US1238838A - Air-propeller. - Google Patents

Description

T. B. SLATE.

AIR PROPELLER.

APPLICATION FILED NOV- 25, I915- Patented Sept. 4, 1917.

2 SHEETS-SHEET l.

T.' B. SLATE.

AIR PROPELLER.

APPLICATION FILED NOV. 25, 1916.

Patented Sept. 4, 1917.

2 SHEETS-SHEET 2.

a para or THOMAS B. SLATE, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO AMERI- CAN MECHANICAL IMPROVEMENT COMPANY, OF WASHINGTON, DISTRICT OF CO- LUMIBIA.

AIR-PROPELLER.

Specification of Letters Patent.

Patented Sept. 4, 1917.

Application filed November 25, 1916. Serial No. 133,367.

To all whom it may concern:

Be it known that I, THOMAS B. SLATE, a citizen of the United States, residing at Washington, in the District of Columbia, have invented new and useful Improvements in Air-Propellers, of which the following is a specification.

My object is to improve the construction of air propellers in order to remedy the in efiiciency experienced in the present type of solid or non-adjustable air propeller blades. I have devised a novel adjustable governorcontrolled air propeller blade for the purpose of adjusting the pitch of the blades according to the load the propeller is subjected to under the various conditions experienced by an aeroplane, or any other use the air propeller is commonly put to, owing to the fact that an aeroplane has to traverse steep grades in rising to considerable heights and likewise in descend-- ing. Or if the propeller is being used on an aerosled, hydroaeroplane, hydroplane, or any other vehicle driven by an air propeller it likewise has to climb or descend grades, subjecting the power plant and propeller to varied loads. For example, if a propeller blade was set at a four foot pitch, by which I mean that the machine if free to move without friction would travel four feet per revolution of propeller, and the propeller was of the proper size to consume the full load of the engine at its maximum speed, (revolutions per minute,) and the power of the engine was suflicient to drive the machine at a proper or desired speed on level ground, or at a level while passing through the air as an aeroplane, and if the machine were brought into an elevating po-* sition, or had to climp' a hill if traversing the ground, the pitch of the usual propeller blades would be far too great to make the climb. It would be necessary therefore with the usual type of propeller blades to carry several times the necessary power to drive the machine at a desired speed on a level in order to be able to climb grades or ascend at a desired rapidity if being used on an aeroplane, makin it impossible to use the power of the engine with a high degree of eficiency on even or descending grades.

It is my object to provide a novel governor-controlled propeller in which the eed of the engine and the propeller shaft revolutions per minute) w1ll increase or decrease automatically the pitch of the propeller blades with the varying power requirements. This operation also automatically controls the speed of the engine to whatever amount the propeller is set for by the adjustment of the spring in the governors. This also automatically adjusts the pulling power or thrustof the propeller ac cording to the speed traveled (miles per hour) and the amount of power supplied by the engine, so as to give the greatest efliciency from the amount of power supplied at all times, regardless of the grades climbed or descended. It also prevents any noticeable change in the speed of the engine, (revolutions per minute,) in case of sudden changes in grade conditions, or in case of accident or error in the control of an aeroplane while in the air. The change in load conditions if suddenly changing from upgrade to downgrade, whether in the air or on the ground would aifect the speed of the engine by releasing the load it is subject to, allowing the engine to suddenly change to a high rate of speed, (revolutions per minute,) setting up gyroscopic force in the propeller, propeller shaft, and crank shaft of the engine, said force being suflicient in various instances to break the shaft, propeller, or possibly wreck the machine. My invention positively prevents this overspeed, regardless of the amount of change of load conditions, as a few revolutions per minute over the speed the governors are set .for will turn the propeller blades to right angles with the direction of the rotation of the blade or as nearly so as the speed 'attained would require, and by this performance hold the engine within a few revolu- 'tions per minute of a predetermined speed.

ber 4 having a corresponding threaded por-' tion, is a governor arm 5. On the outer end of arm 5 is a suitable governor weight 6. And extending between the pair of governor' arms 5 near their outer or weighted ends I provide a suitable governor spring 7,

. as shown in Fig. 1. A bracket Sis provided to carry the end of propeller blade. Attached to mounting 14; in the center of propeller blade is a bracket 9, as shown in Fig. 1. A bolt 10 is provided and extends through mounting 14 in center of propeller blade. I provide a'bolt 11 in end of propeller blade through hub mounting 8. 12 designates bolts through hub pieces-2, and 13 designatesthe end of propeller blade 3. 14 is a bracket in center of propeller blade 3, through which bolt 10 passes.

