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Publication numberUS1655114 A
Publication typeGrant
Publication dateJan 3, 1928
Filing dateOct 4, 1927
Priority dateApr 4, 1921
Publication numberUS 1655114 A, US 1655114A, US-A-1655114, US1655114 A, US1655114A
InventorsTesla Nikola
Original AssigneeTesla Nikola
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for aerial transportation
US 1655114 A
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Description  (OCR text may contain errors)

Jan. 3, 1928. 1,655,114

N. TESLA APPARATUS FOR AERIAL TRANSPORTATION Filed Oct. 4, 1927 2 Sheets-Sheet l U 0 0 o l 5 -6 me. 1.

oq m P s a e 4 7 FIG. 2.



Jan. 3, 1928.



Patented Jan. 3, 1928.




Application filed October 4, 1927. -Serial No. 223,915.

This application is a continuation in art of my application Serial No. 499,518, led September 9, 1921, and. is made pursuant to the rules of the Patent Oflice, its purpose being to describe and claim apparatus which I have invented for carrying into-practice the method therein disclosed.

The invention consists of a new type 0'1- flying machine, designated helicopterplane, which may be raised and lowered vertically and driven horizontally by the same propelling devices and comprises: a prime mover of im roved design and an airscrew, both espec1ally adapted for the purpose, means for tilting the machine in the air, arrangements for controlling its operation in any position, a novel landing gear and other constructive details, all of which will be hereinafter fully described.

The utility of the aeroplane as a means of transport is materially lessened and its commercial introduction greatly hampered owing to the inherent inability of the mechanism to readily rise and alight, which is an unavoidable consequence of the fact that the required lifting force can only be produced by a more or less rapid 'tra-nslatory movement of the planes or foils. This indispensable high velocity, imperilling life and property, makes itnecessar'y to equip the machine with special appliances and provide suitable facilities at the terminals of the route, all of which entail numerous drawbacks and difficulties of a serious nature.

More recently, professional attention has been turned to the helicopter which is devoid of planes as distinct organs of support and, presumably, enables both vertical and horizontal propulsion to be satisfactorily accomplished through the instrumentality of the pro elier alone.

T e prospects of such a flying machine appear at first attractive, primarily because it makes possible the carrying of great weight with a relatively small expenditure of energy. This follows directly .from the fundamental laws of fluid propulsion, laid down by W. T. M. Rankine more than fifty years ago, in conformity with which the thrust LS equal tothe integralsum of the products of the masses and velocities of the projected air particles; symbolically expressed,

' T=E(mv). On the other hand, the kinetic energy of the air set in motion is Zmv' 2 From these equations it is evident that a great thrust can be obtained with a comparatively small amount of power simply by increasing'the aggregate mass of the particles and reducing their velocities. But the seemingly great gain thus secured is of small value'in aviation for the reason that a high speed of travel is generally an essential requirement which cannot be fulfilled except by propelling the air at high velocity, and that obviously. implies a relatively small thrust Another quality commonly attributed to the helicopter is great stability, this being apparently a logical inference judging from the location of the centers of gravity and pressure. It will be found, though, that contrary to this prevailing opinion the device, while moving in any direction other than up or down, has an equilibrium easily T =T SlIla. and at the same time there will be produced a horizontal thrust T =T cosa Under the action of the unbalanced force of gravity, the machine will now fall along a curve to a level below and if the inclination of the propeller as well as its speed of rotation remain unaltered during the descent,

the forces T, T and T will continuously increase in proportion to the density of the air until the vertical component T of the" be, theoretically, the same no matter at what altitude the events take place. To get an idea of its magnitude suppose the elevations of the upper and lower strata measured from sea level be h and 72,, respectively, d, and '1], the corresponding air densities and l-I=26,700 feet the height of the uniform' atmosphere, then as a consequence of,

Boyles Law the relation will exist 1t obvious that i I 1:2

T T sin sin a. in order that the vertical component of the axial thrust in the lower stratum should just support-the weight. Hence sin ix must be equal tog:

in a special case, the angle =60 then m= 0.866- 1-.1547, and

h, 72-, 26,700 X log 1.1547 3,840 feet.

