US1998809A - Means and method for controlling the accumulation of ice upon surfaces exposed to ice forming conditions - Google Patents

Description

April 23, 1935. w c GEER' MEANS AND METHOD FOR CONTROLLING THEACCUMULATION OF ICE UPONYSURFACES EXPOSED TO ICE FORMING CONDITIONS Filed July 7, 1950 3 Sheets-Sheet 1 mvEN-ror'es WILLIAM c.6551? ATTORNEY 9 0 8 W E 9 G ,I 1 F OS N N0 OT. T um um MC U wm m mm PmmTF GE ENC Gm wm R .TD WNE OS 3 mm F S ww A F R MU 5 mn A0 W N A E M April 23, 1935.

Filed July 7, 1930 3 Sheets-Sheet 2 NVENTO 5 LIAM C. GER

ATTORNEY Aprll 23, 1935. 'w c, GEER 1,998,809

MEANS AND METHOD FOR CON OLLING THE ACGUMULATION OF ICE UPON SURFACES EXPOS TO ICE FORMING CONDITIONS v 3 Sheets-Sheet 3 Filed July 7, 1930 ATTORNEY INVENTORS WILLIAM C. GEEK Patented Apr. 23, 1935 UNITED STATES PATENT OFFICE MEANS AND METHOD FOR CONTROLLING THE ACCUMULATION OF ICE UPON SUR- FACES EXPOSED TO ICE FORMING CON- DITIONS William 0. Gear, Ithaca, N. Y.

Application July 7, 1930, Serial No. 465,970

es'claims. (01. 244-31) removal of ice from surfaces exposed to ice forming conditions and more particularly to the prevention of excessive deposits of ice upon the exposed surfaces 5 of aircrafts.

In using airplanes in cold, foggy wather, considerable difliculty and danger have been encountered because of the formation of ice upon the wings, struts, wires and other exposed portions of the airplanes. This ice is formed from the freezing of rain, sleet or by precipitation from a saturated atmosphere.

As the aircraft rushes through the ice ladened atmosphere it cleaves only a portion of it, that is, the p ortion included within the maximum thickness or camber of the wings, struts, wires, etc. Since the ice is removed from that section of the atmosphere included within the maximum thickness of the leading portions thereof, the

the surfaces by rearward portions of the wing or strut are protected by these forward portions with the result that no ice is deposited thereon.

The ice deposited upon the leading edges, being formed from small droplets or from-vapor, comes at once in intimate contact with all the irregularities of the surface upon which it locates.

It is then held there by the the surface is composed.

Upon passing through an ice depositing atmosphere, therefore, the ice is soon the leading edges of the lifting and controlling sections to such an extent that these surfaces will be so changed built up upon the shapes of that they will no longer produce the differential pressures required to sustain the weight of the change in surface shape, together airplane. This with the added weight of the ice, will cause the airplane to quickly lose altitude with the result that it may be suddenly forbed to land in rough,

dangerous territory. Furthermore, the building up of ice upon the wires of the airplanes will change their period of vibration and cause them to break.'

A more complete discussion of this problem may be found iii the Technical Notes of the National Advisory Committee for Aeronautics No.

293 entitled The formation of ie parts of an airplane in flight.

e upon exposed It is impracticable to prevent the formation of ice upon these surfaces and the present invention has to do with lessening the adhesion of the ice to the surface and accomplishing its removal be fore it has become thick enough to become a hazardto the pilot.

Many attempts" have been made to avoid this difiiculty, among them it'hasbeen. proposed to apply an oil directly to the exposed surface of the airplane. Such efforts have not been successful, however, due to the fact that the oil is quickly scrubbed from .the surface by the force of the wind and also that the oils used have had too high a freezing point and have been sticky at the ice forming temperatures with the resultthat instead of lessening the adhesion of the ice, the application of such oils will assist in .the formation and building up of an ice coating.

An object of the present invention is to provide an improved method and means for removing the ice deposits which may be built up upon the exposed portions of'articles subjected to ice forming conditions.

' It is a further object of the invention to provide 7 a method and means for loosening any ice which may be deposited upon the surface and to do so without materially disturbing the equilibrium of the plane. I

Other objects and benefits will become apparent from studying the following description and drawings and from the use of the means and methods defined in the claims.

