US1921805A - Helicopter - Google Patents

Description

Aug. 8, 1933.-

F. BORDONI' HELICOPTER 4 Sheet-Sheet 1 Filed Feb. 26, 1932 FERDINANDO BORDONI INVENTOR ATTORNEYS 3- v I F'..BORDONI 4 ,805

HELICOPTER I 1 Filed Feb. 26, 1952 A SheetsI-Sheet 3 FERDINA NDO BORDON I mvsnrog a ATTQIYQ'SI '1 Aug. 8, 1933.

F. BORDONI HELICOPTER Filed Feb. 26, 1952 4 Sheets-Sheet 4 FERDINANDO BORDONI INVENTOR miudi ATTORNEYS reamed Au 3, 1933 "UNITED STATES PATENT oFFica HELICOPTER Ferdinando Bordoni, Rome, Italy Application February 26, 1932, Serial No. 595,282,- and in Italy February 17, 1931 10 Claims of the pilot, so as to maintain unaltered or to vary at will the lifting power of the propeller,

'both in amount and in direction, and also in order to give rise to a torque lying in a plane normal to the axis of rotation, which may be varied at will both as to amount and direction of rotation.

-verse direction when the angle of incidence actions, or by taking advantage of the moment of the said aerodynamic reactions with respect to the longitudinal axis of rotationmf each blade,

or also by utilizingthe variations of the axial thrust-of the propellers. 3

In all these cases, it is preferable that the blades should possess a small moment of inertia with respect to the longitudinal axis of rotation (and consequently a considerable elongation),

and it is necessary also to construct the blades with such a profile that the resultant centre of the thrust of the aerodynamic reactions may not be shifted, or only slightly shifted in the transthe blade is varied.

When the blades satisfy the above mentioned conditions, it iseasy to provide for their control It thus P i l t cause he pparatus tofbyffollowingwither therfirst, the second or the rise or to fall, or to shift it in the horizontal or an oblique direction, or to incline it in the longitudinal or in the transversal directions, (and also allow the correction of the eventual list) and it is also possible to cause the apparatus to rotate in the horizontal plane. so as to guide it in the direction desired, and also to veer it in any desired manner.

The said mechanism also makes it possible to,

on the fundamental principle consisting in that,-

if to a propellers blade which is hinged to the hub,- the angle of incidence is varied periodically during one revolution (which would have the effect of varying periodically the relative aerodynamical thrust) the said blade performs oscillations, which, combining with the'rotary movement will have the effect of changing the plane of rotation of the blade, and consequently also of the direction of the'lifting thrust.

with regard to the automatic control of the amount of the lifting thrust, the said mechanism can be actuated in three different ways, viz by utilizing,. forthe automatic control, the inclination which the blades assume under the actionof the centrifugal force and the aerodynamic rethird methods above mentioned, as will appear more clearly from the following detailed description, and with reference to the annexed drawings,

which illustrate schematically a helicopter made,

according to the present invention considered as a whole, and includes the construction and 8 Figs. 3 and 4 show respectively in vertical axial section and in plan elevation one way of articulating the blades to the hub.

Figs. 5, 6, 7 and 8 show various sections blades.

Figs. 9 and 10 show schematically'two diiferent forms of construction of the device for the control of the blades.

Figs. 11 and 12 show schematically two diflerent arrangements for connecting the motor to the propellers.

Figs. 13 and 14 illustrate in perspective and in detail, respectively, of-the controlling means by which to tip and adJust the propeller blade adjusting rings. 4 a.

As may be seen in Fig. 1, which shows the helicopter in complete form, including a body 1 in which are arranged the places a for the passengers, and in front of these, the seat 3 for the pilot; the motor 4 being disposed behind.

The body or hull is provided with elastic means 5 and 6 for landing, which, as shown in the draw-' ings, may take the form of skids. No wheels are required 'as the apparatus. has 'no need to run of the wheels may be provided in order to facilitate the shifting of the apparatus on the ground.

