GB2291958A - Disrupter weapon - Google Patents

Abstract

A disrupter weapon based on the Davis Gun principle suitable for use in explosive ordnance disposal, comprises a launch tube 1 containing a pair of pistons 2, 3 slideable in opposite directions between end arresters 7, 11. At the forward end the tube 1 contains a fluid 14, which may be a colloidal suspension eg of chaff in water and at the rearward end the tube contains a countermass 15 which is a non-cohesive body eg comprising bundles of fibres. On ignition of a quantity of propellant 6 located between the pistons 2, 3 the pistons fly apart and eject the mass and countermass in opposite directions. The pistons are trapped by the arresters, thus holding the propellant gases captive. The fluid can be directed against eg a suspected terrorist device. In use the weapon has low recoil force and can thus be mounted on a vehicle with reduced risk of damage to the vehicle or unwanted movement of the vehicle. <IMAGE>

Description

Title: Disrupter Weapon This invention relates to a disrupter weapon in the form of an improved Davis Gun which is suitable for use in an enclosed space, and especially to such a device which can be used as a disrupter in an explosive ordnance disposal (EOD) device.

There are at present in existence several designs of miniature, remotely controlled EOD vehicles which carry a weapon of some kind, capable of firing a conventional solid bullet or shot pellets, or water.

Such vehicles are of immense value in dealing with suspected terrorist devices, in that they can be manoeuvred remotely into a position where a projectile can be fired at a suspect device, and can then be fired from the remote position. The suspect device can thus be disrupted without the need for an individual to undertake the risk of physically approaching and manually disarming the suspect device. In many cases, the suspect device can be disabled without the initiation of any explosive which it may embody. This is of course a great advantage where the suspect device has been planted in or close to property having a high value, such as for example an aircraft or a building.

Although existing EOD vehicles have proved to be extremely useful, the required disrupter power of the projectile which can be fired, in order to effectively disable a suspect device, results in a large recoil force acting on the EOD vehicle. The size of such vehicles is strictly limited by the need for manoeuvrability in confined spaces, and hence the vehicle will become unstable to the point where it will probably fall over backwards under the recoil force, causing damage to the vehicle and the weapon, and spoiling the aim. Thus the target may be unaffected, the vehicle may be rendered incapable of recovery under remote control, and the disrupter device and/or the vehicle may suffer serious damage as a result of such large recoil forces.

In some instances, instead of using a remotely controlled vehicle, a disrupter weapon is manually positioned to fire at a suspect device, using a portable stand. In these cases the recoil forces may be sufficiently high that the entire weapon flies backwards causing damage to the weapon, failure to hit the target device, and possibly initiating another explosive device which has been concealed in the vicinity. It Is therefore highly desirable to reduce or eliminate such high recoil forces in the operation of an EOD disrupter weapon.

It often occurs that a suspect device is located in a position where a conventional projectile fired from an EOD vehicle can cause unwanted damage in the area surrounding the device, or unwanted initiation of another concealed, explosive device, and any free propellant gases or overpressure created within a confined space can also have this effect.

For example, damage might be done to an aircraft structure, or soft furnishings may, conceal another explosive device which might be initiated. It is also possible that persons in the vicinity may be injured. It is highly desirable that an EOD device should not cause such damage, or unplanned initiation or injury.

The Applicant has appreciated that an improved form of disrupter weapon based on the Davis Gun principle can offer a solution which has at least some of the desirable characteristics identified above.

According to the present invention there is provided a disrupter weapon comprising a launch tube having a forward end and a rearward end, a pair of pistons slidable longitudinally within the launch tube, a pair of piston arresters one adjacent each end of the tube each arrester having a longitudinal aperture there through, and wherein the launch tube contains in a forward portion thereof forward of the said pistons a body of fluid, and in a rearward portion thereof rearward of the said pistons a countermass in the form of a non-cohesive body.

The countermass is advantageously formed as a mass of fibrous material, such as glass fibres.

The fibres may be formed into a plurality of individual bundles each containing a plurality of individual fibres.

The countermass preferably has a transverse cross-section which is smaller than that of the aperture in the rearward arrester.

An insert may be provided within the said rearward portion of the launch tube for locating the countermass in alignment with the aperture in the rearward arrester.

