GB2299156A

GB2299156A - A dearmer

Info

Publication number: GB2299156A
Application number: GB9015045A
Authority: GB
Inventors: Derek John Horn; Andrew Donald Shelle Mcfarlane; Jack William Comley
Original assignee: PRECISION AB
Current assignee: PRECISION AB
Priority date: 1990-07-07
Filing date: 1990-07-07
Publication date: 1996-09-25
Anticipated expiration: 2010-07-07
Also published as: GB2299156B; GB9015045D0

Abstract

A dearming device having a reduced recoil includes a barrel 2 in a bore 4 of which is located a liquid projectile between a piston 50 and a cap 48. The barrel projects from a part 6 having a breech 16 containing an explosive charge 18. The breech 16 communicates by way of restricted passage 20 with a force directing plug 30 by which explosive force is directed into one or more reverse thrusting cylinders 14 and, by way of passage 32 through the plug, into the barrel 2 to react on piston 50. Cylinders 14 contain water between displaceable plugs 44 and 46. In response to detonation of the charge 18 the explosive force projects the liquid from the barrel bore 4 for the purpose of penetrating a bomb casing to disarm the bomb. The explosive force simultaneously reacts on the plugs 44 to expel the water from the cylinders 14 and provide a reverse thrust which reduces the recoil of the device. In an alternative arrangement the projectile is a solid slug in the bore 4 (the piston 50 and cap 48 being omitted).

Description

A DEARMER This invention relates to a dearmer.

Dearming devices are known for use in rendering bombs inactive. In some types they are provided with a system whereby a slug or bolt is caused to penetrate the casing of the bomb with the intention of destroying or de-activating the detonator there within.

Recently there has been developed a system for dearming a bomb by projecting a column of water at high velocity at the casing of the bomb, and this has been found to be capable of penetrating the casing and dearming the bomb.

In use, the column of water is retained with a cylinder in a device which is temporarily attached to the bomb, or mounted close to the bomb on a suitable carrier.

A charge is then exploded within the device to propel the column of water through the casing.

One disadvantage of this water jetting device is that there is a high degree of recoil as the charge is exploded and the water column if projected out of the barrel to impinge against the casing. This recoil causes the dearming device and its carrier to be flung in the opposite direction to that of the column of water and often causes damage to the device itself and to any property or personel in the vicinity.

It is an object of the invention to provide a dearming device which has a reduced recoil compared with that of the described known devices.

According to the invention there is provided a dearming device having a reduced recoil, and comprising a barrel for a projectile, a breech adapted to contain an explosive charge, at least one reverse thrusting cylinder, capable of containing fluid, explosive force directing means located between the breech and the said barrel, the explosive force directing means being such as to direct the explosive force to act simultaneously on the projectile and in the reverse force thrusting cylinders in order to simultaneously propel the projectile from the barrel and reduce the recoil of the device.

Although the present invention is directed to a projectile, the projectile may take several different forms depending on the type of mode to which the dearmer is to be put. In a proper mode, the projectile may be a plain slug, a chisel shaped slug, a blade, a blade having a shaft, or a forked blade. Such projectiles are used in the projector mode to cause damage to the device to be dearmed.

Alternatively a disruption mode may be used whereby the barrel is adapted to contain a quantity of fluid may act as a projectile. The fluid may be water, which is jetted by the discharge of the explosive charge.

On firing the explosive force is directed on to the projectile, either a solid or a liquid projectile as described above, causing it to be explosively discharged from the barrel to the device to be disarmed. In the case of a fluid such as water, the barrel is adapted to retain the fluid between two soft plugs such as plastic caps. On firing the dearmer water is projected rapidly from the barrel towards the device to be dearmed disrupting the explosive of the device.

The reverse thrusting fluid containing cylinder may be a single cylinder although there may be a plurality of such cylinders. It is preferred to use two such cylinders such that the longitudinal axis of each of the reverse thrusting fluid containing cylinder is in the same plane as the longitudinal axis of the breech. Fluid may be contained in the cylinders, retained therein by means of plugs both at the top and bottom of the cylinders. Such plugs may be plastic caps. One plastic cap is to prevent the fluid from being expelled from the cylinder when the device is turned up side down. The other plastic cap is located at the base of the cylinder to prevent the fluid from passing into the breech and contacting the explosive charge.

The explosive force directing means may be a chamber having outlets to direct the force of the explosive charge. The chamber, in one embodiment may contain a plug having channels in which to direct the force of the explosive charge.

In the disrupter mode a fluid such as water is used both as a projectile and as a thrust absorbing fluid.

