US 2396811 A
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Description (OCR text may contain errors)
' March 19; 1946.
J. E. BATHRAS AIRPLANE PROPELLER Filed Dec. 10, 1943 Man/55 5A7 7/7 25 5 Inventor ttorneys FFICE AIRPLANE PROPELLER James E. Bathras, Portland, Maine Application December 10, 1943, Serial No. 513,760
This invention relates to an airplane propeller,-
and particularly to the formation of the blades. thereof.
Airplane propellers are of relatively large size or have long blades, and they ordinarily create a loud humming noise when operating at high speed. Also, with the ordinary airplane propeller, there is noticeable loss of efliciency at the tip portion of the blade, due to centrifugal slippage.
The primary objects of the present invention, therefore, are to provide an airplane propeller which, through its particular blade formation. will be relatively quiet when operating at high speed, as well as highly efiicient, and which will nullify tip loss resulting from centrifugal slippage, by causing a centripetal movement of air, through 9, particular arrangement and form of fin on the tip portion of the blade.
A specific object of the invention is to increase the efilciency of the -propeller.and bring about quiet operation through a particular fin formation on the trailing edge of the blade, respectively along the major intermediate portion of the trailing edge and on the trailing'edge at the tip of the blade.
The present invention consists in the novel form, combination and arrangement of features and parts hereinafter more fully described, shown in the accompanying drawing and claimed.
in the drawing, wherein like reference characters indicate corresponding parts throughout the several views:
Figure 1 is a rear elevational view of an airplane propeller constructed in accordance with the present invention.
Figure 2 is a transverse section taken on the line 2-2 of Figure 1, and
Figure 3 is a section taken on line 8-8 of Figure 1.
Referring in detail to the drawing, I have shown an airplane propeller having two blades 5 of similar form and extending from opposite sides of a central hub 8. Each blade has a pressure side 1 and a non-pressure side 8. The leading edge is indicated at 9, and the trailing edge at ill. As usual, the blades are disposed at a desirable pitch or angle to the axis of rotation, which may be on the line H. The direction of rotation is indicated by the arrows l2 and the direction of air movement by the arrows It. The line I is the plane of rotation of the trailing edge and the line it the plane of rotation of the leading edge.
As shown clearly in Figure l, the leading edge 9 is substantially parallel to a line extending lon-. gitudinally of the blades and through the axis of rotation, while the trailing edge is bowed out considerably to give sumcient blade area at the different sections. In accordance with the present invention, a fin i8 is provided to extend along the major intermediate portion of the trailing edge it, and this fin is turned outwardly and forwardly toward the direction of travel of the air-'- plane, as shown in Figure 2. Another smaller fin ii is provided on the trailing edge at the tip end portion of the blade, said fin I7 being turned outwardly and rearwardly in the direction of air 20 tively thick adjacent the nose or leading edge and tapers thinner toward the trailing edge, but the cross sectional or airfoil shape of the blade may vary to some extent. The effect of fin i8 is to lead the air from the pressure side outwardly and forwardly 'for gradually diminishing turbulence and thereby resulting in a considerable reducti n in the loud humming noise ordinarily cause by an airplane propeller when operating at high speed. The fin i'l causes acentripetal movement oi. air and thereby nullifies tip loss from centrifugal slippage.
Although a specific embodiment of the invention is illustrated and described, it will be understood that various changes may be made within the scope of the invention as claimed.
What I claim as new is:
An airplane propeller adapted to berotated about an axis for displacing air and comprising a hub, a plurality of blades of similar form extending from the hub and disposed at an angle to the axis of rotation, each of said blades having an outwardly bowed trailing edge, a fin curved forwardly from the major intermediate portion oi.
the trailing edge oi each blade, and having an outwardly bowed trailing edge, and a second fin on the trailing edge at the tip end of each blade, the lastnamed fin being curved rearwardly and having an outwardly bowed trailing edge.
JAMES 1:. names.