US2892410A - Ram jet projectile - Google Patents

Description

June 30, 1959 D. H. SLOAN ET AL RAM JET PROJECTILE 3 Sheets-Sheet l INVENTORS DAV/D H. SLOA/V W/LBUR H. 6035 Filed April '5, 1946 it I l l I l -L ATTORNEY D. H. SLOAN ET AL June 30, 1959 RAM JET PROJECTILE 3 Sheets-Sheet 2 Filed April 3, 1946 ATTORNEY F4 r'! ,1 tilt-Iii. bur: ii mlis.

June 1959 D. H. SLOAN ET AL RAM JET PROJECTILE s Sheets-Sheet 3' INVENTOhS DA v10 H. SLOA/V wuaun M sass Filed April :5, 1946 ATTORNEY United States RAM JET PRDJECTELE Application April 3, 1946, Serial No. 659,183

6 Claims. (Cl. 102-49) The present invention relates generally to aerial missiles and more particularly to an improved ram jet projectile and method of sustaining combustion therein.

Ram jet projectiles developed up to the present time have been incapable of overcoming drag to the extent necessary to develop thrust usable for permitting climbing. Moreover, such projectiles involve the use of a plurality of moving parts and, without exception, they have been incapable of developing even near-maximum power from the fuel employed, with the overall result that up to the present time a successful practical ram jet projectile has not been available.

One of the objects of the present invention, therefore, is to provide a ram jet projectile (athodyd) which will be light in weight and Which will be capable of delivering large enough force to overcome drag and permit climbing.

Another object of the invention is to provide a ram jet projectile having no moving parts.

Still another object resides in the provision of a projectile of this type which will obtain a higher specific impulse from the fuel employed than may be obtained from a rocket.

As a further object, the invention provides improved fuel storage and feeding means which will make use of air pressure present during flight of the craft through the atmosphere, with the result that smooth, uniform fuel feeding will be assured.

As a further object, the invention contemplates a ram jet projectile capable of obtaining its supply of oxygen, for supporting the burning of the fuel in flight, from the atmosphere, with the result that added space for carrying a greater load or additional fuel will be made available.

Further objects of the invention will become apparent as the description proceeds.

In the drawings:

Fig. 1 is a diagrammatic view of our improved ram jet projectile; V

Fig. 2 is a side elevation illustrating the projectile assembly;

Figs. 3 and 3A comprise a longitudinal sectional view of one embodiment of the invention, partly schematic, having a two-stage ignitershown partly in elevation, the views being connectable on the lines AA and BB;

Fig. 4 is a fragmentary perspective view of theinvention, showing particularly the mounting for the two-stage igniter;

Fig. 5 is a longitudinal sectional view of a modified embodiment of the invention, the view being broken away at its mid and rear end portions and the nose or windshield being shown fragmentarily;

Fig. 6 is a detail end view of the embodiment of Fig. 5 with the outer body, the fuel tank and the guard screen removed;

Fig. 7 is a side elevation, partly in section, of the launching carriage employed with the invention, the rails of the launching ramp being shown fragmentarily; and

Figs. 8 and 9 are perspective and end views, respectively, showing a projectile in operative position in a carriage, portions of Fig. 8 being shown in section.

Referring now more particularly to the drawings and first to Fig; 1 thereof, wherein the ram jet projectile is atent 2,892,410 Patented June 30, 1959 "the shown schematically, let it be assumed that the projectile is moving through the atmosphere at supersonic velocity W in the direction shown by the arrow. Since the velocity at A is supersonic, a shock wave will probably form just in front of the intake (at the forward end of the diffuser to be described presently) of the projectile. If the shock wave is plane, the velocity of the air at 1 will be subsonic but pressure p density d and temperature T of the air will be increased. The velocity of the air is next further slowed by the diffuser until it reaches the desired burning velocity at '13. Fuel is injected between B and B and is burned between B and C. The burning should take place at constant pressure. From C the hot exhaust gases expand through a constriction or nozzle E and their velocity is increased by said nozzle. Broadly speaking, the thrust which is developed by the high velocity gas flow arises from the fact that the momentum of these gases is greater at D than at the intake to the diffuser.

In the embodiment of the improved projectile as shown in Figures 2, 3 and 4 of the drawings, the numeral 10 indicates a tubular body which is formed of heavy gauge sheet metal and which is open at both ends. The body .may be of various selected lengths and diameters, those of a successful embodiment of the invention having been about ten feet long and six inches in diameter. The rear end portion of the body in is reduced and then slightly flared to define a nozzle 11. Pins 12, preferably four in number, are mounted on the rear end portion of the body at angles of ninety degrees and are for the purpose of assuring that the projectile will be maintained on its course in flight. The fins 12 are generally rectangular shaped in side elevation and may have any suitable dimensions.

