US2248221A - Propeller blade - Google Patents

Description

Patented July 8, 1941 PROPELLER BLADE Claude Dornier, Friedrichshafen-on-the-Bodensee, Germany, Werke G. m. b. Bodensee, Germany assigner of one-half to Dornier- 1I., Friedrchshafen-on-the- Application March 15, 1938, Serial No. 195,948' In Germany March 20, 1937 (Cl. 17o-159) 4 Claims.

The present invention relates to a propeller blade and method of manufacturing it, more particularly to a metal air propeller blade of light weight, great strength, and smooth and lasting surface.

It is an object of the present invention to provide a propeller blade and method of manufacturingr it which blade comprises an interior skeleton which is covered with strong sheet likematerial of smooth exterior surface. The skeleton is preferably of-such configuration that the volume of the ribs is smaller than the volume of the free spaces in between the ribs'so that a light structure is produced which is of sufficient strength to support the skin which covers it and to safeguard the propeller against deformation even under strenuous operating conditions.

The construction of a propeller blade according to my present invention is somewhat similar to that of airplane wings in' which the skin transfers the forces acting thereon to an internal framework or skeleton.

Further and other objects of the present invention will be hereinafter set forth in the accompanying specification and shown in the drawing which, by way of illustration, shows what desire to be limited to the exact details of the I method, design and construction shown and described, for obvious modifications will occur to a person skilled in the art.

I now `consider to be a preferred embodiment of v my invention.

In the drawing:

Figure 1 is a diagrammatic illustration of the propeller blade made according to the present' invention.

The blank shown in Figure 1 has substantially the exterior configuration of a propeller blade. This blank must be exteriorly finished by filing, milling, or cutting, or similar operation so that the blade, after the covering skin is applied, has

the correct shape. The body shown in Fig. 1, by means of drilling, milling, cutting or similar operations, is transformed into the 'skeleton resembling the skeleton of a leaf and shown in Figure A2. There is a main central rib 2 the .thickness of which is gradually reduced as it eX- tends from the root I to the tip I of the blade. Adjacent to the root I the side ribs 3 and 4 are branched off which are reunited with the main rib near the tip I'. In addition, a plurality of transverse ribs 5 are provided which form acute "angles a with the main rib 2. Between the in- I claim: 1. A propeller blade consisting of two and only two major constructional elements: a one piece core member having the shape and configuration of the finished blade and having large openings amounting to at least one-half of the size of said core member and forming a framework comprising a central rib, marginal ribs, and a plurality of branch ribs substantially symmetrically branching from both sides of said central rib and extending to said marginal ribs, and skin means of substantially the same size and configuration externally covering said core member.

2. A propeller blade comprising a one-piece frame member having lthe shape and configuration of the finished blade and comprising a stem portion adapted to protrude from the hub end of the blade, a central'rib portion extending from said stem portion substantially through `the center of the blade to the tip thereof, a plurality of branch rib portions extending from both sides of said central rib portion tothe edges of said blade, and an edge rib portion extending from said stem portion around said frame member and forming a loop interconnecting the outer ends of all of said ribs, and a skin member secured to and covering said frame member and being of substan- -tially the'same size and configuration as 'said frame member.

3. A propeller blade comprising a one-piece frame having the shape and configuration of the finished blade and comprising a central rib portion adapted to longitudinally extend through the entire length of the blade, a plurality of branch rib portions individually extending from both sides of said central rib portion to the edges of said blade, and an edge rib portion forming a loop around said frame and binding the outer ends of said central rib portion and of said branch rib portions, and a skin member secured to and covering said frame member and being of substantially the same size and configuration as said frame member.

4. A propeller blade comprising a one-piece frame having the shape and conguration of the nished blade and comprising a central rib portion adapted to longitudinally extend through the entire length of the blade, a peripheral rib portion, a. plurality of branch rib portions individually extending from both sides of said centra! rib portion into said peripheral rib portion, said peripheral rib portion forming a loop around said frame and binding the outer ends oi.' said central rib portion and of said branch rib portions, and a skin member secured to and covering said frame member and being oi substantially the same size and conguration as said frame member.

CLAUDE DORNIER.

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