US1158909A

US1158909A - Screw-propeller.

Info

Publication number: US1158909A
Application number: US1261515A
Authority: US
Inventors: Charles E Evitts
Original assignee: Individual
Current assignee: Individual
Priority date: 1915-03-06
Filing date: 1915-03-06
Publication date: 1915-11-02
Anticipated expiration: 1932-11-02

Description

C. E. EVITTS.

SCREW PROPELLER.

APPLICATION FILED MAR. 6. 1915.

1,158,909. Patented Nov. 2, 1915.

CKEv/H's CHARLES E. Ev'i'r'rs, OF POTTSVILLE, PENNSYLVANIA.

ISCREW-PROPELLER.

Specification of Letters Patent.

' Patented Nov. 2, 1915.

Application filed March 6, 1915. Serial No. 12,615.

tain new and useful Improvements in Screw- Propellers, of which the following is a specification, reference being had to the accompanying drawings. I

My invention relates to propellers, and

particularly to screw propellers of the ordinary type used for propelling motor boats or other vessels, whether in air or water.

The primary object of my invention is the provision of a propeller having its blades so formed and curved as to obviate slippage and further acting to relatively project a column of water directly toward the rear of the propeller or exert a direct rearward thrust against the water or other fluid upon which the propeller acts without allowing the water to pass laterally or radially as it were, of the blades.

A further object of the invention is the provision of a propeller wherein the blades shall not only extend obliquely with relation to the axis of the propeller, but wherein the outer ends of the blades shall be gradually curved rearward, thus preventing slippage and also exerting a thrust toward a line formingan extension of the axis of the propeller.

My invention is illustrated in the accompanying drawings, wherein Figure 1 is a face view of a propeller constructed in accordance with my invention; Fig. 2 is a perspective view looking toward the side of the propeller; Fig. 3 is a diagram showing the manner in which the elliptical curve of the propeller is drafted.

Referring to these drawings, 2 designates the hub of a pro eller and 3 the blades thereof. Each bla e at its base extends as usual diagonally to the axis of the hub. The outer end of each blade is wider than its base and each blade. at its outer end edge is disposed at an obtuse angle to the axis of the propeller. Each side edge of the blade is given an elliptical curve, as shown most clearly in Fig. :2, and therefore the blade itself is curved rearward so that the outer end of the blade is' not only twisted but rearwardly curved, these curves being a section of an ellipse. The side edges of each blade extend radially to the axis of the propeller.

The blade is laid out in the manner shown in Fig. 3 wherein a. is a base line having a length proportionate to that of the blade and b is a pitch line equal to the pitch of the blade. These lines are divided into an equal number of parts by indices. The lines 0 and d are then drawn from the corresponding indices on the pitch line and base line, and the outer intersections of these lines gives the required elliptical curvature for the blades.

It will be noted from Fig. 2 that the forward and rear outer corners of each blade, because of the curvature of the blade, are

disposed rearward of the forward and rear' inner corners of the blade, where the blade joins the hub.

Propellers constructed in accordancewith my invention prevent the water" or other fluid from slipping laterally along the blade of the propeller, and the thrust of the blade is always transmitted directly rearward toward a line forming a continuation of the axis of the propeller, thereby securing a CHARLES E. EVITTS. Witnesses D. W. GALL, F. B. WRIGHT.