Partially closing the forward end of the body 10 is a nose assembly 13 which includes a nose or ogive 14- of plastic, metal or other suitable material, and a metal flange 15 for attaching said ogive to the body 10. The flange 15.is formed with right angular bores 16 which communicate between the outer annular surface of the flange and the annular rear wall thereof. The bores are preferably four in number, spaced at ninety degree intervals about the flange. Preferably, four Pitot tubes 17 are connected with the flange 15 and are mounted with their outer ends directed forwardly and their rear or inner ends soldered or otherwise secured to the flange in surround- 7 ing relation to the mouths of the bores 16. The purpose of the bores 16 and Pitot tubes 17 will be described in more detail hereinafter.

The ogive or nose 14 is formed with a central passage 18 constricted at its mid portion and having its rear end communicating With a generally frustoconical diffuser 19 which has its forward end anchored in a central opening in the flange 15 and which extends throughout substantially one-third the length of the body 10. As will be seen, the open rear end of the diffuser terminates in close spaced relation to the inner wall of the body 10 and is held in rigid position by a mounting ring 20.

The fuel system for the improved projectile includes an annular tank 21 located immediately rearwardly of the nose assembly 13 and having its inner wall defined by a portion of the diffuser 19. The tank includes a tubular outer Wall 22 of rubber, or the like, which surrounds the diffuser in spaced relation thereto and which has its rear end margin clamped by a pair of rings 23 and 24, the ring 24 being anchored to the wall of the difiuser 19. The forward end margin of the tank 22 is clamped about the rear end portion of the flange 15 by a clamping ring 25 which is formed with longitudinal ports 26 therein, said ports being arranged in spaced relation about the ring 25.. An annular series of jets 27 is mounted in the forward end of the diffuser 19 and each jet communicates with the interior of the tank 21 at its forward end. It will now be understood that as the projectile moves through the air in flight, air flow will enter the Pitot tubes 17 and pass through the bores 16 and ports 26 into the annular space between the wall 22 of the tank and the wall 10, with the result that the wall 22 will be compressed inwardly for forcing fuel such as gasoline in the tank 21 through the nozzles or jets 27, where it will be mixed with air entering the central opening 18 and forced rearwardly in the diffuser 19, in a manner and for a purpose to be discussed in more detail hereinafter.

The fuel ignition system employed with this embodiment of the invention will now be briefly described. In this connection, it should be understood that various types and methods of fuel ignition may be employed in lieu of the system embodied in this description. The fuel ignition system illustrated includes a duct 28 which extends downstream in the body 10 concentrically with respect thereto from a point in relatively closely spaced relation to the rear end of the diffuser 19. At its rear end portion, the duct 28 is supported in body 10 by streamlined supports 29 (Fig. 4) arranged at angles of ninety degrees with respect to each other. The duct 28, as shown, extends substantially two-fifths the distance from the rear end of the diffuser toward the rear end of the body. Shorter or longer ducts may be employed if desired. Positioned within the duct 28, preferably by four streamlined inner supports 30, is an igniter holder 31 which is of tubular shape and which extends substantially onethird the length of the duct. The holder 31 is closed at its forward end by an ogive-shaped nose 32 which extends partly into the diffuser 19 substantially axially thereof. An igniter 33 is carried within the holder 31 and is preferably of a construction similar to tracers commonly used in projectiles. The igniter 33 is, however, electrically detonated and, for the purpose of effecting electrical detonation, a pair of wires 34, connected with a primer (not shown) in the igniter, extend rearwardly therefrom for connection in a circuit including a battery 35 and a switch 36, said battery and switch, of course, being located a safe distance away from the launching ramp or platform to be described presently.

Reference is now had to Figures 7, 8 and 9 wherein there is illustrated a launching carriage for effecting launching of our improved projectile. A satisfactory launching carriage is shown generally at 37 and includes a cluster of preferably four rocket motors 38 of the type disclosed in copending applications of C. C. Lauritsen, Serial Numbers 481,644 and 481,652, filed April 2, 1943.

. The rocket motors employed up to the present time have been of the -inch type. It should be understood, however, that launching carriages employing a greater or less number of rocket motors, and rocket motors of different sizes have been and will be used as occasion demands. The rocket motors are connected at the innermost portions of their corresponding rear ends by a thrust plate 39 having apertures 40 therein, and at their corresponding forward ends by a manifold 41. The manifold 41 comprises cups 42 which close the forward ends of the rocket motors 38, and arcuate connecting pipes 43. The manifold 41 serves the twofold function of connecting the forward end portions of the rocket motors so as to V assure uniform burning and of providing a support for spacing the forward ends of the motors with respect to trically with respect to the surrounding motors 38.

