Jan. 3, 1928.
1,655,113
N. TESLA METHOD OF AERIAL TRANSPORTATION
Filed Sept. 9, 1921
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1,65'5,113
Patented Jan. 3, 1928.
UNITEDSTAT_ES PATENT OFFICE. NIXOLA TESLA, 'OF NEW YORE:, N. Y.
METHOD OF AERIAL TRA}lSPORTATION. Application filed September 9, 1921, Serial N.o~ 499,519, and in Great :Britain April -1, 1921.
The utility of the aeroplane asa means of no success has as yet been 'achieved. Evitransport is materially lessened and its com~ dently, this is due to the inadequacy of the' , mercial introduction greatly hampered ow-, engines employed and, perhaps, also to cering" to the inherent inability of the mecha- tain heretofore unsuspected characteristics 5 nism to readily rise and alight, which is an of the device and, fallacies in the accepted 60 unavoidable consequence of the fact that the theory of its operation, an elucidation of, required lifting force c.:an only be produced, which is deemed necessary for the clear, by a more or less rapId translatory move- ,llllderstanding of the subject.' , ment of the planes or foils. In aetnal exThe prospects of a flying machine of this 10 perience the minimum speed for ascension kind appear at first attractive, primarily be- 65 and landing is a considerable fraction of that cause it makes possible the carrying of great"in full fligh~, and the principles of desi~n loads with a .relatively sm~ll expenditure of do. not admIt ?f avery .great advance m. energy., ThIs follows dIrectly from the t~IS respect wIthout sa~l'lfice of some de- fundamental laws of fluid propulsion, laid 15 snable feature. lfor t~llS r~ason p.lanes of down by W .. 'T. M. Ra~ine ~ore than fifty 70 very large area, hIgh hft wlllg-sectlOns, cle- years ago, m conformIty wIth which the fiectors of the slip-stream of the ,propeller, thrust is equal to the integral sum of the , 01' analogous means, whicn might be helpflll products of the masses and velocities of the in these ope~ati?ns, do not a:ffor~ the 1'em~dy projected air particles; symbolically' ex-20 ~ough~ .. ThI.s md1spensable hIgh ~eloClty, pressed, 75 Impel'lIlmghfe and property, makes It neces' T=~(mv). sary to equip the machine with special appliances and provide suitable facilities at On the other hand, the kinetic energy of the the terminals of the route, all of which en~ air set in motion is 80 25 tail numerous c1rawbacks and difficulties of , a serious nature. So imperative has it beE=~(~mv2)- , come to devise _some, plan of doing away with these limitations of the aeroplane that From these equations it is evident that a, the consensus of expert opinion charac- great thrust can be obtained with a compara30 tcrizes the problem as one of the most press-tively small amount of power simply by in- 85 , ing and important and its practical solution creasing the aggregate mass of the particles is eagerly awaited by those engaged in the and reducing their velocities. Taking a de'Velopment of the art, as well as the gen- special case for illustration, if the thrust " ' under given conditions be ten pounds per eral,public. :l;; "Many attempts have been made to this hOJJse-power, then a hundredfold increase of 90 end, mostly based on the, use of independ- the mass of air, accompanied. by a reduction ent devicesJor the express purpose of facili- of its effective velocity to one-tenth, would tating and insuring the start -and finish of produce a force of one hundred pounds per tlieaerial journey, but the oI?erativeness of ,horsepower.. But tpe se~mi~~ly gr~at g~in 40 t~e arrangements proposed 1.S hot conclu- t~us secured IS of httle sIgmfic.ance III aVIa-9l5 sively demonstrated and, beSIdes, they are tum, for the reason that a hIgh speed of objectionable, constructively or otherwise, to' travel. is generally an essential requirement silCh an extent that builders of commercial which can not be fulfilled. except by apparatus have so fai- not considered them propelling the air at high velocity, and 45 of sufficient value to der '{rt ftom present that obviously implies a relatively small 100 practice. ~.' ; _ thrust. , ' More recently, professional attention has ,Another quality commonly attributed tc been turned to the helicopter which is devoid the helicopter is great stability, this being, ,of planes as distinct organs of support aml, apparehtly,a logical inference judging from fiO presnmably, enableshori10 axial thrust in the ,lower stratum should ;zontal speed is great it ~ay be considerable lHi juSt S9Pport the weight. .Hence - --and sufficient to quickly overcome the inertia'. _, _' andgyriiscopic resistances all the more read, ht~h,~II-1qg ily _as the upper blade, wlrich is situated jn a' , " -. _ ! . stn It " _ . -region where the ~nditionS are more nearly , 6$ Taking, iIi it Special case.the anglea=60°, TI(~rmal.' .ope~at«)S ~o the same effect. More~, 120 then " . , : ", ' ,. - - , ' , over,thlS distUrbmg effect partakes of t~e, ~ - .' - , - _ " regenerative, quality, the force increasing ,as_ --.!-_--1---=·t·t547 the angle dinlinishes uP.to a maximum for SIn II 0·866 -«==45°. As the axis mtilted' more and 00 and more, the vertical sustaining effort of the pro- 125 , .' . -~ peller will correspondingly diminish and the Ai-12=26700xl~ 1·i-547=3840feet'- 'machine will fall with a rapidly increasing In reillilj the drop Will be much greater 'velocitYi ,finally exceeding t4e' horizontal _ for the madwie, upOn reaching the- lower 'when the reaction of, the blades will' be 130 .. layer With a high velocity relative ~ the ;_directed upward so as to increase the angle _l
