US2380683A - Propeller - Google Patents

Description

, Patented July 311, 1945 PBOPELLER James ,acm-d1, Los Angela, celu., miglior, by

direct and mesne assignments, of forty-six and per cent to C; Bland Jamison, thirtythree and one-third per cent to Collins Mason, and twenty per cent to Arthur E. Wright, all of Beverly Hills. Calif.

Application May 27, 1941,.Serial No. 395,398

3 ('CL 17o-173) My invention is in the art of propellers and. more particularly. it has to do with ferrules and reinforcements for rendering wooden blades safely useable in variable pitch propellersgas well as in other propeller hubs vin which the blades are detachably mountediinthe hub.

The dilculties attending such uses of wooden propeller blades are well known and have long existed. In conventional practice, the reduced and rounded shank end of the blade is encased in a ferrule which is rotatably mounted in a radially disposed socket in the hub member, the blade tapering outwardly from the rounded reduced shank to an adjacent. relatively largerf cross-section, usually oval. It has been the practice to terminate the ferrule substantially flush with lthe periphery of the socket, or at the outer end of the rounded shank portion of the blade, which is the weakest section of the blade. Thus the fulcrum point, as between. the ferrule and blade, is at the outer -end of the reduced shank section where the trailing edge of the blade abuts toprovide a ferrule which overcomes this shortcoming of known devices, and one which is so designed andmounted Vthat it effectively reinforces the weakest section 'of the blade and provides the fulcrum point at that portion of the blade most capable of withstanding stresses resulting from use of the blades as airfoils. Other objects and advantages are inherent in my invention and 'they will appear hereinafter.

The broaderaspects of my invention are defined by the appended claims, but, for the purpose of making my invention understood, I shall now describe specific adaptations thereof, making reference to the accompanying drawings, in which Fig. l is a longitudinal section of a propeller hub and blade assembly embodying my invention;

Fig. 2 is a section on line 2 2 of Fig. 1;

Fig. 3 is a section similar to Fig. 2, but showing my invention applied to a blade of o,val crosssection; and

Fig. 4 is anelevation of the shank portion 'of a propeller showing a variational form of my invention.

In the drawings, I show at 5 a propeller blade `the blade tapers outwardly into an adjacent portion I of larger and stronger cross-section-f-the leading and trailing edges of the blade being designated by the numerals 8 and 9, respectively. O f course .the cross-sectional shape of blade portion 1 may .be.oval, in fact conventional blades arev so shaped, but I find that it facilitates manufacture and application of the fer-rule if portion 1 tapers toward shank 8 in round crosssection, as then it is possible to manufacture the blades and ferrules with uniform, true and conforming tapers and it is relatively easy to mount the ferrules onto the propeller.n

'The numeral III designates a fragmentary section of a hub assembly presenting a' radial thimble or barrel Il having a bore `l2 to receive the shank 6 of the blade. 'I'he motor drive shaft M is splined to the hub portion ila. Conventionally, such thimbles are longitudinally split and clamped together by bolts I4 and ring ila so that the bolts may be loosened and ring Ila loosened to permit rotation of the blade about its longitudinal axis to adjust the pitch. One end of ring Ma terminates in a bolt portion which extends through an opening in'a flange presented by the other end of the ring, as shown in dash lines in A nut, not shown, screws onto the bolt portion. Before applying the ferrule, to be later described, I turn or otherwise cut a shallow f-V-shaped recess I5 circumferentially of shank i and nt into the recess a split'sleeve I6 having a V-shaped undersurface -I1 to conform to recess I! and a plane outersurface. This enables the shank section 2l of the ferrule, to be hereinafter described, to be of uniform cross-section and eliminates the necessity of spinning the ferrule onto the blade shank to cause the ferrule itself to conform circumferentially to the recess l5, as is customary.

A My improved ferrule is generally` designated by the numeral 20 and comprises an inner end portion 2i of round cross-section to snugly ilt and enclose the shank 6 of the blade, and an extension portion 22 which snugly ts and en closes the blade portion 1, the ferrule flaring outwardly from the portion 2| to a larger crosssection conforming to the taper of the blade. The outer peripheral edge is interiorly beveled at 23 to overly the reversely beveled shoulder 24 of blade portion 1,

Screws 25 extend through fer-rule portion 2| into and through split sleeve I6 and into the propeller. Thus sleeve I6J reinforces the shank and preventsvlongitudinal movement of the blade having a round, reduced shank end t, from which u with respect to the ferrule.

the ferrule and resist splintering at that point..

While various conventional means are known for preventing longitudinal escape of the ferrule from the thimble, I show for the purpose annular nanges 30 on the blade shank and annular recesses 3| in the thimble and projecting at their inner ends into the channel. A

lIn Fig. 3, the blade section 1a and ferrule section 22a are shown as oval in cross-section and have the rivets 21a thereacross. Otherwise the device is identical with Figs. land 2.

' In Fig. 4, the ferrule portion 22h is oval in cross-section to conform to a blade portion 1b of like cross-section, and has its outer peripheral edge 35 extending diagonally along the width of the propeller blade portion 1b, the ferrule being relatively longer at the trailing edge than at the leading edge. This not only eliminates weight while maintaining the fulcrum at the ideal point, but also lends flexibility to the blade.y y

I claim:

1. In combination, a propeller hub having a radial socket, a blade having a shank extending into the socket, and a rerrule encompassing the shank, said ferrulewith its carried shank being secured against escape from the socket 'and having a portion projecting outwardy from the hub and encompassing the blade adjacent the shank, the peripheral edge of the projecting ferrule p`or tion being disposed diagonally inwardly from a point on the trailing edge of the blade spaced outwardly from the hub to a-point'on the leading edge of the blade nearer the hub.

2. A propeller of the class described including, in combination, a blade having a shank portion oppositely tapered towards a point intermediate its ends, said tapers intersecting medially of the shank whereby to-provide a reduced diameter medial portion, a longitudinally split sleeve embracingthe tapered shank portion, said sleeve having an inner surface tapered to conform to the tapered shank portion, and means for constricting the sleeve about the tapered shank portion.

3. A propeller of the class described including, in combination, a blade having a shank oppositely tapered towards a point intermediate its ends,

, said tapers intersectingmedially of the shank whereby to provide a reduced diameter medial portion, a longitudinally split sl'eeve embracing the tapered shank portion,l said sleeve having an inner surface tapered to conform to the tapered shank portion, a ferrule constricting the sleeve about the tapered shank portion and means securingthe sleeve and ferrule against relative longitudinalmovement. 1

. JAlillllS E. CAROL.

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