US2173291A - Aerodynamic rotor - Google Patents

Description

- Sept, 19, 1939. T. ASH

AER (DYNAMIC ROTOR Filed Oct. 10, 1938 Wm) mm @w 6% Patented Sept. 19, 1939 v UNITED "STATES PATENT OFFICE 2,173,291 maonimamo no'r'on Thomas Leo Ash, Los Calit' Application October 10, 1938, Serial No. 234,196

17 Claims.

My invention relatesto aerodynamic rotors and the like for lift and/or propulsion of rotoplanes and other aircraft, and while the invention involvestotally new features it is also in the nature of an improvement upon the rotors set forth in Patent No. 2,108,245 issued February 15, 1938, and PatentNo. 2,120,168 issued June '7, 1938.

A particular object of this invention is to provide for using only one blade which is dynamically balanced; a single blade having the advantage of moving thru relatively undisturbed airwithout interference from other blades.

By areciprocal action on the part of the blades the rotor shown in Patent No. 2,120,168 provides balance all around or offset balance as and where I thickness and angle of attack of the blade from I jects of the invention. Heretofore, speed and efiiciency have been limited by reason of the wing 35 span required for the characteristic'take-ofl and landing for which rotoplanes are noted. It is an object of this to provide a wing, or wings, which while having suitable span for customary takeoff and landing, can be positively retracted to a 40 shorter span in keeping with some of the objects of the invention.

Specifically, it is an object .of this invention to provide a blade which canv be extended to suit landing and take-off requirements but which in 45 cruising position-is quite rigid and which is so controlled thru each and every part of each revolution that its centrifugal force is not employed to hold it in proper position. In fact I provide,

by this invention a blade which in cruising posi- 50 tion is of itself decidedly rigid independently of centrifugal force but which is provided with means for suitably snubbing forces which would otherwise be damaging to a structurally rigid blade.

55 Other objects and advantages of my-invention will appear hereinafter and will. be better un-- derstood by reason of the order in which'they appear.

I have illustrated by-the accompanying drawing, one practical embodiment. In the drawing: 5

Figure 1 is a view mainly in vertical section of such an embodiment.

Figure 2 is a smaller scale plan view of said embodiment; this view showing the blade in position for banking to theleft, for example. 10

Figure 3 is a small scale elevation showing the blade in the position 'shown by .Figure 2.

Figure 4 is a view in elevation similar to Figure 3 but showing the blade fully extended.

In the embodiment illustrated, and in 'com- 5 mon with Patent No. 2,120,168, the wing is made up of. a plurality of telescoping sections such as l, 8; 9, l0 and II respectively and each is provided with an attached cable suchas l2; the wing including the reel I! having graduated winding su'rfaces such as 15; one such surface for each cable. The reel includes an integral pinion I6 and is mounted to rotate on a fixed shaft l'l.

To rotate the reel positively, as required, any

suitable mechanism, as taught by the prior art may be employed and by way of example I have here shown a rack l8 engaging the'pinion Hi.

This rack is hydraulically driven; there being an integral plunger l9 at one end of the rack reciprocal in a hydraulic cylinder 20. The cables are 0 so woundon the reel that centrifugal forc acting to pull the wing sections outwardly will rotate the reel so that the pinion acts on the rack to move the piston or plunger l9 inwardly of its cylinder 20. This will act to displace oil or the like, contained in the cylinder, outwardly thru the port 2!. Means for controlling the escape of fluid from a hydraulic cylinder, and for forcing fluid into such cylinders, are well understood and are not further described or illustrated herein. 40 o It will be understood however, that the hydraulically operated reel here shown will provide for v for this reason and'for purposes-of balance, is

extended as at Ia indiametric opposition to the main extent of the wing, and altho in this embi iiiment the rotor may be described as single- 5 bladed, this extent 10 does do some lifting, as will appear hereinafter. l

The true center of rotation of the wing or blade is located inwardly from extension la and at the center of rotation and on the 'under side, the blade, at section I, is provided with a pivot shaft 22 which is mounted within a boss 23 forming an integral part of the wing section I. This provides for the wingpivoting on an axis right-am gular to the longitudinal axis of the wing. While such pivot has been provided in prior aircraft to provide for automatic coning or for positive coning thru the aid of mechanical devices, .I provide this pivot as part of a snubbing device which prevents undue strains on the root section of the wing.

