GB2314913A

GB2314913A - Projectile launching device

Info

Publication number: GB2314913A
Application number: GB8815900A
Authority: GB
Inventors: John Robert Evans
Original assignee: Hunting Engineering Ltd
Current assignee: Lockheed Martin UK Ampthill Ltd
Priority date: 1987-07-16
Filing date: 1988-07-04
Publication date: 1998-01-14
Anticipated expiration: 2008-07-04
Also published as: GB2314913B; GB8716732D0; GB8815900D0

Abstract

A weapon system comprises a launch tube (1) containing a projectile (2) and means (4) and (5) for the development of ejection gases within the launch tube so as to propel the projectile in a forward direction. The launch tube (1) constitutes a countermass which is ejected rearwardly relative to a guide tube (6) or fixed part of a launcher platform.

Description

"PROJECTILE LAUNCHING DEVICE INCORPORATING A COUNTERMASS" This invention relates to a projectile launching device, typically a weapon, which incorporates a countermass to reduce recoil or other reaction forces at the launcher platform.

It is known to use a countermass in such a manner that, when a projectile is accelerated in a forwards direction the countermass is set free and accelerated rearwards to absorb the reaction, thereby resulting in minimal reaction force at the launcher structure and hence at the launcher platform. Basic systems employing countermasses in such a manner have several disadvantages. They tend to be heavier than rockets or recoil less gun systems of similar performance and are used mainly when a reduced acoustic signature is essential.

Summarv of the Invention One object of the present invention is to provide an improved countermass system, typically a lightweight launch and ejection system which exhibits relatively low reaction forces at the launch platform and low acoustic disturbance. Such a system is particularly suited to an infantry weapon which is intended to be fired from an enclosed site.

The basis of the invention is the inclusion of a launch tube from which the projectile is ejected and which is so constructed and provided within the launch structure and is released in the launching process that it also functions as the countermass.

This enables the design of the launch tube to be optimised by eliminating the separate countermass and thereby reducing the overall weight of the weapon.

It is a desirable feature of such a system that the attitude or direction of the launch tube should remain well defined throughout the launching process. This may be achieved by the provision of means for guiding the launch tube, typically guide rails to maintain alignment between the launch tube as it moves rearwardly and the launcher platform on which it is mounted until the projectile has passed beyond the launch tube. The means for guiding the launch tube may, therefore, comprise an alignment structure such as an outer tube within which the launch tube can move. Preferably, the outer tube is configured to enable ejection gas generated initially within the launch tube to expand into the outer tube and being partially confined thereby so that the ejection gas continues to accelerate the projectile.

Such a combination of launch and guidance tubes permits a significantly higher projectile launch velocity owing to the longer period of acceleration which is made possible. The combination also facilitates the obtaining of a lower acoustic disturbance when the projectile finally clears the launch system, or the launch tube clears the rail tube, because of the very much lower pressures to which the ejection gases have fallen by such a time.

Description of the Drawings Figure 1 illustrates one embodiment of the present invention including a projectile, before the projectile is fired; Figure 2 illustrates the embodiment of Figure 1, shown when the projectile is clear of a launch inside a rail tube; and Figure 3 illustrates the embodiment of Figure 1 shown with a projectile and launch tube clear of a rail tube.

DescriPtion of the Preferred Embodiment One embodiment of the invention is illustrated by way of example in the accompanying Figures. With reference to Figure 1, a launch tube 1 is sealed at its rear end and carries within it a projectile 2, a pusher plate disposed at the rear of the projectile, a propellant package 4 and an igniter 5. Means for guiding the launch tube is provided in the form of an outer tube 6, herein termed a rail tube, which carries the launch tube and is affixed, in any suitable manner, to a launcher platform. It may for example be the fixed part of a launcher for an infantry weapon. In Figure 1, means for retaining the projectile in position in the launch tube and means for retaining the launch tube in the rail tube have been omitted for the sake of simplicity. Such means are not crucial to the concept of the present invention.