The invention contemplates the application of a covering or overshoe to the portions of the exposed metal or other surfaces where the ice is most likely to form, and the application of a suitable non-adhesive liquid to the overshoe, which liquid will substantially reduce the adhesion between the ice and the surface of the. overshoe, or, in otlierwords, willlubricate the, surface upon which the ice is most likely to form. The invention further contemplates the provision of means for disturbing any ice which may be deposited upon the surface of the overshoe by suddenly changing the shape of the surface upon which the ice is deposited.

Although it willbe apparent that the invention may be applied to many different uses, iti scribed.

Where the' word rubber is used in the descrip- I rubber surface is then soaked with an oil mixture which is miscible with it and which will be retained by it and will reduce the adhesion of the ice to the surface to a low value. As the oil mixture may gradually be removed from the surface by the action of wind and rain, and with the ice which is removed, more oil will come to the surface. From time to time, between flights, fresh oil may be applied to the rubber. In place .of the vulcanized rubber, some other vehicle for the oilmight be applied, which vehicle should have a surface substantially devoid of irregularities into which water could penetrate and, upon freezing, anchor itself. Such material may of itself have a surface to which ice will not readily adhere and will therefore reduce or avoid the necessity of applying a non-adhesive material. Celluloid is an example of such a material. In some embodiments of the invention it is also important that this surface should be of extensible elastic material.

' The liquid to be applied to the overshoe should be one which is fluid at the ice forming temperatures and which has a freezing point below the ice forming temperatures. It should be of low viscosity at these temperatures and should not be sticky and hence adhesive toward ice. Furthermore, it should be a materialwhich will be absorbed into the rubber but which will not swell or weaken the rubber to such an extent that it would have insufficient tensile strength for the use to which it is applied. ,It is not intended, however, to limit the liquid to a non-swelling oil in rubber, for such swelling merely shortens the life of the rubber and it is well known that rubber may be swollen and weakened by oil but will regain its strength after removal of the oil. The amount of oil absorbed into' the rubber need not be up to the saturation point as the reduction in adhesion is greater than in direct ratio to the volume of oil absorbed. It is also important that the liquid be of relatively high boiling point in order that it will not evaporate from the surface at the higher temperatures to which it may be subjected.

It isnot intended to limit the invention to the application of oil to the rubber after the latter is manufactured and vulcanized since good results have also been obtained with oils mixed into the composition before vulcanization, more oil being subsequently added to make up for any loss.

The following materials, or mixtures of them,

' havebeen found to be satisfactory for use in this connection.

Freezing point Boiling point Tetrahydronaphthalene -25 0. +206? C. Dekabydronaphthalene -125 C. +l93.'3 C.

' 25 C. +l50-185 C.

34. 6 0 +213. 2 C. -73.5 0 +176. 5 C. Castor oil l2 0. Above 300 C.

u'bricating oil from petroleum I selected for low freezing pointl5 C Above 250 C.

It is preferred however to use a mixture of liquids and 1 ave found the following mixture very satisfactory for this purpose:

Pine oil 4 parts Diethyl phthalate a parts Castor oil 1 part No claim is made however in this application to the specific liquid to be employed to the rubher since this is the subject matter of a copending application. Serial No. 466,049 filed July 7, 1930 by William C. Gecr.

In selecting the rubber of the overshoe, a pure gum mixture which is compounded and cured normally to give a high cutting resistance, is preferred. Such a mixture may be produced as follows:

Smoked sheets 100 parts Zinc oxide 10 parts Sulphur 3 parts Accelerator 1 part The above compound is merely illustrative, the main requirement being that the mixture contains little or no 'oil soluble sticky material which could diffuse to the surface and render the surface sticky and adhesive toward ice.

Even though the adhesion between the ice and surfaces of the overshoes on the leading edges has been reduced to a low value the ice formed upon them is so perfectly shaped to the surfaces, with each miscroscopic. portion in perfect contact with the surface, that it will beheld firmly in position by the atmospheric pressure or suction between the ice and the surfaces and by the very substantial pressure resulting from the air forces created when the plane is in flight. Furthermore, these surfaces are usually curved so that the ice would not be easily dislodged even though no additional pressure were active.

