US 3380340 A
Description (OCR text may contain errors)
l 30, 1968 J. E. H. BERGMAN ETAL 3,380,340
RECOIL-FREE WEAPON Filed May 19, 1966 O O O ohn. [Ni firm 817mm 8 EcZra Z Hid/vac? By United States Patent ABSTRACT OF THE DISCLOSURE A recoilless firearm having a firing tube which is open at both ends, the rear end of the firing tube having an exhaust nozzle; a high pressure combustion chamber of smaller calibre is inserted in the rear end of the firing tube and connected by an interrupt-able connection to a projectile in the firing tube in front of the combustion chamber; the combustion chamber also having a rear exhaust opening provided with a nozzle, the combustion chamber being longitudinally located in the firing tube by means of position-determining means, so that the nozzle of the combustion chamber is surrounded by the nozzle of the firing tube, whereby the gas pressure forces acting on the combustion chamber at the moment of explosion substantially compensate each other so that the combustion chamber will not be thrown out forwardly or 'backwardly at any appreciable speed.
In recoilless weapons the so-called high-low-pressure principle is sometimes used, which means that the propelling gunpowder is burnt substantially within a relatively small container inside the firing tube. This container is designed to endure high pressure and its wall is provided with a great number of rather small exhaust openings. Said container will, therefore, serve as a high pressure combustion chamber without such rising of the pressure immediately outside said chamber (that is the pressure which is acting on the inner wall of the firing tube) that it exceeds what said wall endures, because the gases are allowed to expand from the rather small volume in the container out to the considerably greater space around said container. This, generally tube-shaped, container is usually fastened to the rear end of the projectile, and is concentric with the firing tube.
It has been found out that the use of a high pressure chamber of that kind facilitates the construction of Weapons which are extremely light, because the walls of their firing tubes will be thin, and sometimes other material than metal may be used for the firing tubes. It is, however, difiicult to fasten the high pressure chamber to the wall of the firing tube because of the thin wall of the latter. If, on the other hand, the high pressure chamber is not fastened to the firing tube, it will be thrown out forwards or rearwards and this will cause unpredictable recoil processes and danger for ones own t-roop. The present invention provides a solution to this problem.
The present invention is mainly characterized by the fact that the high pressure chamber comprises an elongated tube, the rear end of which is shaped as or provided with a gas exhaust nozzle, and that the chamber with its rear end is fastened within the rear end of the firing tube in such a way that the gas exhaust nozzle of the firing tube substantially surrounds the gas exhaust nozzle of the high pressure chamber.
In the following, the invention will be described more in detail, reference being had to the accompanying drawing.
FIG. 1 illustrates a longitudinal section of such parts of the weapon for which the invention is of importance.
FIG. 2 illustrates a modified embodiment of the rear part of the device according to FIG. 1.
The weapon comprises a firing tube 6 with thin walls, for example of glass fibre laminate, the rear end of which is shaped as a nozzle 12, and which encloses an aerodynamically steered projectile. In the drawing, only the rear end 1 of that projectile is illustrated. Behind the projectile there is located a tubular high pressure chamber 5, the calibre of which is much smaller than the calibre of the projectile, said high pressure chamber having gas exhaust openings 4 in its side walls. Said high pressure chamber has also a front end wall 3 which is connected to the rear end of the projectile by means of a pin 2. The high pressure chamber 5 is supported within the firing tube 6 at its front end as well as at its rear end by means of one or more centering members 16 and 17, respectively, in the form of fin wreaths which make small resistance to the gas stream. The rear centering member 7 abuts against a constriction 14 in the firing tube through an annular member 8. The high pressure chamber 5 is provided with a rear gas exhaust opening. An exhaust nozzle 9 is fixed in said opening by means of a tube 15 which is provided with inner and outer threads. The ex haust nozzle 9 is closed by a damming washer 13. Another damming washer 10 is adapted to close the annular opening between the high pressure chamber and the nozzle 12 of the firing tube. This damming washer 19 is kept in place by means of an annular member 11 which is threaded onto the nozzle of the high pressure chamber.