The apparatus may also be arranged to rise from or descend upon the water, in which case 5 suitable floats may be provided.

The body is also provided with fixed tail Sta-- bilizing surfaces 7 and 8, the object of which is to improve the stability of flight during the horizontal movement of the apparatus; whereby the horizontal plane 7 can eventually be made to oscillate and to be controllable so as to provide to the centering of the apparatus, and to the variations of the longitudinal trim during the horizontal travel of the apparatus. 0

Also the vertical plane 8 may eventually be controlled, soas to be of assistance in turning.

In addition, the body may also be provided with small wings which prove to be useful during These devices comprise two propellers 10 at? 11, co-axial with each other, rotating in opposite directions and driven by the motor 4.

of the star type cooled by air by means of the fan 12 mounted on the main shaft 13 of the motor; it is however possible to use other types of motors and other systems of cooling.

by a fan, it is necessary to convey and direct the air current accurately on the radiating ribs of the cylinders 14, by guiding the fiuid streams by means"of metal plates 15 suitably shaped (as shown schematically in Fig.2) so as to obtain the desired result with the least possible consumption of power. p

Fig. 2 shows the case in which a motor is fitted obliquely, so that the shaft 13 transmits the movement directly to the first propeller 10 by means of a speed reducing gearing formed by the pinion 16 and the toothed wheel 1'7.

The propeller 10 is provided with a hollow hub 18 revolving on the fixed tube 19 acting as a bear- 50. ing, and transmits the movement to the second propeller 11, which is also mounted on a hollow hub 20, said transmission comprising the two toothed wheels 21 and 22 and the pinions 23.

It is also possible to adopt' other means for transmitting the movement, such alternative means being shown by way of example in the Figures 11 and 12.

In the arrangement shown in Fig. 11, the shaft 13 of the motor 4 drives the vertical shaft 56 by means of a pair of conical wheels 55 (which can be omitted when the motor is placed with the vertical axis below the propellers), the said vertical shaft being provided, in correspondence with each propeller,. with a pinion 57 which engages with one, two, three or more pinions 58 mounted causes therotation of .the first propeller through the pinion 84, the satellite pinions and the toothed crown 66 connected to the said propeller,

- and it also causes the-rotation, m the opposite In Fig. 2 is shown by way of example, a motor When using a motor cooled by air supplied transversally tothe blade) direction, of the second propeller, by means of another pinion 6'7, and other satellite pinions'68, (the cage of which is connected to the second propeller) and of a toothed fixed crown 69.

In order to allow the free rotation of the pro- 8 pellers, even when the motor is cut off or clogged, and in order to be able thus to descend when the propellers rotate freelyby taking advantage of their action as parachute, it is necessary to introduce between the motor and the propellers a dis- 3 connecting device or a free wheel arrangement 24 which is schematically shown in Fig. 2.

The propellers may be provided with a variable number of blades, for example 2, 3, or 4, which may have any suitable. shape; these blades are 9 attached to the hub by means of hinges 25, 26, 2'7 and 28 which allow them to set themselves in thedirection of the resultant of the centrifugal force and of the axial thrust; in this way the bending moment on the blades is eliminated or 9 at least greatly reduced.

The said blades are in addition free to rotate round a longitudinal axis which is approximately parallel to the leading ed'geJQegause they must be able to changetheir angle of -incident:e wit'ITT G respect to the relative wind.

' Itisaisaadvantageous to allow the blades to oscillate slightly in their plane of rotation, so as to eliminate or reduce the alternate movements 10 which developtiiflhat plamdhfllare caused by the combined effect of the rotation me ings of the blades, or by thecombin'ed effect of the rotation of the blades and the movements of the apparatus.

It may however be preferable and more con- 11* venient from an aerodyna'mical point of view to use stops (eventually of the elastic type) inserted in .the hinges. This causes naturally the productionmLhiwstrains in the blades when they are at rest, wmeweyenlmasily 11 maintained within practical limits by allottirig the blades convenient dimensions.