In reality the drop will be much greater for the machine, upon reaching the lower layer with a high velocity relative to the Taking, degrees,

.medium, will be urged further down along the. curved path and the kinetic energy, in the vertical sense, possessed by the moving mass must be annihilated before the fall is arrested in a still denser air stratum. At this point the upward thrust will be far in excess of the opposed pull of the weight and the apparatus will rise with first increasing and then diminishing speed to a height which may approximate the original. From there it will again fall and so on, these operations being repeated during the forward flight, the up and down excursions from the main horizontal line gradually diminishing in magnitude. After a; lapse of time, determined by numerous influences, these deviations should become insignificant and the path described nearl rectilinear. But this is next to impossib e as can be readily shownby pointing out another curious feature of the helicopter.

In the foregoing the axis of the propeller was supposed to move always parallel to itself, which result might be accomplished by the use of an adjustable aileron. In this connection it may be pointed out, however, that such adevice will not act in the manner of a rudder, coming into full play energy,

at intervals only and performing its functions economically, but will steadily absorb this .occasioning a considerable waste of motive power and adding another to the many disadvantages of the helicopter.

Let now the machine he possessed of a certain degree of freedom, as will be the case normally, and observe in the, first place that the blades of the propeller themselves constitute planes developing a reaction thrust, thepressure on the lower leading blade being greater than that exerted on the higher one owing to the compression of the air by the body of the machine and increased density 1n that region. This thrust tending to diminish the angle a, will vary during one revolution, being maximum in a position when the line of symmetry of the two propeller blades and that of flight are in the same vertical plane and minimum when the former is at right angles to it. Nevertheless, if the horizontal speed is great, it may be considerable and suflicient to quick- 1y overcome the inertia and gyroscopic resistances all the more readily as the upper blade operates to the same effect. Moreover, this intermittent action partakes of the regenerative quality, the force increasing as the angle diminishes up to a maximum for a=45 degrees, and may also give rise to disturbing resonant vibrations in the structure. As its axis is tilted more and more, the vertical sustaining effort of the propeller correspondingly diminishes and the machine will fall with a rapidly increasing loo velocity, which may finally exceed the horizontal, when the reaction of the blades directed upward so as to increase the angle a and thereby cause the machine to soar higher. Thus periodic oscillations. accom 105 panied by ascents and descents, will be set up which may well be magnified to an extent such as to bring about a complete overturn and plunge to earth.

It is held by some experts that the helicopter, because of its smaller body resistance, would be capable of a higher speed than the aeroplane. This is an erroneous conclusion, contrary to the laws of propulsion. It must be borne in mind that in the former type, the motive power being the same, a greater mass of air must be set in motion with a velocity smaller than inthe latter, consequently it must be inferior in speed. But

even if the air were propelled in the direcof view, is found in its inability of sup orting itself in the air in case of failure 0 the motor, the projected area of the propeller blades being inadequate for reducing-the speed of the fall sufficiently to avoid disaster, and this is an almost fatalimpediment method of transporting bodies through the air according to which the machine is raised and lowered solely by the propeller and susstresses.

tained in lateral flight by planes.

My present application is based on new and useful features and combinations of apparatus which I have devised for carrying this method into practice.

Full knowledge of these improvements will. be readily gained by reference to the accompanying drawings in which Fig. 1 illustrates the machine in the starting or landing position and Fig. 2 in horizontal flight;

Fig. 3 is a plan view of the same with the upper plane partly broken away and Fig. 4 and Fig. 5 sectional views of constructive details.