The carriage 37, with our improved ram jet projectile therein, is ordinarily discharged from a suitable ramp diffuser element 53.

which includes a pair of spaced, parallel guide rails 44 engageable by bifurcated opposed guides 45, a pair of said guides being carried on the manifold 41, and a second pair being carried on a connecting strap 46 surrounding the motors 38 near their corresponding rear ends.

To assure that the carriage 37 will be maintained on a true course in flight, a fin assembly including fins 47 is carried at the rear end of the rocket motor assembly.

To effect launching of the projectile 10 from the ramp, the rocket motors 38 are ignited by remote control with suitable electrical equipment of conventional design (not shown). At the same time, the igniter 33 is ignited by closing the switch 36 from a remote position. After ignition, the rocket motors 38 will cause the carriage 37 with the projectile 10 therein bearing against the thrust plate 39, to be moved at a high rate of speed along the ramp rails 44 and to be discharged from the ramp at the ends of said rails. The carriage 37 will impart flight to the projectile 10 for a period of one or two seconds; that is, until the propellant in the motors 38 is completely burned. The carriage and the projectile will move through the air at such a high rate of speed that the velocity of air flow through the central opening or throat 18 will be sufficient to support uniform burning of fuel, forced into the mouth of the diffuser 19 through the jets 27 by compression of the tank 22, after the aerodynamic drag has stripped the carriage 37 from the projectile. Uniform burning of fuel in the combustion chamber rearwardly of the diffuser 19 will provide sufficient thrust to drive the projectile 10 through the air at supersonic speeds.

More particularly, as the projectile travels through the air, air flow at high velocity will enter the diffuser 19 through the throat 18 and will be mixed with the fuel from jets 27 in the chamber defined between the jets 27 and the igniter 33. This mixture of air and fuel, at relatively low velocity and high pressure, will be ignited by the igniter 33 and the products of combustion will be ejected through the nozzle 11 at sufficiently higher velocity than that of the air flow entering the throat 18 to provide the necessary thrust for driving the projectile through the atmosphere at supersonic speeds.

It is desired to point out that the use of the ignition system embodying the duct 28 may assure a higher degree of burning, because a portion of the air flow from the diffuser 19 is passed directly about the igniter 33 and thus heated to a higher temperature than the mixture of air and fuel passing outside said duct 28, with the result that preheating of a. portion of the airfiow is effected and a more complete and effective combustion takes place.

Referring now to the modification of the invention illustrated in Figs. 5 and 6, the numeral 50 indicates the cylindrical barrel or body of this device, the body being quite similar to the body 10 of the previously described embodiment of the invention. The body 50 is closed at its forward end by an annular plug 51 having an axial opening 52 enlarged and slightly outwardly flared to define an annular recess and a shoulder for receiving the forward end portion of a diffuser element 53. Injection nozzles 54, arranged in a circumferentially spaced series in the forward end portion of the diffuser element 53, communicate with the interior of a fuel tank the inner cylindrical wall of which is defined by a portion of the As will be seen, the nozzles 54 include generally polygonal blocks having rearwardly inclined walls 55 for protecting the jets 56 from any explosive blasts entering the diffuser 53 from the combustion chamber. A circular plug 57, of rubber or other suitable material, closes the corresponding outer ends of the jets 56. This plug 57 is displaced and blown out of the projectile by air flow passing through said projectile after it has been launched into flight.

The fuel tank of this embodiment of the invention comprises a cylindrical, preferably rubber, outer wall 58 secured at its opposite ends to reduced terminal rings 59 and 60, also of rubber. The free end margin of the ring 59 is clamped on the rear portion of the plug 51, which is reduced and tapered as shown at 61, by a clamping ring 62. As will be seen, the clamping ring 62 is formed with a series of longitudinally extending bores 63 which communicate with bores 64 in the plug 51. The bores 64 communicate with Pitot tubes 65 mounted in said bores and having their corresponding outer ends directed forwardly, or upstream. The rear ring 60 is clamped between confronting inclined surfaces of clamping rings 66 and 67, the ring 67 being fastened tightly to the diffuser element 53 near its rear end portion. The ring 66 is tightly fitted about the rear margin of the terminal ring 60 and, to prevent pressure leakage, the ring 66 is formed with a groove 68 in which is mounted an annular gasket or sealing ring 69 which engages the inner wall of the body 50.

