US1886891A - Propeller - Google Patents

Description

Nov. 8, 1932. F. a. MARTENS ET AL r 1,836,391

PROPELLER Filed July 21, 1950 2 Sheets-Sheet l MKM v 0% @ZZZW NOV. 8, 1932. J E ET AL 1,886,891

PQ PELLER Filed giil 21, 1930 v 2 Sheets-Sheet 2 Patented Nov. 8, 1932 UNITED STATES PATENT OFFICE FREDERICK J. MABTENS AND CLINTON O. THOMPSON, OI MILWAUKEE, WISCONSIN PROPELLEB Application filed. July 21, 1930. Serial No. 469,531.

' most efficient use of the propel or for take-off,

landing, etc.

Another important object of our invention is the provision of hydraulic means for changing the pitch angle of the blades, so as to insure the smooth operation of the blades A still further object of our invention is to provide a propeller having novel form of blades with novel means for changing the pitch angle of the blades whereby the combination of the formation of the blades and the means for changingthe pitch angle thereof to suit varying conditions will result in the production of a propeller of a highly efiicient type, capable for all aeronautical puroses.

A still further object of our invention is to provide .an improved propeller of the above character, which will be durable and eflicient in use, one that will be simple and easy to manufacture and one which can be placed upon the market and incorporated with an aeroplane at'a small cost;

With these and other objects in View the invention consists in the novel construction,

arrangement and formation of parts, as will be hereinafter more specifically described,

claimed and illustrated in the accompanying drawings; in which drawings:

Figure 1 is a front elevation of our im proved propeller, one section of the hub being removed to illustrate the mounting of the propeller blades in the hub.

Figure 2 is a plan view of the improved propeller.

Figure 3 is a detail section taken on line 3-3 of Figure 2 looking in the direction of the arrows and illustrating the means for changing the angle pitch of the blades.

Figure 4 is a diagrammatic view illustrating the hydraulic means employed for changing the angle pitch of the blades.

Figure 5 is a transverse section through one the of the propeller blades taken on the line 55 of Figure 1.

Figure 6 is a transverse section taken through the propeller blade on the line 6-6 of Figure 1.

Figure 7 is a view similar to Figure 3 showing a modified form of the hub.

Figure 8 is a detail section taken on the line 8-8 of Figure 7 looking in the direction of the arrows and illustrating the means employed for mounting the propeller blades in the modified form of hub.

Referring to the drawings in detail, wherein similar reference characters designate corresponding parts throughout the several views, the letter A generally indicates our improved propeller which comprises a hub 10 keyed or secured in any other desired way for rotation with a drive shaft 11. The drive shaft 11 may be considered in the present instance as the crank shaft of the internal combustion engine of an aeroplane.

In that form of the invention, as illustrated in Figures 1, 2 and 3, the hub 10 comprises a pair of companion sections 11 and 12, secured together by the use of bolts 13 or other suitable fastening elements. The sections 11' and 12 are so constructed when placed and secured together to form a pair of parallel cylinders 14 arran ed on opposite. sides of the hub sleeve 15 which receives the engine shaft 11. In the present instance wehave shown two cylinders as the propeller is of the two-bladed type, but it is to be understood that more than two cylinders can be rovided if a three or four bladed dpropeller is to be used. It is to be also note that the c linders are arran d substantially tan ny ge li ub of the engine shaft 11 is the blade adjusting sleeve 17 having formed on its inner end a rack 18 for a pur ose, which will be later described. The rac teeth are ofannular construction and are arran ed within the hub. The inner end of the adjusting sleeve 17 is provided with spaced collars 19, for a purpose which will also be-described.

The propeller blades 20 are of novel con- I struction and form; and each embody a hub boss 21 rotatably received within its cylinder 14. The bosses 21 and the cylinders are suitably grooved for receiving anti-friction bearings 22 and a thrust bearing 23 can be interposed between the inner ends of the cylinders and the bosses 21. The outer ends of the bosses 21 carry discs 24 which abut against the outer faces of the cylinders as c early shown in Figures 1 and 2. The root of each propeller blade 20 at the boss end thereof embodies two stems or blade sections 25 which are formed on the opposite sides of the boss discs or flanges 24. These stems or blade sections 25 gradually converge toward one another in overlapping relation and termi nate in a single blade tip 26.

laying out the new propeller blade design, the natural ggometrical pitch lead or helixis used in ma 'ng a uniform propeller, but in addition a rigid structure is presented giving great strength and reinforcing the more delicate form 'of construction. This rigid structureis more efiective eometrically and an effective lead is obtainetf by duplicatmg or doubling the propeller air-foil to produce a more eflicient, useful dynamic reaction. In vertical position the distance of the stems ofthe air-foil or blade sections 25 is overned by the true and effective gap or lstance between the blades for the most eflicient dynamic action.

