US1478063A - Variable propeller - Google Patents

Description

Dec. 18, 1923.

- 1,478,063 M. scHlEsARl VARIABLE PROPELLER Filed July 11. 1922 2 sheets-'sheet 1 1N VEN TOR Dec. 18,'. 1923, ,478,063

M. scHlEsARl VARI ABLE PROPELLER I y /lf l Patented Du/frs, 1923.

UNITED sTA MARIO SCHIISARI, 0F NEW 'YOBK, N. Y.

VARIABLE PBOPELLEB.

Application led July 11, 1922. Serial No. 574,222.

To all whom it may concern.'

Be it known that I,'MARIo SCHmsARI a citizen of the United States, residing at NJew York, in the county and State of New York, have invented certain new and useful Improvements in Variable Propellers, of which the followin is a full, clear, and exact description, re erence being had to the accompanying drawings, forming a part of this specification,

This invention relates to extensible propellers consisting of a plurality of inclined planes or blades connected to an axle and to each other by flexible retaining means, and rendered operative through the utilization of centrifugal force, of the type described by me in a co-pending'application filed July 14, 1921, having for title Method and apparatus for aerial propulsion, Serial No. 484,825; and its main object 1s to provide a special construction of propeller, whereby variable area in the sweep of the propeller elements may be automatically obtained.

A further object is to provide a novel and improved construction of l propeller whereby variable area in the sweep of the propeller elements may be automatically obtained, and at the same time the pitch of the same automatically changed.

A still further object is to provide a ,pro- .peller the vdiameter and pitch .of which may be controlled automatically or manually, at the will-ofthe operator.

With these and other objects in view, as will more fully appear as the description proceeds, my invention furthermore consists in certain novel constructions and arrange'- ments of parts as will be hereafter fully describedv and claimed in the appended claims. t

-In my otherpatent application above referred to, I describe a propeller of a novel and improved design, the action of which is based on utilizing the lifting or propelling force obtained through causing inclined planes or blades connected to an ,axle and to each other by flexible retaining means, to travel in acircular path at a suitable speed; said propeller having a variable radius of action, under the control. of the operator. The advantages of this type of propeller have been fully set forth in said patent application; the same being substantially an adaptation of aerofoil elements in combina-v tionwith a rotating axle, the lifting or propelling power developed by said aerofoils4 set at a ,certain angle of incidence to their plane of travel belng made available throu h,

a novel method of exploitation of centri gal force. In order to attain greater etliciency in a propeller, it is as a rule desirable to maxe the same of a large diameter, with a low angle of incidence ,but there are instances where the best eliiciency is obtained with a large diameter and a high angle of incidence, and it may broadly be stated, that while it is desirable to have both these factors variable, no general rule may be set down as to how the variations should take place, since the same should be different in order to meet different conditions of power, speed, resistance and density of the medium in which the propeller revolves, etc. With propellers of ordinary design however, there are sharp limitations imposed by practice in determining these factors of construction.

In another co-,pending patent application filed by me March 13, 1922, having for title Extensible pro ller, Serial No. 543,303, I have descri an improved propeller of the same type, but provided with means whereby variations in the diameter of the same will cause simultaneous variations in the angle of incidence of its elements; and in the same I have referred to the advantages to be derived from a construction where the angle of incidence decreases with the in, creasing -of the diameter, this tending to equalize the'torque on the axle, and therefore to realize con'djtions where the speed of the engine may be maintained substantially constant. Thls is true Where the densit of the medium in which the propeller revo ves is practically constant.

With increasing altitude, however, both the atmospheric pressure and density decrease, and since it is now possible to insure the eiliciency of the engine under these conditions by equipping the same with a -supercharger, in order to enable the propeller to balance `the generatipnfof motive power it will be necessary not only to increase its diameter, but also to increase the angle of incidence of its elements.