The structure is composed of two planes or foils 1, 1 .rigidly joined. Their length and distance apart may be such as to form a near-square for the sake of smallness and compactness. With the same object the tail is omitted or, if used, it is retractable. In order to raise the machine vertically a very light and powerful prime mover is necessary and as particularly suited for the purpose, I employ, preferably, a turbine described in my U. S. Patent 1,061,206 of May 6, 1913, which not only fulfills these requirements but lends itself especially to operation at very high temperatures. Two such turbines, designated 2, 2 together with other parts and accessories of the power plant, are bolted to the frame, being pla ed with due regard to the centers of gravity and pressure. The usual controlling means are provided .and, in addition to these, any of the known stabilizing devices-may be embodied in the machine. At rest the planes are vertical, or nearly so, and likewise the shaft driving the propeller 3,'which is of a strength, size and pitch such as will enable it to lift the entire weight vertically and withstand safely the Power is transmitted to the shaft from the turbines through gearing which may be of the single reduction type as illustrated, the turbines rotating in the same direction aIl neutralizing the gyroscopic 'pitch of the propeller,

moment of the screw. If, instead of one,

otherwise disposed, the motors should revolve in opposite directions. The seats 4, t, 4 for the operator and passengers are suspended on tr'unnions 5, 5 on which they can turn through an angle of about 90 degrees, springs and cushions (not shown) being employed to insure and limit their motion through this angle. The ordinary devices for lateral and directional control 6, 6, 7, '7 and 8, 8 are provided with mechanical connections enabling the aviator to actuate them by hand or-foot from his seat in any position.

Stated in a few words, the operation is as follows: At the start, vsufficient power is turned on by suitable means, also within reach, and the machine rises vertically in the air to the desired height when it is gradually tilted through manipulation of the elevator devices and then proceeds more and more like an aeroplane, the sustaining force of the propeller being re laced by vertical reaction of the foils as t e angle of inclination diminishes and horizontal velocity in"- creases. In descending, the forward speed is reduced and the machine righted again,

acting as a' helicopter with the propeller supporting all the load. The turbine used is of great lightness and activity exceptionally qualified to perform such work for which the present aviation motors are un suited. It is capable of carrying an extraordinarily great overload and running at excessive speed, and during the starting,

landing and other relatively short operations, not only can the necessary power be easily developed, but this can be accomplished without incurring a serious loss of shaft will have-the desired inclination which is deemed best for rising in the manner of an aeroplane. Such a helicopter-plane, constructed and operated as described, unites the advantages of both types and seems to meet well the requirements of a small, compact, very speedy and safe craft for commercial use. 7

The abnormal power requirements are met by supplying more of the working fluid to the'motors and driving them faster, or running them at about the same speed and increasing the thrust by adjustment of the On account of simplicity and much greater range it is preferable to resort to the first method, in which erations is of comparativel. ,'s1 nall importance. Instead of a sing'e' 'large-Ipropeller, as described, a numberof small ones can'be used, when the turbine 'unitsjmaybe connected advantageously in stages and .the gearing dispensed with The biplane seems to be particularly well suited for the chief purpose contemplated, but the invention is equally well applicable to monoplanes and other types.

In order to secure thebest results I have found it indispensable .to depart, in some respects, from the usual design of my turbines and embody in them certain constructivef features and means for varying the power developed from the minimum necessary in horizontal flight to an amount exceeding by far their rated performance, as

may be required in the operations of ascent and descent, or spurts of speed, or in corn batting the fury of the elements. Furthermore, I so proportion and coordinate the 'fluid pressure generator supplying the primary energy, th e propelling and the controlling means, that for. any f; attitude or working condition of thejmachinethe requisite thrust may be, almost instantly pro-. duced and accurately adjusted.

