GB2167723A

GB2167723A - Pneumatic deicer

Info

Publication number: GB2167723A
Application number: GB08529472A
Authority: GB
Inventors: Duain Norvan Ely; Joseph Henry Macarchenia
Original assignee: BF Goodrich Corp
Current assignee: Goodrich Corp
Priority date: 1984-12-03
Filing date: 1985-11-29
Publication date: 1986-06-04
Also published as: FR2574048B1; JPS61166800A; CA1319666C; GB2167723B; GB8529472D0; JPH0587437B2; FR2574048A1

Abstract

A deicer pad for use on an airfoil wherein the deicer pad is constructed to have an intermediate portion with a leading edge thereon and two spaced apart portions with inflatable passageways thereon. The pad is mounted on the airfoil with the centerline of the pad coincident with the stagnation line of the airfoil. The stagnation line is generally parallel to the leading edge of the airfoil. The passageways in the two spaced apart portions of the deicer are inflatable either simultaneously or in seriatim order and effect the breaking up of the ice over the entire deicer. The inflatable passageways are the sole means for deicing. <IMAGE>

Description

SPECIFICATION Pneumatic deicer This invention relates to deicers for aircraft and more particularly to an improved inflatable deicer or boot adapted for attachment to the airfoil of an aircraft for use in retarding the accumulation of ice or to remove or break up ice accumulation.

Aircraft inflatable deicers, pads or boots are made of resilient material such as rubber and attached to the leading edge of an airfoil and extend rearwardly therefrom. The deicer has a series of inflatable passages or tubes which are distended by inflation pressure to break up ice accumulation which tends to form on the surface of the deicer.

The passages or tubes are deflated by releasing the pressure medium and drawing a vacuum thereon. The normal sequence of operation is a continuous cycling of the inflation and deflation process.

The present invention is an improvement on the structure and operation of prior deicers wherein the invention recognizes the need to differentiate between the stagnation line and the leading edge of an airfoil. The stagnation line of the wing of an aircraft is the line along which the air separates above and below such line on the wing whereas the leading edge of the wing is in the forward most edge of the wing. In the case of a symmetrical wing, the leading edge and the stagnation line are the same; however, in the case of a non-symmetrical or asymmetrical wing, the stagnation line is either below or above the leading edge of the wing. The present invention locates the deicer's inflatable tubes above and below the stagnation line while leaving the area immediately adjacent the stagnation line free of inflatable tubes.The advantage of this construction is a clamshell effect which takes place on the ice when the inflatable tubes on each side of the stagnation line inflate causing the ice to break in the non-inflatable area around the stagnation line. The wind stream over the airfoil then removes the ice build-up from the airfoil's leading edge. On some asymmetrical airfoils wherein the deicer is constructed in a conventional manner so that the inflatable tubes are also located on or immediately adjacent the stagnation line, the ice is not broken because the inflation tube pushes the ice cap forwardly before it breaks. The ice cap is then held onto the airfoil by the airstream. This in effect does not take advantage of the clamshell type of breaking which is so effective in a symmetrical as well as a non-symmetrical type or airfoil construction.The method of de-icing the airfoil can be improved by use of a deicer as described above, employing inflatable tubes on opposite side of the stagnation line by first inflating all of the tubes, the first set, on one side of the stagnation line and thence deflating such first set of tubes and simultaneously inflating all of the tubes, the second set, on the other side of the stagnation line, and thence repeating this cycle. The above construction of the deicer is particularly economical and effective in its deicing operation while requiring a minimum of power consumption.

The present invention is directed to a deicer pad or boot that is mounted on the forwardly disposed edge of an airfoil. Such deicer pad has the intermediate portion along the stagnation line devoid of inflatable tubes but two spaced apart portions above and below this intermediate portion which are inflated sequentially or simultaneously to effectively deice the airfoil.

Although the present invention may be generally applied to airfoils, for example a wing or a tail section of an aircraft, it will, for the sake of convenience, be particularly described with reference to a wing of an aircraft.