The construction described in my second patent application above referred to, is however e ually applicable to cases where it is desire to have the pitch decrease with the increasing of .the diameter, and cases where the pitch is made to increase with the diameter; the result being dependent merely on the proper design of the elements of construction shown. It is at any rate evident that the variations of these two factors may be caused to take place in such a manner that even with a decreasing pitch an increase in diameter will mean an increase in the power consumed by the propeller at the same speed, and vice versa; so that an increase in diameter will tend to counterb-alance the increase in the number of revolutions which would take place with the increase of the rarefaction of the air.

With manually operated propellers having variable pitch and variable diameter, however, the operation of the same is entirely dependent upon the pilot, who has,

as a rule, enough to occupy-his attention during Hight. There are circumstances furthermore," that the pilot cannot foresee, where it would be desirable that suitable changes altering the power absorbed by the propeller should take place automatically;

for instances when air' pockets are encountered, or when the engine misses fire or for an other reason `it loses power and slows own. On the other hand there are conditions of flight where the variations of these factors should be under the control of the pilot; for instance in climbing, when the pilot should be able to choose and set permanently the best diameter, to which corresponds the best climbingangle.

In order to render automatic the functioning of the propeller, I make use of the antagonistic actions of a spring or other elastic medium tending to contract and centrifugal force tending to expand the same; so that the diameter will increase or decrease when similar variations inthe motor speed take place. Thus, if the density of the air decreases, the diameter of the propeller will increase with a consequent increase in the load; and if the engine slows down the diameter will decrease, and the propeller will not overload the engine, but will assume the dimensions of an yairscrew adapted for the horse-power that the notor is actually delivering at the time. If the pitch of the propeller is not variable the load variations will depend only on thevariations of the diameter, while if also the pitch is variable, said load variations will be increased or decreased according to the variations of said pitch.

In the drawings I show different con-- structions of propellers built according to plane my invention, having both a variable diameter and a variable pitch; it being understood however, that said drawings are intended as illustrative of my invention, but not in a limiting sense.

Referring to said drawings Fig. 1 is a view in perspective of an aeroitted with my improved propeller; Figs. 2 and 3 are diagrammatic views of the composition of centrifugal and lifting forces taking place in the operation of my propeller; l

F ig. 4 is a plan view partly sectioned and brokenl away, showing the construction of my propeller;

Fig. 5 is a cross sectional view in elevation of one of the aerofoils used in connection with a propeller having a variable pitch; and,

Figs. 6, 7, 8,9, are detail cross sectional views of hubs of propellers showing different constructions of the same.

One of the advantagesQ which may be derived from a design of propeller such as shown, and which is quite important, is the possibility of having the pitch decrease as the diameter decreases, until it actually assumes a negative angle; by setting the propeller at such an angle, and by giving full speed, a strong braking effect will be obtained, which will enable the pilot to land in a small landing ground.

In the drawings, Figs. 1, 4 and 5, a propeller possessed of such an advantage is shown, where a decrease in the diameter will effect a decrease in the pitch, and finally its reversal.

The general appearance of my propeller is shown in Fig. 1, where:

lO'represents: revolving aerofoil elements in a get-away position; small diameter and minimum positive pitch.

1-1 represents: flying position of propeller; maximum diameter and maximum positive pitch.

12 represents: reversed propeller; negative pitch.

13 represents: flexible cable connecting the aerofoil elements to each other and'to the revolving shaft. y

In Figs, 2l and 3, in order to facilitate a thorough understanding 'of the present invention, I show in a diagrammatic form the composltion of forces governing the operation of my improved propeller. In the same, for the sake of clarity, the inclination of line B P has been greatly exaggerated, and the dra coefiicient,.rbeing small enough to be negligi le, is omitted. l In the same:

B designates the point of attachment;

B designates the point of application of forces; l

O designates the centrifugal force in P;

f designates the lift-drag exerted in P.