The insert Is preferably formed of a low density low strength material such as expanded polystyrene.

The forward portion of the launch tube may contain a fluid selected from the group comprising water, a mixture of water and alcohol, gelatin, a mixture of water with a conventional antifreeze substance (eg ethylene glycol), and a colloidal suspension in water including some or all of glycol, chaff or talc.

The pistons are preferably cup-shaped with the concave sides of the pistons facing each other.

The pistons may be connected together by means of a connection which is intended to break when a predetermined load is reached.

Preferably the piston arresters are slidable longitudinally In the launch tube and elastic tie means join the said arresters one to the other.

The launch tube is then most conveniently formed of fibre reinforced plastics material.

The reinforcing fibres of the launch tube are preferably laid so that all or a substantial majority of them are aligned In the hoop direction or are In the form of a braid.

Preferably the elastic tie means comprises one or more arrangements of aligned elastic fibres such as fibre rovings, ropes, braids or woven or unwoven tapes.

Suitable materials for the elastic tie means are high strength materials which behave elastically under dynamic loading, eg nylon or Kevlar (Trade Mark).

Advantageously, each arrester takes the form of a sleeve which fits in sliding contact within the launch tube, the sleeve having a portion which extends longitudinally beyond the end of the launch tube and in a radial direction beyond the external wall of the launch tube, said portion including attachment means for attaching the said elastic tie means.

In one convenient arrangement, the attachment means takes the form of a flange provided with holes or slots each adapted to receive an individual elastic tie means. The tie means may then comprise a single length which passes back and forth between the two attachment means and through successive holes or slots thereof. Alternatively, the tie means may comprise discrete lengths, or a tubular braid.

The tie means may pass externally of the launch tube, and in this case they are preferably enclosed by a protective outer cover.

Conceivably the tie means might alternatively pass through channels formed integrally in the wall of the launch tube.

In an alternative arrangement, the elastic tie means pass internally of the launch tube.

The elastic tie means Is then conveniently of tubular form, eg a tubular braid, and is preferably impermeable.

The arresters may than be formed by folding around a former.

The invention will now be described by way of example only with reference to the accompanying drawings, of which Figure 1 is a schematic longitudinal section through a disrupter weapon system in accordance with the invention, shown prior to firing, Figure 2 is an end view of the disrupter shown in Figure 1, Figure 3 is a schematic longitudinal section showing the disrupter weapon system of Figures 1 and 2 immediately after firing, Figure 4 Is a schematic longitudinal section showing the disrupter weapon of Figures 1 and 2 at a stage after firing where the fluid is fully ejected, and Figure 5 is a schematic longitudinal section showing one end of an alternative form of disrupter weapon.

As shown in Figures 1 and 2, a disrupter weapon in accordance with the invention for mounting on an EOD vehicle which is remotely controllable, comprises a launch tube 1 formed of fibre reinforced plastics material having a predominance of its fibres laid up in the hoop direction. The launch tube 1 is cylindrical and of constant circular cross-section throughout its length.

A pair of opposed pistons 2, 3 of cup-shaped form are longitudinally slidable on the inner surface of the launch tube 1. The pistons 2,3 are joined together by a a tie bar 4 having a weak point 5, and also contain between them a mass of propellant material 6 which can be initiated by means not shown, eg electrically.

At the forward end of the launcher there is provided an arrester in the form of a tubular sleeve 7 which fits In sliding contact within the launch tube 1. An annular flange 8 fixed to the sleeve is located beyond the end of the tube 1 and extends radially outwards beyond the external surface of the launch tube. The flange 8 provides attachment means for a plurality of elastic tie means 9. The attachment means take the form of a plurality of key-hole shaped slots 10 passing in the longitudinal direction through the flange, the narrow portion of the slots being open at the radially outer edge of the flange.

An arrester 11 is provided at the rear end of the launcher tube 1, and this arrester is similar to, and locates in the launcher tube in the same way as the arrester 7. The arrester 11 is fixed to a flange 12 similar to the flange 8.