Moreover the propellers, according to the present invention, are also provided with a control mechanism of the blades, which allows the variation of the angle of incidence, either automatically or under the control of the pilot, so as to maintain unaltered or to change at will the lifting power of the machine, both in amount and in direction, as before stated, and also to change at will 121 the resisting torque of the propeller; the said actions being required to produce the vertical, oblique and horizontal movements of the apparatus, and to cause it to veer in any direction re,- quired'. The said control mechanism may assume 131 many different forms, by varying the shape, the arrangement and the working of the parts composing it, while obtaining the same result.

Amongst the various possible forms of construction, some are described hereinafter by way of example. I

A first form is shown in Figs. 3, 4, 5, 6, 'l and 8, in which the blades 29 and 30 are free'to revolve and to oscillate by means of the thrust bearings 31 and 32, and'of the'radial bushes 33 and 34. In 141 the form shown by these figures it'is supposed to do away with the third hinge which allows the blades to oscillate inthe plan of rotation.

The bushes 33 and 34 are fixed on the hubs 35 and as which rotate round the tube 19 by 141 means of the bushes 31 and 38.

The longitudinal axis-oi rotation of each blade is arranged to pass through the centre of thrust of the blade (which-iasabove said does notshift I The blades are moreover constructed and counterweighted so that their centre of gravity also placed on the axis of rotation.

In the conditions above described, whichever be the arrangement or the incidence of the blades,

40, which are connected to the two rings 43 and 44 by means of the links 41 and 42.

Supposing in the first place that the said two rings are invariably mounted on the hubs 35 and 36, the automatic-control of the blades acts in the following way.

If for example an axial wind begins to blow, which has the tendency of increasing or decreasing the angle of incidence of the blades, these will be solicited to rise or fall, in order to reestablish the equilibrium between the centrifugal and the axial forces; however, as the links 4l and 42 are fixed (Figs. 4 and 5) and are also connected to the blades eccentrically with. respect to the longitudinal axis of rotation, they force the blades to rotate round said axis thus bringing back the incidence of the blades to approximately the original value. It will now be evident that the mechanism above described operates in such a way as k to maintain almost unaltered the moment of the axial thrust acting on each blade, for a given velocity of rotation of the propeller, and as the contain within small limits the variations of thethrust, or at least, asv it is found by the mathematical treatment of the problem, they cause to vanish the first harmonic of the variable thrust.

in the conditions of flight above. described it is thus apparent, as before mentioned, that it is convenient that the blades should possess a small moment of inertia, so as to allow them to perform their necessary continuous angular oscillations with very small torsional momentums.

If on the other hand the rings 43 and 44 are not fastened to the hubsfbut by means of two rows of balls, are simply connected with the sleeves 45 and 46 which do not revolve with the propellers but are subjected to axial and angular movements controlled by the pilot, it becomes thus possible to vary at will the conditions of flight. In' other words, if the said sleeves are lifted or lowered simultaneously, the conditions of equilibrium of the blades will be varied, and

consequently also the resultant axial thrust,

plane.

-movement to the rings 70 and "71 by means of Finally if the sleeves 45 and 46 are shifted angularly either in the longitudinal or in the transverse directions, it will be apparent that the said arrangement will causetheperiodical variation of the angle of incidence of the blades at each revolution, which fact, as already mentioned at the beginning of this description, will cause the blades to'oscillate, and will also change the position of the plane of rotation of the two propellers, which will be forced to rotate in planes parallel to each other and obliquely with respect to the tube 19; the resultant thrusts will be shifted and they will'become inclined, giving rise to moments withrespect to the centre of gravity of the apparatus, and will cause this latter to incline in the longitudinal or transversal plane. In particular, if the apparatus is inclined forward and is maintained .in such position, the lifting thrust acquires an horizontal component which causes a movement of translation.

