FR2499708A1 - DAMAGE DISC FOR CANNONS WITHOUT BACK - Google Patents

Abstract

A. DAMAGE DISK 7, 17 FOR NON-RECOIL BARRELS FORMING THE FIXED REAR WALL OF THE COMBUSTION CHAMBER OF THE CYLINDRICAL BODY 11 OF A NON-RECOILING BARREL OR OF THE 3 AMMUNITION CARTRIDGE INSERTED IN THIS BARREL, THE DIMENSIONS OF THIS WALL BEING CALCULATED SO THAT THE EXPLOSION STARTS FOR A PREDETERMINED GAS PRESSURE IN THE COMBUSTION CHAMBER, SO AS TO ALLOW THE FLOW OF GAS PASSING THROUGH THE CANNON TO EXIT THROUGH THE REAR OF THE COMBUSTION CHAMBER. B. DAMAGE DISK 7, 17 CHARACTERIZED IN THAT IT IS MADE IN PRE-STRESSED GLASS. C. THE INVENTION RELATES TO DAMAGE DISCS FOR NON-RECOIL BARRELS.

Description

The invention relates to a gum disk forming the

  fixed rear wall of the cylinder body combustion chamber

  dries a recoilless gun or ammunition cartridge introduced into this barrel, the dimensions of this wall being calculated so that the explosion.se triggers for a predetermined gas pressure in the combustion chamber, to thereby allow at the flow of gas passing in the barrel,

  exit from the back of the firebox.

  Cannon-recoilless ammunition is generally

  placed in a cartridge enclosing a propellant charge and a firing charge placed behind it to ignite the propellant charge. The cartridge forms

  a closed combustion chamber for the above charges.

  To overcome the recoil, the bottom of the cartridge is given the shape of a disk called a damage disk or basic disk, the purpose of which is to close the rear of the combustion chamber until the combustion produce some pressure resulting in an explosion allowing the combustion gases to come out from behind. The dimensions of the disk are calculated so that the explosion occurs approximately at the same time as the departure of the casing projectile. This helps to overcome

of hindsight.

  Instead of constituting the bottom of the cartridge, the damage disk can instead, in the case of ammunition without cartridge, to be fixed in the barrel cylinder behind the propulsion charge of the projectile. In this case the combustion chamber consists of a cylinder section limited forwards by the projectile and towards the rear by the tamping disc. Whatever their type, the grooming discs listed above must always have the following characteristics: - the shards projected to the rear must not injure the soldier using the device (this refers to a small danger zone located behind the aircraft). armed); - the basic disk must be insensitive to humidity; this disc must maintain the same resistance throughout the temperature range between -1000C and + 1000C, that is to say that the explosion must occur at a nominal gas pressure regardless of the temperature; - it must present- a long storage life. Conventional basic disks are generally made of rubber, plastic material, bakelite, paper laminate or other material capable of withstanding an explosion. However, none of these materials present

  simultaneously all the features above.

  Although it has been known for a long time that prestressed glass has the above characteristics, it has never been considered until now that it was possible to propose the use of this material for

  essentially because it did not seem likely

  that the glass is strong enough to withstand the initial pressure developed by the propulsion

the combustion chamber.

  Prestressed glass has therefore been proposed so far only for example to achieve mobile or other reaction masses, repelled by the combustion gases of the propellant charge in the rear part of the barrel where they came to break against a stop, as described by

  for example, U.S. Patent No. 4,132,148.

  On the contrary, it has never been considered logical to propose the use of glass as a material for producing a fixed damage disc in a combustion chamber, this glass having to withstand, in a fixed position, a certain pressure

initial and then shatter.

  The invention is based on the astonishing observation that prestressed glass, contrary to conventional theories, can also be used to make fixed damage discs. For this purpose, the invention relates to a damage disk forming the fixed rear wall of the combustion chamber of the cylindrical body of a recoilless gun or ammunition cartridge introduced into the barrel, the dimensions of this wall being calculated so that the explosion is triggered for a predetermined gas pressure in the combustion chamber, to thereby allow the flow of gas passing through the barrel, to exit from the rear of the combustion chamber, damage record characterized in that it is

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made of prestressed glass.

  The invention will be described in detail by means of the accompanying drawings, in which: FIG. 1 represents an embodiment of the invention in which the disc constitutes the basic part of a recoilless gun ammunition cartridge. ; - Figure 2 shows an embodiment of the invention in which the disc is fixed. in the

  cylinder of a recoilless gun ammunition without cartridge.

  FIG. 1 schematically represents a recoilless cannon of conventional type comprising a cylinder 1 into which a projectile 2 is loaded. This projectile 2 is fixed in a cartridge 3 comprising, in a conventional manner, a propelling charge 4 and a charging charge. fire 5 which can be lit laterally by a firing device 6. The rear wall of the cartridge 3, fixed to this wall 3, constitutes a disc of

  damage 7 of prestressed glass according to the invention.

  FIG. 2 schematically represents a recoilless barrel of conventional type comprising a cylinder 11 into which a projectile without a cartridge 12 is loaded. Behind the projectile 12 is a combustion chamber closed in a gastight manner, this chamber being defined towards the before the projectile 12, on the sides by the cylinder 11 and backwards by a pre-stressed glass tamping disk 17 fixed to the cylinder. In the combustion chamber there is a propellant charge 14 and a firing charge 15 which can be ignited laterally by a firing device.

classic 16.

  The various elements of the recoilless gun and ammunition used are of conventional type and do not form part of the invention, except of course the damage disk itself.

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Claims (1)

CLAIM   Damper disc (7, 17) forming the fixed rear wall of the combustion chamber of the cylindrical body (11) of a recoilless gun or ammunition cartridge (3) introduced into this barrel, the dimensions of this wall being calculated so that the explosion is triggered for a predetermined gas pressure in the combustion chamber, to thereby allow the flow of gas passing through the barrel, to exit from the rear of the combustion chamber, damper disc ( 7, 17)   characterized in that it is made of prestressed glass.