US1142915A - Propeller. - Google Patents

Description

J. L. SCOTT.

PROPELLER.

APPLICATION FILED 11111.30, 1914.

1,142,915. Patented June 15, 1915.

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W a} Wi Hm 'MAJ $11 QQWWC R JOHN L. SCOTT, OF VERMILIOL'N, OHIO.

PROPELLER.

Specification of Letters Patent.

Patented June 15, 1915.

Application filed January 30, 1914. Serial No. 815,446.

To all whom it may concern:

Be it known that I, JOHN L. ScoT'r, a citi Zen of the United States, residing at Vermilion, in the county of Erie and State of Ohio, have invented a certain new and use ful Improvement in Propellers, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings. v

This invention relates to improvements in screw propellers for use with marine vessels.

In the type of propellers which are in common use, the blades radiate from the hub, and occupy a plane which is atright angles to the shaft. Furthermore, the driving or working surfaces of the blades of all propellers with which I am familiar, are concaved. The radial arrangement of'the blades, and the concavity of their driving or working surfaces, causes a centrifugal action upon the water which greatly reduces the driving etliciency of the propeller. In fact, the centrifugal force is so pronounced in the vicinity of the base of the blade. that it entirely overbalances the driving action of the propeller in this region. Also, a void is formed to the rear of the hub of propellers of the aforesaidtype when the propeller is in action, which results in a suction that actually retards the advance movement of the propeller. I have observed, also, that there is an unpleasant and deleterious jarring action or vibration, incident to the operation of this kind of propellers which is caused by a compression of water between; the respective blades of the propeller and the stern post of the vessel as the former pass the latter. It is obvious that'such an effect would result since the blades radiate from the shaft and are therefore parallel with the stern post when passing. the same; it being mentioned at this time that there is only a slight clearance between the blades and said post.

It is the object of my invention to provide a propeller of very high driving efficiency; which is designed with the result in view of creating, near its center, a centripetal action that will direct the water toward the wake of the hub, quickly filling the void made thereby and preventing a suction which, if

permitted to exist, would reduce the efliciency of my propeller.

Other objects of my invention areto provide a propeller which is well balanced thatis to say, in which the strains imparted the angle 'of deflection is rearwardly substantially parallel to the shaft; which will not undulyagitate the water; and which will cause no jar or vibration as its blades pass the stern post of the vessel.

The above and further objects, which will become apparent as this description proceeds, are attained in a propeller constructed in accordance with the accompanying drawings which form a part hereof, and in which- Figure 1 represents the stern of a large vessel in side elevation, the same having one of my improved propellers applied thereto, the propeller being of the detachable blade type; Fig. 2) is a front elevation of the propeller shown in Fig. 1; Fig. 3 is a face View of one of the propeller blades removed from the hub; Fig. 4 is a front elevationof a form of my propeller for use on small boats, the blades and the hub being formed integral; Fig. 5 is a rear elevation, Fig. 6 a side elevation, and Fig. 7 a plan of the propeller shown in Fig. 4; and Fig. 8 is a diagrammatic view of various sections taken through one of the blades of my propeller, each of the sections being lettered to correspond to the designation of the line of Fig. '6, upon which such section is taken.

While the drawings show two modifications of my invention which difi'er considerably in appearance, it will be understood that the principles of both are the same. In propellers for use with large vessels it is an advantage to have the blades removable from the hub section, as illustrated in Figs. 1 to 8, in order that any one of the blades, should the same become damaged, may be replaced without disturbing the remainder of the propeller, and without the expense of replacing the entire propeller; and this may be accomplished, too, without the necessity of placing the vessel such operation, which would be required if the entire propeller were removed. The other form of my propeller, illustrated in Figs. l to 8, is designed especially for use on small boats, and because of the simplicity of this form it is'belie'ved that an understanding of the principles of my invention may be more readily gained frdm a consideration Ofthis for'm' than from that ofthein dry dock during tributed evenly throughout the length ofthe blade. In accordance with the principles of practically all propellers, my pro peller is constructed along the lines of a true screw; and to this end each blade is set at an angle with respect to the longitudinal axis of the hub, which corresponds to the pitch oi the blade at its inner end. Throughout the length of the blade this angle gradually increases in proportion to the increase in radius, in order that the pitch may be true and constant throughout. Not

. only are the blades set at an angle with respect to the longitudinal axis of the hub (as shown particularly in Figs. 7 and 8), but they are also arranged at an angle (substantially that of 30) with respect to the vertical axis of the hub, considering the same in the position shown in Fig. 6. This results in the outer ends of the blades projecting beyond the front of the hub, and the rear corners of the blades extend beyond the rear thereof. It will also be observed that the blades are tangent to the central portion of the h b. Now, taking all of these points into consideration-the transverse angle, theforward inclination, and the tangential arrangement of the blades-it will be seen that, in the operation of the propeller, the forward end of each blade is constantly reaching out-into solid or undisturbed water; that the remainder of the blade, be cause of the proportional change in angle and. radius, follows the leading end without unduly agitating the water; and that the working surface of the blade is comparatively large because of the long diagonal lines of bearing that are produced by its forward inclination. (By the lines of bearing is meant the lines defined by the water as it passes from the leading to the tollowing'edges of the blades in a course substantially parallel to the shaft). Also, the friction of the water upon the blade is reduced to a minimum because of the convexity of its working surface, such convexity resulting from the previously mentioned twist of the blade. The convexity of the working surface also prevents pocketing of the wat'r and they directing of it toward the periphery of the propeller, thereby eliminating the centrifugal action pro-. duced by propellers of ordinary type where-.