According to the present invention there is provided a deicing apparatus for preventing the accumulation of ice upon the forwardly disposed portion of the leading edge of an airfoil, which comprises a flexible resilient sheet-like protective covering including a pair of side edges and a pair of outer edges, the outer edges being adapted to be generally parallel to the leading edge of the airfoil, the airfoil having a stagnation line lying in the same direction as the leading edge, the covering having a smooth non-inflatable portion overlying the stagnation line and to either side thereof, a plurality of spanwise passageways in the deicer lying to either side of the stagnation line and extending from adjacent one of the side edges to closely adjacent the other one of the side edges, all of the passageways having the edges spaced from the stagnation line, the passageways lying to one side of the stagnation line defining a first set of inflatable passageways and the remaining passageways defining a second set of inflatable passageways, means operatively connected to the passageways to selectively inflate and deflate the first set and the second set of passageways, and the passageways being the sole means to deice said airfoil. The first set of passageways may be inflated while the second set of passageways is deflated, followed by inflating the second set and deflating the first set. Alternatively the first set of passageways and the second set of passageways may be inflated simultaneously and deflated simultaneously. The first set and the second set of passageways may be individual separate tubes interconnected by manifolds for inflation and deflation thereof.

The present invention also provides a pneumatic inflatable deicer pad for an airfoil having a stagnation line, an inboard end and an outboard end; the pad having an intermediate portion with a centre line overlying the stagnation line; the pad having a pair of spaced apart portions spaced rearward of the stagnation line when positioned on the airfoil; the pad having a pair of rearwardly disposed edges that are generally parallel to the stagnation line; the deicer pad having an inner ply for attachment to the airfoil and an upper extensible elastic ply overlying the inner ply; each of said rearwardly disposed spaced portions having a plurality of inflatable passageways operative upon successive distensions to break up ice accumulation on the deicer pad, and the passageways being the sole means to deice the airfoil.

The present invention further provides a pneumatic deicer pad for an airfoil of an aircraft having a leading edge, an inboard end and an outboard end; the airfoil having a stagnation line spaced from the leading edge and lying in the same general direction as the leading edge; the pad having an intermediate portion with a centreline overlying the stagnation line and also having a pair of spaced apart portions spaced from the stagnation line and located rearward of the centreline when positioned on the airfoil to provide a pair of rearwardly disposed edges; the centreline of the deicer pad coincides with the stagnation line of the airfoil; the spaced apart portions defining an upper portion and a lower portion; the deicer pad having an inner ply for attachment to the airfoil, and an outer extensible elastic ply overlying the inner ply; each of the spaced apart portions having a plurality of inflatable passageways operative upon successive distensions to break up ice accumulation on the deicer pad; and the spaced apart portions containing the sole deicing means for the airfoil.

The airfoil may be non-symmetrical with the stagnation line spaced below the leading edge of the airfoil. In this embodiment of the present invention also the passageways in one of the spaced apart portions may be inflated while the passageways in the other one of the spaced apart portions are deflated. Preferably the passageways in the spaced apart portions that are nearest to the stagnation line are equi-distant from the stagnation line. Desirably, the passageways that are nearest to the stagnation line are at least one inch apart.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a portion of an airplane with a pneumatic deicer mounted upon the leading edge of the wing; Figure 2 is a cross-sectional view of a portion of the deicer or deicer boot mounted on an asymmetrical airfoil with the inflation tubes or passageways in distended condition; and Figure 4 is a cross-sectional view of a portion of the deicer or deicer boot mounted on a symmetrical airfoil with all of the inflation tubes or passageways in distended condition.

Referring to the drawings, wherein like reference numerals designate like or corresponding parts throughout the several views, there is shown in Figures 1 and 2 a deicer boot or pad 10 mounted on the leading edge of a wing 12 of an aircraft 13, only partially shown. The wing 12 is attached to the fuselage 14 of such aircraft 13.

The deicer pad 10, shown in Figures 2 and 3, is mounted on a non-symmetrical wing 12 and extends rearwardlyfrom the leading edge 15-15 over a portion of the upper and lower surface portions of the wing 12. The deicer pad 10 is a laminated structure having an inner ply 16 (Figure 3) that is substantially a rectangular section of rubber or other resilient rubber-like material that tapers as the other layers to be described at the respective side edges to facilitate the installation on the wing 12 without interfering with the aerodynamic effects of the wing design. In lieu of tapering the plies, the plies can have rectangular sides that fit snugly into recessed portions on the wing. Such deicer pad 10 and ply 16 have a stagnation line 17-17 spaced from the leading edge 15-15.Such stagnation line is the line along which the air separates above and below the wing and in the example shown is generally parallel to the leading edge of the wing.

