US2340417A - Noiseless propeller - Google Patents

Description

Feb. 1,,1944. c. E. ELLE TT NOISELESS PROPELLER Filed Oct. '7, 1941 Clyde E EZ Z Z I E Z BY 6 MAX w Patented Feb. 1, 1944 UNITED STATES PATENT OFFICE NOISELESS PROPELLER Clyde E. Ellett, Los Angeles, Calif.

Application October 7, 1941, Serial No. 413,917

1 Claim.

This invention relates to aero-dynamics and more especially to a noiseless propeller design.

An object of the invention is to provide a simple, practical and eflicient propeller design of the character described.

Another object of the invention is to provide a propeller construction for airplanes adapted to be substantially noiseless in operation.

A further object is to provide improvements in airplane propeller construction which do not require any changes in the shape or dimensions of conventional propellers.

Other objects and advantages will be brought out more fully in the following specification reference being had to the accompanying drawing wherein:

Fig. 1 is a front elevation view of a propeller embodying my invention and Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1.

Airplane propeller noise as is Well known is caused by the impact of the air stream which is cut by the propeller and separated forming a partial vacuum space which, as it is filled by the pressure of the divided air column, creates a slapping noise at the trailing edge of the blade. By my invention I overcome this noise by admitting an air cushion from the leading surface of the blade through a number of small tubular holes or apertures or otherwise which permit suflicient air to be introduced into this otherwise vacuum space and this overcomes the slapping effect of the divided air stream.

Referring more particularly to the drawing I show a propeller blade 5 having a leading edge 6 and a trailing edge I and a leading or pressure surface 8 and a trailing or vacuum surface 9, and the blade 5 is provided with a plurality of small holes I0 bored or drilled at an angle and having an enlarging taper from leading surface 8 to trailing surface 9. Holes ID are formed near the trailing edge 7 and permit air from the leading or pressure side of the blade pass through into the vacuum space Ill otherwise formed by a conventional blade. The divided air stream is indicated at H and the vacuum space by I2.

Having described my invention What I claim is:

A noiseless propeller as described having a plurality of tapered passages extending angularly through from the pressure side to the vacuum side thereof adjacent the trailing edge thereof, said taper expanding from the pressure to the vacuum side, the axes of said passages being substantially parallel to the plane of rotation of said propeller.

CLYDE E. ELLETT.

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