I have found, however, that by providing means forslightly and-suddenly moving the layer of ice deposited upon a surface of reduced adhesion, the ice will quickly be .releasedfrom the surface upon which it is deposited. In order to accomplish'this an air tube. may be positioned beneath the rubber surface, which air tube will normally be deflated but which may suddenly be inflated by applying an air pressure to the tube connected to it. A low pressure, for example, about 10 to .20 pounds per square inch, will expand the tube against the pressure upon it and will serve to move the ice sufhciently to loosen it from the surface. The ice will then be blown away by the air forces. The expanding tubes may be of many different shapes depending upon the surface to I stockinette or a bias-cut flne thread fabric may be rubberized and used in makingthese tubes, or

a rubber tube may be enclosed within and strengthened by such a uniformly expanding fabric.

For the purpose of describing the invention I have illustrated certain embodiments of it in the drawings but it is not intended to restrict the invention to the particular .embodiments shown.

In the drawings Figure 1 is a diagrammatic sketch illustrating an airplane with the overshoes attached. Figure 2. is a plan view of an for the exposed surface overshoe spread out in a flattened position. Figures 3 and 4 are enlarged sections taken on the lines 3-3 of Figure 2 with the air tubes deflated and inflated, respectively. Figure 5 is a fractional plan view of a modified form of overshoe and Figure 6 is a section taken upon lines 66 of Figure 5 with" the air tube inflated. Figure '7 is a fractional plan view of another modified form of overshoe and Figure 8 is a section taken on line 88 of Figure 7 with the air tube inflated. Figure 9 is a vertical section of a wing with an overshoe applied to its leading edge. Figure 10 is a fractional vertical section of the leading portion of the wing structure shown in Figure 9 with the air tube in the overshoe inflated. Figure 11 is a sectional view through a strut with the overshoe applied thereto. Figure. 12 is a view similar to Figure 11 with the air tube expanded. Figure 13 is a sectional view through an elongated wire with-an overshoe attached to it, the air tube being inflated.

In the several flguresthe numerals IE, IS indicate the wing of an airplane. which are supported by struts l1, l1 and wires I8, l8. In Figure 1 the overshoes I9, l9 have been shown as applied to the leading surfaces of wings l6, Hi,

the struts l1, l1, the elevators 20, 20, the radio mast 2| and the-landing gear 22. A compressor 23 may be used to supply compressed air to the air tank 24, and the-air in the tank 24 may be distributed to the air tubes in the various overshoes through the copper tubing '25, 25, each tube being connected to a separate outlet from the rotary air valve 26.

Referring now to the detail drawings of the overshoe, thenumeral 21 denotes a base fabric which serves as a'support for the rubber surface 28 and the expansion tubes. The base fabric 21 may be impregnated with a material adapted to check the penetration of oil in order to prevent the oil from coming into contact with and softening the nitrodope upon the wing structures. A coating of glue may be used for this purpose.

The base fabric may be of extensible material,

inextensible material or it may be a material cut on the, bias to give slight extensibility. The movement of the rubber surface 28 in the embodiment of the invention illustrated in Figures 2,

3 and 4 is brought about by means of the two air tube may be pre-formed by rolling it upon a mandrel and cementing the overlapped edges in the position shown in the drawings, or it may be formed bycementing the edges of a flattened strip of rubberized material to apiece of rubberized material so that an air space is formed between the two pieces. If the air tubes 29, 29 are preformed they may be cemented to the base fabric 21. The rubber surface 28 is cemented to the outer surfacesof the tubes 29, 29 and beyond them, to the base fabric 21. The outer edges of the overshoe may be reinforced by the,stiif fabric strip cemented to and extending around the edges of the base fabric 21 and between the edges of the base fabric 21 and the rubber surface 28. Lacing eyes or grommets 32, passing through the rubber surface, reinforcing strip and base fabric, -or other means of attachment, may be positioned at spaced points along the edges of the overshoe. When the overshoe is applied to a wing section it is placed along the leading edge of the wing section and may be held in place by suitable connecting devices extending through. the eyes 92,

suitable fastening point, preferably behind thepoint of maximum camber.