With regard to the control of the sleeves 45 and 46, Figs. 3 and 4 show that each sleeve is controlled with three rods 47 (and 48) disposed into the tube 19. 1

It is also possible to cause the rods 47 and 48 to descend outside the tube 19 (when this is used as the shaft for the rotation of the blades, as shown in Figs. 11,' and 12) providing of course this tube with suitable expansions in correspondence with the propellers, so' that the rods 48 may be carried without hindrance through the central part of the propeller 10.

Of course, the control of the rods 47 and 48 may be effected in many different ways; one of which consistingin connecting the said rods to discs or rings which by suitable transmission may be controlled by the pilot either axially or angularly (said transmissions may also be made to reach directly the sleeves 45 and 46).

Fig. 13 particularly illustrates the connection of the rods 47 and 48 to the slidable rings 70 and 71, respectively, said rings, as already indicated, being subjected to axial and angular movements.

In order to render such movements feasible, the

rings are mounted on the spherical joints 72 and 73, which latter in turn are fixed upon telescopic tubes '74 and 75, respectively, these tubes being adapted to slide axially the rod 76 secured to the housing 77.

Ihe mentioned slidable rings may be controlled by the pilot by means of appropriate transmission devices, such as for example, a control lever 78, a foot lever '79, and a lifting lever 80. If the control lever '78 which is mounted on a spherical pivot 82 and is therefore shiftable in all directions, should be shifted forwards. .or backwards by the pilot in the direction indicated by the arrow 81, he can impart angular the rods 83, thus producing the angular movement of the rings 45 and 46, through the connecting rods 47 and 48: This angular movement in turn produces the alternate and periodical oscillations of the blades round their longitudinal axes, which, owing to the aerodynamical reactions already described, produce the inclination of. the rotating planes of the propeller and -lar shifting of the rings 70 and'll in a plane 0 of the rods 4'7 and 48.

which is normal to the plane in which the said rings would oscillate when moved by the rods 83, the said angular shifting being similarly transmitted to the rings 45 and 46 by means The resultant of said movement is a transversal inclination of the rotating planes of the propellers and consequently the variation of the transversal trim of the aircraft.

When the pilot with his foot depresses the end of the lever 79 which is pivoted at 91, he will cause this lever to oscillate in a horizontal plane, this oscillation, by means of the transmission formed by the rods 92, the two bent levers 94, pivoted at 95, and the small connecting rods 96, will cause the axial sliding in opposite directions of the telescopic tubes 74 and 75. As a consequence there will occur a shifting of the rings thrusts on the blades increase or decrease, also 70 and 71 which are fixed on the said tubes, which latter are subjected to oppositely directed axial movements, so that while the rods 47 are lifted, the rods 48 are lowered, these movements being followed respectively by the collars 45 and 46, so that the angles of attack of the two propellers, as already described, are modified, the

' resulting dissymmetry of the horizontal couples 1 of reaction causing the apparatus to rotate in the horizontal plane.

Fig. 14 shows the compensating spring 51 adapted to counteract the lift thrust of the blades, and the means for controlling it. This spring will be deformed more or less according to the stresses transmitted to it by the rods 47 and 48, thus causing the movements of the casing 77' and consequently, also movements of the rods 4'7 and 48, for ensuring, as already stated, the automatic control of the sustaining thrust.

In order to set the apparatus into a rising or falling condition, it will be necessary to adjust the compression of the spring 51 so as to change the equilibrium trim at will, and in order to accomplish this it will be sufficient to operate the lifting control 80, which is connected to the spring 51 by means of the connecting rods 9'7 and 99 and the lever 98, instead of said control being directlyconnected to the box 77 by means of the same connecting rods as shown in Fig. 13. i

To the members above described, it will be sufiicient to add the motor handle, or this may be provided with an automatic regulator for maintaining an even speed of rotation of the propellers even when the load varies; or else the pilot may have at its command a handlefor changing the positionof equilibrium of the said regulator and consequently for controlling the speed of the propellers.

A second form of construction can be attained by applying the second of the arrangements above mentioned for the control of theblades.

