US2821838A - Jet propulsion device for operation through fluid medium and method of operating it - Google Patents

Description

Feb. 4, 1958 F. zwlcKY 2,821,838

JET PROPULSION DEVICE FOR OPERATION THROUGH FLUID MEDIUM AND METHOD 0F OPERATING IT med Apnlzs, 194s 4 sheets-sheet 1 v, m :L W m WZ M m A H M W F. zwlcKY 2,821,838 EVICE FOR OPERATION THROUGH AND METHOD OF OPERATING IT 4 Sheets-Sheet 2 A INVENTOR. FR/TZ ZW//(Y TTR/VEYS JET PROPULSION FLUID MEDIUM -.llllllllllllllll .DEDEN-HUUB..

Feb. 4, 1958 Filed April 28, 1945 E? o mm o Feb. 4, 1958 F. zwlcKY DEVICE FOR OPERATION THROUGH ANDv METHOD OF OPERATING IT JET PROPULSION FLUID MEDIUM Filed April 28, 1945 4 Sheets-,Sheet 3 rTY iff" l "l A 7' 1054/5 YJ' Feb. 4, ,1958 2,821,838

F. ZWICKY JET PROPULSION DEVICE FOR OPERATION THROUGH FLUID MEDIUM AND METHODl OF OPERATING IT Filed April 28, 1945 4 Sheets-Sheet 4 INVENTOR. FQ/ rz Z w/cL/.y

United States Patent O JET PROPULsIoN DEVICE FOR OPERATION THROUGH FLUID MEDIUM AND METHOD OE OPERATING I T Fritz Zwicky, Pasadena, Calif., assignor, by mesne asslgnments, to Aerojet-General Corporation, Cincinnati, h10, a corporation of Ohio Application April 28, 1945, Serial No. 590,833 18 Claims. .(Cl. 60-35.6)

This invention relates to propulsion devices of the type adapted to propel crafts, planes or the like through a uid medium, and more particularly to jet propulsion means and methods.

The principal object of this invention is to improve the operating performance and eticiency of such devices.

In my copending application, Serial No. 558,219, filed October l1, 1944, Ihave disclosed and claimed a jet propelled device, adapted to be driven through an air medium in the form of an elongated duct or channel having an entrance at the front through which the fluid from the medium may enter and an exhaust nozzle at the rear through which it may exit. In the operation of that device, fuel is burned within the duct, and the heat of combustion thereby generated is transmitted to the mass of air entering the duct. The air and combustion products are forced through the exhaust nozzle at a high velocity and the reaction thereby created produces the propulsive force.

In the apparatus described in my said copending appli-` cation the gases and heat are formed by the combustion of a fuel-air mixture which is red in the combustion chamber at either atmospheric pressure or the pressure built up in the system above atmospheric, by its structuralv manner converts a greater proportion of the available thermal energy from the fuel into useful work than would otherwise be obtained from exploding the same amount of fuel without compression.

I provide the desired precompression of the regular or main fuel charge by exploding somewhere in the region of the main fuel mixture a preliminary charge which precedes the main explosion of the regular fuel mixture thereby placing it under pressure. The effect is advantageously procured by exploding such a preliminary charge in a chamber within which the regular charge is to be burned. The preliminary charge can be one which burns at a lower temperature or pressure, or both, than the regular charge; and the increased temperature or pressure, or both, caused by the explosion of the preliminary charge may be employed to ignite the regular charge. A preferred feature of my invention is the tiring of a preliminary explosive charge in such a manner that the main explosive charge is subjected to pressure from both ends of the main tiring chamber.A The compressive preliminary explosion'may also be created, for example, by the use of substances which spontaneously' explode whenv contacted with air, or, which may be catalytically exploded in air. tired by some suitable means such as av spark plug or hot spot if necessary. Thistype of an explosionv in which each explosion 4of amain charge is preceded by apreliminary explosion is hereafter referred to asa .cascading explosion.

