US2701696A - Propeller blade deicing means - Google Patents

Description

Feb. 8, 1955 A. E. FELT 2,701,696

PROPELLER BLADE DEICING MEANS Filed May 14, 1951 "Ill/111111111111.

INVENTOR. Adolph Felt www? nA/LV AT TORNEY United States Patent PROPELLER BLADE DEICING MEANS Adolph E., Felt, Milwaukee, Wis., assignor to A. O. Smith Corporation, Milwaukee, Wis., a corporation of New York craft propeller blades and more particularly to a novel bulkhead employed within a hollow propeller blade to improve the de-icing characteristics thereof.

An object of the present invention is to provide a structurally simple and economical method of de-icing a propeller blade, whereby a fluid, such as a hot gaseous medium, is directed through the hollow blade, to the portion of the blade where the greatest ice formatlon is apt to occur, by means of a rubber-coated glass fabric bulkhead.

Another object is to provide a lightweight durable bulkhead to seal all chambers except the leading edge chamber of a sectional propeller blade from the passage of hot gases therethrough, the bulkhead being constructed of a flexible material and adapted for interchangeable use in propeller blades of similar cross section.

A further object is to provide a bulkhead in a blade for directing de-icing fluids to the blade edge, which bulkhead is substantially flexible to absorb the breathing movement of the blade caused by resonant vibrations 1n the blade.

Still another object is to provide a novel means of attaching a heat-resistant fabric bulkhead to the inner surfaces of a hollow propeller blade, whereby the cross sectional area of the blade wall is not reduced by Saul attachment and hence the blade is not susceptible to failure at the point of attachment during service.

The present invention is adapted for use with a hollow propeller blade comprising a shank, into which the hot fluids, generally heated air or exhaust gases, are introduced, a tip, from which the gases are ejected, and a central section which extends between the shank and the tip, and through which the hot gases pass in the1r movement through the blade. To give the blade added strength and rigidity, the central section has one or more longitudinal webs joining its foil sections and forrnmg several longitudinal passages or chambers, rather than a single chamber, and all or a number of these chambers may communicate with the shank depending on the particular construction of the blade.

The present invention comprises a lightweight durable bulkhead, which is employed to direct the hot gases from the shank, where they are introduced into the blades, to the longitudinal chamber adjacent the leading edge of said blade by closing olf all other chambers which communicate with the shank to the ow of said gases. The bulkhead is preferably constructed of a flexible heatresistant fabric, such as glass cloth, coated with silicone rubber which is able to absorb the breathing movements of the blade. This material is molded to the approximate cross-sectional contour of the chamber to be closed olf and secured thereto by vulcanizing, so that the blade will not be injured by chafling of the interior.

Thus, the heated air or exhaust gases which are introduced into the shank of the blades are directed, by virtue of the novel bulkhead, to the chamber adjacent the leading edge of the blade, the portion of the blade subject to the most severe ice formation.

Gther objects and advantages of the present invention will appear in the accompanying description of the embodirnents of the inventions.

ln the drawings:

Figure l is an elevational View of a propeller embodying the invention with parts being broken away and sectioned;

Fig. 2 is a transverse sectional view on the line 2--2 of Fig. l;

Fig. 3 is a fragmentary longitudinal section on the line 3-3 0f Fig. l;

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Fig. 4 is a view similar to Fig. l of a modified form of the invention;

Fig. 5 is a transverse section on line 5 5 of Fig. 4;

Fig. 6 is a fragmentary longitudinal sectionL on line 6 of Fig. 4;

Fig. 7 is a detail View of the bulkhead before assembly with the propeller;

Fig. 8 is a fragmentary transverse sectional view of the propeller with the bulkhead secured therein showing how the walls of the bulkhead adapt themselves to the contour of the propeller wall; and

Fig. 9 is a fragmentary longitudinal section of the propeller showing the bulkhead positioned ready to be vulcanized to the propeller wall.

Referring to the drawings, there is shown in Figs. l-3 an embodiment illustrating a typical propeller blade containing the present invention. The blade consists of a hollow shank 1, a hollow tip section 2, and a central section 3, which extends between the shank and the tip section and comprises a tubular body section 4, to which is secured a leading edge member 5 and a trailing edge member 6. Thus the central section 3 is formed with three longitudinal passages or chambers, the trailing edge chamber 7, central chamber 8, and the leading edge chamber 9, all of which extend substantially the length of said section.

The root l0 of the tubular shank has a generally cylindrical shape. The shank 1 flares outwardly from root liv to provide a generally flatter cross-sectional shape in the portion thereof adjacent the central section 3. The shank is welded to central section 3 with the passage lll in the shank communicating with the central chamber 8 of said section.

