GB1604011A

GB1604011A - Mine-clearing devices

Info

Publication number: GB1604011A
Application number: GB1669873A
Authority: GB
Original assignee: Forces Armees Francaises
Current assignee: Forces Armees Francaises
Priority date: 1972-04-06
Filing date: 1973-04-06
Publication date: 1981-12-02

Description

(54) MINE-CLEARING DEVICES (71) We, ETAT FRANCAIS, represented by the Minister of State in charge of National Defence, DELEGATION MINISTERIELLE POUR L'ARMEMENTS, DIRECTION TECHNIQUE DES ARMEMENTS TERRESTRES (Etablissement d'Etudes et de Fabrications d'Armement de BOURGES), of 10 rue Saint-Dominique-75 PARIS 7e, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to mine-clearing devices.

According to the invention there is provided a mine clearing device comprising: a string in the form of a cable wound on a drum from which it can be freely unwound, the string comprising a plurality of explosive charges disposed at intervals along the cable, propelling means attached to the free end of the cable and which, when launched, unwinds the cable to spread it in a line over a section of terrain, electrical conductor means passing along the length of the cable and control means having the triple function of launching the propelling means and arming and firing the explosive charges.

The string or cable can be stored in a flexed state in a vehicle, for example a tank or other combat vehicle, and extended from the vehicle across a region of an anti-tank mine field. The explosive charges of the device can then be exploded. The resulting shock waves will destroy conventional mines provided with instantaneous pressure-sensitive fuses. The device could be designed to clear, for example, a path about 100 metres long and several metres wide in a mine-field laid with mines comprising pressure-operated fuses.

The device could also be used to clear vertical-action anti-tank mines operated by direct contact and which are laid on top of the ground or buried under a few centimetres of earth, and horizontal- action anti-tank mines operable by triggering by means of a contact-operated fuse.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 schematically shows the unwinding operation of a device according to the invention; Figure 2 is a cross-sectional view of the device of Figure 1 before it is launched; Figure 3 is an axial cross-sectional view of one of the explosive charges forming part of the device shown in Figures 1 and 2; and Figure 4 is an enlarged cross-sectional view in the direction A-A of Figure 3.

Figure 1 shows a mine-clearing device being launched, the device before launching being carried by a vehicle 1 which is preferably armoured and specially equipped, the launching of the mine-clearing device being remotely controlled from the vehicle 1.

Figure 2 shows the mounting of the mineclearing device in the vehicle 1 and shows that the device is launched from a rotatable drum 2 about which is wound cable 3. Blasteffect explosive charges 4 are distributed along cable 3 at equal distances apart. One end (not shown) of the cable 3 is secured to the carrier vehicle 1 by means of a shock absorber, whilst the other end is connected by a resilient link to a conventional type propulsion unit 5 in the form of a solid-fuel rocket for example. The guidance of the propulsion unit 5 is effected by a launching ramp 6.

The propulsion unit 5 may be a single unit, or it may consist of paired propulsion units whose nozzles diverge and a thrust (pressure) balancing system to improve its stability in flight. By way of non-limiting example, a propulsion unit developing a 10 kilonewton (kn) thrust for an operating time of a few or several seconds may be used.

The carrier vehicle I can be provided with several demining devices such as the one shown in Figure 2, each device being ready for use.

The function of cable 3 is threefold in that it physically interconnects the explosive charges 4, in association with the projectile means enables the charges to the emplaced at intervals over a minefield and, in addition, supports or provides electrical wires used for the transmission of arming and wiring control signals to the charges 4. The cable 3 preferably has a generally coaxial structure and comprises: firstly, a centre core made of steel wires and forming a reinforcement; secondly, a flexible insulating sheath covering the core; thirdly, a flexible tubular metal braid (generally copper); and fourthly, an insulating coating providing external protection for the cable 3.

The explosive charges 4 are usually spherical in shape, and are preferably identical and equally spaced along the cable 3, for example at intervals of several or a few metres. These intervals obviously depend on the energy and shape of the explosive charges 4 and are such that the detonation wave fronts produced by the charges will de-mine effectively the whole of an area to be cleared of mines.

Figure 3 shows that each blast-effect demining charge comprises a main charge 7 arranged to be detonated by a priming charge or delay 8 which is itself fired by an electrical detonating fuse 9.

The explosive composition constituting the main charge 7 must combine a high blast effect at the time of detonation with an outstanding shock resistance. There are therefore employed elastomer-bound explosive charges, the binding providing the charge coherence and resistance. Improvement of the blast effect is obtained by preferably selecting compositions which contain aluminium powder.

By way of mon-limiting example the following composition has given good results when used for the main charge 7; Hexogen or pentrite; 60--704b by weight; Aluminium powder; 2F10% by weight; Polyurethane; 20% by weight.