The compressed charge may also bev vided with-'a curvature as shownI in Figs. 6--and"7 The v explosive mixture which is more easily ignited or oxidized than the main fuel charge.

The foregoing and other features of my invention will be better understood by the detailed description and the accompanying drawings in which:

Fig. 1 is a longitudinal cross section view showing the device in which this invention is employed;

Fig. 2 is a cross section view taken on the line 2-2 of Fig. 1 showing the fuel injectors and firing plugs used in an apparatus employing this invention;

Fig. 3 is an enlarged cross section view of the ring chamber and central tiring tube shown in Fig. 1;

Fig. 4 is a'broken detail view of the front elevation of the valve assembly in the valve housing;

Fig. 5 is a perspective view of one of the blades;

Fig. 6 is a perspective view partly in cross section showing the valve blades interleaved between two valve members;

Fig. 7 is a perspective view looking up from beneath one of the channel members;

Fig. 8 is a perspective view showing one of the channel blades for use in twochannels simultaneously;

Fig. 9 is a broken view in cross section showing an alternative cascading tiring chamber equipped to handle substances spontaneously decomposable in air;

Fig. 10 is a broken view in cross section showing van` alternative form of cascading tiring chamber adapted to handle catalytically decomposed substances;

Fig. ll is a broken view in cross section showing an alternative form of cascading firing chamber;

Fig. 12 is a cross section view taken on line 12-12 of Fig. 11, showing the nozzle plate;

Fig. 12a shows a detail taken in cross-section at line' Fig. 13 is a broken view partly in cross section showing another embodiment of a cascading firing chamber; and

Fig. 14 is a graph showing the effect of cascadingcompared to the single explosion operation.

The device illustrated in Figs. 1 to 3 comprises a shell 1 forming a duct or passageway through which air is adapted to flow, the air entering at the mouth 7 and leaving at the exhaust nozzle 12. The shell 1 comprises a leading section 2 which is preferably circular for about one-third of its length from the entrance 7 and then undergoes a transition to correspond to the rectangular outline ofV center section`3. A square spacer frame 17 iits be` Sections 2, 3 and 4 are bolted together by a series of bolts i 5 and 6. Tail section 4 is provided'with `a series of radiation ns 8 to insure cooling of the unit.

A valve assembly 36, for controlling the iiow` of the tluid through the duct, is located near the forward end of the channel and divides the duct into a forward portion and a rear portion. The construction of blade valve assembly 36 is described in detail with reference to Figs. 4, 5, 'and 7. This valve is built up of an assembly of alternating flexible blades 72 and rigid channel members 71. Each rigid channel member 71 comprises agree tangular-shaped plate 74 the upper face of which is pro- Patented Fels.l 4, 1958 lower surfaceofkplate 74 is provided with a number of I channelsv77 formed by channel members 80 which are integral with the plate and run parallel with each other as shown. These channel partitions 80 taper in depth being deeper at the leading edge 79 and tapering at the rear edge 83 to coincide with thethickness of the rear edge' of the blade. The uppersurface of members 71 is provided with a series of parallel ridges `84 corresponding with a number of channels and are positioned so as to be centered with reference to each' respective channel.

In 'assembling the valve assembly 36 several liexible blades" 72 are alternately"interleaved between several channel members 71 and arefrmly held'near their leading edge' 73 between the channel strips 80 of one channel member and the front flat face- 82 of the next."`These valves and rigid channel members are vfurtherl held together bya series of bolts 85 which pass through the holes 75 and 75a drilled in the blades and channel members. When'a series of ythese valves and channel members are installed to form the'cornple'ted valve assembly 36 they completely'occupy the'rectangular space inthe region preceding thering chamber 140. Forpurpose of assembly thesevalves slide'int a machined'rectangular area 10 cut 'in the front endof firing' chamber insert section 9 and are held in placeat the lrearv by shoulder 16 and in front by spacer 17. The arrangement of"thes`e` valves in the valve receiver'is shownin Figsi l, 4, 9, 10, 11 and 13. Y