Resultant R will be in alinement with BP;

A springs 19, 20; and it is to be noted that a the moment of said resultant. about the fixed point B will be zero; and the system will consequently be in equilibrium.

By taking movements of the component forces about B we nd:

equation (2) giving the complete solution of the dynamic problem.

From it, if two elements of the system are assumed, all the other elements will immediately be found. In practice, the magnitude of the centrifugal force will be greater than -the ma itude of the lifting force, therefore the flexible member BP will be only slightly inclined upwardly in respect to' the horizontal. In Fig.v3,vI sliow how foils) forces acting simultaneously will coinpound themselves in a double lifting -force axiall directed.

In r igs. 4, 7, I show the general construction of my ropeller, in which six sections, of a single' ca le 14 are wound together on a core15, secured-by key 16to vshaft 17.-

Core 15 is encasedin drum 18, loosely f mounted on shaft 17, forming a reel for cable 14; said drum being however connected to said shaft 17 by two spiral springs 19, 2()

wound in the direction 'opposite to that of the cable and attached at their inner end 4as at 21, respectively to shaft 17 and to a collar 22 rendered integral therewith by a ke 23, and at their outer ends to the drum itsel as at 23. The shaft is supposed 'to rotate'in the direction ofthe cable windings, 'as the arrow indicates, 'pulling along drum 18" through 'the elastic connection .provided by movement ofrotationof the drum relative to the shaft in the opposite direction, would tend Ito compress the springs, The drum is .provided with six idler rollers 24 around which each cable section is bent to extend from the driun'outwardly to and around a sheave 27 .or 28 of a frame 29, emerging therefrom in the direction of the next sheave 28 or 27" 'of the next frame, and after encircling said sheave returning to the drum,A to. complete one ofthe three loops by means of which cable 14 connects to each other all the' frames carrying the aerofoil elements.

By rotating shaft 17, and with it drum 18, the sections of 4cable 14 are carriedaround, and with it the three aerofoil framescarried thereby; centrifugal force tending to extend-the sections of cable 14 away from' drum I18, and being opposed by the tension of springs 19, 20. v

When the cable 14` is entirely ,wound on core 15,- the frames carrying the -aerofoil ele.

- ments areheld firmly in the position shown in dotted lines in Fig. 4, by having head 30 two lifting ('aeroautomatically.

of each frame inserted between the lian of drum 18. This retracted position is maintained as long as the tension of ysprin 19, 20, is greater` than the pull exerted .by centrifugal force oncable 14. If at any moment the pull of the centrifugal force should Y be greater than the tension of said springs,

foil element, a iexible expansible propeller will thus have been obtained, the diameter of which will increase or decrease, when the centrifugal force increases or decreases; and this in practice will mean. that where the air resistance decreases 4and the engine tendsv therefore to increase its number of revolutions, an excessive increase will be checked by the propeller increasing its diameter It also' will mean that, should the engine for any reason lessen the power dclivered,and slow down, the ropeller would not overload the motor, cause the centrifugal force would decrease so that springs 19, 20, would be enabled to rewind cable 14, diminishing thc propellers dianie# ter up to the point', where the two opposing forces would again balance each other.

l/Vhen a variable pitch is desired in the.

propeller besdes'a variable diameteiga construction inay be resorted to such as described in my co-pending patent application aboveqnentioned for im rovements'in extensible propellers, Serial No. 543,303, and is shown in Figs. 4, 5.

' In the'same it is seen that' each aerofoil element 30 is pivoted at 31,32, to frame 29, and is held at a certain angle of'incidence by positioning screws 33, 34, inserted into the threaded hub ofsheaves27, 28.' Screws 33, 34, are only capable of axial travel, their rotation beingprevented by a pin 37, inserted inelongitudinal groove 38.

Feeding a; given length of cable to increase the diameter of the propeller, will cause sheaves 27 28, to revolve, and therefore screws 33, 34, will axially travel in opposite' directions; thus proportionately vary-V ing't-he angle of incidence of the aerofoil element. The variations of said angle of incidence Qf the' aerofoils in relation to tha diameter ofthe propeller depending' not only from the length .of cable which has at will, to suit all requirements which .may

arise indifferent cases.

