COMBUSTIBLE CHARGES ADHERING TO THE INNER WALL OF A COMBUSTIBLE STRUCTURE CONTAINING A PROPELLANT CHARGE

Description

FIELD OF THE INVENTION

The technical field is that of additional combustible charges to a propellant powder charge of a shell or mortar-type ammunition. These additional combustible charges act as ignition relays, deliver functional additives (e.g. an anti-glow, anti-copper or anti-erosion additive), or provide propulsive energy. According to the present invention, these combustible charges are adhered to the inner wall of the combustible structure, in particular the combustible case, enclosing the propellant charge of a munition. These combustible charges are particularly suitable for ammunition with a large internal footprint, for example those in which the projectile tail is integrated into the core of the propellant charge, such as an arrow shell.

STATE OF THE ART

The propellant charge of a munition is ignited by an ignition device. This ignition device, which initiates combustion of the ammunition, comprises a primer and optionally a pyrotechnic charge. This ignition device can be coupled with one or more ignition relays to ensure even ignition of the propellant charge.

On a first level, the prior art describes ignition relays inserted in the case containing the propellant charge of an arrow shell. These ignition relays make it possible to optimize ignition for modern ammunition, which has a long length and/or a volume of powder that is difficult to reach with the flame of a conventional ignition device, comprising a primer, an igniter and an igniter tube forming the primer carrier tube (TPA). The use of low-vulnerability composite propellant powders that are difficult to ignite, such as LOVA or HE LOVA, also makes it necessary to increase the performance of ignition systems.

These ignition relays are connected to the TPA and ensure more evenly distributed ignition of the propellant charge.

According to a first technology, these ignition relays are packaged in a support, for example a plastic tube, in the form of cords. They comprise a pyrotechnic composition, such as black powder or a boron/potassium nitrate or aluminum/potassium perchlorate or else Magnesium/Teflon® or Viton® composition. Depending on the ammunition, the ignition cords are arranged in the mass of the charge and/or are fixed to the inner surface of the case and/or to a rear part of the projectile inserted in the charge.

Patent application WO 93/12400, for example, describes this type of device. The ignition cords [FIGS. 10 and 11, ref. 32], connected to the igniter, are distributed throughout the propellant charge. U.S. Pat. No. 5,129,324 also describes this type of architecture using ignition cords in a simple munition and also in a staged munition.

Patent application FR2799832 describes a device of the same type as that of patent application WO 93/12400, but also including ignition cords (ref 8a) glued or taped to the inner wall of the case and to the projectile tail.

In standard ammunition of the arrow shell type (see the schematic diagram in FIGS. 3a and 3b below), a first part of the propellant charge is first placed in the case with its base supporting the TPA. A space is left free in the upper part of the case. This space is used to accommodate the tail of the arrow, which supports a cylindrical cage around it, enclosing a second part of the charge. The feathered arrow (projectile), fitted with the cage on its tail, is secured to the upper part of the case by means of a connecting part. The upper part of the case then contains, above the first part of the charge, the tail plane and its cage enclosing the second part of the propellant charge. The connecting part, made of plastic or fibrous combustible, is riveted and/or glued to the upper part of the case. The ammunition is thus made in two assembled parts, each including a part of the propellant charge. The powder grains can also, according to another method, be loaded via holes in the rear base of the preassembled ammunition with its case and projectile. The ammunition base is then fitted, closing the loading holes. For this type of ammunition, for example, it is understood that the corded ignition relays proposed by the prior art make ammunition assembly operations complex. Precautions must be taken to avoid moving/damaging the cords located in the heart of the case and/or on the wall of the case and/or tail, as well as their connection to the ignition device. When the ammunition is composed of two assembled parts, the part of the ammunition supporting the cords is limited to the case and does not cover the area of the connecting part. Generally speaking, the cords distribute the ignition of the propellant charge locally along their line of operation and/or in only part of the charge's height. The distribution of propellant charge ignition is therefore not homogeneous and is likely to generate ignition pressure waves between the rear and front of the munition. The modularity of the positioning and number of cords is also limited. Their installation requires complex adaptations to each new ammunition architecture.