Fig. 6 shows a perspective view illustrating one of the flexible blades 72 sandwiched between two adjacent chan' nel members 71.`

Fig. `7 is `a view from the underneath 'side of 'channel' member 71k and` shows a portion of the blade valve in! cludngblade'72l The curvature of the face 74 offeach channel memberis such that the rear edge 83' of'each 3 channel comes down to meet the rear edge 78 of the corresponding adjacentvalve blades 72 as more clearly shown in Fig. '6.- The arrangement is such that the lower edge'81 of all the l1channel partitions 80 of each channel member is hat against the at surface ofblade 72 as illustrated in Fig. 7.` By this assembly arrangement the rear edges 78 of the flexible blades 72 are enabledl to vibrate so as to alternately contact and move away from the rear edges of 83 of members 71. This creates the valve action as the valveis closed when blades 72 'are tight against the channel members of valve body 71.

There is located within shell "1 a combustion chamber 40 which is heldiin place by'vane's 31 which are attached to insert section 9 and tofiring'char'nbert) by any suitable means such as welding;y Insert sfe'ction 9 is rectangularly shaped and slides into'therecessed section 39 cut in the center section 3. Thei`nse rt` 9v isfelarnp'ed into position v against sho'ulder118 when' section 2 dand`spacer 17 are bolted to section 3. The ring'chamber' 40l is cylindrical in shape and is provided with fuel injectorsV 43. yInjector i 43 is preferably a spray nozzle'typfe of injector' capable of introducing the fuel as a fine sprgayor mist.

A cylindrical tube 20`fof rsmaller diameter than-,the

main ring chamber 40' is heldgin position withinl firing chamber 40by a series of supportin g`l eg s 2 1 fastened to the small tube and the firing chamber 40 by any suitable means such as welding. The leading end 22 of vthe ytube 20 is slightly flared makingthe tube slightly 'larger Ain diameter at this point than throughoutthe rest of xits length. Tube 20 is equipped with a fuel injector 2 3 located near the forward or flared end 22 ofthe tube. A

sparking device, 24 is prsvidedin the. tube, Tube 20. is shoterin length than the main tiring Chamber 40.v This.` is done to provide aregionuat either end of small v tube where the effects of theexplosion within the y u lbe'can act upon the main explosive charge in ring chamber 40.

.Fd ndr..prssu,re. for.. @sample gasoline, is Yintro-. duced. into the` main iringhmber .40. thr0uehconduits 25 whic`h feed injectors 43. A more reactive orexplosive 4 material is lfired in the smaller tube. Itis introduced into that region through conduits 26 and injector 23.

The way in which the apparatus operates is as follows: Tube 20 is charged with a more easily explodable fuel than ring chamber 40. For example, if the fuel supplied to chamebr 40 is gasoline, the fuel supplied to tube 20 may beoxygenand hydrogen, propane, butane, pentanef or otherlight hydrocarbons. 'The more stable 4fuel is supplied to firing chamber 40 simultaneously with the fuel supplied to the smaller tiring tube 20. The charge lin tube 20 is ldetonated and the force of the explosion creates regions of pressure at' both ends of thering chamber 40. This operation places the charge in 40 under pressure. Whenthis charge has been compresed a sucient degree and the temperature has been raised to the proper point the charge lin chamber 40 will automatically explode. The force of the explosion will cause valve 36 to shutl olf thej flow of' air enteringthrough mouth' 7 and will permit products of combustion to escape out ofboth ends of firing chamber 40. Part of the' products of combustion pass directly toward the rear andthe remainderissue from the front of'firing chamber 40 and then escape toward the rear throughthe outer duct 38.` As soon as the pressure generated by the explosion diminishes to the -point where it is exceeded by the pressure acting on the forward side ofthe' valve 36 the valve will again open and permit free flow of 'air throughout the entire duct.' As soon as the valve opens to permit scavenging of the products of the prior explosion of a new charge 'of fuel is admitted into the combustion chamber which when mixed with the air forms a new explosive charge. Likewise, a new charge of the more easily explodable mixture is introduced into the smaller ring chamber within the large ring chamber 40. The'smaller charge Ais exploded and the entire process of combustion repeated. The operation consists of a series of these double explosions rapidly following each other in such a manner that a substantiallycontinuous thrust is produced.

