GB2400163A

GB2400163A - Pyrotechnic device for in-situ disposal of unfired ordnance

Info

Publication number: GB2400163A
Application number: GB0403801A
Authority: GB
Inventors: Ernst-Christian Koch
Original assignee: Diehl Munitionssysteme GmbH and Co KG
Current assignee: Diehl BGT Defence GmbH and Co KG
Priority date: 2003-02-22
Filing date: 2004-02-20
Publication date: 2004-10-06
Anticipated expiration: 2024-02-20
Also published as: GB0403801D0; DE10307639B3; GB2400163B

Abstract

A pyrotechnic device 7 is disclosed for in-situ disposal of unfired ordnance containing an explosive charge in a casing. The method of disposal involves melting or burning the casing of the ordnance firstly by means of a first gas jet 9 generated by a first pyrotechnic propelling charge 3. The casing 10 is then perforated by means of a second gas jet 11 which is rich in oxidising substances, generated by a second pyrotechnic propelling charge 4. The explosive charge is thereby brought to deflagration or to combustion.

Description

24001 63 Method and device for in-situ disposal of unfiecd ordnance The

invention relates to a method and a device for in-situ disposal of unfired ordnance, containing an explosive charge in a casing.

On today's battlefields and on the battlefields of the past, there continues to be a permanent risk to personnel from untired, i.e. unexploded ordnance (UXO). This ordnance consists of the warheads of ballistic weapons and of army engineer ordnance, for example m.'ipersoruel and arti-!anlc mines. Mines in particular pose the greatest potential risk, since these are not easily detected. Also, in the development of many mines, safety devices were developed against retrieval or clearance, which make sate disposal and disassembly effectively impossible. For this reason, it is necessary to destroy such unfired ordnance in-situ, i.e. to destroy it without any further manipulation of the ordnance itself, since any movement of the ordnance could lead to the triggering of its explosive train.

A variety of methods have been proposed for the disposal of unfired ordnance: In one method, the ordnance is fired by intonation, by inserting or imposing a, usually plastic, explosive. This leads to problems, since firstly the firing by detonation, especially when it comes to larger ordnance, is accompanied by considerable risks due to pressure waves and generation of shrapnel. Secondly, it is also disadvantageous that the disposal of mines using means of explosive force inuposes particular demands on logistics, since lhcsc means usually have to be transported by air.

In other methods, the unfired ordnance is shot at with special hollow charges.

Often this merely cracks open the casing: of the ordnance and the explosive charge is only partly fired by detonation. Another disadvantage of this method is the need to transport explosive material, i.e. the hollow charges, to the battlefield.

A further method consists in shooting the unfired ordnance with rifle ordnance and subsequent injection ol' a hypergol substance reacting with the explosive, which leads to a controlled combustion of the explosive material without detonation. This is described by D. L. Patel et al. in 'In-situ Landmine Neutralization Using Chemicals to initiate low order burning of main charge", 2903 Int. Pyrotechnics Seminar, Westminster, Colorado, USA, pp. 463-475, 14- 19.07.2002. This method requires an expensive construction of the device in order to perfonn the procedure, which --- especially in the ease of mass deploy;ne;it - leads to high costs.

Torches have also been developed which release hot particles from the alloy reaction of nickel and aluminium through a clay nozzle and in this way erode metallic ordnance easings and, as the result of the heat, cause denagration or combustion of the explosive. Such a method is described in A. E. Cardell, T. 'l'.

Griff'iths, Pyrotechnic 'I'orehes for safe disposal of mines, 270' Int. Pyrotechnics Seminar, Grand Junelion, Colorado, USA, pp. 567-570, 16-21. 07.2000. This method is disadvantageous because it is ineffective when the unfired ordnance has thick casings, since these cannot be melted. This method is also disadvantageous for easings made Prom wood, since wood cannot be sufficiently perforated by the impact of the fused alloy particles and further combustion and progression of the locally-limited thermal effect is prevented by the spread of carbonization. A further disadvantage of this method consists in the release of toxic nickel vapours during the combustion, in addition lo the need to work with nickel dust while labouring.

DE 199 64 172 Al describes a pyrotechnic composition for generating 111 rays.

I'hc problem of the invention is to propose a method and a device in which the above disadvantages either do not occur or arc reduced.

The problem with respect to the method is solved by the characteristics of claim 1 and with respect to the device by the characteristics of claim 4.

I'hc method described and the device described are equally suitable for the explosion ol' ordnance with casings made of metal, wood, plastic or combined materials. 'I'hus there is no need to provide different devices for the respective instances of deployment.

Since tale method and the device work only with pyrotechnic propelling charges, i.e. no cxpiosives, 'me i.npleAe.=Ata'.ion of She.metilod Hind the logistics and tile construction of the device are simplified.

The method and the device can also be used to fire ordnance with very thick casings, without there being any detonation of the explosive in the ordnance.

In the first slop, the casing is heated strongly by means of the gas jet from the first pyrotechnic propelling charge specifically at a flame temperature of > 3000 K, specifically > 3500 K. The metal casing is thereby melted or the wooden casing starts to incandesce. In the following, second step, the metal casing is oxidised in a strong exothennic reaction by the second gas jet generated by the second propelling charge, while the reaction heat guarantees a further fluidification of the metal casing. A wooden casing is briskly burnt off in the oxidising gas jet.

The ordnance casing thus perforated guarantees that ultimately the explosive charge is brought to combustion or dcflagration without any detonation occurring.

