US1421460A - Propeller - Google Patents

Description

F. L. GUILLEMET.

PROPELLER.

APPLICATION FILED OCT 3,19I9- Patented J 111) 4, 1922.

I 3 m 0a 1+ ion B11111 EmEL propeller of metal or a combination spring steel, with all FRANQOIS LEON IDAS GUILLEMET,

OF SAN FRANCISCO, CALIFORNIA;

PROPELLER.

Specification of Letters Patent.

Patented July 4, 1922.

Application filed October 3, 1919. Serial No. 328,273.

To all whom it may concern Be it known that I, FRANgois LEONIDAS GUILLEMET, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented a new and useful Improvement in Propellers, of which the following is ,a specification and the accompanying drawing a part thereof.

The invention relates more particularly to propellers used in aircraft, but with certain modifications of dimensions, is applicable to watercraft also. The main objects of my invention are, first, to provide a propeller that will more efliciently utilize the power applied to it than those at present in use; second, to permit of making such of metal as a base with some other finishing material instead of wood, and yet remain light enough for practical use in air craft, thereby removing to a large extent the danger of breakdown and consequent accidents. A third object is to make this propeller of shorter diameter with wider blades than those in use for any given propelling power, and yet capable of imparting a more powerful and steadying thrust forward to the aircraft to which it is fitted. A fourth purpose is to make the center or hub of the propeller' present a streamline front in conjunction with the fuselage of the airplane. I attain these objects by the form of construction described hereinafter, in which:

Fig. 1 is a back view of the propeller; Fig. 2, a side view of the same; Fig. 3, a view of the other side with the propeller turned over and in this case having the blades inclined forward to form an angle; Fig. 4 is a section through the hollow hub; Fig. 5 is a section taken in the line 55 of Fig. 3, looking in the direction of the arrows; Fig. 6, a portion of a blade provided with perforations, to be covered over with some suitable light material, the last three views being on an enlarged scale; Fig. 7 is an enlarged transverse section through one of the blades of the propeller.

At the present time the whole propeller.

(not including covering when perforated).

would preferably be made of thin'sheet parts welded together, unless some other metal or alloy should be found more suitable. A good substitute would be the new metal beryllium, when discovered in quantities making it available for this purpose, as that metal is said to be twice as strong as aluminum and much lighter.

While the propeller is made of sheet metal it is preferred that the whole be tempered after all of the welding is done.

Proceeding with the description, the bla es A are scooped on their whole length and provided with a series oftransverse partitions B, the scooped form giving rigidity to the blades which is increased many folds by the addition of the partitions, thereby permitting the use of thin sheet metal. The hollow, slightly rounded conical hub or boss C is-intended to form a streamline, conjointly with the fuselage D of the airplane. Aqcurved slot is out through the hubfor insertion of the inner end of each blade which is welded within the slot, the weld line inside being shown at E and E"; the latter indicate the relative position in "the removed part. The sleeve F, formed integral or welded with the hub, is for insertion of the propeller shaft G. A notch is cut away on each side at the base of the sleeve F' and the shaft is provided with two lugs H filling in said notches. The screw I holds the shaft fast with the propeller. while the lugs H prevent the shaft turningwithin the sleeve F. The curve of the blades in cross-section should not exceed one quarter of a circle or 90, as shown in Fig. 5, which also shows one of the partitions B. While it is stated that the curve of the blade in cross section should not exceed one quarter of a circle or ninety degrees, the curt e can be less than that if so desired. As describable in words the shape of the blades may be said to be substantially like the fourth part of a long cylinder or tube cut lengthwise, with sharpened edges, and the hollow side of it divided by a number of transverse partitions having the outer edge preferably curved and slightly protruding as shown in Fig. 5.

The plan of each partition is to form a -curve or segment of circle corresponding to its radius from the center of the hub, so that these partitions will cut on edge through the air and offer practically no detrimental resistance to the motion of the propeller. If it is desired to force the air current produced by the propeller toward the wing tips or away from the center of the airplane. then the blades may be mounted at any proper angle forward, such as shown in Fig. 3. The air pressure acting on the blades will amply compensate for the eilect of centrifugal force and the latter may rather reduce the stress brought to bear on the blades by'the air pressure. This pressure will. produce a twisting or torsional stress on the blades and it is advisable to reinforce the blades by doubling the thickness of metal at their base between the hub and the first partition. I