Considering for a moment one 'of these double 'or cascaded explosions, the effect of the preliminary explosion' in the tube 20 upon the power to be derived from the ultimate explosion in chamber 40 is clearly illustrated inthe graph shown in Fig. 14 in'which the pressure devel- -oped by the Vcascadingof the explosions is shown com'- pared to the effect of a single explosion. The graph Shows a/plot of time'ag'ainst pressure. The pressure' reached at the end of the initial detonatio'n is shown by P and the resulting pressure developed after the explosion of the second, or more difficultly ignitable material in tube 40 is indicated at point'Pc. The graph taken during the operation of the deviceshows' clearly the gain in pressure and Work which 'are made'available when my invention is employed.

A modication yof the arrangement of Fig. l which may be used for producing a similarv result is illustrated in Fig. 9. The apparatus 'partly shown in Fig. 9 is similar to that in Fig." l except' that the firing chamber insert 9 of Fig.'1 is replaced by a firing chamber section insert 19.

This section possessessimilar features to the one shown in Figjl with the exception that the valve adjoins the tiring chamber.

'.In apparatuses of the type employing the firing chamberl adjoining thevalve `as shown in Figs. 9, 10,'11, and l3-'iall`valve blades which come in contact with the circular area of firing'chamber are cut as shown in Fig. 8 by suitableslots 76to permit various portions of the valve blade to act'in-depende'ntly. The distance between these slots will'vary according to the portion of the firing i geniesse:`

the firing chamber to operate'independentlyfofsthat portion-f of the same blade which opens into the duct'38. Proregion of the chamber has been filled to the desired extent with the combustible mixture by injectors 43. When the substance entering through injectors 61 comes in contact with sucient air it explodes and this explosion compresses the charge in the forward portion of the chamber. The forward charge may then either be ignited by spark plug 41 or may be exploded automatically when the pressure and temperature are elevated to the proper degree. Substances which are suitable for spontaneous decomposition in air are aluminum borohydrides, boron hydrides such as B2H5, trimethylborine, aluminum trimethyl and zinc diethyl.

Another alternative which may be substituted for the firing chamber assembly of Fig. 1 is shown in Fig. 10 and a substance which is catalytically decomposable in air is employed in place of a substance which is automatically decomposable in air. A catalyst bed 62 is provided at some convenient position such as the nose portion of a deector 46 to support the catalytic bed 62. This catalytic bed performs the function of initiating the decomposition of the substance. Propellant substances of this class are, for example, nitromethane and nitroparatiin. The catalyst may be platinum sheet or manganese dioxide mixed with other suitable metal oxides to increase its strength. Conduits 60 are installed in the rear of the firing chamber and through nozzles 60a spray catalytically decomposable substances against the bed. This assembly is otherwise similar to the first alternative shown in Fig. 9. Spark plugs 41 may be provided in the forward portion of the firing chamber of Fig. to make certain that the decomposition or ignition of the heavier fuel-air mixture Ytakes place.