Patent application WO 2009/043876 describes an ignition relay consisting of at least one ring (ref. 4) integral with the inner face of the case. This ring has a flexible surface supporting a firing pin (ref. 4e) on the propellant charge side. This ring contains a charge of priming composition (ref. 8) likely to ignite on impact of the firing pin (following deformation of the flexible surface when the ammunition is pressurized). Ignition of the propellant charge takes place in two stages:

• • partial ignition of the propellant charge and rapid pressurization of the ammunition following operation of the main ignition device (ref. 6),
  • rapid deformation of the soft surface (ref. 4d) of the rings, causing percussion and ignition of the charge in the ring's priming composition. Operation of the ring ignition relays thus contributes to accelerating and completing ignition of the propellant charge.

This type of design therefore requires ring relays comprising a priming composition charge with firing pin, which entails safety and handling constraints, particularly when the charge is installed. The two-stage ignition of the propellant charge lengthens the time required to pressurize the munition. The reproducibility of firing pin operation may depend on the arrangement of the loose propellant charge in the case. Finally, complementary ignition effects are localized in the zones where the rings are arranged in the charge.

The skilled person is therefore always looking for a device that acts as an ignition relay in an ammunition case, that can be easily positioned in the case (even with the ammunition tail flush with the ignition device), and that does not require any additional fastening or linking device, does not interfere with the installation of the propellant charge made up of loose powder grains, with adjustable positioning and quantity according to the type of ammunition and leading to evenly distributed ignition throughout the propellant charge.

On a second level, functional additives, such as anti-glow, anti-copper or anti-erosion agents, are incorporated into the propellant powder or into the fibrous matrix of the combustible case of the ammunition. They can also be supplied via pouches/sleeves arranged in the ammunition structure. Patent application FR2374278 describes a weapon powder composed of grains containing the anti-glow additive K₂SO₄. U.S. Pat. No. 1,963,116 describes powder grains coated with a tin-based compound as an anti-copper additive. Patent application FR2802918 describes a propellant charge for ammunition or a combustible case incorporating a charge comprising a metal oxide with a wax, polyurethane or cellulose binder as an anti-erosion additive. U.S. Pat. No. 4,098,193 incorporates a textile combustible sleeve incorporating an anti-erosion agent between the case and the propellant charge. In all cases, these methods of incorporating additives degrade the overall propulsive performance of the munition. Their incorporation in the matrix of the combustible casing or in sachets/sleeves placed in the case does not enable optimal delivery during ammunition operation. In addition, positioning pouches or sleeves in bulky ammunition is either impossible or adds a complex operation to the ammunition build-up.

The skilled person therefore seeks to incorporate functional additives into the ammunition:

• • without degrading the ammunition's energy performance,
  • by delivering them progressively according to the combustion gas flow rate of the propellant charge, and
  • in a layout compatible with ammunition with a large internal footprint.

On a third level, the skilled person knows that the level of energetic charges (of the octogen or hexogen type, for example) in a powder grain is limited (typically <75% by weight) in order to maintain sufficient mechanical strength properties, particularly at low temperatures. Too high a charge content also leads to low combustion rates at low pressure, which also degrades the charge's ignition properties.

The skilled person therefore seeks to increase the weight ratio of energetic charges in the ammunition above conventional values without degrading the mechanical or ignition properties of the propellant charge, while maintaining a gradual release of this added charge during ammunition operation.

The present invention concerns combustible charges providing an ignition relay, and/or the delivery of functional additives and/or a doping energy supply, said combustible charges being able to be installed with great positioning latitude in a munition with a large internal footprint, thus freeing itself from the limitations and constraints of the prior art.

