sep 11, 2006Nov 25, 2008Lucent Technologies Inc.Method and apparatus for controlling friction between a fluid and a body
US7644977Oct 22, 2007Jan 12, 2010Drews Hilbert F PPost pressurizing material treatment for bodies moving through fluid
US20050039661 *Aug 27, 2003Feb 24, 2005Avinoam KornblitMethod and apparatus for controlling friction between a fluid and a body
US20080236473 *Sep 11, 2006Oct 2, 2008Avinoam KornblitMethod and apparatus for controlling friction between a fluid and a body
EP0212167A2 *Jul 2, 1986Mar 4, 1987Messerschmitt-Bölkow-Blohm Gesellschaft mit beschränkter HaftungDevice to reduce friction drag
EP0212167A3 *Jul 2, 1986Nov 19, 1987Messerschmitt-Bolkow-Blohm Gesellschaft Mit Beschrankter HaftungDevice to reduce friction drag
EP0659641A1 *Dec 12, 1994Jun 28, 1995Mitsubishi Jukogyo Kabushiki KaishaA fluxional force-generated sound reducing device
WO1993025432A1 *Jun 7, 1993Dec 23, 1993Juristbyrån Indirekt AbCoating on marine constructions
Classifications
U.S. Classification244/200
International ClassificationB64C21/10
Cooperative ClassificationB64C21/10, Y02T50/166
European ClassificationB64C21/10