Another embodiment of my invention is shown in Fig. 11. This apparatus may be substituted for tiring chamber insert 9 used in Fig. 1. This firing chamber insert 19b comprises forward firing chamber 100 adjacent to valve bank 36 and a rear firing chamber 101. Chambers 100 and 101 are held in a central position by vanes 31. Firing chambers 100 and 101 are separated bya nozzle plate 102 shown in Figs. 1l and 12. Nozzle plate 102 is secured in the proper position to the walls of the firing chamber by any suitablemeans such as welding. Nozzle plate 102 is equipped with a plurality of small nozzles 106, preferably ofthe De Laval type. One of the nozzles is shown in cross-section in Fig. 12a. These nozzles 106 are arranged in such a manner that the axis of each nozzle is parallel to the longitudinal axis of the firing chamber and perpendicular to the cross sectional area of the plate. The nozzles are preferably uniformly distributed over the plate area so as to insure equal conduction between the firing chambers 100 and 101. The opening 107 at the forward end of nozzle 106 is larger in diameter than the discharge end 108. A fuel mixture such as hydrogen and oxygen, or pentane and air, which is more readily ignited than the main fuel used in the propulsion of the apparatus, is introduced into chamber 101`through injector nozzle 104. At the same time the main fuel-air charge is introduced into firing chamber 100 through injector 103. The mixture in chamber 101 is flashed by any suitable means such as a spark plug 105. The pressure and the heat generated by the explosion in chamber 101 acts upon the less readily ignitable fuel-air mixture in chamber 100 and places the mixture under pressure, and the' heat generated by the explosion in chamber 101 also is partly transmitted into the chamber 100.' When this pressure and temperature are suflciently high to ignite the mixture in lchamber 100, the -fuel-air 6 products ofcoxnbustion/ndnthe heat toward the rear through the nozzle plate 102 and into the incoming mass of airwhich is entering through duct 38 which surrounds firing chamber A and 101. With some types ofl fuels it mayl be necessary to use suitable ignition means such` as a spark` plug 109 or a hot spot located in the forward end of the tiring chamber100. The air passing over the firing chamber through thefduct 38 is warmed by 'the radiation ofheat given olf by the firing chamber after each explosion has occurred. ln this manner the air whichis mixed with the products of combustion has already. gained additional energy and velocity.

Another formof apparatus which is suitable to carry outlm'y inventionris illustrated in Fig. 13. In this apparatus the `firing chamber insert 19e replaces insert 9A holding the firing chamber of Fig. `1`. This insert section comprises acentral firing chamber held in position by vanes 117. Firing chamber 110 is provided with three sets of injectors 111, 112, and 113 which have firing plugs 114, v11S4 and 116 located rearwardly of each set of injectors. t

Fuels which'are readily ignitible by spark plugs or hot spots are introduced into the firing chamber by nozzles 111 and 113 and at the same time a fuel which requires more pressure and heat to cause its spontaneous decomposition is introduced through nozzle 112. Spark plugs 114` and 116 lire the charge which has been introduced through injector 111 and 113; The pressure waves created by the explosion of the easily ignitable substance at either -end of the tiring chamber travel toward the center in such a way as to compress and heat the less easily ignitable fuel which is injected between them. Again this fuel under pressure may be set off by any suitable means such as spark plug 115' or may be ignited when the temperature and pressure developed by the simultaneous" explosion at each end of the firing chamber have raised the pressure and temperature of the main charge to a suicient degree to cause its spontaneous ignition. A similar procedure may be used with a single tuel. This may `be injected through forward injector 111 and allowed to travel the length of the firing chamber. When the chamber is filled the charge is flashed at both ends by plugs 114 and 116 thereby compressing the central portion of the fuel before it is fired.

I claim:

1. A reaction propelled device adapted for propulsion through air comprising a duct having an inlet opening and an exhaust nozzle, a valve separating the duct into a forward and rear portion, a combustion chamber located within the rear portion, an auxiliary combustion chamber of shorter length than the first-mentioned combustion chamber located within the first-mentioned combustion chamber, means for supplying a combustible charge to a forward portion and a rear portion, said valve being operable to admit air from the forward portion to the rear portion when the pressure in the forward portion exceeds that in the rear portion and to prevent any flow of gas from the rear portion to the forward portion when the pressure is greater in the rear portion than in the forward portion, a main combustion chamber located within said rear portion, an auxiliary combustion chambervo shorter length than the main combustion chamber 1ocated within the main combustion chamber, means for supplying a combustible charge to the main combustion chamber and'means for supplying an explosive` charge `in i the auxiliarycombustionfchambenand means for-initiatingthe explosion of the explosive charge -in the auxiliary combustionchamber. s n