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1,6IUS,113 a and thereby cause 'the machine to' so~r . From the preceru.ngfa~ts, which are higher. Thus periodic oscillations,accom- ignored in the technical publi~ations on the panied by ascents and descents, will be set up subject, it will be clear that the successful .which may Fell be magnified t6 an extent solution of the problem is ina different IS such as to bring about a complete overturn direction. .. 70 and phmge to earth. . My invention meets the present necessity It is held by some· experts that the heli- in a simple manner without radical 'deparcoptet, because of its smaller body -resist- ture in construction: and sacrifice of vahiance, would be capa.ble of a higher speed able features,' incide,ntally securing advan10 thane t.he aerophane. But this is an' el'- tages which shoula prove v.ery beneficial 75 roneous conclusion, contrary to the laws of in the further development· of' the art. propulsion. It must be borne in mind that Broadly expressea, it consists in a novel in the former type, the motive power being method of transporting bodies through the the same" a greater mass of airmus{ he set air according to which the machine is rfl,ised lIS in motion with a velocity smaller than in and lowered solely by the propeller and 80 .the latter, consequently it must be ii:tferior sustained iIi lateral flight by planes. To in speed. But even if the air were pro- accomplish this a light and powerful primepelled in the direction of the axis of the mover is nee~ssary and as particularlysuitClI screw with· the 'same speed V in both of for the purpose . I employ, preferably,. a 29 them, while the aeroplane can approximate turbine of the kinq. described in myu. S. 85 . the same, the' helicopter could never ex- Patent No. 1,061,206; of May 6,1913, which ceed the horizontalc component V cos a. not only fulfills these requirements, but is To be explicit, imagine that the air Ctll'- especially adapted to operation at high temrent flowing with the v(llocity V along the perature.. ' r also make arrangements 26 propeller axis inclined to form an angle a whereby the flying machine may be, auto-tO with the horizontal, be .replaced by two iD.aticallyor .:it will of .the operat,or, causer!. streams one vertical and the other hori- to ··function either as a. helicopter or an zontal of velocities respectively equal to V aeroplane. " . . sin a and V cos a, it will be evident that a. Full knqwledge of.·these improvements 30 helicopter in its forward -flight could only, will be readily gained by. reference to the 95 approximate and never equal the speed V acco!llpanying drawings in which Fig. 1 ilcos a of the horizontal air current no matter lustrates the machine in the starting or landhow much the resistance be reduced for; ing position and Fig. 2, in horizontal flight. according to a fundamental law of propul- . Fig. 3 is a plan view of the'-same with the 3,5 sion, the thrust would be nil at that velo- upper plane partly hoken away. 100 city. The highest efficiency should be ob- ' The structure is composed of two planes or taIned with the niachineproceeding at the foils 1, 1 rigidly jollied. Their length and rate 1h V cos ex but the' most economical distance apart may be such as to form a nearutilization of power 'would be effected when .square for t1le sake of slliJ.l1ness and com40 d=45° in which case the speeds of both the pactness. With the same ,}bject the tail is. 103 horizontal and, vertical streams wiII 00 omitted or, if used, it is retra ctable. The mo0.7 V. From this it may.be inferred that, tors 2, 2·hi. this case turbines. of. t.he kind detheoretically, the. best performance mi,(tht scribed iIi" my patent before referred to, and be secured in propelling the helicopter :to1'- other' parts of the motive apparatus are 45 ward with a speed mo~e or less approxi-. placed with due regard to the centers of grav- llO mating 0.35 V but the results' attained in· ity and pressure and the usual controlling practice will be necessarily muchinferio..... means are provided. In addition to these beeause~without special provisions . such any of the known stabilizing devices may be as are herein set forth the device, as point.edembodied in the machine. At rest the planes 50 out above, would plunge down and shoot are vertical, or nearly so, and .likewise the 115 up in succession, at the same time executing shaft· driving the propeller 3, which is COll.. smaller oscillations,. which motions willstructOObfa strength, size and pitch that retard its flight andoonsume a considerable willenabIe it to raise the '""entire weight with portion of the motive energy all the more the motors running at an even greater rate 55 so as' the losses incident to the controlling than when propelling the· machine hori _ 120· means will be correspondingly increased. . zontally. Po~r is transmi~tedto the shaft· . Another very serious defect this kincl from the turbines through suitable gears. of flying machine, from the practical point The seats 4, 4, 4 for tIre' operator' of view, is found in its inability of support- and passengers aresuspendecl on trunnions 125 ~o ing itself in the air in,case of failure of the 5, 5 on which they can tarn throug-h motor, the' projected area of the propeller an angle of about 90°, springs and {'lIshblades being inadequate for reducing the ions (not shown) being employed to inspeed of the fall sufficiently to avoid disas~ sure and limit their motion through this _ t;er, and this, is an almost fatal impediment angle. The usual devices for lateral and dila.