US4907765A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wall with a drag reducing surface and method for making such a wall
Assignee: Airbus Defence and Space GmbH
•
Filing: 1988-04-07
•
Granted: 1990-03-13
•
Expires: 2008-04-07
Abstract
Abstract A wall having a surface in contact with a fluid, has a surface configuration which reduces drag if there is relative movement between the surface and the fluid. The wall is made of metal or of fiber composite material in such a way that sharp edged or fine ridges and grooves between the ridges are formed as integral surface components of the wall structure for simplifying the construction, reducing the weight, and increasing the useful life of structures having such walls.
Inventors
- 👤 Ernst H. Hirschel
- 👤 Hubert Fleckenstein
- 👤 Peter Thiede
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:52
CPC Classifications
B; B64; B64C; B64C21/00; B64C21/10; F; F15; F15D; F15D1/00; F15D1/002; F15D1/0025; F15D1/003; F15D1/0035; B64C2230/00; B64C2230/26; Y; Y02; Y02T; Y02T50/00; Y02T50/10
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
82 words
A wall having a drag reducing surface configuration to be contacted by a fluid, comprising a wall structure made of fiber composite material including reinforcing fibers embedded in a resin matrix material, said wall structure having sharp edged ridges separated by valleys, and wherein said resin matrix material is recessed in said valleys so that said fibers extend into said sharp edged ridges and are at least partially exposed at least along said ridges for an increased resistance against wear and tear.
Claim 2
Dependent Claim
82 words
A wall having a drag reducing surface configuration to be contacted by a fluid, comprising a wall structure made of fiber composite material including reinforcing fibers embedded in a resin matrix material, said wall structure having sharp edged ridges separated by valleys, and wherein said resin matrix material is recessed in said valleys so that said fibers extend into said sharp edged ridges and are at least partially exposed at least along said ridges for an increased resistance against wear and tear.
Claim 3
Dependent Claim
14 words
The wall of claim 1, wherein said valleys have been formed by micro etching.
Claim 4
Dependent Claim
17 words
The wall of claim 1, wherein said valleys have been formed by burning with a laser beam.
Claim 5
Dependent Claim
59 words
The wall of claim 1, wherein said ridges and valleys have been formed by pressing a respective mold into the surface of said fiber composite material when the fiber composite material is still uncured and then curing said fiber composite material to harden said wall structure including said ridges and valleys forming an integral part of said wall structure.
Claim 6
Dependent Claim
14 words
The wall of claim 1, wherein said fibers are endless fibers arranged in layers.
Claim 7
Dependent Claim
14 words
The wall of claim 5, wherein said endless fibers are arranged as fiber rovings.
Claim 8
Dependent Claim
23 words
The wall of claim 1, wherein said fibers are short fibers having a fiber orientation substantially in parallel to said sharp edged ridges.
Claim 9
Dependent Claim
34 words
The wall of claim 7, wherein said short fibers have a length within the range of about 1.0 μm to about 3.00 mm, and a diameter of about 0.1 μm to about 1.0 μm.
Claim 10
Dependent Claim
40 words
The wall of claim 1, wherein said matrix material is a synthetic resin having embedded therein, in addition to the reinforcing fibers, a powder of an erosion resistant material including emery, silicon carbide, and tungsten carbide singly or in combination.
Claim 11
Dependent Claim
21 words
The wall of claim 9, wherein said powder has a grain diameter in the range of 0.1 μm to 1.0 μm.
Claim 12
Dependent Claim
23 words
The wall of claim 1, wherein said matrix material is a synthetic resin and wherein said fibers are made of glass and/or carbon.
Claim 13
Dependent Claim
51 words
The wall of claim 1, wherein said mairix material is a synthetic resin, and wherein said fibers are metal fibers made of aluminum, titanium, or an alloy thereof, said metal fibers being embedded in said synthetic resin matrix and atleast partially exposed along said valleys and along said sharp edged ridges.
Claim 14
Dependent Claim
18 words
The wall of claim 11, wherein said metal fibers have an anodized oxide coating on their fiber surface.
Claim 15
Dependent Claim
37 words
The wall of claim 1, wherein said valleys have a radius D of curvature such that a concave curve forming each valley reaches all the way to the neighboring sharp edged ridges, thereby avoiding flat wall portions.
Claim 16
Dependent Claim
33 words
The wall of claim 1, wherein said valleys and sharp edged ridges are arranged in zones in which the valleys and ridges extend in parallel to each other and in the same direction.
Claim 17
Dependent Claim
14 words
The wall of claim 15, wherein said zones are staggered relative to each other.
Claim 18
Dependent Claim
34 words
The wall of claim 1, wherein said valleys and sharp edged ridges are arranged in zones, and wherein certain zones extend at an angle relative to other zones extending in parallel to each other.
Claim 19
Dependent Claim
31 words
The wall of claim 1, wherein said valleys and sharp edged ridges are arranged in zones, and wherein certain zones extend at an angle of about 45° relative to other zones.
Claim 20
Dependent Claim
21 words
The wall of claim 18, wherein the valleys and sharp edged ridges within each zone extend in parallel to each other.
Claim 21
Dependent Claim
15 words
The wall of claim 1, wherein said valleys and sharp edged ridges have curved configurations.
Claim 22
Dependent Claim
45 words
The wall of claim 1, wherein said valleys and sharp edged ridges are arranged in zones with the valleys and ridges extending in parallel to each other within each zone but at right angles relative to neighboring zones to form a checkerboard type zone distribution.
Claim 23
Dependent Claim
20 words
The wall of claim 1, wherein said valleys and sharp edged ridges have a random distribution on said wall structure.