SUMMARY OF THE INVENTION

The invention relates to combustible charges adhering to the inner wall of a combustible structure of a shell-type munition containing a propellant charge (composed of loose powder grains) and an ignition device for initiating combustion. These combustible charges can act as ignition relays and/or deliver one or more functional additives and/or provide additional energy (doping) to that of the propellant charge. The combustible structure, in particular a combustible case, can therefore accommodate one or more combustible charges with the same or different functions. Although primarily concerned with the ammunition's combustible case, the invention is also applicable to any additional combustible element of the structure enclosing the ammunition's propellant charge. The object of the invention is more particularly devoted to ammunition of the 120 mm tank shell type, explosive shell or shell with a large footprint, such as an arrow shell, but can also be implemented in any type of ammunition with a combustible structure, for example ammunition of other calibers such as 155 mm large-caliber ammunition with monolithic or modular charges, or ammunition for mortars, particularly those of 60 mm, 81 mm or 120 mm caliber.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 shows different types of patterns of combustible charge on a combustible casing.

FIG. 2a shows the rear part of an ammunition of the arrow shell-type comprising a combustible charge on its combustible structure formed by the case.

FIG. 2b shows the front part of an ammunition of the arrow shell-type comprising a combustible charge on its combustible structure formed by the connecting part.

FIG. 3a shows the assembly of the rear and front parts of an ammunition of the arrow shell-type comprising a combustible charge on its combustible structure.

FIG. 3b shows an ammunition of the assembled arrow shell-type arrow comprising a combustible charge on its combustible structure.

DESCRIPTION OF THE INVENTION

It will be noted that within the scope of the present disclosure, the various embodiments described may be combined with one another.

According to one aspect, the invention relates to an ammunition containing, in a cellulose ester-based combustible structure, a propellant charge of powder grains and an ignition device for initiating combustion, at least one cellulose ester-based combustible charge being deposited in the form of a solid geometric volume pattern adhering to the inner wall of the combustible structure.

The above-mentioned combustible charge can perform the following functions:

• • it can be used as an ignition relay for the propellant charge (in this case, the combustible charge is also referred to as a relay charge),
  • it can enable the delivery of functional additives (said combustible charge is then also referred to in the following as additive charge),
  • it can contribute to a doping energetic supply (the said combustible charge is then also referred to in the remainder of this document as an energetic charge).

The cellulose ester-based propellant charge has the advantage of being able to be installed directly on a propellant charge-containing combustible structure, independently of the propellant charge. This combustible structure containing the propellant charge includes in particular a combustible case, but also any additional combustible structure, such as connecting or closing elements for the ammunition. It is also conceivable to install said propellant charge on any other combustible structure subsequently added to form the architecture of the munition.

The cellulose ester-based combustible charge is obtained from a cellulose ester-based collodion loaded with either ignition powder for the relay charge, or at least one functional additive for the additive charge, or at least one energetic charge for the energy charge. The collodion, in the form of a paste, is deposited on the surface of the combustible structure and then dried.

In some embodiments, the geometric volume pattern formed by collodion deposition is a linear, helical, curvilinear pattern, or shapes combined to form a mesh.

The collodion used in the invention is of the cellulose ester base+solvent(s) type. In one embodiment, the collodion base consists of a cellulose ester (for about 70% to about 90% by weight) and generally contains in addition, conventionally, at least one plasticizer (about 1% to about 20% by weight, preferably about 10% by weight) and at least one cellulose ester stabilizer (about 0.5% to about 5% by weight). It may contain a residual quantity of solvent(s), in particular phlegmatizing solvent(s) and/or cellulose ester dissolving solvent(s) used in its manufacture.

Advantageously, the cellulose ester used as the majority component is selected from cellulose nitrate, cellulose acetate or nitrocellulose, the latter being preferred. The nitrogen content by weight of nitrocellulose is suitably 10.5% to 13.5%, an example being grade E nitrocellulose with a nitrogen content by weight of 11.8% to 12.3%, advantageously 12%.