AsI stated before, in certain cases,

for ,no

gine speed. To this end the pilot by means of suitable levers not shown in the draw# mgs, may control a device consisting of a clutch collar 39 slidably keyed on collar 22, and provided with pins 40 adapted to enter perforations 41 through flange 42 of collar 22, and through one of the flanges' of drum 18. When the pilot, operating the lever (no t shown), moves pins 40 towards .drum 18, said pins engaglng perforations 41 will connect shaftV 17, and therefore core to said drum. All reciprocal variations of speed between; the two parts becoming thus prevented, the propellers diameter -will be maintained constant.

` In' landing, when cable 1.4 is nearly all retracted, andthe aerofoil elements assume a zero'a-ngle of incidence, heads 30 of frames '29 are nearing their housings' between the flanges of the drum. As soon as cable- 14 is retracted a little further` the. aerofoil elements will assume a small negative angle which may manually be made permanent at the will of the pilot, by causingpins 40 to en e perforations .41. as soon as said headgsaave entered their housings in their resting position.

At this moment the pilot, by giving again full speed to the motor, will obtain a strong braking effect, antagonistic to the travel of the machine.

In starting, the pilot, through the manual control will ,have to let out cable 14 for a short distance, and then lix 'it .in the new extended position, before giving full speed to the motor.

Instead of the springs shown, it is obvious that springs of other types may be used, or other elastic mediums, such as, for instance. compressed air, as shown in Fig. 6. In the same, 43 designates a chamber. containing air under high pressure, pumped through valve 44, and 45 a piston made air tight by piston rings 46, playing into said chamber.

Said piston is screwed on threaded part 47 of shaft 48, and is compelledto rotate atA the same speed as chamber 43, being connected to the same by means of pins 49finserted in longitudinal grooves 50.

Said chamber 43 is integral with reel 51, and shouldthe same revolve at a lower speed. than shaft-, 48, .as must be the case. if the propellers diameter is increasing, piston 45 would be caused to unscrew from part 47, and to travel towards the bottom of chamber 43 up to a point where the increased pressure of theair would again balance the stronger tension on. the cable g practice.

sections, exerted by .centrifugal force.

designed so that the motion of piston 45.

will compress the enclosed air so as to maintain'practically constantv 'the relations between Said pressure, the centrifugal force,

and the diameter lof the propeller. A springI or springs may be addedif desired, to co-VA operate with the. reaction of said a'ir under' pressure, and many other different; arrangements may be devised, without .departing from the spirit of my invention..

In Fig. 8 I show another 'construction -the same, 52, 53, designate two flanges, ,integral with shaft 54.` within which is retained, 'so as lto be free to re whereby my invention maybe carried into volve, drum 55. Said drum is hollow, and

is attachedjto shaft 54 by means of three .spiral springs' 56, acting in a waysimilar to that described in connection with springs 19, 20, of the device shownV in Fig. 7.

Drum 55 is formed on the outside', with a helical groove 57, adapted to receive the six sections of cable 58, which will thus become wound on the drum along al cy'- lindrical spiral, instead 'of a dat spiral. This arrangement permits of decreaslng the diameter of the drum, while its thickness will belincreased. The cable sections areguided,

during their extension and retraction, by idler roller c59, which are mounted on threaded pins 60, and will therefore follow the longitudinal or axial travelof Athe cable' sections. Y

In connection with this arrangement, a different device for substituting manual control to automatic, is shown. -The same consistsof a plurality of radial arms 61, having their outer end pivoted at 62 to flange 53, and their free inner end abutting against a ilange 64 of a collar 65 sl-idably mounted -on the hub of said flanges 53, so as to be capable of axial motion under-the control of the operator.