Various aspects of the invention will become apparent from the following description given by way of example only with reference to the accompanying drawings in which:- Figure 1 is a cross section of the dearming device according to the invention; Figure 2 is a plan view of the dearming device; Figure 3 is an elevation of an explosive force directing means; Figure 4 is a plan view of the force directing means of Figure 3a; Figure 5 is an underneath view of the force directing means; Figure 6 is an embodiment showing an alternative dearming device having a chamber; Figure 7 is an exploded view of the components of the present invention.

As seen in the drawings a dearmer according to the invention comprises a barrel 2 defining a cylinder 4 and a reaction absorbing device 6 which may comprise one or more further cylinders. The device 6 is screwed to the topmost portion of the barrel by means of the screw thread 8.

As seen clearly in Figures 1 and 2 the reaction absorbing device is formed with a pair of wings 10 joined by a central portion 12 forming the breech. The wings 10 are bored to form two cylinders 14 and the central portion 12 is bored at 16 to form a breech adapted to receive an explosive cartridge 18. A bore 20 extends downwardly from the breech 16 terminating in a conical recess 22. A breech block 24 is screwed into the central portion 12 to retain the cartridge therein and firing wires 26 extend from the cartridge to pass through a small diameter hole in the breech block and lead to an electrical triggering device [not shown]. The longitudinal axis of the cylinders 14 and central portion 12 forming the breech are generally arranged in the same plane.

An explosion force directing device, seen in detail in Figure 3, comprises a plug 28 formed with a neck 30 tapered to correspond with the taper of the conical recess 22 of the reaction absorbing device 6.

The plug 28 is formed with a central bore 32, which, as illustrated in Figure 3, leads to three further bores 34 having their axes angled with respect to the axis of the bore 32.

An O-ring 36 fitted around the plug 28 produces a seal between the plug and the cylinder 34, and a shoulder 38 formed on part of the reaction absorbing device 6 clamps a flange 40 on the plug 28 against the top face 42 of the barrel 2.

As an alternative to the plug 28 having a central bore 32 as shown in Figure 3 the barrel itself may have a constriction as shown in Figure 6.

In Figure 6 like items to those shown in Figures 1 and 2 are shown with like reference numerals. A barrel 2 having a cylinder 4 which can be filled with water as necessary, is connected by a large pitch screw thread 8 to a bridge 16. A reaction absorbing device formed with a pair of wings 10 is joined by a central portion 12 forming the axis to the bridge 16. The central portion of the bridge is bored and is adapted to receive an explosive cartridge [not shown]. A bore 20 extends downwardly from the bridge into a constriction. The constriction opens outwardly into the cylinder 4 and has two passageways 32 extending to the cylinders 14 of wing 10. In the embodiment shown in Figure 6 the plug 50 can extend fully to the end of the cylinder 4 to provide a large volume for containment of water if desired. The general arrangement of the cylinders 14 and central portion 12 is similar to that shown in Figure 1. However the explosive charge is diverted via the two passageways 32 which extend transversely from the longitudinal axis of the breech connecting with openings in the cylinders 14.

Pistons 44 are provided within the cylinders 14, and each cylinder is provided with a removable cap 46.

The barrel 2 is also provided with a removable cap 48 and a piston 50 fits within the cylinder 4.

Figure 7 shows an exploded view of the dearmer of the present invention. Alternative barrels 2a and 2b can be connected to central portion 12 forming the bridge which fits in between the cylinders 14. Barrel 2a is used in a disruptor mode and contains water for jetting contained in the barrel by caps 48 and 50. The barrel is screwed on to the base of the breech in the central portion 12. An explosive shell 18 is inserted in the bridge and located in position by a breech cap 24 through which projects firing wires 26 extending from the cartridge 18 to an electrical triggering device not shown.

The alternative barrel 2b used in the projector mode allows the plane slug 70, the chisel shaped slug 72 a forked slug 74, or a spade slug 76 to be used to disarm the barrel. These projectors are fired from barrel 2b by means of exploding cartridge 18. Each projectile 74 and 76 can be attached to extensions 78 and 80 respectively forming a shaft which extends into the barrel 2b. The projector barrel 2b is set up in a similar manner to the disruptor mode barrel 2a as previously described. The barrel 2b is screwed into the breech 12, the projectile, for example projectile 74 is connected to shaft 78 and inserted into the barrel 2b as far up the barrel 2b as is possible. The cartridge 18 is entered into the opposite end of the breech 12 and located in position by breech plug 24. The firing wires 26 pass through the bridge plug to a triggering device.Plugs 44 are placed in the cylinders 14 which are then filled with water and sealed by caps 46. The plugs 44 and caps 46 may be plastic caps. On triggering the cartridge 18 explosive force forces the projectile 74 out of the barrel. Part of the explosive force is returned to cause the caps 44 to be expelled from the cylinders 14 against the resistence of the fluid contained therein minimizing the recoil of the device.