Instead of using two air tubes as described above, one wide tube may extend over the entire width of the leading edge. This tube may be positioned at the middle of this width or it may be offset from such middle position.

When the overshoe is used upon a smaller surface such as a strut or wire it may extend entirely about the strut or wire and be fastened to or behind the trailing edge in some suitable manner, as illustrated in Figures 11, 12 and 13. It may be desirable in such cases to reduce the weight of the overshoe by using lighter materials and lighter construction. On the other hand, if the overshoe is to be positioned where it is exposed to ice which may be thrown from the revolving propeller it may be advisable to reinforce it to' prevent the puncturingof the air tube by flying ice. This reinforcement may be accomplished by applying a layer of resistant material, for example, such as is used in preparing the tread of a tire, to the surface covering the air tube. It may also be advisable to reinforce the air tube by covering it with a layer of extensible fabric.

The details of construction described above may be altered materially in order to provide an overshoe of suitable shape and constructed for application to the particular surface upon which it is to be used. For example, by altering the shape and size of the overshoe it may be applied to wires of circular cross section. In all cases where stream line configuration is essenpeller will create suiflcient centrifugal force to dislodge any ice which might form upon the nonadhesive surface. In this embodiment of the 'invention the fabric layer may be cemented-to the metal or wooden surface of the propeller by a suitable cement. When used in this connection, it is advisable to insert a layer of oil resisting material, such as glue, upon the layer of fabric in order to prevent the oil from soaking into the propeller. Another layer of fabric material may be cemented to the oil resisting layer and the rubber surface may be flxed to this layer of fabric. A similar application may be made to other'surfaces, such as the shutters of the radiator, from which the ice may be shaken by opening and closing the shutters.

Instead of using the longitudinal air tubes under-the rubber surface for suddenly changing the shape of the surface, this may be accomplished by having intermittent portions of the surface of relatively extensible material. In Figures 5and 6a cellular .type of overshoe is illustrated in which the squares 33 are of extensible material and the surrounding portions 34 are of relatively non-=extensible material. In Figures '7 and 8 the, extensible portions are in the form of elongated strips 35 separated by the less extensicells may be connected to a common air space 3! which communicates with an air tube 30.

The size and shape of the inflatable tubes should be carefully chosen in order to avoid unnecessary loss of lifting force when the tubes are expanded. In the deflated position the tube may follow the normal shape of the surface to which it is attached, but it is apparent that when the tube is expanded its shape will be materially altered, thus changing the effective shape of the, wing or other surface to which it is attached. In order to prevent bumping or loss of lifting power when the tubes are expanded, it is preferable to have them divided longitudinally into sections, for example, about 10 feet long, and to have separate tubes leadingto the several sections in order that they may be expanded separately and in the desired order. As described above the several tubes may be connected to a rotary valve in the pipe leading from the" air supply tank, which valve may be continuously or intermittently operated by a clockwork or other suitable means. As the rotary valve is'rotated, the several tube sections will be alternately connected with inlet and outlet pipes in order that the tube sections may be expanded and deflated in the desired order. If any air tube should become punctured it may be cut off by a valve in the cockpit. The several air tubes may, of course, each be inflated from one end or from both ends or at numerous points.

' The overshoes described to illustrate an application of my invention provide means for protecting the surfaces against ice formations, which means may be readily attached to and detached from the surfaces and which add only a relatively small amount of weight to the plane. It is apparent that my invention may be applied to manyother types of moving or still surfaces which are exposed to ice forming conditions and it is not intended to restrict it to the particular embodiments described.

What I claim is:

l. A method for reducing the accumulation of ice upon a surface exposed to ice formingconditions, comprising applying to such surface a covering having an exposed surface impregnated with a nonadhesive material.

2. A method for reducing the accumulation of ice upon a surface exposed to ice forming conditions, comprising applying to such surface a covering having a colloidal surface impregnated with a material adapted to reduce the adhesion of ice to the colloidal surface. 1

3. A method for reducing the accumulation of ice upon a surface exposed to ice forming conditions, comprising applying to the surface a covering having a rubber surface impregnated with a liquid adapted to reduce the adhesion of ice to the rubber surface.