In this embodiment the tie means 9 comprise a single cord or rope which passes longitudinally back and forth on the outside of the tube 1, between the arresters 7, 11 and locating in circumferently successive slots 10. The tie means can be of any suitable high strength, lightweight material which behaves elastically under impulsive loading for example an aramid fibre such as Kevlar (Trade Mark), an ultra-high modulus polyethylene, or possibly nylon. The selected material must be sufficiently stiff in tension to prevent escape of the arresters 7, 11 from the end of tube 1 under impulsive loading from the pistons 2, 3 as described hereinafter. In this embodiment the tie means 9 consists of a Kevlar rope comprising a braided outer cover and a core of Kevlar rovings, although other aligned fibre arrangements are possible.The tie means 9 are enclosed by a protective outer cover 13 which can be of any suitable lightweight material such as for example aluminium or polyethylene. The function of the cover 14 is to provide protection against damage to the tie means, and confidence that the tie means remains undamaged prior to use. Protective caps 16, 17 of lightweight material such as polyethylene or other plastics material are provided.

The forward portion of the launch tube 1 contains a fluid 14 which can be water and is retained in place by the protective cap 16. In some circumstances it is found advantageous to include a minor proportion if alcohol in the water. Other fluids may be used, and gelatine can be advantageous because of its ability to retain a form. If greater density is required, a colloidal suspension may be used as the fluid 14, comprising one or more of water, glycol, chaff or talc.

Densities of 1.7 to 1.9 gm/cc can be obtained in this way. Where the disrupter weapon is to be stored at temperatures below freezing, with the liquid 14 in place, an anti-freeze such as ethylene glycol may be included.

The rearward portion of the launch tube 1 contains a countermass 15, which is a non-cohesive body formed in this embodiment from individual bundles of glass fibres weakly held together to form a cylindrical countermass body. This cylinder has a diameter somewhat less then the central aperture in the rearward arrester 11, so that the countermass can pass therethrough relatively unimpeded. The countermass 15 is supported centrally in the launch tube 1 by means of an insert 26 formed from expanded polystyrene. This weak, low density material is selected because it can easily be destroyed by the piston 3 without impeding its passage.

In use of the weapon system, the disrupter weapon is mounted on a remotely controllable miniature EOD vehicle (not shown), which can be manoeuvred from a remote station to a posltion where the weapon Is aimed at a suspected bomb or other explosive or harmful device at close quarters. The propellant 6 is then electrically initiated remotely, and when a certain pressure of propellant gas is reached in the space between the pistons 2, 3 the tie bar 4 breaks at the weak point 5.

The pistons 2, 3 are then driven apart, their concave shape assisting obturation, and accelerate the fluid 14 and the countermass 15 in opposite directions. Each will have a velocity on projection from the tube 1 which may be of the order of 150 to 200 m/s, and the pistons 2, 3 reach the end of the tube 1 with this velocity, where they encounter the arresters 7, 11 respectively. The arresters are elastically restrained from outward movement by the tie means 9, and hence are decelerated over a small but a appreciable distance. The necessary movement is accommodated by longitudinal sliding of the arresters 7, 11 in the ends of the tube 1. The peak forces required to arrest the pistons 2, 3 are thus dramatically reduced as compared to known arrangements operating on the Davis Gun principle, in which the pistons simply impact against fixed end stops.The reduced loading Imposed by the pistons can thus be supported by the tie means 9, and the need for the launch tube 1 itself to carry an extreme longitudinal impulsive loading is entirely eliminated, and in an extremely lightweight construction, which provides a considerable advantage for mounting on a miniature EOD vehicle.

The shock induced on arrest of the pistons 2, 3 can be significantly reduced by appropriate selection of the material of the arresters 7, 11 and the flanges 8, 12. The pistons 2, 3 and the flanges 8, 12 have to withstand exceedingly high stress, and so are formed of a high strength metal such as Aluminium alloy HE15 (UTS 450 Mpa). The end stops 7, 11 are formed of a lower strength material such as Aluminium alloy HE30 (UTS 300-250 Mpa), and this enables the end stops to yield earlier and so absorb some of the impulsive shock load.

After firing, the pistons 2, 3 remain captive within the end of the launch tube 1, and retain the propellant gasses sealed within the tube.

The pistons are arranged to reach the end of the tube 1 simultaneously, and the weapon thus experiences virtually no recoil.