The-shape of the blades removes the necessity of. a twist or pitch in them, as their action is not that of a screw, but a slight pitch maybe tried if desired by decreasing the curve of the blade. One edge of each blade cuts straight through the air, which is rolled in serpentine billows flying backward. One efiect of the pitch in the propel.- lers generally in use is to project the air from the base toward the tip of the blades and is a cause of inefficiencyQ This inefiiciency is the most marked in thin air on account of the high speed required of the propeller, coupled with the lower air pressure, which causes cavitation. The slipping motion of the air toward the end of the blades cannot take place with my propeller on account of the artitions in it and there is no feature tending to produce said slip. The blades will always embrace a substantial mass of air atall practical altitudes provid ing the necessary backing of air for attain-- ing great speed at great heights with moderate speed of the propeller. on account of which the airplane will also readily negotiate so-called air holes when encountered. The air having to turn around transversely across the plane of motion of the blades, before it can get out of contact with them, instead of being merely pushed back, with nothing to prevent it from slipping off over the upper edge of the blades and toward their tip. as usual with the regular propellers in use, it follows that with my propeller the air remains longer in contact with the blades and is appreciably compressed, before leaving said contact, thereby offering a more solid or resistant backing to the action of the propeller. and all lost motion of both air and propeller is avoided. It is only in so far as the fluid is thrown forcibly backward of the propeller moving in it, without a chance for any of it to spread away even at very low speed of the propeller that its eficiency can be gauged. Furthermore the blades of propellers in general use have to be thicker at the middle. with surface rounded toward the edges and increasing thickness from the tip to the base, which tends to produce a wasteful slip of the fluid medium in which they work. Excepting that my propellers blades should be sharp at the edges with suflicient reinforcement at or near the base, they are intended to be menace uniformly thin throughout their entire area, as applied to aircraft,

In order to further reduce the weight of this propeller, the blades may be honeycombed with perforations, such as shown in Fig. 6, and more than half of the weight of metal thus removed. The blades would then be covered over with some suitable light material, such as rubber or some rubber or leather substitute, one of the most suitable being what is known as iron paper, which is stronger than leather. The space of the perforations may be filled with the same material as the covering or some other having the same size shape and thickness as the metal removed and forming a bending connection between the outer and inner covering, the whole being gluedtogether as well as with the metal. The blades could also be covered with very thin sheets of aluminum. Possible variations in the use of material are numerous however, and I do not wish to limit myself to any particular kind or kinds of metal or material for this form of *propeller'as applied to air craft, but it must be understood that I claim and consider the same form of propeller equally applicable to all watercraft, with only alterations in the length and breadth of the blades, which for a given power should be of a much smaller area than for aircraft, the blades shorter and wider proportionally. and of course of a more substantial structure,

W'hat I claim as m invention and desire to secure by Letters atent is:

1. A. propeller comprising a hub, a plurality of outwardly extending blades carried by the hub, the blades being curved transversely throughout their entire lengths, transversely extending arcuate partition plates carried by the blades, the plates being scribed on an arc with the hub as their center, and of substantially elliptical form and terminating flush with the side edges of the blades.

2. A propeller comprising ahub, a plurality of blades extending outwardly from the hub, the blades being of the same width throughout their entire length and curved transversely, a plurality of substantially elliptical shaped partition plates arranged transversely 'of the blades at equi-distantly spaced points throughout their entire lengths, the plates being curved arcuately and scribed in an arc with the hub as their center. the plates defining a plurality of spaced pockets.

3. An aeroplane propeller comprising a hub, outwardly extending blades carried by the hub, the blades being of the same width throughout their entire length, and transversely extending reinforcing and partition plates carried by the blades.

4. A propeller comprising in combination,

I by and radiating a hub of conoidal shape, and blades carried from said hub, said blades each curved transversely at its juncture with the conoidal surface of the hub and throughout its length and Width to form a scoop like pocket from the outer surface of the hub to the end of the blade with the leading edge of the blades nearest the point of the conoidal hub.

5. A propeller comprising in combination, a hub and blades carried by and radiating from said hub, said blades inclining forwardly at an angle with the plane of rotation of the hub and with their leading edges nearest the forward end of the hub.

6. A propeller comprising in combination a hub and blades carried by and radiating from said hub, the blades arcuated transversely and positioned with their leading edges nearest the forward end of the hub, and their trailing edges each bounding a portion of the convex surface of its respective blade to which the line of travel is tangential, said blades being of uniform width throughout their lengths.

7. In an aeroplane propeller, the ,combination with a metallic body having a plurality of openings therein to lighten the Weight thereof, of means for presenting an unbroken surface for the body including plugs of relatively light material fitted in said openings, and a skin of relatively light material surrounding the body and plugs.

8. In a propeller, the combination of a body formed of relatively heavy material having a plurality of perforations therein to lighten the weight thereof, and plugs of relatively light material fitted Within the said perforations.

LAURENCE BURTON,- E. M. PHELAN.

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