EP3064889A1 - Bi-component explosive artillery shell - Google Patents

Abstract

The invention relates to a two-component explosive artillery shell (1) comprising an envelope (2) containing at least two non-explosive materials (3,4) but which, after mixing, form an explosive composition. This shell is characterized in that it comprises at least one container (8) integral with the envelope (2) and disposed coaxially therewith, the container delimiting an internal cavity containing a first material (3) in liquid or gelled form container, the wall of which is pierced with a plurality of orifices (15) which are closed by a closure means (16), the container or containers (8) delimiting with the envelope an annular space which encloses a second material (4) in solid and porous form, the closure means (16) being capable of opening during firing to allow diffusion by centrifugal effect of the first material (3) in the second material (4) through the porosity of the latter.

Description

The technical field of the invention is that of explosive artillery shells and in particular that of two-component explosive shells.

Conventionally, explosive shells contain an explosive charge comprising a fusible explosive such as trinitrotoluene (TNT) combined with one or more complementary grains explosives such as hexogen (RDX) or oxynitrotriazole (ONTA).

The explosive in a classic way is initiated on trajectory or impact by a rocket.

When the rocket does not work, the shells remain on the ground in an unexploded state and constitute a danger. They can indeed be reused by enemies in the form of improvised explosive devices.

To mitigate this risk, it is desirable to define a shell whose loading can be neutralized automatically after a certain period in case of non-initiation.

Two-component explosives have long been known. Each component is itself non-explosive, that is to say that the implementation of a detonator can not cause its detonation. On the other hand, the mixture of the two materials is explosive and can be detonated by the action of a suitable detonator.

The patent US4253889 thus describes two-component explosives that are used for mines and quarries. Both components are mixed by an operator before use, which allows components to be stored that are individually safe.

It is also known that these two-component explosives can be made inert by the action of particular additives. The patent FR2289472 thus describes a liquid explosive composition based on nitromethane which is sterilizes after a few hours when mixed with diethylenetriamine.

However, there is no known concrete implementation of such two-component explosives in shells or projectiles.

The patent FR994041 describes two-component explosive bombs or projectiles. However, these projectiles use liquid materials that are mixed on the trajectory. It is necessary to break the envelope containing one of the materials to mix with the other material. The fragile envelope is for example made of glass or ceramic. Such an architecture is complex and expensive.

In addition, a liquid explosive charge is not suitable for a shot projectile by gun effect, given the vortex effects that may occur on the liquid loading, effects reducing the stability of the projectile in ballistic flight.

We know by the patent WO2010 / 044716 a projectile which can contain several charges having different effects. This document specifies that it is possible to combine a liquid oxidizing material placed in an axial container and a fuel in porous form. The axial container also contains an initiation means in the form of strands extending longitudinally over the entire container. With such a projectile, the axial inertia forces exerted when firing on the liquid material will cause premature rupture, at the rear of the container, the plastic films closing the radial holes of the container. The reaction between the components will then occur within the barrel of the weapon, before the spinning of the projectile, and in a non-homogeneous manner, the films breaking only at the rear of the container.

It is the object of the invention to provide a two-component artillery shell which is simple in design, inexpensive, reliable operation and ensures a shot without ballistic disturbances.

The invention thus makes it possible to define a shell which does not contain products considered individually as explosives. This results in increased security for the transport and logistics phases.

According to a particular embodiment, the invention also makes it possible to define an artillery shell whose explosive charge can be sterilized after a certain period of time in the event of non-explosion on a target.

Thus the invention relates to a two-component explosive artillery shell comprising an envelope containing at least two non-explosive materials but which after mixing form an explosive composition, shells comprising at least one container integral with the envelope and arranged coaxially with the envelope. ci, container delimiting an internal cavity containing a first material in liquid or gelled form, container whose wall is pierced with a plurality of orifices which are closed by a closure means, the container or containers delimiting with the envelope a annular space which encloses a second material in solid and porous form, the closure means being able to open during the firing to allow diffusion by centrifugal effect of the first material in the second material through the porosity of the latter, characterized in that it comprises at least one stack of axially aligned containers which are connected to one another, each container is and separated from its neighbors by at least one transverse wall, or in that it comprises a single cylindrical container extending axially over the entire height of the second material, this container being compartmentalized and having partitions transversal dividing its internal volume into several chambers.

