US1301108A

US1301108A - Aeroplane-propeller.

Info

Publication number: US1301108A
Application number: US11784916A
Authority: US
Inventors: Clifford A Cutler
Original assignee: Individual
Current assignee: Individual
Priority date: 1916-08-31
Filing date: 1916-08-31
Publication date: 1919-04-22
Anticipated expiration: 1936-04-22

Description

C. A. CUTLER.

AEROPLANE PROPELLER. APPLICATION FILED AUG.3I; 191s.

Patented Apr. 22,1919.

wag

1N ZVTOB A T'TOENEY cnrroan A. CUTLER, or BurrALo, new voax.

AJEBOPLANE-PROPELLER.

Specification of Letters Patent.

Patented Apr. 22,1919.

Application filed August 81, 1916. Serial No. 117,849.

To all whom it may concern:

Be it known that I, CLIFFORD A. CUTLER, a citizen of the United States of America, residing at Buffalo, in the county of Erie and State of New York, have invented certain new and useful Improvements in Aeroplane-Propellers, of whlch the following is a full, clear, and exact description.

It is well known to those skilled in the art, that aeroplane propellers of the present art are formed out of a block of wood made of five or more pieces of material, ofttimes of different kinds, glued together. The result of this construction is that each of the blades of the finished propeller comprises' everal different pieces of material. It is well known that no two pieces of material have exactly the same coeflicient ofexpansion. Therefore, there is always a strain set up between the laminae by reason of different climatic or temperature conditions. When a blade of this type is put under load the laminae are subjected to additional strain and this tension added to the tension existing in the section ofttimes results in the rupture and breaking of the blades. Furthermore, blades of the present art are usually made with the wide portion or working surface of the blade near the tip.

In my invention I have sought to. overcome the disadvantages above enumerated and to provide a propeller formed with single piece blades, thereby eliminating all undue strain.

My propeller is so designed that the surface receiving the eatest load comes near the reinforced hub instead of at the tip as is usual practice, and therefore I very strong propeller.

Furthermore, I havesought to provide a propeller in which the blades shall. have a true pitch throughout their length.

Moreover, the blades of my propeller are so designed that they are narrower at their tips than near the hub and are thus flexible so that they will yield and thereby drop part of an excessive load.

I The above objects and advantages have been accomplished by the device shown in the accompanying drawings, in which:

Figure 1 is an elevation showing the front or advance side of the propeller.

Fig. 2 is an elevation showing the rear or trailing side ofthe propeller.

F 3 is a side elevation of the propeller.

Fig. 4 i a perspective view showing the provide a pro eller in the rough and before it is wor ed u to shape.

Fig. 5 1s a sectional view taken on line 5-5 of Fig. 4.

Fig. 6 is an enlarged sectional view of the propeller taken on line 6-6 of Fig. 1.

Fig. 7 is an enlarged sectional view of the propeller taken on line 7--7 of Fig. 1.

Fig. 8 is an enlarged sectional view of the propeller taken on line 88 of Fig. 1.

Fig. 9 is an enlarged sectional View of the propeller taken on llne 99 of Fig. 1.

Fig. 10 is an enlarged sectional view of the pro eller takenon line 10-10 of Fig. 1.

y propeller is formed essentially of three parts, namely, a center hub block 11 and two blades 12. The hub part 11 is of laminated construction and formed of a number of pieces of plain sawed wood 13, glued together in the usual manner. block is finished and the glue is set, there is cut into each end thereof a slot 14. These slots are cut diagonally across each end of the block and in opposite directions and terminated at the center. The outer boundary of the slot is coincident with the corner of the block as clearly shown in Figs. 4 and 5. The inner end of each slot, at the center of the block, forms an acute angle 17 with the inner surface of the slot as clearly shown in Figs. 1 and 3. In each of, these slots is placed one of the blades 12.

The blades 12of my propeller are preferably made of quarter sawed oak and the two blades are preferably made from the same board. This board is sawed at the middle and the ends 15 are then reversed,

so that they will form the tips of the blades. By this construction I am more certain of getting material in the tips of the blades which is more uniform in texture and weight. The ends 16 of the boards which are to be placed in the block 11 are chamfered atan angle which will fit the angle 17 formed at the bottom of the slot 14:. After these boards forming the blades 12 are fitted to their respective slots, they are glued in position and when dry the pro peller is then ready to be finished.

. The proportions of the center hub block, 11 are such that when the slot 14 is formed diagonally therein, the angle of such slot will be substantially the general angle formed by the finished blade. By this construction it will be seen that the major part of the blade 12 will be formed from a sin- After this gle piece of material. Inasmuch as the blades 12 are made from quarter sawed material, preferably oak, it will be clear that the flights of the material will run parallel with the face of the blade, thus reducing the tendency to warp to a minimum. It is well known that quarter sawed wood does not weather check and that it shrinks and swells in thickness only and not in width, thereby producing apropeller blade which keeps its shape, without internalstrains, under varying atmospheric conditions.

By reason of my improved construction, I am enabled to provide the Widest area of the blade near the hub, and from the drawings it will be noticed that the working area of the blade starts at substantially the vertical center line. By this construction the efficient work done by the propeller is kept near the hub where the necessary amount of strength can be provided. This also permits the blade to be tapered off and made thin and flexible at its outer end, whereby when my propeller strikes an overload the tips of the blades may flex or bend somewhat and thus automatically drop a part of the load and relieve the strain on the propeller. The line of work in my propeller is nearly radial and therefore the centrifugal force does not tend to distort the blade, but tends to stiffen it.

18 are the hub plates of the propeller, which, as usual, are secured to the propeller by a plurality of bolts 19 passing through the material of the propeller, from one late to the opposite plate. As the boards orming the blades 12 eachterminate at the center of the hub, it is clear that substantially all of these bolts 19 pass through the boards thus firmly securing them in place against centrifugal force.

As the efficiency of any blade depends upon its width andspeed, I have formed my blade with its Widest part at the hub and its narrowest part at the tip. In this way the greater width at the hub makes up for the slower speed at this point and thereby also reduces the resistance of the rotary motion.

Obviously some modifications of the details herein shown and described may be made without departing from the spirit of posite directions between the corners to the center of the hub block where the inner ends of the slots terminate across each other and end blades fitted into and occupying the whole width of the slots.

In testimony whereof, I have hereunto signed my name in the presence of two subscribing witnesses.

I CLIFFORD A. CUTLER.

Witnesses:

J. WM. ELLIS, WALTER H. KELLEY.