Another part of the snubbing. device is provided in the form of a counter-weight W carried at the outer end of a cable 25. This cable is woundupon a special winding surface 25a, also provided by the reel I4, and this winding surface provides that for any position to which the wing sections are extended, the cable 25 will have corresponding unreeled length and thru centrifugal force will provide for dynamically balancing the single wing. This cable extends out from extension !a thru a tube 28; which tube is downwardly directed to hold the cable 25 and weight W at a plane of rotation lower than that of the wing.. This not only prevents the cable from moving in the same plane, and thru the same air, thru which the wing moves, but it causes the weight W to act at all times during rotation to keep the wing in a nearly level "or horizontal position. Therefore, no stops are needed for the pivot 22. Thus the weight W not onlyacts as a balance for the single wing, but it also provides the aforesaid snubbing device to protect the otherwise quite rigid wing from sudden stresses which might produce a twist or shear at the root section 1. Also the combination of the pivot 22 and the weight W provides an ideal means for suspending aircraft from a rotary wing or lifting system.

The numeral 21 indicates a part, either the- 29. This shaft, below the member 21, is provided with a set of bevel gears, indicated at 30, which connect the shaft 29 with a power shaft 3|; it being understood that in. rotoplanes the rotor is started by power. I further propose to use this shaft 3| and gears 30, at times, to connect the rotor of such a craft (with the usual propeller)- to apply any excess turning effort of the rotor to use inproviding a long and otherwise powerless glide.

The rotor shaft is provided at the upper end with a bracket 32 in which the pivot 22 is carried so that while the wing may pivotit is connected to the rotor shaft for positive rotation therewith. Altho the wing being described provides for meeting various loads by being extended as required and does not depend, as do prior rotors, for

changing angle of attack, I have shown the pivot,

shaft 22 as having right-angular extensions or arms 34'mounted to pivot in bracket 32 so that the angle ofattackof the wing may be changed if desired. For instance, to show the efficiency that when the, craft is inverted the angle of attack will be efiective positively. Also I show this type of pivot to remind those skilled in the art that the weight W may be positioned so that it will act to control angle of attack. The weight may have any suitable cross sectionand this section may be such as to give either positive or negative lift, but of course minimum drag is important. In'Figures 2, 3, and 4 respectively, it.

\ and it is a feature'of the invention that when the blade is so extended it will cone slightly to give stability during landing, takeoff and slow speed,

while in Figure 3 the blade is shown about onehalf retracted.

This partially retracted position provides inherent structural rigidity on the part of the blade and while the shortened wing provides the required lift at cruising speed it offers much less drag than were the wing required to be always extended to the span "required for landing and take-ofi'. In the embodiment illustrated the action of weight W at the regular cruising speed is such as-to permit little or no coning on the part of the relatively rigid short blade, altho this same weight and the pivot do allowfor coning in an emergency where a rigid non-coning blade might be damaged.

Pivotal mounting of the blade in combination with the action of weight W is particularly advanta'geous in take-off where the blade is first revolved by power and then suddenly expanded to provide a sudden vertical ltake-ofi, for under those conditions this blade, which of itself is quite rigid, will be suddenly subjected to reactions far greater than the weight of the aircraft.

It will be apparent now that I have provided a blade which is structurally rigid and which does not depend upon its centrifugal force to keep it suitably rigid, but which blade is so mounted and so controlled by the weight W that it will pivot under extreme load or sudden changes of air density. Thus the advantages of a rigicibladev are enjoyed while the previous disadvantages are overcome. As compared with prior aircraft of the type to which this invention more particularly relates, the reduced drag of the blade and the higher speeds made possible by this invention,

which encloses those parts of the wing in the vicinity of the center of rotation and this hub is movable to, and adapted to be held in, any

eccentric position, such as the position in which it is shown in Figures 2, 3 and 4. In Figure 1 it is shown fully concentric with the center of rotation. 4

The means for shifting the hub comprises an arm III which passes up thru the hollow of the hollow rotor shaft, then thru the pivots, then thru the wing section! where it is supported revolubly by opposed thrust bearings ll and 42, and

Vance, where the blades project as at 43a, to permit of -the blade being tilted without the hub being tilted. Within the hollow ofthehub, and above the wing, there is provided a hydraulic cylinder 44, fixed to the hub as at a. This cylin- 50. by a link 52. Thus increases the wing sections tend der is horizontal as is the arm 40, which .arm' turns at 40c and after passing into the cylinder, terminates in a plunger 45. The arm is hollow.

thruout and at the lower end is enlarged to pro-' vide a second hydraulic cylinder which, thru the hollow arm 40' communicates with the bore of the cylinder 44.