According to a particular embodiment, the closure means may be constituted by at least one sheet integral with the wall, the sheet may break during firing to let the first material.

The container or containers may be cylindrical or frustoconical.

According to another embodiment, the shell may comprise at least two cylindrical containers of different diameters succeeding one another along the axis of the shell.

Advantageously, the containers may be positioned relative to the envelope by at least one radial wedge.

The second material may comprise at least one oxidant, such as potassium perchlorate, ammonium perchlorate, ammonium nitrate, or potassium nitrate.

The first material may comprise at least one nitro aliphatic hydrocarbon, such as nitromethane or nitroethane.

According to a particular embodiment, the shell may include at least one sterilization material of the first material.

The sterilization material may comprise at least one of the following materials: ethylene diamine, diethylene triamine.

Advantageously, the sterilization material may be placed in at least one housing.

• La figure 1 est une vue en coupe longitudinale d'un obus selon un premier mode de réalisation de l'invention, conteneur axial non coupé ;
• La figure 2 est une vue analogue à la précédente mais montre le conteneur axial coupé ;
• La figure 3 est une vue en coupe longitudinale d'un obus selon un second mode de réalisation de l'invention, conteneur axial coupé ;
• Les figures 4a et 4b sont des vues schématiques de deux autres modes de réalisation d'un conteneur axial, la figure 4a montrant un conteneur en vue externe et la figure 4b un conteneur en coupe longitudinale ;
• La figure 5 est une vue schématique partielle d'un empilement de conteneurs incorporant un boîtier pour matériau de stérilisation.

The invention will be better understood on reading the following description of particular embodiments, a description given with reference to the accompanying drawings and in which:

• The figure 1 is a longitudinal sectional view of a shell according to a first embodiment of the invention, uncut axial container;
• The figure 2 is a view similar to the previous one but shows the axial container cut;
• The figure 3 is a longitudinal sectional view of a shell according to a second embodiment of the invention, cut axial container;
• The Figures 4a and 4b are schematic views of two other embodiments of an axial container, the figure 4a showing a container in external view and the figure 4b a container in longitudinal section;
• The figure 5 is a partial schematic view of a stack of containers incorporating a housing for sterilization material.

Referring to the figure 1 an explosive artillery shell 1 according to the invention comprises a casing 2 enclosing at least two non-explosive materials 3, 4 which, after mixing, form an explosive composition.

The envelope 2 here consists of two parts: a front portion 2a ogivée, and a cylindrical rear portion 2b. Such an arrangement is intended to facilitate the loading of the shell 1 with the materials 3 and 4.

The casing 2 is closed at its rear part by a base 5 which is fixed to the casing 2, for example by riveting.

The casing 2 carries at its front part a rocket 6 of a conventional type, for example a percussion rocket, proximity or chronometric.

It can be seen in the figures that the base 5 carries a device 7 which may be a device for reducing base drag (better known by the English name "base bleed"). The device 7 can simply to be a hollow pellet. This device does not form part of the invention.

According to the invention the shell 1 comprises at least one container 8 which is integral with the casing 2 and which is disposed coaxially therewith.

The shell 1 here comprises a stack of six containers 8 which are cylindrical and all have axis axis 9 of the shell 1.

All the containers 8 are of identical structure and, as we see more particularly on the figure 2b each comprises a tubular wall 8a delimiting an internal cavity 12 which encloses the first material 3, which is in a liquid or gelled form.

Each container 8 has a transverse wall or bottom 13 closed and is closed by a cover 14 which is screwed to the tubular wall 8a. The tubular wall 8a is pierced with a plurality of radial orifices 15 which are closed by a closure means.

According to the embodiment that is shown, the sealing means is constituted here by a sheet 16 integral with the tubular wall (for example glued to the wall 8a). The sheet will for example be a sheet 0.1 mm thick of a plastic material such as polyethylene.

The tubular wall 8a is extended at the rear of the container 8 by a cylindrical flange 8b which is housed on a cylindrical surface 14a of the plug 14 of a neighboring container. The container 8 which is located furthest behind the shell has its cylindrical flange 8b which is positioned in a circular groove 10 of the base 5 of the shell. Collet 8b and span 14a may carry threads and threads.

The groove 10 makes it possible to position the stack of containers radially with respect to the envelope 2 of the shell. The base 5 provides axial retention, this axial retention is completed by a ring 17 which is screwed to the mouth of the shell 1 and which also receives the rocket 6. The ring 17 abuts against the cap 14 of the container 8 most forward of the shell.