The plasticizer used to prepare the collodion may in particular be a ketone (such as camphor), a vinyl ether (such as poly(ethyl vinyl ether) marketed under the name LUTA 50-50%® by the company East Harbour Group), a polyurethane (such as NEP-PLAST 2001 marketed by the company Hagedorn-NC), an adipate (such as dioctyl adipate) or a citrate (such as triethyl 2-acetyl citrate).

The stabilizer used to prepare the collodion can be, in particular, a compound whose chemical formula includes aromatic rings (appropriately two aromatic rings), capable of fixing the nitrogen oxides from decomposition of nitric esters (currently nitrocellulose). Examples of stabilizers include 2-nitrodiphenylamine (2-NDPA), 1,3-diethyl-1,3-diphenyl urea (centralite I), 1,3-dimethyl-1,3-diphenyl urea (centralite II) and 1-methyl-3-ethyl-1,3-diphenyl urea (centralite III).

Solvent(s) is (are) selected from acetic esters (e.g. ethyl acetate, butyl acetate), carbonic esters (e.g. methyl carbonate, ethyl carbonate), propylene glycol ethers (e.g. Dowanol® PM), acetates (e.g. 1,3-dioxolane), ethyl esters (e.g. ethyl lactate).

The solvent is, for example, a double solvent of the acetone/butyl acetate (BA) type at 50%/50% by weight or a double solvent of the ethyl lactate type for 35% to 60% by weight and butyl acetate for 40% to 65% by weight for a total of 100%.

The collodion is advantageously formulated to give a dry extract (after evaporation of the solvent) of 10% to 40% by weight.

The composition of the cellulose ester base to form the collodion is, for example, that shown in Table 1:

	TABLE 1
	Cellulose base	Nitrocellulose	84
		Plasticizer	13
		Stabilizer	3
		Total	100

Table 2 below shows a 14% solids by weight collodion formulation using the cellulose base of Table 1.

	TABLE 2
	Collodion

	Composition (% by weight)

Cellulose base	Nitrocellulose	84	14
	Plasticizer	13
	Stabilizer	3
	Total	100
Solvents	Butyl acetate		43
	Acetone		43
	Total		100

In some embodiments, the combustible charge (relay charge) is obtained after deposition and subsequent drying of a paste (adhering to the surface of the munition's combustible structure) consisting of a cellulose ester-based collodion loaded with ignition powder (classified in hazard division 1.1 under the UN GHS (UN Globally Harmonized System of Classification and Labeling of Chemicals) classification) or with the ingredients forming the ignition powder.

The composition of the ignition powder is most frequently black powder (BP), consisting of an agglomerated mixture of potassium nitrate (saltpetre), charcoal and sulphur. There are also other agglomerated ignition powder compositions, such as: Boron/KNO₃, in a ratio generally of 70/30 (% by weight), a metal (e.g. iron, aluminum, zinc, magnesium), a perchlorate-type oxidant (e.g. potassium perchlorate) or a fluoropolymer-type oxidant (e.g. PTFE such as Teflon®).

In one embodiment, the collodion loaded with ignition powder(s) comprises about 50% to about 70% by weight of ignition powder(s), and the balance to 100% (i.e. about 30% to about 50% by weight) of collodion. Conventionally, the ignition powder(s) is (are) added to the collodion.

Table 3 below shows an example of a collodion composition from Table 2, loaded with ignition powder to form the relay charge.

	TABLE 3
	Raw materials	Composition (% by weight)

	Black powder (or equivalent)	59
	Collodion	41
	Total	100

Collodion loaded with ignition powder is classified in hazard division 1.3 of the UN GHS (UN Globally Harmonized System of Classification and Labeling of Chemicals). The danger zones to be taken into account when handling the loaded collodion are therefore reduced, making it easier to deposit the collodion on the tube.