Areacti'on propelled device adapted forfpropulsio'n throughair comprising a duct having an inlet openingand an exhaust nozzle, a valve separating theductl into a forwardV portion` and a rear portion, said valve being operable toadmitmainfrom the forward portion. to the rear portion, whenI the pressure invthe forward 'portion exceedspthat in therear portion and to prevent anyhow of gas Yfromtherearportion tothe forward portion when theupressurehis greater in the rear portion 'than'in the forward portion,l a combustion chamber inthe rear. portion, said combustionchamber being contiguous with said valve and of smallerj cross-section area than .thejinside' cross-,section area of the `part of the duct withinwhich it is located,r meansY for'introducing la. combustible charge ina region of said combustionuchamber, means for inmitair Vfrom the forward,portion to` the'rear portionl when the pressure in the forward portion exceeds that in therear portion and to prevent any` flow` of gas from the rear `portion Ito the forward portion when the pressureis greaterin the rear portion ,than in Athe forward portion, a

combustion chamber in the 'rear portion, said combustion chamberhaving an opening which is Acontiguous with said valve end another lopening'away fromv said valve, and

being equipped with'means f or introducingja maincom" busptible charge in the centralregion' of the chamberand means at either side of said combustion region for in` trolucing an, explosive charge that maybe more easily ignited than the main'combustible charge, andmeans for initiating saidgeharges at .either side ofsaid central region. Y5. A reaction propelled device adapted.for propulsion through air comprising a duct havingan inlet opening and anlexhaust nozzle, a valve separating the duct into a for-` ward and rear portion, said valve being operable'to admit air from the forward portion to the rear portion when the pressnrein theforward portion exceeds Lthat in thev rear portion and to; prevent Janyhow of gas from the 'rearlportion to the Aforward portion when the pressure is greater inthe rear portion than in the forward portion, a .combustionochamber in therear portion, said combustion chamberhavingan opening which is contignous with said ValYe. .and anothet-.openingaway from the valve, means insaidcombustion harnber for introducing a combus tihle charge in a region of the saidcombustionchamber near the valve and Imeanswforl introducing a self-explosive substance capable of spontaneous ignition in air at `a region f thegmhstipn chamber awavfrom the valve- 6. A reaction propelled device adapted for propulsion through air comprising a ducthavingan ,inlet opening and anlexh'austy nozzle, av valve separating thejduct into a fory ward and rear portion, a combustion' ichamber in the rear Y portion, said combustionl char'nber""havingman opening which'iscontiguous'iwith saidvalve'and anHo'pfening v away y from the valve, means for introducingfaniexplosive charge in 'a forward region `of the combustion chambenfmeans for introducinga substance'which isA eatalytically decomposed in air in a rear region of 'the chamber, catalytic means vfor initiating'the decomposition of the 'air explodable substances, saidrneans located inthe region where the catalytic explodable -substance is introduced.

7. A reaction propelled device adapted forpropu'lsion through; air comprising a duct having an inlet opening and" when the pressure in the forward' portion 'exceeds that ini' the rear portion and torprevent anyflow of gas from the rear portion to, the forward portion when vthe pressureis greater in the rear portion than inthe forward portion,' a main tubular combustion4 chamber open 'at both ends' and 'located downstream from said valve and'of smaller` diameter than the duct thereby creating a ch'a'nnel'withiriA the duct and surrounding themain combustion chamber, a second tubularcombustion chamber open at both ends and of shorterv length than the main tubular'chamber'and' located within the main combustion chamber, 'means'for supplying a combustible charge to the main tubular combustionchamber, means f'or supplying anexplosive chargel into the second tubular combustion chamber, and' means for initiating the explosion within the second combustion chamber.