The first propelling charge is advantageously a composition as described in DE 199 64 172 Al. Such a composition is distinguished by the fact that it contains, as oxidant, between 10-85 /o poly-carbon monotluoride, as fuel between 15-90% of a halophilic metallic fuel Irom the group of metals magnesium aluminium, titanium, zirconium, hafnium, calcium, beryllium, boron or mixtures or alloys of these metals, an organic binder containing fluoride with a percentage by mass of between 2.5 and 7.5% together with graphite with a percentage by mass of 0.1 to 5%. Advantageously a composition is used in which the stoicliometric ratio of magnesium to graphite is approximately 0.28:0.72.

The second propelling charge is advantageously a composition which releases oxidising substances such as oxygen, chlorine, fluorine or oxidising compounds of these elements. The second propelling charge can contain lithium perchlorate, lithium chloride and a metal powder.

Particles in the first uld/or second gas jet improve its effect. Particles in the second propelling charge earl enhance the perforation of the casing.

The drawings show: Fig. I a schematic longitudinal section of a pyrotechnic device, Fig. 2-4 the method involving a metal casing and Figs. 5 - 7 the mcthotl involving a wooden casing. s

The pyrotechnic device 7, which can be rcLerred to as a linear cutter, consists of a tubular container 1, in which are disposed, one behind the other: an igniter 2, a first propelling charge 3 and a second propelling charge 4. On the back, the container I is provided with a gas-tight closure 5 (cf. Fig. l).

If a metal-cased mine 6 is to be converted, then the device 7 is ignited and aimed at the metal casing 10 of the mine 6 (cf. Fig. 2). Firstly the first propelling charge 3 generates a first gas jet as a high temperature flame 9 with a flame temperature of > 3500 K. This results in the creation on the casing 10 of a zone of melted metal 8 (cf. Fig. 3).

Following the combustion of the first propelling charge 3, the second propelling charge 4 burns and gcocratcs a second gas jet which acts as an oxidising jet of gas and particles 11 or eroding jet respectively. This oxidises a cavity 12 in the casing 10, with metal oxide particles 13 being flung old' (cf. I<ig. 4). In the continuation of this action the casing 10 becomes perforated and the explosive charge behind it made from explosive material is easily brought to combustion or to dellagration.

If a mine 14 with a wooden casing is to be fired, the device 7 is ignited and aimed at the wooden casing 15 of the mine 14 (cf. Fig. 5). The first propelling charge 3, as the result of its high temperature flame 9, leads to the combustion or incandescence of the wooden casing 15, creating a zone of incandescent wood (cf. Fig. 6). In the following jet of oxidising gas and particles I 1, a cavity 17 is burnt away and ash particles 18 are flung off (cf. Fig. 7). After that, the explosive charge is brought to combustion or to deflagration rcspectivcly.

Claims

Claims I. Method for in-situ disposal of unfired ordnance, containing an

explosive charge in a casing, characterised in that the casing (10, 15) is initially melted or burnt by means of a first gas jet (9) generated by a first pyrotechnic propelling charge (3), that the casing (10, 15) is then perforated by means of a second gas jet (11) which is rich in oxidising substances, generated by a second pyrotechnic propelling charge (4) and thereby the explosive charge is brought to deflagration or to combustion.
2. Method according to claim 1, characterized in that a temperature of > 3000 K, specifically > 3500 K, is generated by the first pyrotechnic propelling charge (3).
3. Mc;hod accor ':ng to clair,, I or 2, characterized in that the first gas jet (9) and/or the second gas jet (11) contain(s) particles.
4. Device for in-situ disposal of unfurl ordnance, containing an explosive charge in a casing, characterized in that a first pyrotechnic propelling charge (3) and a second pyrotechnic propelling charge (4) are arranged one behind the other in a container (1), with the first pyrotechnic propelling charge (3) being capable of generating a gas jet which melts or burns the casing ( 10, I S) and the second pyrotechnic propelling charge (4) is capable of perforating the casing (10, 15) and of bringing the explosive charge to leDagration or to combustion.

S. Device according to claim 4, characterized in that in the first pyrotechnic propelling charge (3) there are contained as oxidation means between 10-X5% poly-carbon monoiluoride, as fuel between 15-90% of a halophilic metallic fuel from the group of metals magnesium aluminium, titanium, zirconium, hafnium, calcium, beryllium, boron or mixtures or alloys of these metals, an organic binder containing fluoride with a percentage by mass of between 2.
5 and 7.5% together with graphite with a percentage by mass of 0.1 to 5%.
6. Device according to claim 5, characterized in that in the first pyrotechnic propelling charge (3) tle ratio of magnesium to graphite is approximately 0.2X:0.72.
7. Device according to one of the preceding claims 4 to 6, characterized in that the second p-yToiecu,ic propclli;.g charge (4) releases oxidising substances which react exothennically with the melted or burnt casing ( 10, 15).
8. Device according to claim 7 characterized in that the second pyrotechnic propelling charge (4) releases oxygen, chlorine, fluorine or oxidising compounds of these elements.
9. Device according to claim 7 or 8 characteriscd in that the second pyrotechnic propelling charge (4) contains lithium pcrchlorate, lithium chloride and a meta] powder As oxygen-yielding composition.
10. A device for in-situ disposal of unfired ordnances containing an explosive charge in a casing as substantially described herein with reference to figures 1-7.
11. A device for in-situ disposal of unfired ordnance, containing an explosive charge in a metal casing as substantially described herein with reference to figures 2-4.
12. A method for in-situ disposal of unfired ordnance, containing an explosive charge in a wooden easing as substantially described herein with reference to figures 5-7.