Such ply 16 may be a woven textile fabric which is desirably made air impervious, for example by coating with a rubber compound. The inside of the plies forming the passageways to be described may have a heavy nap to facilitate the flow of air thereabove. Such nap or fibres collectively prevent complete closure and direct contact between opposing internal surfaces of the passageways to be described when the deicer pad is deflated, but have interstices through which residual air in the passageways may be vented or pumped as by a vacuum. By such uniform distribution of nap or fibres, the external surface of the deicer pad is smooth and regular when the passageways are deflated and flattened. The terms "spanwise" and "chordwise" are used herein to designate the general direction of the passageways within the deicer pad as orientated on the wing of the aircraft.

"Spanwise" is in a direction generally parallel to the leading edge or the stagnation line of the wing of the aircraft while "chordwise" is along a line extending transverseiy from the leading edge or stagnation line of the airfoil to the trailing edge of the airfoil. A ply 19 (Figure 3) (for example of tricot fabric) overlays ply 16 and is adhered to the centrai portion of such ply 16 including along the leading edge 15-15 and stagnation line 17-17. The plies 16 and 19 are then adhered or bonded along the outer edge portions to form a unitary deicer.

Using the stagnation line 17-17 as a basis, three parallel spanwise passageways 20, 21 and 22 may be formed by stitching the plies 16 and 19 together along parallel lines or by bonding such plies along parallel lines to form such passageways. In lieu of stitching or bonding such plies to form such passageways, separate tubes may be used. The inside of ply 19 may be napped as ply 16 to facilitate the flow of air to and from such passageways 20, 21 and 22.

That portion of the deicer pad that lies below the stagnation line 17-17 has four parallel spanwise passageways 25, 26, 27 and 28 which may be formed by stitching the plies 16 and 19 together along parallel lines or by suitably bonding such plies along such parallel lines to form such passageways. In lieu of forming such passageways 25 to 28 by stitching or bonding, separate inflatable tubes may be used. Such stitched spanwise passageways are sealed and together with passageways 20, 21 and 22 are pressurized and evacuated by separate manifolds 30 and 31 respectively. As seen in Figure 2, the manifolds are located closely adjacent the outer extremity of the deicer pad.

Each manifold 30 and 31 may be provided with an interior napped surface, for example with short flexible fibres of uniform thickness to prevent com plete closure. To inflate the manifolds 30 and 31 and their corresponding passageways 20 to 22 and 25 to 28 suitable conduits are connected thereto and to a suitable air pressure source and a suitable vacuum source.

Those passageways 20 to 22 located above the stagnation line 17-17 define a first set of inflatable passageways in the upper deicer portion and those passageways 25 to 28 located below the stagnation line 17-17 define a second set of inflatable passageways in the lower deicer portion. The area of the deicer immediately below and above the stagnation line 17-17 is completely void of inflatable tubes or passageways. In the example shown in Figures 2 and 3, the linear distance along the deicer from the stagnation line to where the first portion of passageway 20 is located is approximately one-half (1/2) inch; while the linear distance along the deicer from the stagnation line to where the first portion of passageway 25 is located is approximately one-half (1/2) inch. These dimensions will vary in accordance with the size of the wing.

A modification of the described invention is shown in Figure 4 wherein a deicer pad 35 is shown as mounted on a symmetrical airfoil 36 having a stagnation line 37-37 coincident with leading edge. The deicer pad 35 is a laminated structure substantially as described in the first embodiment having an inner ply 38 having a substantially rectangular section of rubber or other resilient rubber-like material that tapers as the other layers to be described at the respective side edges to facilitate the installation on the airfoil 36.

In lieu of tapering the plies, the plies can have rectangular sides that fit snugly into recessed portions on the airfoil. Such ply 38 may be a woven textile fabric which is coated with a suitable rubber compound to make such ply air impervious. A ply 39 (for example of tricot fabric) overlays ply 38 and is adhered to airfoil 36 above and below the stagnation line an equal distance as shown in Figure 4.