The high velocity slug of fluid is eJected from the forward end of the disrupter weapon as shown at 18 (figures 2 and 3), the lightweight cap 16 being easily swept aside. The slug 18 possesses high energy which can very effectively disrupt a suspect device at close quarters, but is then dissipated within a relatively short distance so that unwanted damage or risk to individuals is avoided.

The countermass 15 on ejection from the rear end of the launch tube readily disintegrates as illustrated at 19 (Fig 3) into small discrete elements, such as individual fibres, which very rapidly lose their kinetic energy, and thus unwanted damage from this source is virtually eliminated.

The propellant gases are retained within the launch tube, and hence no overpressure or burnt gases are released into the environment.

The EOD vehicle upon which the disrupter weapon is mounted will experience little or no recoil force.

Figure 5 shows one end of an alternative form of disrupter weapon comprising a launch tube 20 of fibre reinforced plastics material, In which the reinforcing fibres are aligned in the hoop direction. An elastic tie means is provided in the form of a tubular braid 21 of elastic fibrous material such as nylon or Kevlar (Trade Mark). In the relaxed state, the braid 21 conforms to the internal surface of the tube 20.

The braid 21 is coated or impregnated with a material such as a rubber or plastics material which renders the braid impermeable to propellant gas.

The braid tube 21 is folded back at each end 22 over a former 23 in the form of a short length of tubular sleeve. There is thus formed at each end of the braid 21 a thickened part integral with the braid 21 and constituting an arrester.

Slidable longitudinally within the braid 21 are a pair of pistons 24, of which one is shown in Figure 5 as having reached the end of its travel. In use the launch tube shown in Figure 5 is assembled into a disrupter weapon in a similar manner to the configuration of Figures 1 to 4, ie a fluid such 14 as is contained in one end of the tube 20 and a countermass such as 15 is inserted from the other.

To fire the weapon a charge of propellant between the piston 24 is initiated, the projectile and countermass are propelled from the tube by the pistons 24, and the weapon experiences virtually no recoil.

The pistons 24 are captured by the arrester 22, 23. In this embodiment the propellant gas is retain between the pistons within the braid 21. and the braid will tend to collapse inwardly under the longitudinal forces imposed by the arrest of the pistons.

The collapse of the braid is thus opposed by the pressure of the propellant gases, which thereby contribute to the elasticity of the braid 21 in the longitudinal direction.

Claims (20)

Claims

1. A disrupter weapon comprising a launch tube having a forward end and a rearward end, a pair of pistons slidable longitudinally within the launch tube, a pair of piston arresters one adjacent each end of the tube, each arrester having a longitudinal aperture therethrough and wherein the launch tube contains in a forward portion thereof forward of the said pistons, a body of fluid, and in a rearward portion thereof rearward of the said pistons a countermass in the form of a non-cohesive body.

2. A disrupter weapon according to claim 1 wherein the countermass is formed as a mass of fibrous material.

3. A disrupter weapon according to claim 2 wherein the fibrous material comprises glass fibres.

4. A disrupter weapon according to claim 2 or claim 3 wherein the fibres are formed into a plurality of individual bundles each containing a plurality of individual fibres.

5. A disrupter weapon according to any one preceding claim wherein the countermass has a transverse cross-section which is small than that of the aperture in the rearward arrester.

6. A disrupter weapon according to any one preceding claim wherein an insert is provided within the said rearward portion of the launch tube for locating the countermass in alignment with the aperture in the rearward arrester.

7. A disrupter weapon according to claim 6 wherein the insert is formed of a low density low strength material.

8. A disrupter weapon according to claim 7 wherein the said low strength material is expanded polystyrene.

9. A disrupter weapon according to any one preceding claim wherein the forward portion of the launch tube contains a fluid selected from the group comprising water, a mixture of water and alcohol, gelatin, a mixture of water with a conventional antifreeze substance (eg ethylene glycol), and a colloidal suspension in water including some or all of glycol, chaff or talc.

10. A disrupter according to any one preceding claim wherein the pistons are cup-shaped with the concave sides of the pistons facing each other.

11. A disrupter weapon according to any one preceding claim wherein the pistons are connected together by means of a connection which is intended to break when a predetermined load is reached.

