US1628716A - Aerial propeller - Google Patents

Description

- 1,628,716 May 1927' J. FISCHER AERIAL PROPELLER Filed mm 28, 1925 2 Sheets-Sheet l J 1 25016 er May 17, 1927. 1,628,716

J. FISCHER AERIAL I ROPELLE IR Filed-A112. 28. 1925 2 Sheets-Sheet 2 rss PATENT OFFICE;

JOSEPH FISCHER, OI IlFAITH, SOUTH DAKOTA.

AERIAL PROPELLEB.

Application filed August 2a, 1925. Serial m. 53,155.

This invention relates to aerial propellers and has as its object to provide a propeller which will be more eflicient in its aepropellers as ordinarily tion that cavitation will be minimized in the openings thereof, and air will be pocketed and banked behind the blades of the propeller so that the blades will, in effect, .op-

' erate against a more or less compressed bank of air rather than against rarefied air.

Another object of the invention is to so construct the blades of the propeller that the portions thereof which constitute the means for banking air behind the blades will tend likewise. to prevent distortion of 'the blades by continually reinforcing the so bld In the accompanying drawings:

Figure 1 is peller embodying the invention.

1Iiigure 2 is a front elevation of the prope er. I

Figure 3 is an end view of the propeller.

Figure 4 is a side elevaton of th propeller.

Figure 5 is a vertical sectional view taken substantially on the line 5'5 of Figure 2, looking in the direction indicated by the arrows.

Figure 6 isa horizontal sectional view taken substantially on the line 66 of Figure 2, looking in the direction indicated by the arrows. y

Figure 7 isa similar view taken substantially on the line 7-7 of Figure 2, looking in the direction indicated by the arrows.

In the illustrated embodiment of the invention, the propeller comprises a pair of counterpart blades indicated in general by the numeral 1, and a hub portion 2 to which pelled. Each of the blades the standard hub (not shown) may be fitted and the propeller thus mounted upon the propeller shaft of the air craft to be pro- 1 comprisesa a perspective view of a pro-v body 3 which is of approximately ovate mar inal contour and is substantialy flat at its orward face, which is indicated by the numeral 4, and has its'rear face slightly convex, as indicated by the numeral 5, the body being relatively thin, as will be observed by rcference to Figures 5, 6 and 7 of the drawings. The leading edge of the blade is indicated by thenumeral 6 and the trailing or opposite edge ortion is indicated by the numeral 7. At its liist mentioned ed por tion, the blade is formed to provide an aircompacting pocket indicated by thenumeral 8. This pocket extends from the tip or outer end of the blade longitudinally of the trailing edge portion of the blade to the hubportion 2 and merges with the latter portion.

By reference to the several figures of the drawings, it will be observed that the pockets 8 are located at the forwardfaces 4 of the blades and that the walls of these packets are rounded transversely, the outer wall 9 of each pocket being spaced from and opposing the said flat face 4 of the respective blade. Said wall 9 of the pocket is merged at its inner end with the surface of the hub portion 2, as indicated by the numeral 10,

and the edge of the said wallis curved Ion-- gitudinally near the outer end of the pocket,

as indicated by the numeral 11, so that each pocket is of gradually decreasing depth froma point inwardly of the tip of the respective blade to the outer end of the pocket.

It will furthermore be observed by reference to the drawings, and particularly Figure 2, thereof, that the material of the blades is gradually thickened along the bottoms of the pockets, in the direction of the hub portion 2, as indicated by the numeral 12, so that the pockets are of gradually decreasing depth in the direction of their inner ends.

As the pockets are located at the trailing edge portions of theblades, their open sides are presented in the, direction of rotation of the propeller audit will, therefore, be evident that as the propeller is rotated, air will be trapped in the pockets andcompacted so as to establish, in eflect, a bank of air against-which the body 3 ofthe respective blades may act. Therefore, cavitation is re IOI duced to a minimum and the air surrounding the revolving propeller is not so rarefied as where cavitatlon is'caused to a marked degree. Furthermore, there is less slip in the operation of the propeller embodying the in vention than would be the case if the pockets were not present. B gradually'deereasing the height of the wal s 9 of the pockets near their outer ends, and forming the pockets of maximum depth at their intermediate portions, the greatest cfiiciency is obtained H1 compacting the air and, at the same time, the air trapped 1n the pockets may esca e with minimum resistance, by way of t e outer ends of the pockets, through centrifugal force, in the rotation of the propeller;

It will be observed that the blades are oppositely diagonally disposed, as is the case in the ordinary propeller, and that the pockets of the two blades are substantially co-extensive as regards their outer walls 9.

g It will be understood, of course, that while ing a wall confronting the forward face of the blade, the, said Wall, from a point near the outer end of the pocket being gradually decreased in depth in the direction of the said end of the pocket.

2. An aerial propeller comprising rudiallr extending blades and an intermediate hub portion, each blade comprising a substantial- 1y flat body of ovate marginal contour dis posed obliquely to the axis of the hub portion, and an air-compacting pocket extending along the trailing edge portion of in blade body.

3. An aerial propeller comprising oppositely extending blades and an intermediate hub portion, each blade comprising a sub stantially flat body disposed obliquely to th axis of the hub portion, and an air-compacting pocket extending along the trailing edgr portion of the blade body, said pocket be ing transversely concave in cross section and having a wall confronting the forward surface of the blade body, said wall merging at its inner end into the hub portion and the material of the blade being gradually thickened toward the hub portion wherein the pocket gradually decreases in depth to ward its inner end.

In testimony whereoi I ailix my signature JOSEPH FISCHER. [1,. 5.1

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