-Arms 61 are formed with a projection 66,

inserted through openings 67 in flange 53, which will, when collar 65 is forced outwardly, exert a braking action against drum 55, and thus render the same integral with shaft 54. p

The advantage of such an arrangement is that connection between the reel on which the cable sections are wound. and the shaft, may be formed at any vrelative posit-ion of said two members. In Fig. 9 I show a. similar arrangement, where instead of the operating in the manner 4stru'ctlcms shown in order to c'arry a compressedair chamber is used,

explained 1n consprings,

' from the spirit of my invention, and I considerpart of my invention those apparently different embodiments of the same which may enter, fairly, into the scope of the appended claims.

claim:

ll. In'A a propeller, the combination 'of an axle, a plurality of fiexible'carriers 'attached thereto. and extensible therefrom, plane elements carried by said carriers, and elastic means opposing the extension of said carriers. 2. In a propeller, the 'combination of an axle, a plurality of flexible carriers attached thereto and extensible therefrom, plane ele'- .with an ax 'ments carried by said carriers means causing variations 1n thel angle o vincidence of said planes as saidcarriers are extended or retracted, 'and elastic means-opposing the extension of said carriers..

3. In a Ipropeller, and in combination e, a pluralitv of loutwardly ex# tensible elements carrie thereby, and elasticl means opposing the outward motion of said elements, means under the control of the operator for establishing 4a rigid connection between said elements and said axle.l

4.' In a propeller having -a variable pitch anda vvariable diameter, propeller to assume 'a negative pitch when reaching a predetermined diameter.

5. In a, propeller, and in combination with an axle, and a p lurality of extensible elements carried there a Huid under pressure tending to oppose the extension of'said. elements. .I

6. In a ro eller, the combination of .an axle, a p ura ing to oppose the extensionf thereof, and

means`under the control tweenI said elements a 11 d sli,i;laxle,v

means causing saidV means therefor,

ty of outwardly extensibleV elements carried thereby, velastic means tendthe operator' adapted to establish arigid'nonneetlon be- 7. In a propeller, the combination of an axle, 'a plurality of flexible carriers attached thereto and extensible therefrom, plane elements carried by said carriers, elastic means tending to oppose the extension of saidcarriers, and means under the control of the operator adapted to establish a rigid connection between Vsaid elements and said axle.

8. Ina propeller," the combination ofv an axle, a plurality of flexible carriers attached.

thereto and extensiblev therefrom, plane elements carried by said carriers, elastic means tending to oppose theextension of saidcar-i riers, means cansing Variations inthe angle of incidence of said plane elements as said carriers are extended or retracted, and means under the control of the o rator adapted to establish a rigid connection between said elements and said axle.

9. In a. propeller the combination of an flexible extensible eleaxle, a plurality ot ments, attached thereto, winding means therefor, an elastic connection between said axle .and said winding mea'ns tendi` -to operate 'saidlwinding means in the wiii' direction, and means under the control of the operator adapted-to establish 'a rigid con-r neet-ion between said axle.' A v 10'. I n a propeller, the combination of an axle, a plurality of flexible carriers attached thereto and extensible therefrom', windingA means therefor, plane elements` carried by said carriers, an elastic connection between said winding means and 'I said axle and said winding means tending` to operate said Winding means in the wlnding direction, and means under thel control of the operator `adapted to establish a rigid connection -between said winding means and said axle. 11. In a propeller, the combination o'a'n axle, a plurality of flexible carriers attached thereto .and extensible therefrom, Awin plane elements carried by said carriers means causing variations in f ,the` angle vlo incidence of said lane 1,0- `i ments as; said carriers are exten edv or 'I e-Y tracted',anr, e las t 1c connection between said axle :saidgfwinding means tend ing' V to operate'saigl lwinding means in the winding direction, and under the control of the -operatorxalaptedto establish a rigid connection betwe'en said .winding 'means and Samaria; a

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