iaaeia the tangential arrangement of the blades and the overhanging of their rear corners beyond the rear end of the hub that creates the centripetal action in the region of the hub which, as previously expressed, directs the water inwardly and prevents suction at the rearthereof.

In Fig. 8, the dotted lines 6 and f represent, respectively, the front and rear ends of the hub, and the dotand-dash lines a, 7), etc, its longitudinal axis. The angular inclination of the blade, at the planes of the various sections a, 7), etc, with respect to the longitudinal axis of the hub, is shown by the association of the sections a, 7), etc. with the lines a, 7), etc, respectively. Fig. 8 serves, further, to show the convexity of the working surface of the blade, the direction of rotation of the propeller being indicated by the arrows in this and certain other views of the drawing.

It will be seen from Figs. 6 and 7, and section cl of Fig. 8, that the blade becomes thicker as it approaches the hub, as shown at 4., in order to withstand the heavier work which falls upon this portion of the blade as a consequence of the decrease in the angle between the inner end of the blade and the hub.

, Referring to Fig. 1. 10 represents the stern of a large vessel, to the shaft 11 of which is applied the hub 12 of a detachable blade type of my propeller. The blades 13 are secured to the hub 12 by screws 14 which pass through holes in the bases 15 of the blades and are threaded into the hub. The tangential arrangement of the blades is especially well shown in Fig. 9; because of the necessarily, proportional increased radius of the hub in this form of my invention, over that shown in connection with the previously described form. In Fig. 3, l have indicated the central line of the shaft in order to express the angle of inclination between the blade and the shaft. The advantage gained by this inclination of the blade, to-

wit, the absence of vibration as the blades pass the stern post of the vessel, has been brought out hereinbefore: and the relation of the forward or leading edges of the blades with respect to the stern post of the vessel is very clearly illustrated in Fig. 1, wherein the stern post of the vessel is indicated at 16.

Having thus described my invention,what I claim is 2-- 1. A propeller comprising a hub, and a plurality of blades which extend tangentially therefrom, the working surface of each blade being convexed.

2. A. propeller comprising a hub, and a plurality of blades which extend tangentially therefrom, the blades being inclined tit the hub, the blade projecting forwardly and outwardly and forwardly from the hub, each blade having a portion which projects beyond the rear end of the hub.

3. A propeller comprisingva hub, and a plurality of blades which extend tangentially therefrom, the blades being incllned outwardly and forwardly from the hub,

each blade having a portion which projects beyond the rear end of the hub, the working surface of each blade being convexed.

4. -A propeller comprising a hub, and a plurality of blades which extend tange'ntially therefrom, the blades beifig disposed V at an acute angle with respect to the rotating axis of the hub said angle gradually increasing from the inner tolthe outer end of the blades, the blades being inblined outwardly and forwardly from the hub,,each blade having aportion which projects beyond the rear endof the hub.

5. A propeller comprising a hub and a plurality of blades carried thereby, 'each blade having a portion adjacent its inner end which extends beyond the rear-end of outwardly from such portion.

6. A propeller comprising a hub and a plurality of substantially rectangular blades, each blade having one of its corners cut diagonally by the hub Where it merges thereinto, tli'e blade joining the hub at an acute angle with respect to the rotating axis of the hub, said-angle increasing gradually from the inner to the outer end of the blade,

the corner of the blade adjacent to Where it is attached'to'the hub projecting beyond the rear end thereof and the diagonally opposed corner of the blade extending beyond the plane of the forward end of the hub.

- into, the

7. A propeller comprising a hub and a plurality of substantially rectangular blades, each blade having one of its corners cut diagonally by the hub where it merges thereladejoining the hub at an acute angle wlth respect to therotating axis of the hub, said angle increasing from the inner to the outer end 0 he hub,

the corner of the blade adjacent to Where it is attached to the hub projecting beyond the rear end thereof and the diagonally opposed corner of the blade projecting beyond the plane of theforward end of the hub, the

fiadually blades being substantially tangent to the hub.

8. A propeller comprising a hub, and a plurality of blades detachably secured thereto, each blade consisting of a base to one edge of which is joined the side of one end-' of a. Wing, the wingbei'ng disposed at an acute angle with respect to the plane of the base, said angle increasing toward the free end of the Wing, the leading edge of the wing andthe base being in substantially the same lane.

9. .propeller comprising 'a hub, and a plurality of blades detachably secured there-.

to, each blade consisting. of aba'se to one edge of which is joined the side of one end of a wing, the wing being disposed at an acute angle with respect to the plane of the

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