To prepare the dearmer for action, the components are fitted together. The projectile barrel is selected according to the action to be taken. For use in a disruptive mode a barrel capable of containing fluid such as water is used. Caps 46 are removed and the piston 44 positioned towards the lower ends of the cylinders 14, which are then filled with water. The caps 46 are then replaced and the dearmer is inverted.

In a disruptor mode the barrel is filled with water. To do this the cap 48 is removed and the piston 50 is moved to a position closely adjacent the plug 28. The cylinder 4 is then filled with water and the cap 48 replaced, after which the dearmer is reverted to its upright position. The breech block 24 is removed and a cartridge 18 is loaded into the breech 16, firing wires being fed through the hole in the cap, after which the breech block is replaced and screwed firmly in place.

The dearmer is then secured in position either directly on to the bomb or by means of a suitable support or carrier and the firing wires are connected to the electrical triggering device.

Upon actuation of the triggering device the cartridge 18 is exploded and the explosive force passes through the bore 20 to the conical recess 22. Thereafter part of the force is transmitted via the central bore 32 and either the angled bores 34 within the plug 28 or through the constriction of the barrel to act upon the upper surface of the piston 50 as indicated by the arrows A, and so propel the column of water contained within the cylinder 4 out of that cylinder, removing the cap 48 during its passage. The water is thus projected through the casing of the bomb to dearm the firing mechanism.

Simultaneously, part of the force of the explosive charge is diverted via the passageway formed between the conical recess 22 and the tapered neck 30 of the plug 28 to act on the underside of the pistons 44 as indicated by the arrows B and propel the water contained within the cylinders 14 upwardly out of those cylinders, removing the caps 46 as the water leaves the cylinders.

In the alterntive embodiment shown in Figure 6, on firing of the cartridge the explosive force passes through the constriction 20 and expands into the chamber 21 at the top of the barrel forcing the plug downwards expelling water in cylinder 4 through the mouth of the cylinder capped by end cap 48. The explosive force of the water expelled in this manner is sufficient to disrupt or dearm a firing mechanism of a bomb. The chamber 21 also causes the explosive force to be diverted through the channels 32 into the cylinders 14 expelling pistons 44 and the water contained in the chamber in an opposite direction to the main thrust of the disarmer. In this manner it is possible to re-direct the explosive forces from the cartridge such that they are balanced resulting in a dearmer/disruptor which is recoilless or substantially recoilless.

When a projectile barrel is fitted the explosive force is applied directly to the projectile. To operate the dearmer in this mode projectile barrel shown in Figure 6 is fitted to reaction absorbing device 6. A projectile is forced into the barrel by a loading tool such that it abuts the constriction in the barrel. On firing the explosive charge forces the projectile from the barrel whilst at the same time causing a reverse reaction to discharge water from the cylinders 14 upwardly and out of the cylinder as previously described. Recoil of the device is thereby avoided or is substantially reduced.

It is found that the arrangement described is effective in considerably reducing the recoil to the extent that little or no reverse reaction is transmitted to the dearmer as it is fired.

Although the cylinder 4 in the barrel 2 is shown as being truly cylindrical it may be tapered, its diameter reducing from the end nearer the plug 28 towards its outermost end.

Furthermore, although two cylinders 14 are shown in the drawings as part of the reaction absorbing device, more than two such cylinder may be provided, or an annular water jacket may surround the breech.

Although the plug 28 is described as having three angled bores 34 in order to spread the explosive force across the surface of the piston 50, there could nevertheless be one straight bore 32 formed axially within the plug. Alternatively that bore may be formed bell-mouthed or tapered outwardly as it approaches its lower face.

Claims

CLAIM8

1. A dearming device having a reduced recoil, and comprising a barrel for a projectile, a breech adapted to contain an explosive charge, at least one reverse thrusting cylinder capable of containing fluid, explosive force directing means located between the breech and the said barrel, the explosive force directing means being such as to direct the explosive force to act simultaneously on the projectile and in the reverse thrusting cylinder or cylinders in order to simultaneously propel the projectile from the barrel and to reduce the recoil of the device.

2. A device as claimed in claim 1 in which the breech communicates with the explosive force directing means by way of a restricted passage.

3. A device as claimed in either claim 1 or claim 2 in which the explosive force directing means comprises a chamber communicating with the breech, first passage means communicating from said chamber with the or each reverse thrusting cylinder and second passage means communicating from said chamber with the barrel.

4. A device as claimed in claim 3 when appendant on claim 2 in which the restricted passage is disposed between the breech and the chamber.