If the longitudinal axis of rotation of the blades is placed a little forward with respect to the centre of thrust of the aerodynamic reactions (viz, between the leading edge and the said centre of thrust) and the blades themselves are counterweighted so that the centre of gravity lies instead on the axis of rotation (or in any case be nearer to this axis than the centre of pressure) every blade will be constantly affected by a yawing moment which, supposing the centre of thrust to be fixed, results in becoming proportional to the said pressure.

Assuming that the mechanism of control of the blades is similar to that shown in the Figures 3, 4, 5, 6, 7 and 8, having however the bushes 31, 32, 33 and 34 so close to the axis that the extensions 39 and 40 have a very small length, the oscillations of the blades will not produce in this case any perceptible variations in the incidence of the said blades, but the yawing moment of the blades will be transmitted to the rods 47 and 48 through the links 41 and 42 and the sleeves 45 and 46.

If therefore (Fig. 9) the, said rods 47 and 48, after traversing a control box 49, engage upon a flat disc 50, which is free to move axially, on this disc there will be developed a force which will be proportional to the sum of the yawing moments of the blades, viz. proportional to the sum of the lift thrust of the blades, which force can be equilibrated or counteracted by means of a spring 51, or by other equivalent means, based for example on the centrifugal force developed.

If therefore, because of the axial wind the by the rods 47 and 48 on the disc 50 will become greater or smaller than the reaction exerted by the spring 51; the disc 50 will consequently be shifted and the blades will revolve until the thrust is re-established. g

Of course, by adjusting the compression ofthe spring, the conditions of equilibrium can be altered as required and consequently the apparatus rises or falls, shifting then, by means of the control box 49, the rods 47 in a direction opposite to the rods 48. Thus it is possible to distribute the driving couples between the propellers, and consequently the whole apparatus can be made to rotate. Furthermore, by shifting the rods 47 and 48 through unequal amounts (always by means of the control box 49) it is possible to incline angularly the sleeves 45 and 46, and consequently the planes of rotation of the propellers and the direction of the lifting force can'be set obliquely.

Finally it is also possible to operate the control of the blades by a third method "which is based on the utilization of the variations of the axial thrust.

If the tube 19 (Fig. 10) supporting the propellers is connected to the body or hull of the apparatus not rigidly but through an elastic system 52 (comprising for example a si'nglespring and a pile of rings mounted concentrically with respect to the tube 19 and enclosed within a tube 53 fixed to the body) to any variation of the resultant lift thrust, there will be a corresponding axial movement of the tube 19, caused by the yielding of the elastic system.

Supposing now that the blades are controlled by the above described link rods 41 and 42, attached at one end very close to the hinges of the blades themselves and the other end to the rings 43 and 44, controlled by the sleeves 45 and 46 and by the rods 47 and 48.

If the rods-47 and 48 are fixed to the body 53, as every variation of the lift thrust produces, as stated before, a shifting of the tube 19, a relative movement is thus produced which alters the angle of incidence of the blades, and this is suflicient to restore the equilibrium, in the same way as described in the second form of construction.

When, on the other hand, the rods 47 and 48 are'not rigidly fixed to the body, but are led to a control box 54, fixed on the body, similar to the box shown in Fig; 9,.it is possible to perform all the operations that may be desired; in particular, when the rods 47 and 48 shifting together, the inclination of all the blades is changed simultawhen its state of compression or tension is varied,

the equilibrium becomes restored for a slightly different value of the axial thrust, and by continuing the manual operations, the desired variation of thrust can be attained.

In the system now described it is of course necessary that the tube 19 be attached to the body so as to be free to slide but not to rotate, so that it may also transmit the torsion moments which are obtained by displacing the rods 47 in the contrary direction to the rods 48.

' Itis moreover necessary that in the transmission between the motor and the propellers, a shaft of the telescopic type or even of the cardan jointed type (if obliquely disposed), is inserted, so as to ensure the transmission of power in spite of the relative displacements occuring between the propellers and the body, unless it is preferred to connect the motor rigidly to the system of the propellers and to elastically connect the whole apparatus to the machine body.