-to its commercial use. rectional control, 6, 6 1, 7 and 8,. 8 are pro- 130
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1,6515,113
vided with mechanical connectiQns ~nabling able in operation, but should, the power give the :operator to actuate the devices by hand out accidentally, la~ding can stiP. be. easily or foo.t froI~.fhis seat ~any position. -At the effected by volphtnmg. For thIS purpose, " start, suffiCIent'power bemg turned on by. in addition to wheels 9, 9 and 10, 10 wheels :; suitable means, also within'·his reach, the. 11; 11 are employed, the latter being mount- 70 machine rises. vertically in the air to the ed on the forward end under the lower plane desired height when it is gradually tilted and"so that when the machine rests on level, by manipulating the elevator devices. and ground the. propeller shaft will have the . proceeds like ,an aeroplane, the load being desired inclination which is de.emed best 10 transferred from the propeller. to the foils for rising in the manner, of an' aeroplane. 15 as, the' 'angle of inclination diminishes .and Such an aeroplane construCtedaiid operated th~speed in horizontal direction increases. as described, unites the advantages of both · From the foregoing it will be. understood types ana seems to meet best the requirethat, ,simultaneously with the 'tilting of the mentEl of a. small, cQmpact, exceedingly . 15 machine, . the'. operator will \ increas.e· the speedy and yet very safe machine for com- 80 'thrust of the propeller in order to compense' mercial use. Especial,Iy 'good practical refor the reduction of sustaining force which sultsare obtainable by the use:of my turbine · follows inevitably' from the diminution, of' which can be depended upon to develop the angle a and before the Ileaetion of the necessary energy for lifting, even if it should 20 planes qtn come into full effect. He will be considerably greater tb.a~ that consumed 85 thus prevent' a downward pllin.ge ,and the ··in fEght :under normalconaitions., Tills eJ;l.d~. production of dangerous oscillations which can be conveiiientlyattained by.temporarily . have been dwelt upon above, anC!. by suitable' supplying more of the working fluid to the " manipulation of the apparatus and graduaIrotor and driving it -faster, or running it at ' 25 cuttjpg. down' of the power developed by. about the same speed and iIicreasing the e£_ gO · the prim~ moyer, as forward velocity is gained fort by adjustment of the pitch of the proand the planes. take up, the load,. he may peller, or _other means .known in the art. , cause the machine to advance horIZontally The latter should be deSIgned to"Workmost along a sensibly straight line, a< condition economically during' the flight, as its effi. '. 30 essential, to the attainment of the .best prac- ' ciency,in the starting and landing ,operations 95 tical resUlts.,fudescending, the forward 'is of relatively~small importance. Instead speed is reduced and the machine, righted of a single large screw as described a number ,again, acting asa helicopter with the pro- of smaller oneS may be used, il! which case , _ peller supPorting 'all the load. '. Obviously, gearing~can be dispensed with. The biplane ~" as the device'is ,slow'~d down and righted seemsjo behest suited for the chief purpose IOn , cau§ing the planes to lose part or all of their contemplated but the inventi~m is:applicable "sustaining e:ll0ri.'3, ,;the., operator ~1\P:plY:.to mon0J>lanes~d ot}!-er types.' . more . power to the' propell~r' mcreaSIng To sum up,' tHe helicopter type of. flymg r . . · thereby the thrust to the required magnitude, machine, especially with large inclination : ~o . and in' allsu~h p~rations of starting. and . angl~ of the proPeller axis to the horizontal,. 105 lOadfug as well as tilting"for reguIa.tingihe at which it is generany e~ted to operate, ~. height, nieetingtheairconditions 9dol'other is quite ~table for speedy aerial trans· purposes, it Will.':~ his' object to· modifywrt; it is incapable of proceeding horizoil~ , . the 'propeller' thrust in about the,same mesS.:. , tally along a straight line unde~ tlie prevail- '. 46·iIre as the varying, reaction of the planes ,ing aiI-conditions; i~ is~bject to darigeroUl) 110 ,I~ay: de~and in: ol'!ler iliat the lifting force plunges and oscillations ~d, what is most ,;-> be 'sensibly wnstm.lt. EVidently· also, when--· im,portant from the co~ercialand practi- , e~r necessary or· desirable~ - pQwer far in cal, point of, ~ew, it is almost