My invention operates as follows: The propeller blades 3 are movably mounted to rackets 9, 8 and 9, havingtheir axes almost at right angles with propeller shaft 1, but offset in the center where they intersect each other by means of the geared bands, to permit of the provision of gear elements 15, as illustrated. The object is to cause both blades to operate simultaneously and to cause each one to move exactly the same on its axis as the other, in order to exactly balance the load on both blades at all degrees of their pitch. When the propeller shaft and propeller are revolved at a high rate of speed, the centrifugal force of governor weights 6, revolving around the axis of propeller shaft 1, tends to stretch spring 7, causing the propeller blades to turn on their axes, shown at 10 and 11, the gear teeth 15 operating to cause both blades to turn to the same extent, whether the speed is increasing or decreasing. The object of this particular type of governor is to simplify construction, reducing the number of working parts to a minimum, and making positive its operation, as positiveness is very essential in this class of machines. The governor arms 5, governor weights 6, governor bands 4, and propeller blades 3 are fastened together in a manner to operate as one piece, having only two-bearings for each blade, as shown by bolts 10 and 11. The only other place for wear or lost motion is in gear teeth 15, which carry no load of operation any more than merely causing the two propeller blades to revolve on their axes evenly or in the sameproportions. The governor arm 5 is preferably threaded at the end connected to governor band 4, it being adjustably connected with band 4 by a correspondingly threaded portion of that member, thereby clamping band 4 onto the circular end or shank of propeller blade 3.

The governor arm 5 takes the place of a propeller blade can be set in proper position as regards the pitch of the blade at any predetermined position of the governor weights. v y

An important improvement is attained by controlling the pitch of the blade and keeping the pressure all on one side ofthe blade.

A thin metal blade is made possible and such a blade cuts through the air without disturbing it, leaving it in solid formation and thereby giving the propeller a foundation on which it-is possible to transmit the power from the engine to thrust on the propeller shaft. The air being in solid formation after the propeller blade has passed through it and pushed it back from the blade, leaves an undisturbed substance or body of air on the back or rear side of the propeller blade. When a thick blade is employed or a blade that would create resistance as it passed through the air in itsv course of rotation, it causes the air to whirl and twist with the blade. This leaves a disturbed body of air back of'the blades and causes the pressure created from the force of each of the blades to break into the disturbed air of the last revolution of the blades, thereby greatly reducing the solidness of air back of the blade. This causes the blade when on the usual construction to depend on the vacuum created in front of the blade by the air pushed back. Experiments conducted with the invention have demonstrated that this propeller attains the new result above described.

When traveling through air at the rate of 350 miles an hour the largest circumference or the extreme ends of'the propeller blades are afforded the resistance described as the air becomes at this high rate of speed a sub stance more solid than water so' far as resistance is concerned. The use of a thin metal propeller blade as employed in my invention makes possible the transmission of more power exerted, to the propeller in thrust longitudinal with the propeller shaft instead of consuming a large per cent. of

the power in rotative' resistance as occurs with the usual type of propeller.

' What I claim'is:

1. An air propeller comprising a governor controlling the pitch of its blades which includes the meshing geared bands mounted upon the blades, whereby the blades are caused to move in unison under the action of the governor.

2. A governor-controlled propeller comprising governor-controlled blades offset at right angles to the propeller shaft and mounted to operate in opposite directions to each other for changing the pitch of the messes 1 1661386. to the blades and operating as a part thereof.

3. In a governor-controlled air propeller, the combination of a propeller shaft, a proh peller hub mounted tothe shaft, propeller blades movably connected to the propeller hub, a centrifugal governor directly connected to and controlling the propeller blades, resilient mechanism, extending between the Weighted governor arms to regulate and counteract the centrifugal force of the governor weights.

4. The combination of a propeller shaft, a hub affixed to it, a propeller blade, a governor attached to the propeller blade, an

elastic member operatively attached to the governor and operating to counteract the centrifugal force of the governor weight.

v 5. Ina device of the class described as a new article ofmanufacture, a governor device comprising a weight, an arm to which the weight is attached, a band adjustably engaged by the opposite end of the arm, the band having means operatively connecting it with a similar governor device.

6. As a new article of manufacture in a device of the class described, a governor device comprising a weight, an arm, a band to which the arm is engaged, and means on the governor band operatively connecting it with a corresponding governor element, substantially as set forth.

' THOMAS B. SLATE.

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