The stack of containers 8 is also positioned radially relative to the envelope 2 of the shell by two radial shims 11. The radial shims 11 will for example be made of plastic, for example polyamide.

They will advantageously have holes parallel to the axis 9 of the shell to facilitate the distribution of the liquid material 3 as will be explained later.

This embodiment of a stack of containers 8 all identical makes it easier to manufacture and integrate the shell. Moreover, the transverse walls or bottoms 13 and covers 14 form partitions which make it possible to isolate the material contained in each container 8 from that of neighboring containers. Such an arrangement makes it possible to reduce the influence on the first material 3 of the axial acceleration exerted during the firing.

This reduces the pressure differential that can appear inside a container 8 between the bottom 13 of the container and the part of the container near its cap 14.

Instead of having a single column of first liquid material that would be subjected to axial acceleration, there are here as many columns of the first material as there are containers and the pressure differential is the same within each container.

This also makes it possible to avoid premature rupture of the leaves 16 closing the orifices closest to the base 5 by the sole effect of the axial inertia. This results in a better reliability of operation. The rupture of the leaves does not intervene in fact asymmetrically and before rotation of the shell. A break as a result of the only axial inertia would lead to the premature mixing of the first material 3 with a second material 4 only at level of the rear part of the shell and into the barrel of the weapon.

The containers 8 delimit with the envelope 2 an annular space 18 which encloses a second material 4 in solid and porous form.

For example, the second material 4 may be made in the form of compressed annular blocks. The grain size of the constituent grains of the second material as well as the compressive forces will be chosen so as to ensure the desired porosity.

As we see on the figures 1 and 2a it will be possible for example to place in the cylindrical portion 2a of the casing 2 two annular blocks 4a and 4b separated by a shim 11. The stack of containers 8 will then be positioned in the axial channel of the annular blocks 4a, 4b.

A third block 4c of the second material 4, machined to the internal profile of the ogivée portion 2b of the envelope, will then be positioned in this ogivée part 2b. Then the ogivée portion 2b will be fixed to the cylindrical portion 2a of the casing 2 with the interposition of a second shim 11.

The first material 3 is a fuel, or fuel mixture in the liquid or gelled state. It may comprise at least one nitro aliphatic hydrocarbon, such as nitromethane or nitroethane.

It is possible to choose as a gelling agent the substances usually used in formulation, of mineral or organic origin, such as fumed silicas, natural or synthetic gums, polymers or any other substance of circumstance.

The first material 3 may comprise a sensitizer associated with the nitro aliphatic hydrocarbon. It will however be necessary that this sensitizer does not have the effect of sterilizing the hydrocarbon.

The second material 4 comprises at least one strong oxidant, ie a compound capable of giving oxygen to the reaction medium, such as potassium perchlorate, ammonium perchlorate, ammonium nitrate, or nitrate. of potassium. The grains of this material may be coated with a binder, for example an inert binder such as wax or an active binder such as DNAN (2,4-dinitroanisole) which is an insensitive explosive.

The binder will facilitate the compression molding of the blocks of the second material 4.

According to a particular embodiment, to allow the sterilization of the explosive material in case of ground impact without detonation, may be provided a sterilization material of the first material.

The sterilization material will comprise for example at least one of the following materials: ethylene diamine, diethylene triamine. These materials are liquid at the usual temperatures of use. The sterilization material will therefore be placed in a specific housing (not shown) which will isolate the first material 3 and which will be broken during firing.

This specific housing may for example be interposed between the ring 17 and the stack of containers 8.

Advantageously, and as represented at figure 5 , the sterilization material 24 can be put in place in at least one specific housing 25 which will be fixed to the stack of containers 8 containing the first material 3. This housing 25 will have the same diameter as the containers 8 and it will be equipped with a plug 26 and a bottom 27 similar to the plugs 14 and the transverse walls or bottoms 13 of the containers 8 (and it will eventually also thread and tapping to secure it to the containers).

The housing 25 can thus be positioned at any axial position on a stack of containers 8. example place it at the top of the stack, in the vicinity of the ring 17. It can also be positioned as shown on the figure 5 between two containers 8.

The housing 25 will carry orifices 28 which will be closed by a closure means which will be formed for example by the sheet 16 surrounding the stack of containers 8.