The plies 38 and 39 are then adhered, bonded or stitched along the upper portion forming three parallel spanwise passageways 40, 41 and 42 as in the first embodiment. Separate tubes may be used to form these passageways.

That portion of the deicer pad below the stagnation line 37-37 has five parallel spanwise passageways 45, 46, 47, 48 and 49 formed by stitching the plies 38 and 39 together along parallel lines or by suitably bonding such plies along such parallel lines to form such passageways. In lieu of such stitching or bonding separate tubes may be used to form such passageways. Passageways 40 to 42, and 45 to 49 are pressurized and deflated via suitable manifolds as described in the first embodiment. The passageways 40 to 42 located above the stagnation line 37-37 define the first set of inflatable passageways while passageways 45 to 49 define the second set of passageways. The distance above and below the stagnation line 37-37 to the passageways 40 and 45 are equal and are void of inflatable passageways. The respective inner surfaces of plies 38 and 39 may be napped as with short flexible fibres of uniform thickness to prevent complete closure of the passageways. The number of passageways above or below the stagnation line in each example may be varied and the number used in the examples above are only illustrative of the invention in a specific example.

The operation of the deicer pad as shown in Figure 4 is substantially similar to the operation as described in the first embodiment with the cycling of the inflation and deflation of the passageways effectively providing a clamshell effect in breaking up the ice on either side of the stagnation line 3737 including that area to either immediate side of such stagnation line.

Claims

1. A deicing apparatus for preventing the accumulation of ice upon the forwardly disposed portion of the leading edge of an airfoil, which comprises a flexible resilient sheet-like protective covering including a pair of side edges and a pair of outer edges, the outer edges being adapted to be generally parallel to the leading edge of the airfoil, the airfoil having a stagnation line lying in the same direction as the leading edge, the covering having a smooth non-inflatable portion overlying the stagnation line and to either side thereof, a plurality of spanwise passageways in the deicer lying to either side of the stagnation line and extending from adjacent one of the side edges to closely adjacent the other one of the side edges, all of the passageways having the edges spaced from the stagnation line, the passageways lying to one side of the stagnation line defining a first set of inflatable passageways and the remaining passageways defining a second set of inflatable passageways, means operatively connected to the passageways to selectively inflate and deflate the first set and the second set of passageways, and the passageways being the sole means to deice said airfoil.

2. A deicing apparatus as claimed in claim 1, in which the first set of passageways is inflated while the second set of passageways is deflated followed by inflating the second set and deflating the first set.

3. A deicing apparatus as claimed in claim 1, in which the first set of passageways and the second set of passageways are inflated simultaneously and deflated simultaneously.

4. A deicing apparatus as claimed in any of claims 1 to 3, in which the first set and the second set of passageways are individual separate tubes interconnected by manifolds for inflation and deflation thereof.

5. A pneumatic inflatable deicer pad for an airfoil having a stagnation line, an inboard end and an outboard end; the pad having an intermediate portion with a centre line overlying the stagnation line; the pad having a pair of spaced apart portions spaced rearward of the stagnation line when positioned on the airfoil; the pad having a pair of rearwardly disposed edges that are generally parallel to the stagnation line; the deicer pad having an inner ply for attachment to the airfoil and an upper extensible elastic ply overlying the inner ply; each of said rearwardly disposed spaced portions having a plurality of inflatable passageways operative upon successive distensions to break up ice accumulation on the deicer pad, and the passageways being the sole means to deice the airfoil.

6. A pneumatic deicer pad for an airfoil of an aircraft having a leading edge, an inboard end and an outboard end; the airfoil having a stagnation line spaced from the leading edge and lying in the same general direction as the leading edge; the pad having an intermediate portion with a centreline overlying the stagnation line and also having a pair of spaced apart portions spaced from the stagnation line and located rearward of the centreline when positioned on the airfoil to provide a pair of rearwardly disposed edges; the centreline of the deicer pad coincides with the stagnation line of the airfoil; the spaced apart portions defining an upper portion and a lower portion; the deicer pad having an inner ply for attachment to the airfoil, and an outer extensible elastic ply overlying the inner ply; each of the spaced apart portions having a plurality on inflatable passageways operative upon successive distensions to break up ice accumulation on the deicer pad; and the spaced apart portions containing the sole deicing means for the airfoil.