A bracket 48 is connected rigidly to the cyl-.

.inder l6 and to this bracket is pivoted, as at 49,

a lever;50. This lever is in reality the stick" by which the craft is controlled. Withinthe cylinder 46 is a plunger 5| connected to the lever when the outer end 50a of the lever is depressed, fluid contained in cylinder IE will be displaced thru the hollow of arm 40 into cylinder 46.

The hub, or at least a portion thereof, is nonrotative so that the arm 40 maybe pointed in any direction and held there. Accordingly the lower part 39b of the hub is provided with an annular bearing 54 so that it 'may turn within the hub and rotate with the wing.

While the operation of some parts has been de scribed herein, the operation of the-rotor as a 'whole'will be understood from the'following:

With'all parts in the idle position indicated by Figure 1 take-off may be accomplished by power rotation of the rotor shaft. As the rotative speed to fly outward, restrained by fluid in the cylinder. When suit-" able rotative speed is reached the sections. are allowed to move out. If this is done suddenly and the wing expanded to full span'the lift becomes considerably greater than the weight of the craft to which it is attached and a rapid rise or takeoff will result. As soon as the aircraft is under way the wing may be contracted to a span just sufficient to sustain the craft while setting up the minimum of drag. Since the root section I, and the extension Ia where it projects from the hub, has as much lift per unit of length as do other sections, the wing is eflective right down to the hub.

It will be found that for level flying under normal conditions a slightly eccentric position of the hub will provide aerodynamic balance so that .the wing will show equal lift in all partsof the disc area and there will belittle or no tendency for the wing to fflap. In fact this rigid wing is not designed to flap and will not even tilt on its pivot, or cone, except under a temporary load greater than that found in normal flight at cruising speed. Whenever the blade is expanded or contracted the weight moves in or out accordingly, since its cable is wound on the same reel as that upon which the blade-section cables are wound. Thus dynamic balance is alwaysprovided.

To bank the aircraft to make a turn, or to nose it up in a climb, or down in a dive, the stick is turned to point in the desired. direction Thus in Figure 1 it is shown pointing to the left, which means-that cylinder 44 is pointing in the same direction. Now, by depressing the stick slightly the cylinder 48 and its plunger act as a pump to move fluid in to cylinder 44 to thus move the hub in that direction away from the center of rotation blade sections. It will be seen from this that section I while passing thru the right-handside of the disc area is fully effective in producing lift while section or extension la is also effective in producing lift when passing thru the right-hand part of the discarea. However, both of these are moved into'the hub and are quite ineffective when passing thru the left-hand part of the disc area. Accordingly the wing has much greater lift on the'right-hand portion and this will cause the craft to bank and turn to the left; just as is indicated by the stick. A right-hand turn, a climb, or a dive may be brought about in'the same manner by swinging the stick around-to point in the desired direction while depressing the. outer end of the stick. Raising the end of the single-blade or multi-bladed wing may be used with other means for snubbing.

This disclosure will suggest to those'skilled in the art many other modifications, suchas employing some of the features .of this invention in a flexiblewing, altho I hold that I am first in the art' to make it really practicable to employ a blade which isdecidedly rigid; which does not tend to flap because it is aerodynamically bal-- anced all around the discarea; and which blade has increasing rigidity with increase of speed by reason of the fact that it can be retracted to such span for each speed and load combination as to give just the right lift with minimized drag. Also in quick'vertical take-off. rigidity of the wingor blade is not'a detriment since snubbed coning can take place. Also this invention results in a further advantage from using blade sections of increasing chord," thickness and angle of attack inwardly; this providing uniform lift from root to tip and evenly distributing the load so that rigidity becomes an advantage ratherthan a disadvantage.

tend to vibrate very slightly but it will beseen that the hydraulic shifting means for same provides a non-positive connection between the hubv and the rest of the assembly so that dynamic balance as a whole is not altered. It. willalsobe understood that the invention applies to apropeller as well as to a lifting rotor, and may also be applied to fans and other I claim: v

1. In a rotor of the class described, an airfoil blade comprising a plurality of telescopically associated airfoil sections of increasing chord, thickness and angle of incidence respectively inwardly of the blade whereby the blade has substantially constant lift per unit of span 'from'the' tip to ,approximately the center of rotation, a movable hub normally co-axial to the center of rotation 75 I aerodynamic rotors.

