US1864803A - Marine and aeroplane propeller - Google Patents

Description

June 28, 1932. J. M. CLARK 1,864,803

MARINE AND AEROPLANE PROPELLBR Filed July 11, 1929 ATTORNEY Patented June 28, 1932 JOHN M. CLARK, OF WHITESTONE, NEW YORK MARINE AND AEROPLANE PROPELLER Application filed July 11, 1929. Serial No. 377,584.

The subject of this invention has to do with the construction of propellers adapted to be used on aeroplanes or boats. I do not mean that the same propeller is used on aeroplanes and boats, but I do mean that the improvement in the construction of propellers, which I am about to describe, is equally adaptable to aeroplane propellers or boat propellers.

The object of this invention is to increase the effective area of a propeller, to give the propeller a sharper and better defined contact surface with the fluid through which it is passing, and to prevent to a very great extent. at least propeller slip, and the foaming occasioned by the slipping of the propeller.

Another object of this invention is to direct the discharge from the propeller blades, and by that, I mean that as the fluid leaves the propeller blades, it is directed'into a slotted cone, and is not whipped or churned into abubbling mass, as is so often found in smooth propellers, particularly when such propellers are operating at a high speed.

Another object of the invention is to direct the fluid discharge toward the outer edges of the propeller blades, as it is the outer edges, or tips of the propellers that are most eflicient. I have found that increased propeller efficiency is obtained when the fluid is directed toward the blade tips, to be discharged therefrom.

The means for accomplishin these objects, and others not specifically re erred to, will be fully set forth, as the specification progresses, and the following is what I consider the best means Qfcarrying out my invention. The accompanying drawing should be referred to for a complete understanding of the specification which follows.

In the drawing:

Fig. 1 shows an aeroplane propeller in rear elevation.

Fig. 2 is a side elevation of the propeller shown in Fig. 1.

" Fig. 3 shows a marine propeller.

Fig. 4 is a sectional view taken about on the line 44 in Fig. 3.

Fig. 5 is an enlarged sectional view taken about on the line 55 of Fig. 1.

Fig. 6 is an enlarged sectional view show ing modifications, and

Fig. 7 is a diagrammatic view, suggesting different shapes of grooves that may be employed.

Similar reference numerals indicate like parts in all the figures where they appear.

s aeroplane propellers and marine pros pellers operate in opposite directions, the propellers shown in Figs. 1 and 3 may be considered in reverse relation to each other. The surface of the propeller shown in Fig. 1, is that surface which in operation, may be considered the back of the propeller; that is, it is the surface nearest the aircraft, and in observing this propeller, looking from before the front of an aeroplane, the surface of the propeller observed, will be flat and smooth, as is the ordinary propeller, but the back of the propeller when viewed in the direction above suggested, and which I term the effective surface of the propeller, will be provided with a plurality of grooves, and while a number of grooves may be varied, in Fig. 1, I show four suchgrooves, as indicated by the reference characters 2, 3, 4 and 5.

It will be noted that these grooves, commencing at the hub end of each propeller blade, curve outward and away from the direction of rotation of the blade,

I have assumed that the direction of rotation of the propeller shown in Fig. 1, is that indicated by the arrow D, and that the eneral shape of the grooves in the prope ler blades, as that suggested in Fig. 5.

The number of grooves, and the angle at which they are arranged, will be determined by the length, contour and speed of the propeller, it being always had in mind that it is my desire that the grooves will tend to direct the fluid outward, to be di charged at the greatest diameter of the propeller, or that is, fairly adjacent to the wind tips, although some of the grooves, as shown at 2 and 3, are of less length than other grooves.

I consider this also important, as I believe that were all of the grooves to terminate at one point, a choking efiect might result.

My experiments have demonstrated that an increased propeller efl'ect is obtained by forcing the fluids outward toward the propeller tips.

In the propeller shown in Fig. 3, the same general arrangement of grooves is followed, but as the device shown in Fi 3, is a marine propeller, the width of the 'b a des is greater, while the length is shorter. The greater width of blades makes it advantageous to provide a greater number of grooves.

In the propeller shown, I have provided seven grooves, indicating them with the reference characters 6, 7, 8, 9, 10, 11 and 12,

while the propeller blades are'indicated at 13, 14 and 15. The grooves in the marine propeller are arranged in the back surface; that is, looking forward from the stern of the vessel, the grooves will be toward the eye. This follows the general idea that the grooves are upon the pressure side, or pusher side of the blade, while the opposite side may be smooth.

Because of the slower rotation, I believe that it is desirable to make the grooves in the marine propeller with somewhat sharper walls, as will be noted by observing the sectional view in Fig. 4, and comparing them with the grooves 2 to 5 inclusive in the sectional view of Fig. 5,'which is a sectional View through the aeroplane propeller.

In Fig. 7 I show a series of diagrams suggesting that to meet special, or other conditions, the grooves may be given a somewhat different shape.

In Fig. 6, I show that the effect of grooves may be obtained by the addition of a series of blocks to the surface of the propeller. These blocks are shown at 16, 17, 18, 19 and 20, and each is secured by screws, or other suitable means, as shown at 21.

It is believed from the foregoing, that the operation and the results of the operation of my device, may be fully understood, and that modifications in the shape and length of grooves, or in the general constructive features, may be made, within the scope of the appended claims without departing from the principle or sacrificing the advantages of this invention. I consider it quite important, however, that all of the grooves, or abutments, if such are used, be arranged on a true stream line, so as to reduce resistance and increase operating efficiency.

Having carefully and fully described my invention, what I claim and desire to secure by Letters Patent is:

1. A propeller blade having a plurality of grooves in approximately one half of the surface of the blade and extending longitudinally of the blade, said grooves spaced approximately equal distances apart, and terminating at one ed of the blade.

2. A propeller aving a plurality of blades, each said blade being provided with a plurality of grooves produced in less than the entire surface of each blade, all of the grooves commencing at a point approximating the hub of a propeller and extending outward and curved to terminate at one edge of the blade in which they are produced.

JOHN M. CLARK.

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