The main charge may have an approximate weight of several kilograms, but the main charge may also be made by premoulding in two parts. After moulding, the parts are then assembled on to the cable by adhesive bonding, the firing system being retained between the two parts. In this case, the two explosive charge parts are preferably moulded onto the sheath of the cable 3, which sheath is preferably formed of a reinforced elastomeric material.

The system for firing the main charge is fixed to a sleeve and is clipped, or is maintained on the cable by clamping, and is electrically connected to the cable. In one embodiment, the main-charge firing system is first placed in position on the cable 3 and, after the priming charge 8 has been fitted, the main charge 7 is moulded onto the firing system, which forms a skeleton for the main charge 7.

The firing of the main charge 7 is effected by means of the priming charge 8 which is generally made of plastics-bound explosive such as hexogen/polyvinyl acetate or octo gen-"NYLON" mixture.

The firing system includes an electric detonating fuse 9 of conventional design, for example of the wire type, which is loaded with lead oxide and pentrite. requiring a minimum operating energy of about 2 millijoules (mJ). This use is initially disconnected and misaligned in the safety position; the fuse-carrying slide 10 is held in its safety position by a blade 11. The arming of the charge is effected by means of an electropyrotechnical actuator 12 of known design. for example having a force of about 10 decanewtons (daN); this actuator 12 is controlled by an electrical signal issued from a control station located in the carrier vehicle 1. The current value of the electrical signal is, say, about I ampere for a few or several microseconds. The energising of actuator 12 causes the blade 11 to tilt.Under the action of spring 13 the fuse-carrier 10 is then free to move to the bottom of its recess and pins 14 of the fuse then penetrate the corresponding sockets. The detonating fuse is then positioned adjacent the explosive of the priming relay 8.

A mine-clearing operation can be performed in the following sequence: a deployment of the mine clearing device along the ground, by applying an electrical signal to the propulsion unit igniter through one wire of the cable 3, thus causing the propulsion unit to be launched; b arming of the explosive charges, by an electrical signal which allows displacement of the fuse carrying slide 10 from its initial position to the base of its recess when it is in a position opposite to the explosive of the priming charge, which signal is applied to another wire of the carrier cable 3; and c simultaneous firing of the charges by an electrical signal transmitted along the same wire as used for the arming signal.

Steps b and c of the preceding sequence can be automatically performed by a suitable signal generator.

It is possible to use different signals for different purposes, notably the use of a DC arming signal followed by an AC firing signal, the two types of signal being separated by means of a capacitor at each explosive charge. Alternatively, two DC signals or pulses with opposed polarities could be used, there being a diode suitably connected in the electrical circuit of each detonating fuse.

For obvious safety reasons steps b and c of the foregoing sequence should only take place after the cable has been satisfactorily spread out over the area to be cleared of mines.

