Devices for firing a projectile

Abstract

A housing (1; 100, 104, 102) of a cartridge for a device for firing a projectile has separate first and second chambers (10, 12; 106, 114), each of which contains a respective charge (34, 36; 108, 110, 116, 120) of propellant material. Gas produced by the detonation of one of the charges exits the first chamber to propel the projectile, whilst gas from the detonation of the second charge exist rearwardly from the device so as to counteract recoil. A one way valve may also be provided to help to achieve a high pressure difference between the chambers, where the cartridge has a common igniter assembly.

Description

FIELD OF THE INVENTION[0001]This invention relates to a cartridge for a device for firing a projectile and to a device for firing a projectile. Although described in relation to a device for de-arming / disrupting an explosive device, the invention is not limited in application to de-arming and disrupting devices.BACKGROUND TO THE INVENTION[0002]A conventional de-arming device (also referred to as a disrupting device or a de-armer disrupter) operates by firing a solid, liquid or gel projectile at an explosive device so as to disrupt the fuse assembly of the latter, ideally without detonating the explosive device. Such a de-arming device comprises a barrel, the breech of which contains a conventional gun cartridge which, when detonated, propels the projectile, also initially contained in the barrel, towards the target.[0003]It is generally desirable to provide means for reducing the recoil caused by the firing of the projectile, and to that end it is known to fit the end of the barrel ...

AI Technical Summary

Benefits of technology

[0009]Since the two charges of propellant, one for firing the projectile, the other for counteracting recoil, are contained in a common cartridge, a device which fires a projectile using that cartridge can have a single breech, and can therefore be more compact and lightweight than a device which uses two separate cartridges. The device is also more compact and lightweight than types of anti-recoil de-armer that do require a jacket of water. Since the propellant charge for firing the projectile is in a separate chamber from that for counteracting recoil, the force with which the projectile is fired is not affected by the gases by which are ejected so as to counteract recoil. Accordingly, the amount of the first propellant charge can be varied independently of the second propellant charge during the stages of design and development of the cartridge. This facilitates the creation of a cartridge which provides a desired force of firing and adequate anti-recoil characteristics. Indeed, it has been found that a cartridge in accordance with the invention can completely neutralise recoil.

[0014]This facilitates the balancing of the device so that the force generated by the rearwardly ejected gases is coaxial with the recoil force caused by the firing of the projectile.

[0017]The reaction forces on the device caused by the exiting projectile are higher than the reaction caused by ejecting gas alone. This is accommodated in the cartridge by increasing the amount and / or velocity of the gases ejected through the outlet of the second chamber compared with those ejected by the detonation of the first charge.

[0020]Consequently, the increased volume of the second chamber does not require an increased length of cartridge.

[0023]This helps to ensure that the detonation of the two charges of propellant material is synchronised.

[0030]This acts as a choke which helps to increase the pressure of gases ejected from the second chamber.

Problems solved by technology

However, these ports reduce the pressure of the gases which are used to propel the projectile, and thus result in the device requiring a relatively large charge and long barrel in order to be able to accelerate the projectile to a sufficiently high velocity.

Although the anti-recoil system of such device does not require a longer primary barrel (for the projectile), the additional barrel breech does increase the size and weight of the device.

Furthermore, the device can take a relatively long time to be primed for firing and it can be difficult to detonate both cartridges simultaneously.

However, the water and the additional components needed for the firing device to contain the water increase the weight of the device, and the need to fill the chamber with water prior to firing the device (and to close the chamber once full) also increases the time needed to prime the device for firing.

However, the upper arm of such a vehicle would not be able to carry a de-armer which weighs more than 1.5 kilograms whereas the various designs discussed above generally weigh at least 3 kilograms.

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