8. A reactionpropelled device adapted for propulsion through air .comprising a duct'having an inlet opening' and an exhaust nozzle, a valve separating the duct into' a forward and rear portion, said'valve being operable to admitair from the forward' portion to the rear portion' when the pressure in the forward portion exceedsthat in therear portion and to prevent any flow of gas from the rear -portion to the forward portion when the pressure is greater in the rear portion than in the forward portion, a mainV tubular `combustion chamber open at both ends and located downstream from said` valve, an inner tubularl combustion chamber open at both ends and of shorter length than the'main tubular chamber located within the main combustion chamber, means for supplying a com" bustible charge to the main tubular combustion chamber; means` for supplying an' explosive charge into the inner tubular combustion chamber, ignition means to ignite the' explosivecharge'in the innertubular combustion chamber, and ignition means'provided inthe main tubular com-- bustion chamber'to assist the decomposition of the main combustible charge. n

9N. A reaction propelled device adapted for propulsion through air comprising a duct having lan inlet opening and an vexhaust nozzle, a valve separating the duct'into a forward and rear portion, said valve being operable to admit air from the'forward portion to the rear portion' when the pressure in the forward portion exceeds that in the rear portion and to prevent any ow of gas from the rear portion to the forward portion when the pressure is greaterl in the rear portion than in the forward portion, a tubular combustion chamber locateddownstream from said valve and of smaller diameter than the inner diameter of the ductthereby providing a space for air to pass by the combustion chamber, said combustion chamber having an inner combustion chamber of shorter length than the main combustion chamber, means for supplying a combustible charge to the main combustion chamber, means for supplying an explosive charge to the inner combustion'chamberand means for initiating the explosion in said'inner combustion chamber.

l0. A'method'of operating `a combustion motor having a combustion chamber, which comprises introducing a combustiblel charge: into `the combustion vchamber and` introducing'amore easilydecomposable explosive charge on either Sideiof Ithe main combustible charge, exploding the more readily cornbtistible'charges and promoting the explosion of thev main combustible charge by employing pressure and'temperature created by the explosion'of the more easily decomposable charges. l

l1. The methodf'of operatingan internal combustion motorl having a main combustion chamber enveloping a smallerncombuistion chamberwhich opens into themainj chamber, which "comprises introducing a combustible charge .in the main combustion chamber and introducing an explosive charge'in thesmaller combustion chamber, igniting the charge in said smaller combustion-chamber thereby creating pressure at the opening of the smaller. combustion chamber and exploding the main combustible charge by employing the pressure and temperature generated by the preliminary explosion.

Y 12. The method of operating a reaction propelled device having a main combustion chamber with front and rear openings and surrounded by an air duct, said chamber enveloping a smaller combustion chamber of shorter length than the main combustion chamber, comprising introducing a combustible charge in the main combustion chamber, introducing an explosive charge into the smaller combustion chamber, igniting the charge in said smaller combustion chamber and exploding the main combustible charge in the main combustion chamber by the pressure and temperature created by the explosion of the charge within the smaller combustion chamber, said explosion discharging the gases from the rear and front openings of said main combustion chamber in such a manner that the air 1n the region between the combustion chamber and the duct is heated and is forced toward the rear of the duct at increased velocity and temperature.

13. A reaction propelled device adapted for propulsion through air comprising a duct having an inlet opening and an exhaust nozzle, a valve dividing the duct into a forward portion and a rear portion, a tubular combustion chamber located within the rear portion, the longitudinal axis of the tubular chamber being colinear with the axis of the duct, means for introducing a combustible charge in a region of said tubular combustion chamber, means for introducing a second charge more combustible than the first-mentioned charge, in another region of the chamber, and means for initiating the combustion of the second combustible charge, whereby the combustion of the second charge ignites the first-mentioned charge, thereby creating gases which are expelled through the exhaust nozzle.