4. A method of removing ice from a surface exposed .to ice forming conditions, comprising applying a covering having a surface impregnated with a liquid adapted to reduce the adhesion of ice to the surface, and altering the configuration of the impregnated surface.

5. A method of removing ice from a surface exposed to ice forming conditions, comprising ap-' plying a covering having a surface impregnated with a liquid adapted to reduce the adhesion of ice to the surface and intermittently altering the configuration of the impregnated surface.

6. A method of removing ice from a surface exposed to ice forming conditions, comprising applying a covering having a resilient surface and intermittently stretching and relaxing said sur-' face.

7. A method for reducing the accumulation of ice upon a surface exposed to ice forming conditions, comprising applying a cover having a rubber surface impregnated with a liquid adapted to reduce the adhesion of ice to the surface without substantially deteriorating the rubber.

8. A method for reducing the accumulation of ice upon a moving surface, comprising applying to such surface a covering having its outer surface impregnated with a liquid which will reduce the adhesion of ice to the surface.

9. A method of removing ice from a moving surface,'c0mprising applying to such surface a covering having its outer surface impregnated with a liquid which will reduce the adhesion of ice to the surface and altering the configuration of said impregnated surface. 4

10. A method of removing ice from the exposed portions of an aircraft, comprising applying to leading surfaces of the aircraft a covering having a surface impregnated with a material adapted to reduce the adhesion of ice to said covering surface and varying the configuration. of said covering surface.

11. A method of removing ice from the leading surfaces of an aircraft, comprising applying to said surfaces an extensible covering material impregnated with a material adapted to reduce the adhesion of ice to the covering material and intermittently varying the configuration of separate sections of said covering material.

12. A covering for surfaces exposed to ice forming conditions, comprising a colloidal surface impregnated with a material adapted to reduce the adhesion of ice to the colloidal surface.

13. A covering comprising a rubber surface in pregnated with a liquid adapted to reduce the adhesion of ice to the rubber surface without substantially deteriorating the rubber.

14. A covering comprising a colloidal surface impregnated with a liquid adapted to reduce the adhesion of ice to the colloidal surface and having means for varying the configuration of the surface.

15. A detachable covering for leading edges of an aircraft, comprising an air tube of rubberized extensible fabric covered by a colloidal surface.

16. A covering adapted to be applied to a lead- 1 ing edge of an aircraft, comprising an inflatable tube strengthened by an extensible fabric, said tube being covered by a colloidal surface capable 'of absorbing a non-adhesive liquid.

18. The combination with a covering comprising an extensible surface, of means for intermittently varying the configuration of the surface.

19. The combination with a covering comprising an extensible surface and an inflatable tube positioned to vary the configuration of said surface upon inflation, of means for inflating said tube.

21. The combination with a covering comprising an extensible surface and a plurality of inflatable tubes positioned to vary the configuration of said surface, of means for inflating said tubes.

22. The combination with a surface of an aircraft of a covering extending along a leading edge of said surface, said covering having a surface impregnated with a material adapted to reduce the adhesion of ice to the surface, and means for varying the configuration of said covering surface.

23. The combination with a surface of an aircraft of a covering extending along the leading edge of said surface, said covering having a surface impregnated with a material adapted to reduce the adhesion. of ice to the surface, and means for intermittently varying the configurationof separate sections of said covering.

24. Means for reducing the accumulation of ice upon an airplane comprising a shield applied to parts of an airplane, said shield having an exposed surface impregnated with a non- -adhesive, substance.

'castor oil.

25. Means for preventing. formation of ice and to break up ice formations on the wings ofaeroplanes comprising a flexible sheath ana 'means for agitating the same. I I

26. Means for preventing formation of ice and to break up ice formations on the wings of aeroplanes comprising a flexible sheath and mechanical means for agitating the same.

27. A method for-reducing the accumulation.

28. Amethod for reducing the accumulation of ice upon a surface exposed to ice forming conditions, comprising applying tothe surface a covering having a rubber surface impregnated with WILLIAM C GEER. 20

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