WHAT WE CLAIM IS: 1. A mine clearing device comprising: a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. at intervals over a minefield and, in addition, supports or provides electrical wires used for the transmission of arming and wiring control signals to the charges 4. The cable 3 preferably has a generally coaxial structure and comprises: firstly, a centre core made of steel wires and forming a reinforcement; secondly, a flexible insulating sheath covering the core; thirdly, a flexible tubular metal braid (generally copper); and fourthly, an insulating coating providing external protection for the cable 3. The explosive charges 4 are usually spherical in shape, and are preferably identical and equally spaced along the cable 3, for example at intervals of several or a few metres. These intervals obviously depend on the energy and shape of the explosive charges 4 and are such that the detonation wave fronts produced by the charges will de-mine effectively the whole of an area to be cleared of mines. Figure 3 shows that each blast-effect demining charge comprises a main charge 7 arranged to be detonated by a priming charge or delay 8 which is itself fired by an electrical detonating fuse 9. The explosive composition constituting the main charge 7 must combine a high blast effect at the time of detonation with an outstanding shock resistance. There are therefore employed elastomer-bound explosive charges, the binding providing the charge coherence and resistance. Improvement of the blast effect is obtained by preferably selecting compositions which contain aluminium powder. By way of mon-limiting example the following composition has given good results when used for the main charge 7; Hexogen or pentrite; 60--704b by weight; Aluminium powder; 2F10% by weight; Polyurethane; 20% by weight. The main charge may have an approximate weight of several kilograms, but the main charge may also be made by premoulding in two parts. After moulding, the parts are then assembled on to the cable by adhesive bonding, the firing system being retained between the two parts. In this case, the two explosive charge parts are preferably moulded onto the sheath of the cable 3, which sheath is preferably formed of a reinforced elastomeric material. The system for firing the main charge is fixed to a sleeve and is clipped, or is maintained on the cable by clamping, and is electrically connected to the cable. In one embodiment, the main-charge firing system is first placed in position on the cable 3 and, after the priming charge 8 has been fitted, the main charge 7 is moulded onto the firing system, which forms a skeleton for the main charge 7. The firing of the main charge 7 is effected by means of the priming charge 8 which is generally made of plastics-bound explosive such as hexogen/polyvinyl acetate or octo gen-"NYLON" mixture. The firing system includes an electric detonating fuse 9 of conventional design, for example of the wire type, which is loaded with lead oxide and pentrite. requiring a minimum operating energy of about 2 millijoules (mJ). This use is initially disconnected and misaligned in the safety position; the fuse-carrying slide 10 is held in its safety position by a blade 11. The arming of the charge is effected by means of an electropyrotechnical actuator 12 of known design. for example having a force of about 10 decanewtons (daN); this actuator 12 is controlled by an electrical signal issued from a control station located in the carrier vehicle 1. The current value of the electrical signal is, say, about I ampere for a few or several microseconds. The energising of actuator 12 causes the blade 11 to tilt.Under the action of spring 13 the fuse-carrier 10 is then free to move to the bottom of its recess and pins 14 of the fuse then penetrate the corresponding sockets. The detonating fuse is then positioned adjacent the explosive of the priming relay 8. A mine-clearing operation can be performed in the following sequence: a deployment of the mine clearing device along the ground, by applying an electrical signal to the propulsion unit igniter through one wire of the cable 3, thus causing the propulsion unit to be launched; b arming of the explosive charges, by an electrical signal which allows displacement of the fuse carrying slide 10 from its initial position to the base of its recess when it is in a position opposite to the explosive of the priming charge, which signal is applied to another wire of the carrier cable 3; and c simultaneous firing of the charges by an electrical signal transmitted along the same wire as used for the arming signal. Steps b and c of the preceding sequence can be automatically performed by a suitable signal generator. It is possible to use different signals for different purposes, notably the use of a DC arming signal followed by an AC firing signal, the two types of signal being separated by means of a capacitor at each explosive charge. Alternatively, two DC signals or pulses with opposed polarities could be used, there being a diode suitably connected in the electrical circuit of each detonating fuse. For obvious safety reasons steps b and c of the foregoing sequence should only take place after the cable has been satisfactorily spread out over the area to be cleared of mines. WHAT WE CLAIM IS:

1. A mine clearing device comprising: a

string in the form of a cable wound on a drum from which it can be freely unwound, the string comprising a plurality of explosive charges disposed at intervals along the cable, propelling means attached to the free end of the cable and which, when launched, unwinds the cable to spread it in a line over a section of terrain, electrical conductor means passing along the length of the cable and control means having the triple function of launching the propelling means and arming and firing the explosive charges.

2. A device according to claim 1, and comprising storage means for storing the cable in a flexed state, the propelling means being operable to project one end of the cable away from said storage means to cause the unwinding of the cable.

3. A device according to claim 2, wherein said storage means comprises a rotatable drum about which the cable is wound when in its flexed state.

4. A device according to any one of the preceding claims wherein said conductor means are disposed within said cable.

5. A device according to claim 4, wherein the cable in which conductor means for effecting each of said triple functions are disposed is a coaxial cable.

6. A device according to claim 4 or 5, wherein said cable has a sheath of reinforced elastomeric material.

7. A device according to any one of the preceding claims, wherein each of said charges comprises a main charge and a priming charge, each main charge consisting of explosive having an elastomeric binder.

8. A device according to claim 7, wherein each of said charges further comprises an electric detonating fuse for detonating the priming charge, and an electropyrotechnical actuator operable to arm the detonating fuse.

9. A device as claimed in claim 8, when appended directly or indirectly to claim 5, wherein the cable comprises one conductor means for use in launching of the propelling means and a second conductor means for transmitting signals for the arming and for the firing of the explosive charges.

10. A device according to claim 8 or 9, when appended to claim 6, wherein each main charge is moulded onto the cable sheath.

11. A device according to any one of claims 7 to 10, wherein said main charges are substantially spherical.

12. A device according to any one of the preceding claims, wherein the explosive charges are identical and are spaced at equal distances apart in the chain.

13. A device according to any one of the preceding claims, wherein said propelling means comprises a solid-fuel rocket.

14. A device according to claim 13.

wherein the rocket comprises paired solid fuel rocket portions whose nozzles diverge and a thrust-balancing system.

15. A mine-clearing device according to any one of the preceding claims, when carried by a vehicle from which the propelling means can be projected.

16. A mine-clearing device substantially as hereinbefore described with reference to, and as shown in, Figures 2, 3 and 4 of the accompanying drawings.