I claim: 1. A helicopter provided with a shaft and fitted with two coaxial propellers revolving in opposite directions and having blades which are provided with an articulation allowing the blades to oscillate in a plane passing through the center of said shaft and automatically adjust themselves in the direction of the resultant of the centrifugal force combined with the aerodynamical thrust, which propeller blades are rotatable about their longitu dinal axes, and oneach propeller are connected to I a ring vwhich is individual to the propeller and individually movable relatively to the propeller shaft in order to produce variations of the angle of incidence of the blades, whereby to vary the value of the lifting thrust, and means for moving each of said rings, which latter, in'uneven or dissimilar setting, cause the formation of a differential couple for veering the machine as a whole, and in even or similar setting, cause a periodic variation of the angle of incidence of the blades so as to oscillate the latter and thereby produce inclination of the plane of rotation of the propellers and vary the direction of the lifting thrust thereof, there being means for rotating said propellers.

2. A helicopter according to claim 1, having automatic means for moving the rings pertaining to the propellers.

3. A helicopter according to claim 1, having controlled means for moving the rings pertaining to the propellers.

' 4. A helicopter according to claim 1, having link rods connecting the blades of the propellers with movable rings controlling the angle of incidence. of said blades, which produce the rota-' tion of the-blades about their longitudinal axes by the eflectof the variations of the light thrust,

and as 'a result produces the automatic variation of theang le of incidence in the proper direction for maintaining the axial thrust of the apparatus practically constant. T

5. A helicopter according to claim 1, wherein Y the centre of thrust of the propeller blades is disposed outside their longitudinal axes of rotation, a disk associated with the helicopter capable of assuming solely axial displacements, axially sliding control against said disk and communicating stresses and strains thereto tending to displace the same, and regulatable means simultaneous exerting an opposing force on said disk, so that axial sliding of the rods and automatic control of the propellers is produced by the resultant force exerted on the disk, there being,

other control "devices for obtaining other movements of the helicopter. 1

6. A helicopter according to claim 1, and thrust bearings controlling the rings which regulate the angle of incidence of the propeller blades, together with two groups of control rods disposed along the shaft of the propellers, there being control devices for operating and moving said control rods.

'7, A helicopter accordingto claim 1, provided with a tube carrying the propellers, means elastically suspending the body of the machine to said tube in order to actuate the automatic control of the rings during flight, and means cooperating therewith for increasing or decreasingthe axial thrust in order to vary the length and thereby produce concordant rotation of theblades about their longitudinal axes, there being" additional means for further controlling the operation of the machine.

8. A helicopter according to claim 1, wherein the body of the machine carries the means for. rotating the propellers in the form of a motor having a shaft, the propeller shaft being common to both propellers which are rotatable about the same while one propeller is mounted above the other, a hollow hub on the lower propeller provided with a gear thereon, a pinion on the motor shaft meshing with said gear to directly drive said lower propeller, a hollow hub on the upper propeller also having a gear thereon, and means including additional gearing communicating ro- I tation to said latter gear and the upper propeller from the gear of the lower propeller and driving ing a crown gear,'the means for driving the propellersconsisting of a motor having a shaft, and the propeller shaft being rotatable within the propeller hubs, and means communicating rotation from the motor shaft to the propellers including gears rigid; on said propeller shaft meshshaft which is vertically disposed and driven by 5 said motor shaft, a pinion connecting the motor shaft with said vertical propeller shaft, which propeller shaft communicates its rotation to one propeller by-means of a pinion, one or more satel- 1'25 ing with pinions on one end of rotary spindles lite pinions and acrown gear engaging'wit'h said one propeller, and similarly communicates its rotation to the other propeller by means of anotherpinion, asecond group of satellite pinions mounted in a casing which is connected to said other propeller, and a flxed crown gear.

\ FERDINANDO BORDONL-

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