The understanding-of these improvements will be facilitated by reference to Fig. land Fig. 5. In the; first named the turbines are intended to operate as rotary engines, expanding the gases in the rotor as well as the inlet nozzle -or port 12, the depth of which can be varied by shifting a block 13, fitting freely in a milled channel-of .the easing, through the medium of lever 14 controlled by the aviator. ,The orifice for the passage of the elastic fluid is straight or slightly convergin so that a much smaller velocity is obtaine than with an expanding nozzle, this enabling the best relation between the peripheral speed of the rotor and that of the fluid to be readily attained. The performance of such an engine at constant pressure of supply is, within wide limits, proportionate to the quantity of the working medium passed through the inlet port and it is practicable to carry, for indefinite intervals of time, an exceedingly great overload, by which I mean up to three or even four times the normal. Exceptional strength and ruggedness of the motors being imperative in view of centrifugal stresses and critical speed, their weight need not be appreciably increased as would be the case in other forms of prime movers in which, as a rule, the weight is in nearly direct proportion to the power developed. To accomfplish my purpose I further provide commensurately larger inlet and outlet openings. No serious disadvantage is thereby trolling lever 14.

incurred because windage and other losses are virtually absent and most of the rotary efl'ort is due to the peripheral discs. As shown inthe figure, block 13 is in the position correspondmg to minimum effort, the section of the inlet channel being about one-fifth of the whole which is obparts of the,

tained when the block is pulled in its exing" fluid being fully expanded, or nearly so,

through divergent exchangeable nozzles as 15, having a throat of sufficient section for the passa e of fluid required during maximum per ormance. The exhaust opening is also correspondingly enlarged, though not necessarily to the extent indicated in Figure 4. The power is varied; by means of a throttle valve 16, as used in automobiles, located in the conduit supplying the air and carbureted fuel to the fluid pressure generator andmechanically connected to the conhis apparatus is -of .a capacity adequate to the maximum demand by which I do not-mean that it is necessarily much larger than required for normal performances, but is. merely designed to supply the. working fluid or, broadly stated, energy-whenever desired, at a rate greatly exceeding the normal. In Figure 3 this apparatus is. diagrammatically indicated by 17, and may be any one of a number of well-known types, producing pressure by internal combustion ofa suitable fuel or by external firing of a steam boiler. In the latter, case, with constant pressure, the arrangement shown in Figure 4 is best to employ, while the plan illustfated in Figure 5 can be used to advantage when both pressure and quantity of fluid are-varied.

In operation for vertical ascent, the machine being in the attitude of Figure 1, the aviator will push forward lever 14 and supply suflicient .primary energy to the motors for lifting the machine with *the desired velocity. When the objective elevation is reached rudders 7 7 are manipulated to incline the machine at a. certain angle, the aviator simultaneously applying more pressure to the lever and augmenting the fluid supply to the motors, thereby increasing the propeller thrust in the vertical direction so as to prevent the machilfe from descending. He continues these operations always coor- IUD dinating the thrust developed with the changes in attitude of the machine until a certain angle of inclination is attained and the machine is supported chiefly by reaction of the planes. At this stage he begins to reduce the pressure on the lever and supply of working fluid simultaneousl decreasing the. angle of inclination thus ii hally efl'ecting, by insensible steps, horizontal flight. It should be understood that descent and alighting, as well as rising in the manner of a true aeroplane may be accom lished as usual. In such case the motors wi 1 be operated at their normal rated capacity. However, when excessive speed becomes necesthe effort of the motors may be lnstantsar ly and greatly augmented by merely manipulating block 13 or valve 16 as described.

Whenever it is desired to descend vertically', the aviator will reverse the operations as applying to substantial vertical ascent, which is to say, bring the machine gradually into starting attitude, at the same 20 time increasing the supply of fluid to the motors and the vertical component of the propeller thrust, while reducing the horizontal. Finally, he will steadily reduce the fluid supply and the vertical thrust so as to descend to the landing place at a very low,

safe velocity.