7. A decier pad for an airfoil as claimed in claim 6, in which said airfoil is non-symmetrical and the stagnation line is spaced below the leading edge of the airfoil.

8. A deicer pad as claimed in claim 6 or 7, in which the passageways in one of the spaced apart portions are inflated while the passageways in the other one of the spaced apart portions are deflated.

9. A deicer pad as claimed in any of claims 5 to 8 in which the lower portion has a substantially greater length than the upper portion.

9. A deicer pad as claimed in any of claims 6 to 8, in which the passageways in the spaced apart portions that are nearest to the stagnation line are equi-distant from the stagnation line.

10. A deicer pad as claimed in any of claims 6 to 9 in which the passageways that are nearest to the stagnation line are at least one inch apart.

11. A deicing apparatus substantially as hereinbefore described with particular reference to and as illustrated in Figures 1, 2 and 3 or in Figure 4 of the accompanying drawings.

12. A pneumatic deicer pad substantially as hereinbefore described with particular reference to and as illustrated in Figures 1, 2 and 3 or in Figure 4 of the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1,2,5,6 and 8 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows: (c) Claims 3,4,7, and 9 to 12 above have been re-numbered as 2,3,6,7,8,10 and 11 and their appendancies corrected.

1. A deicing apparatus for preventing the accumulation of ice upon the forwardly disposed portion of the leading edge of an airfoil, which comprises a flexible resilient sheet-like protective covering including a pair of side edges and a pair of outer edges, the outer edges being adapted to be generally parallel to the leading edge of the airfoil, the airfoil having a stagnation line lying in the same direction as the leading edge but spaced laterally therefrom, the covering having a smooth non-inflatable portion overlying the stagnation line and to either side thereof, a plurality of spanwise passageways in the deicer lying to either side of the stagnation line and extending from adjacent one of the side edges to closely adjacent the other one of the side edges, all of the passageways having the edges spaced from the stagnation line and from the smooth non-inflatable portion that overlies the stagnation line, the passageways lying to one side of the stagnation line defining a first set of inflatable passageways and the remaining passageways defining a second set of inflatable passageways, means operatively connected to the passageways to selectively inflate and deflate the first set and the second set of passageways, and the passageways being the sole means to deice the airfoil; and the passageways on inflation being spaced from the smooth, non-inflatable portion overlying the stagnation line and those portions on either side of the stagnation line.

4. A pneumatic inflatable deicer pad for an airfoil having a stagnation line, an inboard end and an outboard end; the pad having an intermediate non-extensible portion with a centre line overlying the stagnation line; the pad having a pair of spaced apart extensible portions spaced rearward of the non-extensible intermediate portion and the stagnation line when positioned on the airfoil; the pad having a pair of rearwardly disposed edges that are generally parallel to the stagnation line; the deicer pad having an inner ply for attachment to the airfoil and an upper extensible elastic ply overlying the inner ply; each of the rearwardly disposed spaced portions having a plurality of inflatable passageways operative upon successive distensions to distend the pad at all portions except the intermediate portion to break up ice accumulation on the deicer pad, and the passageways being the sole means to deice the airfoil.

5. A pneumatic deicer pad for an airfoil of an aircraft having a leading edge, an inboard end and an outboard end; the airfoil having a stagnation line spaced from the leading edge and lying in the same general direction as the leading edge; the pad having an intermediate non-extensible portion with a centreline overlying the stagnation line and also having a pair of spaced apart extensible portions spaced from the intermediate portion and located rearward of the centreline when positioned on the airfoil to provide a pair of rearwardly disposed edges; the centreline of the deicer pad coinciding with the stagnation line of the airfoil; the spaced apart portions defining an upper portion and a lower portion spaced from the intermediate portion; the deicer pad having an inner ply for attachment to the airfoil; and an outer extensible elastic ply overlying the inner ply; each of the spaced apart portions having a plurality of inflata ble passageways operative upon successive distensions to break up ice accumulation on the deicer pad; and the spaced apart portions containing the sole deicing means for the airfoil.