After drying, a combustible charge useful as an ignition relay is formed, which adheres to the inner surface of the combustible structure and comprises about 88% to about 92% by weight of ignition powder(s), about 7% to about 10% by weight of cellulose ester, the remainder to 100% being provided by the plasticizer, stabilizer and residual solvent from the collodion. The residual solvent from the collodion generally represents less than 1% by weight of the total weight of the combustible charge. As an indication, the dry combustible charge obtained after drying (solvent evaporation) of the collodion in Table 3 contains the weight ratios indicated in Table 4 below.

	TABLE 4
	Dry composition	Weight %

	Black powder (or equivalent)	90.08
	Nitrocellulose	8.35
	Plasticizer	0.96
	Stabilizer	0.35
	Residues (water, solvent, etc.)	0.26
	Total	100

In some embodiments, the combustible charge (additive charge) is obtained after deposition and subsequent drying of a paste (adhering to the surface of the munition's combustible structure) consisting of a cellulose ester-based collodion loaded with at least one functional additive. These additives are either inert (e.g. calcium carbonate) or low-energy (e.g. potassium nitrate), and to guarantee the absence of residues after combustion, the paste can also contain a small proportion by weight (≤10%) of a combustible charge to regulate the combustion properties of the additive charge after the paste has dried. This combustible charge can be an ignition powder or a propellant powder.

Examples of functional additives which can be used in the context of the invention are anti-glow additives, anti-erosion additives, anti-copper additives, and mixtures of one or more of these additives.

The anti-glow additive is, for example, selected from potassium nitrate, potassium or sodium sulfate, potassium nitrate, potassium or sodium cryolite, sodium oxalate, sodium bicarbonate, potassium or sodium carbonate, potassium or sodium cobalt nitrite, sodium nitrite, preferably potassium sulfate.

The anti-erosion additive is, for example, selected from camphor, dinitrotoluene 2-4, butyl phthalate, calcium carbonate, titanium dioxide, molybdenum trioxide, tungsten trioxide, silicon oxide, magnesium silicate (talc), preferably titanium dioxide. The additive may also be centralite, which may already be present in very small quantities in the collodion as a stabilizer.

The anti-copper additive is, for example, selected from tin, tin oxide, lead oxide, preferably tin oxide.

In some embodiments, the collodion loaded with functional additive(s) comprises about 30% to about 50% by weight of collodion and the balance to 100% by weight of at least one functional additive and optionally a combustible charger, for example about 40% to about 70% by weight of functional additive(s), and 0% to about 10% by weight of a combustible charge.

After drying, a combustible charge useful as an additive charge is formed, which adheres to the inner surface of the combustible structure and comprises about 70.3% to about 92% by weight of additive(s), 0% to about 17.6% of a combustible charge, about 7% to about 10% by weight of cellulose ester, the balance to 100% being provided by the plasticizer, stabilizer and residual solvent from the collodion. The residual solvent from the collodion generally represents less than 1% by weight of the total weight of the combustible charge.

An example of the composition of the dry material forming the additive charge after deposition is given in Table 5. This example is obtained using the same collodion as that given in Table 2 and the same ratio between the charge(s) added to the collodion as that given in Table 3. In this example, the total weight percentage of the charge of the at least one functional additive and of the optional combustible charge thus represents 90.08% of the total dry composition.

	TABLE 5
	Dry composition	Weight %
	Additive(s) charges	74.81 to 90.08
	Combustible charge	0 to 15.27
	Nitrocellulose	8.35
	Plasticizer	0.96
	Stabilizer	0.35
	Residues (water, solvent, etc.)	0.26
	Total	100

In some embodiments, the combustible charge (energetic charge) is obtained after deposition and subsequent drying of a paste (adhering to the surface of the combustible structure) consisting of a cellulose ester-based collodion loaded with at least one energetic charge. Said energetic charge is, for example, selected from hexogen (RDX), octogen (HMX), FOX-7 (1,1-diamino-2,2-dinitroethene (DADNE)), FOX-12 (guanylurea dinitramide, GUDN), or a composite powder composition (also known as LOVA powder) comprising an energetic charge and a cross-linked binder, for example of the polyurethane, polyglycidyl azide (PGA) and/or thermoplastic type, e.g. PMMA or an ethylene/vinyl acetate (EVA) copolymer.