One or more housings 25 containing the sterilization material may be provided.

It is necessary to provide an amount of sterilization material which is about 5% of the total mass formed by the first material and the sterilization material.

This reduced quantity can be distributed in several boxes 25, the size of which will therefore be much smaller than that of the containers 8 enclosing the first material 3.

It may alternatively be grouped into a single larger-sized box (but smaller than that of a container 8).

Moreover, the dimensions of the containers 8 will be defined according to the relative volumes sought for the first material 3 and the second material 4. A configuration as shown in FIGS. figures 1 and 2a corresponds to a relative volume which is substantially 20% for the first material 3 and 80% for the second material 4. The porosity of the second material 4 is chosen to represent a volume sufficient to accommodate the first material. The air contained in the second material 4 will circulate within the porous blocks and it will eventually occupy the internal volume of the containers 8 after ejection of the first material. To facilitate the circulation of the first material 3, it may be provided to achieve a partial air gap in the shell during assembly.

The operation of this shell is as follows.

During the storage phases of the shell 1, the first and second materials 3 and 4 are isolated from one another. The shell 1 is completely inert and can be transported without any danger.

During firing, the high speed of rotation imparted by the striped tube of the weapon to the shell by virtue of the belt 19 will radially evacuate, by the effect of centrifugal force, the first material 3, out of the containers 8, through The centrifugal inertia forces will ensure the rupture of the sheet 16 for each container 8. It will suffice to define the thickness of the sheet 16 as a function of the desired strength.

Moreover, and if such a material is provided, the inertial forces will ensure the ejection of the sterilization material out of the housing (s) 25.

The level of effort is sufficient to ensure mixing and distribution of all liquid components in the porous matrix.

Once the sheets 16 broken, the diffusion of the first material 3 in the second material 4 is achieved through the porosity of the latter. Centrifugal inertia forces accelerate this diffusion. The air evacuated out of the porosity will concentrate inside the emptied 8 containers.

Once the two materials 3 and 4 are mixed, the composition formed by the mixture of these two materials is detonating. The optional sterilization material 24 ensures for a limited time an effect of sensitizing the first material 3.

This composition is initiated in a conventional manner by the rocket 6 of the shell.

By way of example, a composition associating 70% by weight of potassium perchlorate and 30% by weight of nitromethane has a detonation speed of 6100 to 6200 m / s. This is of the same order as the TNT (6900 m / s).

It should be noted that the sterilization material also has a sensitizing effect for a period of at least one hour. Sterilization only occurs beyond a period of more than 3 hours depending on the amount of sterilization material used.

When the rocket 6 does not work and the shell ends up on the ground, the explosive charge ends up being sterilized. The reaction time between the sterilization material and the first material is compatible with the operational requirements.

It will ensure the neutralization of the explosive charge in case of no detonation on a target. Unexploded shells will therefore be inert and can not be used as improvised explosive devices.

Various variants are possible without departing from the scope of the invention.

It is possible, as shown in figure 3 , to have in the shell 1 at least two cylindrical containers 8 of different diameters succeeding one another along the axis of the shell.

According to the embodiment shown in figure 3 there is a first stack of three large diameter containers 8 ₁ which extends from the base 5 of the shell 1 to a median zone Z of the shell, and there is a second stack of three containers 8 ₂ small diameters that extends from the central zone Z of the shell to the ring 17.

A first shim 11 radially maintains the first stack. A second shim 11 radially maintains the second stack.

The containers 8 ₁ and 8 ₂ have substantially the same structure as the container described above with reference to the figure 2b . The rearmost container 8 ₁ engages in a groove 10 of the base 5. The smaller diameter container 8 ₂ which is rearmost engages in a groove 20 which is arranged in the lid 14 of the large diameter container 8 ₁ to which it is applied. As previously the ring 17 ensures the axial immobilization of the stack of containers.

This embodiment makes it possible to provide a different volume and mass ratio for the first and the second material. The configuration according to the figure 3 This makes it possible to have a volume ratio of 30% for the first material and 70% for the second material.

It is also possible with this embodiment to provide one or more boxes enclosing a sterilization material (not shown in the figure).

The container or containers 8 may have a different shape, for example frustoconical. The figure 4a thus schematically shows a stack of frustoconical containers 8, the diameters of which are progressively increasing from the rear to the front. The larger diameter container being positioned for example against the base 5 of the shell.