A further advantage of having the root section equally as effective as the other sec-.

of said blade and enclosing the blade for an appreciable distance outwardly from its center of rotation, and means for eccentrically shifting said hub.

2. The rotor as is claim one and including means operable during rotation of 1 said blade and independently of said hub-shifting means for contracting said blade against centrifugal force.

3. The rotor as in claim one and in which said hub includes aplate superposed immediately over said blade, and said shifting means includes an extension element for said plate radial to the-center thereof and means for moving the element radially about the center of rotation of said blade.

4. The rotor as in claim one and further including, a winding reel carried in the innermost section of said blade and provided with a plurality and attached to each .wing section of graduated winding surfaces, cables, one for and each wound on a corresponding winding surface.

5. The rotor as in claim one andfurther including a stub-end to the innermost section of said blade projecting radially from the center of rotation of said blade in diametric opposition to other parts of the blade, a centrifugal weight and a cable connecting said weight to said stub-end.

6. The rotor as in claimone and in which said last named means comprises; means for turning said hub about the center of rotation of said blade, and meansfor moving the hub radially outward with respect to said center of rotation.

'7. In a rotary lifting system for aircraft, a centralrotary shaft, a single airfoil blade carried by said shaft extending approximately radially thereof, a cable extending radially with respect to said shaft from the inner end of said blade in diametric opposition thereto, and a relatively small area weight carried at the outer end of said cable to provide dynamic balance.

8. The system as in claim seven and including means for contracting said-wing and for winding in said cable co-ordinately to provide maintained dynamicbalance.

9. The system as in claim seven and in which said cable and said blade are disposed. to move in 'planes of differing elevations.

10. The rotary lifting system as in claim seven and in which said blade is structurally rigid and pivoted to said shaft so as to be free to cone; said cable connected to said blade so that the centrifugal force of the weight tends to resist coning of the blade.

11. The system as in claim seven in which said blade comprises a plurality of blade sections.

telescopically associated so as to provide rigidity independently of centrifugal force.

12. In a rotary lifting system central shaft, a blade section projecting radially for aircraft, a

winding reel, a motor housed in said first section for'rotating said winding reel, a second cable wound on said reel and section outwardly in diametric opposition to the sections, and a weight connected at the outerend of said cable acting to dynamically balance said sections.

- 13. The rotary lifting system as in claim twelve and including a pivot connecting said inner section with said shaft to allow said sections to cone; said weight and corresponding cable acting under centrifugal force to resist such coning.

l4. The rotary lifting system as in claim twelve and including an eccentrically shiftable hub enclosing the inner 'end of said first section normally co-axial with said shaft, and means for shifting said hub eccentrically of the center of rotation of said sections.

15. The rotary lifting system as in claim twelve and further including a freely floating hub en-. closing the inner end of said first section, a secextending thru the first ond shaft within the first shaft supporting said hub and adapted to be turned, a piston projecting horizontally radially from said second shaft, a cylinder carried by said hub and contalning'said piston, means for turning said second shaft and means'for injecting fluid into said cylinder.

16. In an aerodynamic rotor, a shaft, a single blade projecting from and driven by said shaft,-a hub normally tions of said blade, and means for moving said hub axially of said blade and for then constraining said hub to rotate with said blade around a point eccentric to the shaft.

17. In a rotary lifting system for aircraft, a hu a single blade projecting radially from said hub, a dynamic balance weight for said blade, -a cable extending from said hub in diametric opposition to said blade and connected at its outer end to said weight, said system including means operable once during each revolution of said blade to retract said blade relatively inwardly of said hub during a predetermined part of each revolution and to allow said blade to move relatively outwardly of saidhubduring other portions of the revolution; said means acting to move said cable relatively outwardly of said hub when said blade is being moved inwardly relatively thereof, and to move said cable relatively inwardly of said hub when said blade is movingrelatively outwardly of said hub.

\ THOMAS LEO ASH.

enclosing the corresponding 'po'r-,

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