14. A reaction propelled device adapted for propulsion through air comprising a duct having an inlet opening and an exhaust nozzle, a valve dividing the duct into a forward portion and a rear portion, whereby air is adapted to enter the inlet opening, and pass through the valve when the valve is open, and flow out the exhaust nozzle, a combustion chamber located within the rear portion with a space between the combustion chamber and the inner Wall of the duct so that the air can readily ilow past and around the combustion chamber, means for introducing a combustible charge in a region of said cornbustion chamber, means for introducing a second combustible charge more combustible than the first-mentioned charge, in another region of the chamber, and means for initiating the combustion of the second combustible charge, whereby combustion of the second charge ignites the first-mentioned charge, thereby creating gases which are expelled with the air through the exhaust nozzle.

15. A device according to claim 14 in which the combustion chamber has openings at both ends thereof, one opening being located to face the valve and the other opening being located to face the exhaust nozzle.

16. A reaction propelled device adapted for propulsion through air comprising a duct having an inlet opening and an exhaust nozzle, a valve dividing the duct into a forward portion anJd a rear portion, a tubular combustion chamber located within the rear portion, the longitudinal axis of the tubular chamber being colinear with the axis of the duct, an auxiliary tubular chamber, the combustion chamber and the axis of the auxiliary chamber being colinear with the axis of the combustion chamber, means for introducing a combustible charge into the combustion chamber and means for introducing a second charge more combustible than the rst-mentioned charge in the auxiliary chamber and means for initiating the combustion of the second combustible charge, whereby the combustion of the second charge in the auxiliary chamber ignites the first-mentioned charge in the combustion chamber thereby creating gases under pressure which cause the gases to be expelled through the exhaust nozzle.

17. A reaction propelled device adapted for propulsion through air, comprising a Iduct having an inlet opening and an exhau'st nozzle, a valve dividing the duct into a forward portion and a rear portion, the valve being constructed to open when the pressure in the forward portion is greater than in the rear portion and to close when the pressure in the rear portion is greater than in the forward portion, a combustion chamber situated in the rear portion, and an auxiliary combustion chamber situated within the main combustion chamber, means for intro'ducing a combustible charge in the main combustion chamber and means for introducing a second combustible charge more combustible than the rst-mentioned charge in the auxiliary chamber, means for initiating the combustion of the second combustible charge whereby the combustion of the second charge ignites the rst-mentioned charge in the main combustion chamber, thereby creating gases under pressure which close the valve cau'sing the gases to be expelled through the exhaust nozzle.

18. A reaction propelled device adapted for propulsion through air, comprising a duct having an inlet opening and an exhaust nozzle, a valve dividing the duct into a forward portion and a rear portion and being constructed so that when the pressure is greater in the forward portion than in the rear portion the valve is opened, and when the pressure is greater in the rear portion than in the forward portion, the valve closes, a tubular combustion chamber open at both ends and located within the rear portion so that it is coaxial with the longitudinal axis of the duct, one olf the openings being placed adjacent the valve, and the other opening being directed toward the exhaust nozzle, injection means for injecting a main combustible charge into the combustion chamber at a position near the valve, a second injection means for injecting a second combustible charge more readily combustible than the first-mentioned charge at a position within the combustion chamber, more remote from the valve than the first-mentioned injection means, means whereby ignition of the more readily combustible charge serves to ignite the main combustible charge thereby producing gases under pressure which operate to close the valve causing the gases to be exhausted through the exhaust nozzle.

References Cited in the le of this patent UNITED STATES PATENTS 657,868 Gobbe Sept. 11, 1900 1,021,521 Hroult Mar. 26, 1912 1,269,989 Williams June 18, 1918 1,616,157 Werner Feb. 1, 1927 1,753,253 Tacchella Apr. 8, 1930 1,947,375 Broderson Feb. 13, 1934 2,096,184 Lasley Oct. 19, 1937 FOREIGN PATENTS 7,912 Great Britain Apr. 4, 1907

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