US293777A

US293777A - Screw-propeller

Info

Publication number: US293777A
Authority: US
Publication date: 1884-02-19
Anticipated expiration: 1901-02-19

Description

' UNITED STATES PATENT OFFICEo HAEEIsoN o. rEAEsoNs, 0E 'EEEEYsEUEa MICHIGAN.

soREwPRoPELLER- SPECIFICATION forming part of Letters .Patent No. 293,777, dated February 19, 1884. Application filed January 15, 1883, l(Model.)

To all whom t 'may concern.-

Be it known 'that I, HAEEIsoN G. PEAR! soNs, of Ferrysburg, in the county of Ottawa and State of Michigan, have invented new and useful Improvements in Screw-Propellers; and I hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, which form a part of this specification.

This invention relates to certain new and useful improvements in the construction of screw-blades for propellers, the object of the invention being to utilize a portion of the great amount of power that is lost by the present construction, and the invention consists in the peculiar construction of the blade, as hereinafter more fully described, and then pointed outin the claim.

Figure 1 is a perspective view of my propeller. Fig. 2 is a'sectional end view of the same through the line Jv x of Fig. 1. Fig. 3 is a section of one of the blades, obtained Vby the intersection with a cylinder and thenl developed on a plane, showing my improve ment By sharpening the blade on the after or working edge, as illustrated in Fig. 3, and constructing the working-face with a convex surface, I obtain useful work with less friction and resistance due to the blade from all the power applied to the wheel than has ever before been accomplished. Conceive the blades of a propeller-wheel constructed after my improvement to be intersected by a lcylinder whose axis is coincident with the center'of the shaft on which the wheel turns, and let the section of one of the blades be developed on a plane, as shown in Fig. 3. Through the after edge,- A, of the blade draw the line A B perpendicular to the shaft or in the plane of the wheels motion'. Then draw from the forward edge, C, the line B O parallelwith the shaft. We have in BGthe pitch of the wheel corresponding to the width of one blade. Then, if

y from the point C We set down the amountof slip to D and join A D, we shall' have in A D what Inay be called the line of motion-- that is to say, by the combined endwise motion of the Wheel, every point in the section will revolve in a helix, which, when developed on a plane', will be strictly parallel with the line A D, and inthe line. B D we have the net pitch corresponding to the width of one blade. It is the negative resistance due to the thickness ofthe blade that I Wish to get rid of, as

vthis is a very important part of the total work of the wheel; and this I accomplish by constructing the forward face of the blade with a convex surface, or on the curve of a parabola, or are of a circle of large radius, 4and so arranged as to be tangent to the line of motion at the forward edge of the blade, whereby the angle of resistance is at a minimum, as the direct resistance against the motion of the blade in edge is less and the component promoting the forward motion of the vessel is greater as the angle between the line drawn parallel to the line of motion, and at the same time tan gent to the upper convex surface at its forward edge, andthe line drawn tangentto the sharpened after side ata point midway of the thickness of the blade, is less.

I am aware of English Patents Nos. 12,020 of 1848, 2,671 of 1853, and 1,376 of 1855, and make no claim to the constructions shown therein.

What I claim as new is A propeller-wheel blade sharpened on the after sideat the forward or leading edge, and having its forward side vconstructed with a convex surface, so as to make it tangent to the line of motion7 at the forward edge of the blade, substantially as and for the purpose set forth.

i HARRISON C. Witnesses: v A

'0. A. PEARsoN, B. F. GUETIss.

PE ARSONS.