In operation, a pressure is generated in the high pressure chamber 5 when the gunpowder is burnt, said high pressure causing gunpowder gases to stream out through the openings 4 into the space nearest behind the projectile. The gas pressure in this space acts on the pro jectile 2 as well as on the damming washer 10, which is so designed, that it will break at the same time as the pin 2 is broken off, or somewhat earlier than that. Also the damming washer 13, which is exposed to the strain from the pressure within the high pressure chamber 5, is so designed that it will break at about the same time. The sum of the different forces acting in the high pressure chamber is approximately zero, if the damming washers and the pin 2 break approximately at the same time and if the area of the nozzle of the firing tube and the nozzle 9 of the high pressure chamber are properly adjusted. When the projectile has been disconnected from the high pressure chamber, the latter will be actuated by the rearwards directed gas stream, but also by the reaction force in its nozzle 9 and said forces are -balanc ing against each other. If the balance is perfect, the high pressure chamber will remain still in the firing tube. It is, however, difficult to obtain this perfect State and to balance the forces against each other, but by means of the present invention it is possible to achieve that the high pressure chamber, even if it is not remaining still in the firing tube, will not be thrown out forwards at any appreciable speed, or be pressed backwards with such a force, that the centering members are deformed and the combustion chamber is thrown out backwards.
In the foregoing description it has been assumed, that the Weapon during the handling thereof is not exposed to greater shocks or other forces, than the damming Washer 10 is capable of enduring, so as to keep the combination of the projectile and the high pressure chamber in place in the weapon. If there are great demands on the handling security of the weapon, it may, however, happen, that the damming washer 10 is not sutficient to endure the strains. According to a modified embodiment of the invention illustrated in FIG. 2 this problem is solved.
In this embodiment the high pressure container is provided with a further centering member 18 which, together with the centering means 7, keeps the combination of the projectile and the high pressure chamber in place during the handling of the weapon by clamping the annular constriction member 14, said constriction member being protected against punctual load by means of two annular members 8 and 17, respectively. The operation of the weapon will be the same as described before but the high pressure chamber and the projectile are now locked in the firing tube during the handling of the same without exposing the washer 10 to any strain.
1. A recoilless weapon comprising, an aerodynamically stabilized projectile, a firing tube enclosing said projectile, said firing tube having a gas exhaust nozzle, a highpressure combustion chamber enclosed by a part of the firing tube, the high-pressure combustion chamber having a strong wall and being provided with a number of exhaust openings, the high-pressure combustion chamber being located behind the projectile and being connected to the projectile by an easily interrupted connection that is adapted to be interrupted under the action of propelling gases; the high-pressure combustion chamber having a calibre smaller than the calibre of the surrounding firing tube and the calibre of the projectile, the high-pressure combustion chamber consisting of an elongated tube having a gas exhaust nozzle at its rear end, said highpressure combustion chamber being fastened to the rear end of the firing tube in a location where the exhaust nozzle of the firing tube surrounds the exhaust nozzle of the high-pressure combustion chamber, the annular walls of the nozzle being radially spaced by an annular air gap, and said air gap forming a longitudinal continuation of an annular air space located within the firing tube and surrounding the high-pressure combustion chamber along the whole length of the said chamber.
2. A recoilless weapon according to claim 1, wherein a constriction is provided in the exhaust nozzle of the firing tube, said constriction surrounding said gas exhaust nozzle of the said high-pressure combustion chamber at the front part thereof.
3. A recoilless weapon according to claim 2, wherein the highpressure combustion chamber has a greater outer diameter than the gas exhaust nozzle connected to said combustion chamber, so that there is a shoulder portion at the transition zone between the combustion chamber and said nozzle, the constriction of the firing tube being located slightly behind the shoulder portion.
4. A recoilless weapon according to claim 2, wherein said high-pressure combustion chamber is provided with centering means for centering the chamber in the firing tube, said centering means being permeable to combustion gases.
5. A recoilless weapon according to claim 4, wherein said centering means comprises a plurality of fin wreaths.
6. A recoilless weapon according to claim 1, wherein said gas exhaust nozzle of the high-pressure combustion chamber is provided with a damming washer which is easily ruptured or ejected by the gunpowder gas stream through the nozzle.
7. A recoilless weapon according to claim 1, wherein a damming washer is provided around the nozzle of the high-pressure combustion chamber, the periphery of the washer abutting against the inner wall of the rear part of the firing tube, said rear part being funnel-shaped, said washer serving as a locating means for determining the longitudinal location of the high-pressure chamber and the projectile in the firing tube.
8. A recoilless weapon according to claim 4, wherein said wntering means is mechanically connected to said high-pressure combustion chamber and comprises two longitudinally spaced fin wreaths, one of which is located in front of the constriction in said firing tube and engages the front surface of the constriction and the other fin wreath engages the rear surface of the constriction behind which it is located.
9. A recoilless weapon according to claim 8, wherein there are load-distributing annular metal members disposed between said fin wreaths and said surfaces of said constriction.
References Cited UNITED STATES PATENTS 2,598,256 5/1952 Hickman 89--1.704 X 2,313,119 3/1943 Brand -45 2,986,973 6/1961 Waxman 891.704 X 2,919,635 1/1960 Levine et a1. 8824 SAMUEL W. ENGLE, Primary Examiner.