The trailing edge member 6 is tapered inwardly toward shank 1 and closes off chamber 7, there being no communication at the shank end of the blade between the trailing edge chamber 7 and either the central chamber 8 or the shank passage 11.

The leading edge member 5 is similarly tapered inwardly toward shank l and closes off chamber 9. However, an aperture l2 is formed in the wall of tubular body section 4 adjacent the shank permitting communication between the leading edge chamber 9 and the central chamber 8 and shank passage 11.

The portion of the central section 3, adjacent the tip 2, takes a flatter shape and is secured to said tip by suitable welding, the chambers 7, 8 and 9 communicating with the chamber 13 in said tip.

The tip 2 is formed with an aperture 14 in the upper flat portion thereof adjacent the trailing edge of the blade. The hot fluids which are introduced into the blade through the shank l, are drawn through aperture 14 to the atmosphere by the centrifugal action caused by blade rotation.

A flexible heat resistant bulkhead 15 is disposed within the tubular body section 4 to prohibit the ow of the heated air or exhaust gases therethrough.

The bulkhead 15 is preferably constructed of a glass fiber cloth which is friction coated on both sides with silicone rubber. This material is extremely durable and is capable of withstanding the high temperatures of the hot gases. The temperatures are generally in the range of 400-500 F., and it is essential that the material employed will not burn or char at this heat.

Bulkhead 1S is of elongated trough-like shape, comprising a base 16 and side walls 17. The bulkhead is disposed within the tubular body section 4 to the outboard or tip side of aperture 12, with the open top of said bulkhead facing toward the shank of the blade, and the base 16, which has a generally elliptical shape substantially similar to the cross-section of bodysection 4, effectively closing off the inner end of chamber 8 of section 4. The walls 17 of the bulkhead 1S extend from base 16 toward the shank end of the blade to a position ontboardly adjacent the aperture 12 and are in flexible engagement with the inner surfaces of section 4.

The walls 17 of the bulkhead are secured to the adjacent inner surfaces of section 4 by vulcanizing. This may be accomplished by interposing a thin band of raw silicone rubber 18 between walls 17 and the body section 4 .adjacent the open end of the bulkhead, as shown in Fig. 9.

Heat is applied to the joint, and a suitable pressure means is utilized within the blade to force the walls 17 against the inner surface of tubular section 4 to produce the desired vulcanization of bulkhead to section d.

Thus, the bulkhead, while closing lolf the body section 4 to the ow of gases, does not prevent the flow of gas from the shank through aperture 12, and hence to the leading edge -chamber 9.

In operation, the heated air or exhaust gases are introduced into the shank 1 of the blade by a means, not shown, and pass through the aperture 12 to the leading edge chamber 9, the gases being prevented from passing through the tubular body section IlV by the bulkhead 15. The gases travel through chamber 9 to the tip chamber 13, where they are drawn laterally across the t-ip of the blade to the aperture 14 by centrifugal force caused by rotation of the blade.

There is shown in Figs. 4-6 another embodiment illustrating a typical propeller blade containing the present invention. The blade consists of a tubular shank 19, a tip section anda hollow central section 21, which extends between the shank and the tip. The central section 21 comprises a leading edge member 22 and a trailing edge member 23, which are connected by an upper foil plate 24 and a lower foil plate 2S. A reinforcing web 26 longitudinally divides the section 21 into a trailing edge chamber 27 and a leading edge chamber 28. The web 26 is secured edgewise between the upper foil plate 24 and lower foil plate 25, and extends from the shank end of said section 21 to a slight distance short of the tip end thereof, to provide a port 29 between the chamber 28 and the chamber 27 at the tip 20.

The tubular shank 19 has a generally cylindrical shape at its root 30, and flares outwardly from said root to provide a generally atter cross-sectional shape in the portion thereof adjacent to the central section 21. The shank 19 is welded to the section 21 with the passage 31 in the shank communicating with both the leading edge chamber 28 and the trailing edge chamber 27.

The portion of the central section 21 adjacent the tip 20 has a generally flat shape and is welded thereto.

The trailing edge member 23 is formed with an aperture 32 in the portion thereof adjacent the tip, which serves as an exit for the hot gases introduced through the shank 19, and passing through leading edge chamber 2S and port 29.

A bulkhead 33, of similar construction to bulkhead 15 previously described in the rst embodiment, is employed to seal the trailing edge chamber 27 from the entry of the hot gases. The ow of the gases is thus restricted to the leading edge chamber 2S producing a more effective deicing of the leading edge member 22.