When the weapon is to be discharged, the igniter 5 is operated to initiate ignition of the propellant package, which burns quickly to develop a high pressure in the breech volume defined by the launch tube 1 and pusher plate 3. As this volume expands under pressure, it produces relative motion between the pusher plate and the launch tube. The projectile moves forwards whereas the launch tube moves rearwards within the fixed rail tube 6. The circumferential clearance between the tubes 1 and (6) is such that there is minimal friction between the tubes.

As the launch process progresses, the projectile and the pusher plate move forwards clear of the launch tube, as shown in Figure 2. At this point, ejection gases have expanded into the rail tube 6 and continue to accelerate the projectile and the launch tube in the direction shown by the arrows A and B respectively.

Finally, as shown in Figure 3, the projectile and the launch tube accelerate clear of the rail tube in opposite directions.

The relative masses and dimensions of the projectile and launch tube may readily be selected by conventional methods to ensure optimum use of the propellant and minimum acoustic disturbance. In a typical system, the launch and rail tubes would be of similar lengths and the projectile and launch tube would have similar masses. The precise sizes and weight and other characteristics will depend upon the particularl type and usage of the weapon. For example, in a practical shoulder launched system, it may be desirable to make the launch tube slightly heavier than the projectile. This would ensure that it would not become free of the rail tube until the projectile was clear and had allowed ejection pressure to fall, thereby minimising the acoustic shock to the operator.

However, the use of a rail tube is not essential to the invention in all aspects. The launch tube may be mounted within a structure not including a rail tube as such but having some form of guidance rails or other means. Such an arrangement is more suited to a space or air platform for the weapon.

It is, however, a characteristic of the invention that a launch tube having a significant mass is ejected rearwards. The remaining structure may be as light as practical.

For a weapon for use from confined locations it is desirable to localise the ejected launch tube and dissipate its energy. This may be accomplished by suitable shaping of the rear face of the launch tube so that it tends to bite into a surface on impact and by constructing it so that it collapses under external pressure to dissipate its energy.

Claims

CLAIMS:

1. A countermass launch system including a launch tube for the development of gaseous pressure for the ejection of a projectile forwards from the launch tube, characterised in that the launch tube functions as a countermass which is ejected backwards when the projectile is launched.

2. A system according to claim 1, further comprising means for guiding the launch tube during ejection thereof.

3. A system according to claim 2 in which the means for guiding comprises a tubular structure in which the launch tube is guided.

4. A system according to claim 3 in which the tubular construction comprises a tube which is fixed to or forms part of a launcher platform.

5. A system according to claim 4 in which the guide tube partially confines the propellant gas which is developed within the launch tube for the ejection of the projectile, the propellant gas expanding into the guide tube as the projectile leaves the launch tube and being partially confined by the outer tube so as to continue to accelerate the projectile.

6. A system according to any foregoing claim in which the launch tube is collapsible on external impact.

6. A system according to claim 1 or claim 4 in which the launch tube is collapsible on external impact.

7. A weapon comprising a launch structure, a launch tube for containing a projectile and for the confinement of propellant gas for the projectile, said launch tube constituting a countermass and being free to move relative to said launch tube in an opposite direction to that in which the projectile is ejected.

Amendments to the claims have been filed as follows CLAIMS 1. A countermass launch system including a launch tube for the development of gaseous pressure for the ejection of a projectile forwards from the launch tube, the launch tube being adapted to function as a countermass which is ejected backwards when the projectile is launched, and means for guiding the launch tube during the said ejection thereof, the said means being fixed to or forming part of a launcher platform.

2. A system according to claim 1 in which the means for guiding comprises a guide tube.

3. A system according to claim 2 in which the said pressure is exerted by propellant gas developed within the launch tube, and the guide tube is configured such that the propellant gas expands into the guide tube as the projectile leaves the launch tube and is partially confined by the guide tube whereby it continues to accelerate the projectile.

4. A system according to claim 2 or 3 in which the launch and guide tubes are of similar lengths.

5. A system according to any foregoing claim in which the projectile and the launch tube have similar masses.