Claim 24
Dependent Claim
30 words
The wall of claim 1, wherein said valleys and sharp edged ridges are arranged in first zones with straight valleys and ridges and second zones with curved valleys and ridges.
Claim 25
Dependent Claim
26 words
The wall of claim 23, wherein at least one first zone is flanked by at least one second zone on each side of said first zone.
Claim 26
Dependent Claim
21 words
The wall of claim 23, wherein said first and second zones are symmetrically distributed over the surface of said wall structure.
Claim 27
Dependent Claim
15 words
The wall of claim 1, wherein said valleys and sharp edged ridges have random lengths.
Claim 28
Dependent Claim
26 words
The wall of claim 26, wherein said valleys and sharp edged ridges of random lengths have a random distribution over the surface of said wall structure.
Claim 29
Dependent Claim
22 words
The wall of claim 26, wherein said valleys anbd sharp edgerd ridges of random lengths extend appropriately in parallel to one another.
Claim 30
Dependent Claim
19 words
The wall of claim 26, wherein said valleys and sharp edged ridges overlap one another laterally at least partly.
Claim 31
Independent Claim
151 words
A method for making a wall having a drag reducing surface to be contacted by a fluid, comprising the following steps: (a) providing a mold having a mold surface with sharp edged ridges separated by valleys in said mold surface, (b) placing preimpregnated, but not yet fully cured fiber composite material into said mold so as to uniformly contact said mold surface with said fiber composite material, and so that reinforcing fibers are exposed on the surface of said fiber composite material at least along said sharp edged ridges on said mold bottom, whereby the resulting drag reducing surface has said reinforcing fibers exposed in said sharp edged ridges, (c) applying compression between said fiber composite material and said mold surface sufficiently to form sharp edged ridges and valleys in said drag reducing surface, and (d) curing said fiber composite material in said mold and removing said wall from said mold.
Claim 32
Independent Claim
151 words
A method for making a wall having a drag reducing surface to be contacted by a fluid, comprising the following steps: (a) providing a mold having a mold surface with sharp edged ridges separated by valleys in said mold surface, (b) placing preimpregnated, but not yet fully cured fiber composite material into said mold so as to uniformly contact said mold surface with said fiber composite material, and so that reinforcing fibers are exposed on the surface of said fiber composite material at least along said sharp edged ridges on said mold bottom, whereby the resulting drag reducing surface has said reinforcing fibers exposed in said sharp edged ridges, (c) applying compression between said fiber composite material and said mold surface sufficiently to form sharp edged ridges and valleys in said drag reducing surface, and (d) curing said fiber composite material in said mold and removing said wall from said mold.
Claim 33
Dependent Claim
33 words
The method of claim 30, wherein said step of placing said fiber composite material into said mold is performed in such a manner that said reinforcing fibers are exposed also along said valleys.
Claim 34
Dependent Claim
65 words
The method of claim 30, comprising preparing said fiber composite material by mixing an erosion resistant powder of emery, silicon carbide and tungsten carbide singly or in combination into a synthetic resin for forming a matrix material and then embedding reinforcing fibers in said matrix material and so that the fibers along said sharp edged ridges are exposed on the surface of said matrix material.
Claim 35
Independent Claim
132 words
A method for making a wall having a drag reducing surface, comprising the following steps: (a) forming a wall structure having said drag reducing surface of fiber composite material having reinforcing fibers embedded in a resin matrix material, (b) locating said fibers in said matrix material by layering at least surface forming fibers so that said sharp edged ridges are formed by said surface forming fibers which are thus exposed at least along said sharp edged ridges, (c) shaping, prior to curing of said resin matrix material, in said surface of said wall structure a surface configuration comprising sharp edged ridges spaced by valleys, (d) and curing said resin matrix material, whereby said sharp edged ridges and valleys become an integral part of said wall structure as a result of said shaping.
Claim 36
Independent Claim
132 words
A method for making a wall having a drag reducing surface, comprising the following steps: (a) forming a wall structure having said drag reducing surface of fiber composite material having reinforcing fibers embedded in a resin matrix material, (b) locating said fibers in said matrix material by layering at least surface forming fibers so that said sharp edged ridges are formed by said surface forming fibers which are thus exposed at least along said sharp edged ridges, (c) shaping, prior to curing of said resin matrix material, in said surface of said wall structure a surface configuration comprising sharp edged ridges spaced by valleys, (d) and curing said resin matrix material, whereby said sharp edged ridges and valleys become an integral part of said wall structure as a result of said shaping.
Claim 37
Dependent Claim
16 words
The method of claim 33, wherein said surface forming fibers are also exposed along said valleys.
Claim 38
Dependent Claim
32 words
The method of claim 33, wherein said step of shaping said surface configuration comrpises treating said surface of said fiber composite material so that said valleys result between said sharp edged ridges.
Claim 39
Dependent Claim
21 words
The method of claim 35, wherein said treating step involves removing matrix material from and partially between fibers at said surface.
Claim 40
Dependent Claim
36 words
The method of claim 33, wherein said step of shaping said surface configuration comprises winding said reinforcing fibers in such a way that said sharp edged ridges and valleys are formed in said drag reducing surface.
References Cited (Backward Citations)
US2927022A
Cited
US3574040A
Cited
DE1923633A1
Cited
US4323637A
Cited
US3902944A
Cited
US4060016A
Cited
US4320188A
Cited
US4430417A
Cited
US4750693A
Cited
EP0250948A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-12 | 1993-09-11 | 1994-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-12 | 1997-09-11 | 1998-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-12 | 2001-09-11 | 2002-03-13 | $7700.00 | Window Closed / Lapsed |