The bulkhead 33 is of trough-like shape comprising a base 34 and outwardly flared side walls 35. The bulkhead is disposed within the chamber 27 adjacent shank 19 of the blade with the open side facing toward the shank, and having the base 34 effectively closing off the wedge-shaped chamber 27. The side walls 35 of the bulkhead are in yielding engagement with the inner surfaces of bottom foil plate 25, trailing edge member 23, top foil plate 24 and reinforcing member 26 respectively.

Figure 7 shows the bulkhead as molded before attachment within the blade, and Figure 8 illustrates the same bulkhead disposed within the chamber 27, the exible nature of the bulkhead permitting it to conform to the rather irregular cross-sectional contour of said chamber.

The bulkhead .33 may be formed with a small vent hole 36 in the base 3d to facilitate the draining of any accumulation of oil, dirt, or similar undesirable matter.

The bulkhead 33 is attached within the blade preferably by vulcanization in a manner similar to that previously set forth in the first embodiment.

Due to Vresonant vibrations set up in a propeller blade such as by operation of the engine and gears in the hub, passage of the blade past the wing of the plane, different air densities and certain maneuvers and the like, the blade tends to breathe or expand and contract in service. The bulkhead provided by the invention is able to breathe with the blade. In addition, the manner of attachment of the bulkhead to the blade avoids chaing of the interior surface of the blade.

While the present invention has been described with respect to use with certain ,particular propeller blades, it is understood that its use is not limited thereto, but 'it may be employed with any type Vof hollow or 'tubular-propeller blade into which hot gases may be introduced, to direct or delle'ct said gases to the portion of the blade most susceptible to ice formation.

Various embodiments of the invention are employed within the scope of the following claims.

I claim:

l. In a hollow propeller blade comprising shank and tip sections joined by foil members having leading and trailing edge members, a heat resistant flexible nonmetallic bulkhead secured chordwise to the inner surfaces of the blade adjacent the shank and employed to direct hot ilu-ids received from the shank to the leading edge portion of said blade most susceptible to the formation of ice during service, said bulkhead including a closed end having a periphery substantially conforming to the `chordwise cross section of the portion of the blade wherein the bulkhead is to be disposed and having side walls extending inboardly from the periphery of said end and being disposed in lapping contacting relation with the foil members and the trailing edge member, and a non-metallic bond securing the overlapping side Walls of 'the bulkhead to the blade members over which the bulkhead lies.

2. In a .hollow metal propeller blade adapted to pass hot gases therethrough with the gases having a temperature in excess of 400 F. to de-ice the blade in service and said blade comprising shank and tip sections joined by foil members having leading and trailing yedge members, at least two chambers extending for substantially the length of the blade from the shank to the tip thereof with said chambers being provided by a longitudinally extending partition member joined t0 the foil members of said blade, a bulkhead having a closed end with side walls extending inboardly from said end and having an open end opposite said closed end, said bulkhead disposed across the end of one of said chambers adjacent the shank of the blade to direct hot gases received from the shank into the other of said chambers and along the leading edge of the blade, said bulkhead being of flexible non-metallic material and capable of withstanding the temperatures of the hot de-icing gases without burning or charting, and said bulkhead having substantial depth with the open end thereof facing the shank and the side Walls thereof overlapping the foil members and the trailing edge member of said blade for a substantial distance to cornpletely close off the chamber across which the bulkhead is secured, non-metallic means securing the overlapping side walls of the bulkhead to the blade members over which the bulkhead lies, and means in said blade to discharge the hot gases therefrom.

3. In a hollow metal propeller blade adapted to pass hot gases therethrough with the gases being in the range of temperatures of about 400 to 500 F. to fle-ice the blade in service and said blade comprising shank and tip sections joined by foil members having leading and trailing edge members, at least one partition member joined to the foil members `of the blade to provide the interior of the blade with at least two longitudinally extending chambers, a bulkhead disposed across the end of one of said chambers adjacent the shank of the blade to direct hot gases received 'from the shank into the other of said chambers and along the leading edge of the blade, said bulkhead comprising an inner layer of glass liber cloth coated with a durable rubber-like material and capable of withstanding the temperatures of the hot de-icing gases without burning or charring, and said bulkhead being of a deep drawn shape with the open end thereof facing the shank and the side walls overlapping the members of the blade for a substantial distance to completely close off the chamber across which the bulkhead is secured, vulcanizing means securing the overlapping side Walls of the bulkhead to the blade members over which the bulkhead lies, and means in said blade to discharge the hot gases therefrom.

References Cited in the lile of this patent UNITED STATES PATENTS 1,937,966 Junkers Dec. 5, 1933 1,988,202 Hoover Jan. l5, 1935 2,470,128 Barrick et al. May l 1949 2,522,955 Martin Sept. 19, 1950 2,541,661 Palmatier et al. M Feb. 13, 1951 2,556,736 Palmatier June l2, 1951

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