US655958A - Screw-propeller. - Google Patents

Description

No. 655,958. Patented Aug. I4, |900.

.1. cALsvsoM. SCREW PROPELLER.

(Application ledIeb. 7, 1899.)

(N0 Model.)

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; UNITED STATES PATENT OEEICE.

JOHN CARLVSSON, OF WORCESTER, MASSACHUSETTS.-

SCREW-#PROPELl- ERl srEcIr'rcATIoN fol-ming part of Letters Patent No. 655,958, dated August 14, 1966.

Application filed February '7, 1899. Serial No. 704,814. (No model.)

T all wtmn t may concern.-Y

Be it known that I, JOHN CARLSSON, a citizen of the United States, residing at Worcester, in the county ofWorcester and Comm onwealth of Massachusetts, haveinvented a new and useful Improvement in Screw-Propellers, of which the following is a specification, laccompanied by drawings forming a part of the same, and in which* Figure 1 represents a front elevation of a screw propeller embodying my invention. Fig. 2 is a side elevation of the same; and Fig. 3 is a sectional view on line 3 3, Fig. 1.

Similar reference-letters refer to similar parts in the different views. l

My invention relates toscreW-propellers for vessels, having for its object to increase the efficiency of the propeller; .and it consists in the conformation of the propeller-blade, as hereinafter described, and set forth in the anueXed claim.

Referring to the drawings, Figure 1 represents a Vscrew-propeller having Ain thel presentinstance four blades-A, although the number of bladesmay be increased or diminished, if desired. B denotes the rear end of the propeller-shaft, to which a hub C is attached, having the propeller-blades extending radially therefrom, with the plane of the blades placed at anysuitable inclination or pitch to the plane of the axis of the shaft. In Fig. 2 the arrow 1 represents the direction of Ino-v tion of the propeller-blades as they arecarri'ed through the Water bythe `forward movement of the ship, said. motion being parallel to the axis of the propeller-shaft B. As the ship moves through the water the edges a of.

the propeller-blades are the ,front or advancing edges and the edges b are the rear edges. Each of the blades is wedge-shaped in cross-- section, as shown in sectional view in Fig. 3, with the front edge of theblade thicker than the rear edge.

The front edges a of the blades present surfaces a, lying inplanes at right angles to the axis of the propeller-shaft B. From the front edge ct the blade is gradually reduced in thickness toward the rear edge b, so that as the blade travels in a forward line, due tothe forward motion of the vessel and indicated by the arrow 1, the thick front edge or1 is presented to the water and the resistance ofthe water against the edge of the blade is received upon the surface a', which lies in a plane at right angles to the forward line of motion of the. blade, causing an immediate separation of the water greater than the thick- Vness of the blade at the rear of the edge a, so

that as the blade passes through the Water the pressure required to separate the water is removed from the sides of the blade and the friction thereon is consequently reduced. The separation of the Water at the front edge of the blade/is in a line at right angles with the axis of the propeller-shaft instead of at an oblique angle thereto, as would be the case 'if the front edge of the blade Were round- 4ed or beveled. Friction is thereby reduced vupon the front edge of the blade, and counter currents between the surfaces of the blades are avoided.

I do not conne myself to any particular angle or pitch at which the blades stand relatively to their plane of rotation nor to the shape of the impinging surface of the blade as it rotates through the Water; but I have shown in the accompanying drawings one embodiment of my invention.

What I claim as my invention, and desire to secure by Letters Patent, is

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