In the preceding I have described a flying machine characterized by a number of novel constructive and operative features and well suited for meeting a pressing necessity in the present state of the art. The chief improvements consist in first, adapting my turblne motor for excessive overload w1th-' out appreciable increase of its weight, sec- 0nd, providing large variable inlet ports and corresponding'exhaust openings, with the object of meeting the abnormal power requirements in the starting, landing and other. short operations, and still preserving a high efliciency in horizontal flight; third, combining with the turbine a fluid pressure generator of adequate capacity with means for control and, fourth, embodying these and other features in a suitable structure improved in various details. These may be greatly varied and I wish it to be understood that I do not limit myself to the precise arrangements illustrated and described.

I claim as my invention:

1. In an aeroplane adapted for vertical and horizontal propulsion and change from one to the other attitude, the combination of means for tilting the machine in the air, a fluid pressure generator of a capacity several times greater than normally required in horizontal flight, a motor capable of carrying overloads adequate for support in all attitudes, and means for controlling the supply of the fluidto the motor in accordance with the inclination of the machine. I p

2. In, an aeroplane adapted for vertical and horizontal propulsion and change from one to the other attitude, the combination with means for tilting the machine in the -a motor capable of carrying over-loads adequate for support in all attitudes, and means for, controlling the supply of the fluid to the motor in accordance with the inclination of the machine.

3. In an aeroplane adapted for vertical and horizontal propulsion and change from one to the other attitude, the combination of means for tilting the machine in the air, a fluid pressure generator capableof sup lying fluid at a rate several times greater t an required for horizontal flight, a prime mover consistingof a rotor of plane spaced discs with central openings and an enclosing casing with inlet and outlet orifices of a section much greater than required for normal performances respectively at the periphery and center of the same, and means for controlling the supply of the fluid to the motor in accordance with the inclination of the machine.

4. In an aeroplane adapted for vertical and horizontal propulsion and change from one to the other attitude, the combination of means for tilting the machine in the air, a thrust producing system having its principal energy producing elements designed for normal load in horizontal flight but capable of. carrying over-loads adequate for support of the aeroplane in all attitudes, and means for controlling the energy .produced in said system in accordance with the inclination of the machine.

5. In a flying machine of the kind described in combination with means for vertical and lateral control of two wheel bases at right angles to one another as set forth.

6. In a flying machine of the kind described in combination with means for vertical and lateral control of two wheel bases at right angles to one another and having one or more wheels common to both.

In. testimony whereof I hereunto aflix my signature.


I the formula and insert instead Certificate of Correction.

Patent No. 1,655,114. Granted January 3, 1928. to I NIKOLA TESLA.

it is hereby certified that error appears in the printed specification of the above.- munbered patent requiring correction as follows: Page 1, after line 57, strike out E=2 %mv and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oifice.

S1gned and sealed this 20th day of March, A. D; 1928.


Actmg (l'omm/issioner of Patents.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2479125 *Oct 6, 1943Aug 16, 1949Lloyd H LeonardVariable attitude helicopter airplane
US2564370 *Mar 19, 1945Aug 14, 1951Myers George FrancisAircraft
US2931596 *Apr 27, 1954Apr 5, 1960Pickering James THelicopter plane
US2952422 *Aug 3, 1955Sep 13, 1960Fletch Aire Company IncAnnular wing aircraft
US5765783 *Feb 26, 1996Jun 16, 1998The Boeing CompanyVertically launchable and recoverable winged aircraft
US6086015 *May 7, 1999Jul 11, 2000Aerovironment, Inc.Aerial transport method and apparatus
US8505846 *May 9, 2011Aug 13, 2013Gordon Sanders II StanleyVertical takeoff and landing aircraft
WO2000068077A1 *Mar 16, 2000Nov 16, 2000Aerovironment IncAerial transport method and apparatus
U.S. Classification244/7.00B, 244/100.00R
International ClassificationB64C27/04, B64C29/00
Cooperative ClassificationB64C2700/6281, B64C27/04, B64C29/0025
European ClassificationB64C27/04, B64C29/00B2B