The figure 4b shows another embodiment of a single container 8 which is intended to extend axially over the entire height of the second material 4.

This container is compartmentalized and comprises transverse partitions 21 which divide the internal volume of the container 8 into several chambers 22. In order to allow the introduction of the first material 3 in the container 8, each partition 21 has an axial hole 23 communicating the 22. The container is closed by a plug 14 and has a bottom 13. A sheet 16 wound around the container 8 closes the orifices 15.

The partitions 21 make it possible to reduce the pressure gradients between the upstream part and the downstream part of the container 8. This reduces the forces that would be transmitted to the sheet 16 as a result of the axial inertia forces.

As in the previous embodiment, thus avoids a rupture of the sheets asymmetrically and before rotation of the shell. Premature mixing of the first material with the second material is avoided only at the rear part of the shell and in the barrel of the weapon.

Embodiments of the invention are shown here in which the orifice closing means is constituted by a sheet which is pierced during firing by the effect of the centrifugal forces exerted on the first material.

It is possible to define one or more containers in which the orifices are closed by a shutter means of different structure.

For example, it is possible to provide plugs that can be broken off by centrifugal forces.

It will also be possible to make a container whose orifices are not open but are closed by a thinned portion of the tubular wall of the container. These thinned portions form zones of weakening of the tubular wall of the container which will break due to the effect of the centrifugal forces exerted during the firing by the first material.

It is thus possible to provide simple precuts or embrittlement of the container wall at the orifices.

These structural modifications are of course also possible to define the means for closing the orifices of the housing (s) containing the sterilization material 24.

A shell in which sterilization means was provided was described.

It is of course possible to define a shell according to the invention does not include sterilization material.

Such a two-component shell will, however, have greater security of transport than conventional explosive shells because the materials it contains are not in themselves and individually considered as explosive materials.

Claims (11)

Two-component explosive artillery shell (1) comprising an envelope (2) containing at least two non-explosive materials (3,4) but which, after mixing, form an explosive composition, shells comprising at least one container (8) secured to the envelope (2) and arranged coaxially therewith, container defining an internal cavity (12) enclosing a first material (3) in liquid or gelled form, container (8) whose wall (8a) is pierced with a plurality of orifices (15) which are closed by a closure means (16), the container or containers (8) delimiting with the envelope (2) an annular space (18) which encloses a second material (4) in solid form and porous, the closure means (16) being able to open during the firing to allow the centrifugal effect of the diffusion of the first material (3) in the second material (4) through the porosity of the latter material, a shell characterized in that it comprises at least one stack of containers (8) axially aligned and connected to each other, each container being separated from its neighbors by at least one transverse wall (13), or in that it comprises a single cylindrical container (8) extending axially over the entire height of the second material (4), the container being compartmentalized and having transverse partitions dividing its internal volume into several chambers. Explosive artillery shell according to claim 1, characterized in that the closure means (16) is constituted by at least one sheet integral with the wall (8a), which sheet may break during the firing to let the first material. Explosive artillery shell according to one of claims 1 or 2, characterized in that the container or containers (8) are cylindrical in shape. Explosive artillery shell according to one of claims 1 or 2, characterized in that the container or containers (8) are of frustoconical shape. Explosive artillery shell according to claim 3, characterized in that it comprises at least two cylindrical containers (8 ₁ , 8 ₂ ) of different diameters succeeding one another along the axis (9) of the shell. Explosive artillery shell according to one of claims 1 to 5, characterized in that the containers are positioned with respect to the casing by at least one radial wedge (11). Explosive artillery shell according to one of claims 1 to 6, characterized in that the second material (4) comprises at least one oxidant, such as potassium perchlorate, ammonium perchlorate, ammonium nitrate, or potassium nitrate. Explosive artillery shell according to claim 7, characterized in that the first material (3) comprises at least one nitro aliphatic hydrocarbon, such as nitromethane or nitroethane. Explosive artillery shell according to claim 8, characterized in that it comprises at least one sterilization material (24) of the first material (3). Explosive artillery shell according to claim 9, characterized in that the sterilization material (24) comprises at least one of the following materials: ethylene diamine, diethylene triamine. Explosive artillery shell according to one of claims 9 or 10, characterized in that the sterilization material (24) is placed in at least one housing (25).

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