s clearly shown in Figures 1 and 2, the

two air-foil portions or blade sections 25- continue from the rootor disc on the radius line to the standard nominal pitch line or about two-thirds of the radius, finally of which they converge into a single air-foil and continue as a sing e unit air-foil to the tip. It can be readily seen that in this construction, the projected efl'ective pro ller area is greater on the blade face and lade back siderably, i. e., the thickness of the a r foil of the two blade sections 25 and alsoat the root would be less. This also would effect the remaining single portion or tip 26. The minimum camber of the air foil in effective drag being overcome by the changeable an le of incidence due to the adjustment of the lades and reduced resistance drag. Due to the effective pitch area, it will be noted that a propeller of lesser disc area may be used. An important dynamic factor lies in the fact that the center of pressure on the blade face will cause little or no flexing and will be equalized throughout the blade area regardless of the air foil angle of incidence.

As to the angle of incidence of the trailing (lower) airfoil or blade section 25 it may or may not be made greater. 1

The bosses 21 of the propeller blades are provided with pinion teeth 30 which mesh with the rack 18, at the opposite sides thereof, formed on the adjusting sleeve 17.

It is obvious that by shifting the adjusting sleeve 17 longitudinal of the engine shaft 11 that the blades can beturned about their axis for changing the angle ofv pitch to suit varying conditions. 7

As best shown in Fi ures 5 and 6, the blade sections 25 and winge tip portions 26 are of true stream line formation in cross section, which produces the most efiicient dynamic thrust, as has been established by actual tests.

It has also been found that because of the resulting advantages, this feature of construction is equally applicable to any air-foil, and it is, therefore, to be understood that the inventionis not limited to propeller blades. It will be noted that the blade members are rotatable upon axis offset with relation to the axis of the propeller shaft 11, which is the normal center line of the blade tips 26. Obviously, as the blades are rotated to increase the cord width, the overall or winged tip diameter of the blades is proportionately decreased, although in a much lesser degree. This is due to the fact that each winged tip has a rotative action, which varies the center line of the tip with relation to the axis of the propeller shaft, thus causing the tips to approach or recede from a diametrical line passing through the axis of the propeller shaft, the effect of which is to increase or decrease the overall diameter.

It is believed that the advantages of the Y foregoing will be quite apparent, in that the blades.

Any desired means can be utilized for shifting the adjusting sleeve longitudinally of the shaft, but we prefer to provide an hydraulic means for this purpose and the means provided forms an important part of my present invention. The chief advantage in using my hydraulic means for the purpose of shifting the pitch angle of the blades, is that, due to the mechanical method of the rack and pinion portions of the blade hubs it is not necessary to have an oscillation of more than one half to one and one half inches even on the largest diameter of propeller and also that this method can be used efficiently and in a simple manner on multi-motored planes.

This hydraulic means comprises an operating lever 31 pivoted at one end, as of 32, to a rigid part of the aeroplane or engine, such as the crank case of the engine. This operating lever 31 intermediate its ends is provided with a shift yoke 33 for engaging the shift collars 19 on the adjusted sleeve 17. The opposite end of the operating lever 31 from its pivot point 32 is pivotally connected as at 34 to the piston rod 35 of a double acting piston 36. This double acting piston 36 is reciprocally mounted ina pressure cylinder 37, as clearly shown in Figure 4 of the drawings. The piston 36 is normally mounted intermediate the ends of the pressure cylinder 37 and the opposite ends of the cylinder 37 have communicating therewith pressure feed pipes 38 and 39 respectively. These pressure feed pipes 38 and 39 communicate with the opposite ends of an operating cylinder 40, preferably arranged within the cock-pit of the aeroplane (not shown).

Reciprocally mounted within the operating cylinder 40 is an operating piston 41 which is normally arranged between the opposite ends of the cylinder. A piston rod 42 is connected with the piston 41 and extends out of one end of the cylinder 40 through a suitable stuffing box. A suitable bracket 43 having a segmental rack bar 44 formed thereon is carried by the mentioned end of the cylinder and one side of the bracket has pivotally connected thereto a hand lever 45. The hand lever 45 intermediate its ends has pivotally secured thereto the piston rod 42. For cooperation with the segmental rack bar 44, the hand lever 45 carries a finger grip operated locking dog 46. By this construction the position of the piston 41 can be controlled and locked against accidental movement.

We also provide an equalizing cylinder 47 and this cylinder has communication with one end thereof, the equalizing pipes 48 and 49 which communicate respectively with the pressure pipes 38 and 39.