12. A disrupter weapon according to any one preceding claim wherein the piston arresters are slidable longitudinally in the launch tube and elastic tie means join the said arresters one to the other.

13. A disrupter weapon according to claim 10 wherein the launch tube is formed of fibre reinforced plastics material.

14. A disrupter weapon according to claim 13 wherein the reinforcing fibres of the launch tube are laid so that all or a substantial majority of them are aligned in the hoop direction or are in the form of a braid.

15. A disrupter weapon according to any one of claims 12 to 14 wherein the elastic tie means comprises one or more arrangement of aligned elastic fibres such as fibre rovings, ropes, braids or woven or unwoven tapes.

16. A disrupter weapon according to any one of claims 12 to 15 wherein the elastic tie means are of a high strength material which behaves elastically under dynamic loading.

17. A disrupter weapon according to any one of claims 12 to 16 wherein each arrester takes the form of a sleeve which fits in sliding contact within the launch tube, the sleeve having a portion which extends longitudinally beyond the end of the launch tube and in a radial direction beyond the external wall of the launch tube, said portion including attachment means for attaching the said elastic tie means

18. A disrupter weapon according to claim 17 wherein the attachment means take the form of a flange provided with holes or slots each adapted to receive an individual elastic tie means.

19. A projectile launcher according to claim 18 wherein the tie means comprises a single length which passes back and forth between the two attachment means and through successive holes or slots thereof.

20. A disrupter weapon according to claim 10 wherein the tie means passes externally of the launch tube.

20. A disrupter weapon according to claim 10 wherein the tie means passes externally of the launch tube.

21. A disrupter weapon according to claim 20 wherein the tie means are enclosed by a protective outer cover.

22. A disrupter weapon according to any one of claims 12 to 19 wherein the elastic tie means pass internally of the launch tube.

23. A disrupter weapon according to any one of claims 12 to 22 wherein the elastic tie means are of tubular form.

24. A disrupter weapon according to claim 23 wherein the elastic tie means is In the form of a tubular braid.

25. A disrupter weapon according to any one of claims 22 to 24 wherein the elastic tie means is of impermeable material.

26. A disrupter weapon according to any one of claims 22 to 25 wherein the arresters are formed by folding over the elastic tie means at each end thereof.

27. A disrupter weapon according to claim 26 wherein the arresters are formed by folding the elastic tie means around a former.

28. A disrupter weapon substantially as hereinbefore described with reference to any of the accompanying drawings.

29. An explosive ordnance disposal vehicle in combination with a dlsrupter weapon as claimed in any one preceding claim.

10. A disrupter according to any one preceding claim wherein the pistons are cup-shaped with the concave sides of the pistons facing each other.

11. A disrupter weapon according to any one preceding claim wherein the pistons are connected together by means of a connection which is intended to break when a predetermined load is reached.

12. A disrupter weapon according to any one preceding claim wherein the piston arresters are slidable longitudinally in the launch tube and elastic tie means join the said arresters one to the other.

13. A disrupter weapon according to claim 10 wherein the launch tube is formed of fibre reinforced plastics material.

14. A disrupter weapon according to claim 13 wherein the reinforcing fibres of the launch tube are laid so that all or a substantial majority of them are aligned in the hoop direction or are in the form of a braid.

15. A disrupter weapon according to any one of claims 12 to 14 wherein the elastic tie means comprises one or more arrangement of aligned elastic fibres such as fibre rovings, ropes, braids or woven or unwoven tapes.

16. A disrupter weapon according to any one of claims 12 to 15 wherein the elastic tie means are of a high strength material which behaves elastically under dynamic loading.

17. A disrupter weapon according to any one of claims 12 to 16 wherein each arrester takes the form of a sleeve which fits in sliding contact within the launch tube, the sleeve having a portion which extends longitudinally beyond the end of the launch tube and in a radial direction beyond the external wall of the launch tube, said portion including attachment means for attaching the said elastic tie means.

18. A disrupter weapon according to claim 17 wherein the attachment means take the form of a flange provided with holes or slots each adapted to receive an individual elastic tie means.

19. A disrupter weapon according to claim 18 wherein the tie means comprises a single length which passes back and forth between the two attachment means and through successive holes or slots thereof.