5. A device as claimed in any one of the preceding claims in which fluid in the or each reverse thrusting cylinder is retained between a plug in the cylinder and a cap for the cylinder, said plug being displaceable in its cylinder in response to the explosive force directed thereto by the force directing means, said displacement of the plug serving to expel the fluid and the cap from the cylinder.

6. A device as claimed in any one of the preceding claims in which the breech and the or each reverse thrusting cylinder are provided in a reaction absorbing device from which the barrel extends longitudinally with its bore in alignment with the breech.

7. A device as claimed in claim 6 in which the barrel is removable from the reaction absorbing device for fitting a replacement barrel to accommodate a different projectile.

8. A device as claimed in either claim 6 or claim 7 in which the breech extends longitudinally and is formed by a central portion in the reaction absorbing device, and the or each reverse thrusting cylinder extends longitudinally adjacent to the central portion.

9. A device as claimed in claim 8 and having a single reverse thrusting cylinder of substantially annular form, said central portion being located substantially centrally of the annular form and co-axial therewith.

10. A device as claimed in claim 8 and having at least two reverse thrusting cylinders spaced about the periphery of the central portion.

11. A device as claimed in claim 10 in which two reverse thrusting cylinders are provided with the central portion disposed between said two cylinders so that respective longitudinal axes of the reverse thrusting cylinders and of the breech are co-planar.

12. A device as claimed in any one of claims 6 to 11 in which the explosive force directing means comprises a force directing plug located between the breech and the barrel.

13. A device as claimed in claim 12 in which said force directing plug presents a surface to the breech for directing a portion of the explosive force to the or each reverse thrusting cylinder and has channel means through which a further portion of the explosive force is directed to the barrel for propelling the projectile.

14. A device as claimed in claim 13 in which the force directing plug has its said surface substantially frusto conical and is received with clearance in a corresponding frusto conical recess which communicates with the breech.

15. A device as claimed in either claim 13 or claim 14 in which the channel means of the force directing plug causes said further portion of the explosive force passing therethrough to diverge as it approaches the barrel.

16. A device as claimed in any one of claims 12 to 15 when appendant to claim 7 in which the force directing plug is located and secured by a flange thereof being clamped between an end of the barrel and part of the reaction absorbing device.

17. A device as claimed in any one of the preceding claims in which the barrel has a substantially cylindrical bore.

18. A device as claimed in any one of claims 1 to 16 in which the barrel has a bore which tapers longitudinally to converge as it recedes from the breech.

19. A device as claimed in any one of the preceding claims in which the projectile comprises or is to comprise a fluid retained in the barrel between a piston in the bore thereof and a cap for the bore, said piston being displaceable in the bore in response to the explosive force directed thereto by the force directing means, said displacement of the piston serving to project the fluid and the cap from the barrel.

20. A device as claimed in any one of claims 1 to 18 in combination with a solid projectile.

21. A device as claimed in claim 20 in which the projectile comprises a plain slug, a chisel shaped slug, a blade or a forked blade.

22. A dearming device substantially as herein described with reference to Figures 1 to 5 and 7 of the accompanying illustrative drawings.

23. A device as claimed in claim 22 and modified substantially as herein described with reference to Figure 6 of the accompanying illustrative drawings.

Amendments to the claims have been filed as follows 1. A dearming device having a reduced recoil, and comprising a barrel for a projectile, a breech adapted to contain an explosive charge and having a single outlet end through which an explosive force from said charge is to be directed for propelling the projectile, at least one reverse thrusting cylinder capable of containing fluid, explosive force directing means located between said outlet end of the breech and the said barrel, the explosive force directing means being such as to direct the explosive force emanating from said outlet end to act simultaneously on the projectile and in the reverse thrusting cylinder or cylinders in order to simultaneously propel the projectile from the barrel and to reduce the recoil of the device.

5. A device as claimed in any one of the preceding claims in which fluid in the or each reverse thrusting cylinder is retained between a piston in the cylinder and a cap for the cylinder, said piston being displaceable in its cylinder in response to the explosive force directed thereto by the force directing means, said displacement of the piston serving to expel the fluid and the cap from the cylinder.

8. A device as claimed in either claim 6 cr claim 7 in which the breech extends longitudinally and is formed by a central portion in the reaction absorbing device, and the or each reverse thrusting cylinder extends longitudinally adjacent to the central portion.

12. A device as claimed in any one of claims 6 to 11 in which the explosive force directing means comprises a force directing plug located between the outlet end of the breech and the barrel.

13. A device as claimed in claim 12 in which said force directing plug presents a surface to the outlet end of the breech for directing a portion of the explosive force to the or each reverse thrusting cylinder and has channel means through which a further portion of the explosive force is directed to the barrel for propelling the projectile.