A spring pressed piston 50 is arranged within the cylinder 47 and normally creates pressure on the fluid in the system, it being understood that the various cylinders and pipes are filledwith a suitable fluid such as oil. i

By this construction when the piston-.41

J is manually operated, the fluid will be forced from the end thereof, according to the direction of movement of the piston and this fluid sleeve 17.

. It is obvious from the foregoing that a simple and effective means has been provided for manipulatingthe said adjusting sleeve.

Referring to Figures 7 and 8, wherein the preferred form of the hub structure is illustrated, the samelis of a one-piece' construction, either forgedor cast; The outer ends 'ofthe cylinders 10 being open" and provided at their outer and inner. ends with enlarged bearing chambers 51. i

The blade bosses 20 areinserted in the cylinder and thrust anti-friction bearings 52 are placedin the chambers 51-. One of the anti-friction bearings resting-against the boss flanges of the blades and the other bearing against a holding plate 53 placed upon a reduced stud 54 carried by the end of each blade boss. The plates 53 are of such a diameter as to bear against the cylinder ends.-

Suitable lock nuts 55 are threaded on the studs 54 into engagement with the plates 53. Thus, it will be seen that an extremely simple, durable and economical structure has been provided,=which lends itself to simple mach1n1ng operatlons and insures closeness of fit and alignment, as well as materially reducing the manufacturing costs.

Our propeller and the means employed for shifting the angle of pitch of the bladeshas' many noteworthy advantages over the propeller now commonly used, and an aircraft engine with a propeller of our type will give steady divergence through its various speeds, resulting in complete staple oscillation and the consistent units of the changeable blade angles of attack and placement thereof will go for propulsive efiiciency.

Aside from the mechanical design and efficienoy of the propeller as shown, advantage is derived in aviation as follows: First, ground; second, taking off; third, free flight 5 fourth, ceiling; and fifth, landing.

First, ground, the advantage of the propeller on the ground is that the propeller blades can be set at zero thrust thereby doing away with the blocking or holding of the aeroplane wheels. This condition of zero thrust would also give a zero torque, resulting in a perfectly free running engine.

Further the warming up process of the engine would be cut down to a minimum due to no inflow or slip stream upon the engine.

Second, at taking off, the angle of the blades can be set for giving the greatest amount of ?spee(l.-.and pull thereby resulting. in .permitting of a quick take ofi to be had. The ordiznany propel1er'now .in use; with fixed pitch is adapted and liinitedto the: prerascertained rating of zP. of .motor, revolutions per uninute, plane pay :load .etc., 1 in :taking off.

With our 1propeller,.:the adjustable vcontrollableapitch, being madezwhile in flight, the take-off can be *made ifrom. a; small field eat .a: lead angle :correct forithe 1H. 1 plane load, etc., or in other words the pilohmay rproduce rth'e :most .efiicient propeller thrust a to meet the condition to take ofi his plane into freeflight; irregardless of wind, LH. 1

5 5 erevolutions .perrminute and. load.

.Third,.'in,-free flighty'the correct angle of incidence can be made by. thezpilot to obtain the greatest air .speed'without efl'eoting the engine. :Itisifoundithabthere is a change of approximately-v fifty to .'.sixty revolutions per -minute.-f0r ;each degree of *movement for the blades. :Thisholds, good for either an increase or decrease: of :speed, :therefore the propeller can be .used 1 ion different en- ,.gines by controlling thepitch to suit the Y speed -land: power of each, While in flight.

:Fourth,-the propeller-blades-can be ad- ;justed for the ceiling, in other words'the angle ofthe blades can be changed to accord 3o withthe conditions ofthe atmosphere.

Fifth, in landing, ithas been demonstrated :that a, plane with a verylow lead angle, the .propeller undermotor power tends to stabilize and approach the landing speed slower.

- 5 This is givenwiththepropeller described.

7 Changes in. details :may be made; without departing-from the spiritbrflscope of this invention :but what we claim as new is 1..-A.propeller..blade comprising a disc- 40 shape'd-fiange,-body. portions projecting from one-face of the flangeat opposite sides thereof, and asingle connecting tip, said body portions "partially overlying one another through their entire lengths.

1'45 2. A ,propeller blade comprising spaced body sections and a single connecting tip,

said. body portions and tip being gradually tapered in crosssection from their leading edges to their trailing edges, said body 50 portions partially overlying one another throughout their entire lengths, the tip extending in the same direction as the body portions.

In testimony that We claim-the foregoing do We have hereunto set our hands at Milwaukee, in'the county of Milwaukee and State of Wisconsin.

FREDERICK J. MARTENS.

CLINTON O. THOMPSON.

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