In order to assure uniform flow of fuel to the nozzles 54 regardless of the distribution of pressure about the wall 58 of the fuel tank, We provide a plurality of ducts or conduits 70. As best seen in Figure 6, the ducts 70 are of substantially U-shape and extend throughout the major portion of the length of the tank along its inner 'wall 53. The ducts 70 are each provided with a plurality of spaced inlet ports 71 (Fig. at their corresponding rearward ends. To assure that the inner ends of the nozzles 54 will be protected in the event that the outer wall 58 and the ring 59 should be completely collapsed by air pressure entering the Pitot tubes and surrounding the tank, we provide a sheet of foraminous material 72. The sheet 72 extends throughout substantially the entire length of the tank and thus provides effective means for assuring free flow of fuel to the nozzles from any point along the length of the tank.

As in the previously described embodiment of the invention, a nose or windshield is fitted in the forward end of the body 50. More specifically, a windshield 73 is fitted in an enlarged recess 74 in the forward end of the plug 51 and has a central passage 73 communicating with the diffuser 53. The operation of this embodiment of the invention is quite similar to that of the embodiment previously described. When the projectile is launched, in the manner of the first described embodiment, air flow will enter the diffuser 53 from passage 73' and will blow out the plug 57, with the result that fuel from tank 58 may be fed through jets 56 to the interior of the forward end of the diifuser. This fuel will, of course, be blown rearwardly by the air flow and mixed therewith. In view of the fact that we have provided the ducts 70 and the foraminous sheets 72, fuel flow will be uniform to the nozzles 54 with the result that, in so far as fuel flow is concerned, uniform burning will be assured.

We claim:

1. In a ram jet projectile including an open-ended duct, and expendable means for initially imparting flight to the duct to direct an air stream therethrough; in combination, a source of fuel carried by the duct, means for injecting said fuel into the air stream in the duct, and means for igniting the mixture of fuel and air, the combustion products of said ignited mixture being discharged from the duct for imparting thrust thereto and sustaining flight thereof upon cessation of operation of said expendable means, said fuel source including a tank within the duct and having a compressible wall, and a pipe for directing into said duct a portion of the air stream flowing about the duct after the launching into flight of the projectile by said expendable means, for compressing said wall and forcing fuel through said injecting means.

2. The combination with a projectile body in the form of a duct, and a difiuser in the duct, of a fuel source having a tank defined by said diifuser, a compressible wall and anchoring means for said compressible wall, a nozzle communicating between the tank and the interior of the duct, and a Pitot tube carried by the duct and communicating with the interior thereof for leading air under pressure to flow about the compressible wall of the tank for compressing said wall and forcing fuel through the nozzle.

3. In a ram jet projectile, the combination with a cylindrical elongated body, and a frusto-conical diffuser in the body, of a fuel tank comprising a portion of the outer wall of said diffuser, a compressible wall surrounding said outer wall, and anchoring means for the opposite ends of said compressible wall, said anchoring means sealing the ends of said tank.

4. In a ram jet projectile, the combination with a cylindrical elongated body, and a frusto-conical diffuser in the body, of a fuel tank comprising a portion of the outer wall of said diffuser, a compressible wall surrounding said outer wall, and anchoring rings for the opposite ends of said compressible wall, said anchoring rings sealing the ends of the tank.

5. In a ram jet projectile as recited in claim 3, a Pitot tube for leading fluid under pressure to the interior of the body for compressing the compressible wall, and a nozzle communicating between the tank and the interior of the body for leading fuel from said tank.

6. A ram jet projectile including a hollow elongated body for receiving air flow therethrough, a diffuser in the body in the path of said air flow, means for supplying fuel to the diffuser for admixture with the air stream, an ignition system including a tracer mounted in the body near the downstream end of the diffuser, a duct mounted concentrically within the body about the tracer for leading a portion of the air-fuel stream to pass about the tracer and be heated thereby for promoting combustion, and supports in said body for the tracer and the duct, said diffuser directing a portion of the products of combustion of the ignited air fuel mixture downstream and through the rear of said body at a higher rate of flow than the flow of incoming air, for imparting reactive thrust to said body.

References Cited in the file of this patent UNITED STATES PATENTS 1,021,521 Heroult Mar. 26, 1912 1,102,653 Goddard July 7, 1914 1,888,749 Urquhart Nov. 22, 1932 2,395,435 Thompson et a1 Feb. 26, 1946 2,398,871 Turnbull et a1 Apr. 23, 1946 2,419,866 Wilson Apr. 29, 1947 FOREIGN PATENTS 347 Great Britain of 1878 293,594 Great Britain Apr. 16, 1928 554,906 Germany Nov. 2, 1932 439,805 Great Britain Dec. 6, 1935 866,598 France May 26, 1941

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