In some embodiments, the collodion loaded with an energetic charge comprises about 50% to about 70% by weight of energetic charge, and the balance to 100% (i.e. about 30% to about 50% by weight) of collodion.

The paste used to form this energetic charge is classified in hazard division 1.3 of the UN GHS (UN Globally Harmonized System of Classification and Labeling of Chemicals). The danger zones to be taken into account when handling the loaded collodion are therefore reduced, making it easier to deposit the collodion on the tube.

After drying, a combustible charge useful as an energetic charge is formed, which adheres to the inner surface of the combustible structure and comprises about 88% to about 92% by weight of the at least one energetic charge, about 7% to about 10% by weight of cellulose ester, the balance to 100% being provided by the plasticizer, stabilizer and residual solvent from the collodion. The residual solvent from the collodion generally represents less than 1% by weight of the total weight of the combustible charge.

An example of the composition of the dry material forming the energetic combustible charge after deposition is given in Table 6. This example is obtained using the same collodion as that given in Table 2 and the same ratio between the charge(s) added to the collodion as that given in Table 3. In this example, the total weight percentage of energetic charge thus represents 90.08% of the total dry composition

	TABLE 6
	Dry composition	Weight %

	Energetic charge	90.08%
	Nitrocellulose	8.35
	Plasticizer	0.96
	Stabilizer	0.35
	Residues (water, solvent, etc.)	0.26
	Total	100

Said paste, containing either an ignition powder, or at least one functional additive, or an energetic charge, or a mixture of several of these constituents, is obtained by introducing the constituents into a standard paddle mixer or a twin-screw continuous mixer or into an acoustic resonance mixer. Said paste is then extruded via a plunger press or a single screw extended by an extrusion channel and a nozzle to form patterns on a support (the inner surface of the munition's combustible structure for the present invention), for example by means of a device of the type described in patent application WO 2021/144539.

In implementing the present invention, the nozzle described in patent application WO 2021/144539 is optionally articulated so as to deposit patterns perpendicular to the surface of a curved support not co-linear with the extrusion axis of the plunger press or single screw. This makes it possible to deposit patterns on a curved support, such as the rear base of an ammunition case.

The combustible structure of the ammunition is made of a cellulose ester-based combustible material (having the appearance of a felt). The combustible materials making up the combustible structure and said combustible charge must be chemically compatible and have the property of adhering to one another. To this end, they have a common cellulose ester base, such as cellulose nitrate, cellulose acetate or nitrocellulose. Nitrocellulose, advantageously containing an average nitrogen content of 12.4% to 13.5%, is the preferred common base and is retained, in a non-limiting way, in the remainder of the description

In some embodiments, the combustible structure is a fibrous structure, such as that marketed by the company Eurenco, consisting of 45% to 81% by weight of cellulose ester (fibers), 3.5% to 33.5% by weight of cellulose (fibers), 4% to 14% by weight of resin (binder), 0% to 1.6% by weight of a stabilizer, and 0% to 15.5% by weight of additional acrylic or polyester fibers (the sum of these various constituents being equal to 100%). An example of the composition of the combustible structure is given in Table 7.

	TABLE 7
	Composition	Weight %

	Nitrocellulose	69
	Cellulose	25
	Resin	5
	stabilizer	1

Depositing the paste of said combustible charge in solvent(s) produces localized dissolution of the surface of the combustible structure, ensuring good adhesion of the deposited combustible charge once the paste has dried.

The paste is deposited on the inner wall of the ammunition's combustible structure in one or more patterns which, after drying, form the said combustible charge. The deposited patterns may be of linear, helical or curvilinear form, or of a combination of these forms so as to obtain a mesh in the optimum configuration for igniting the munition or delivering at least one additive or energetic input (dopant). Different patterns can also be deposited over the height of the combustible structure.

When the at least one combustible charge acts as an ignition relay (relay charge), it does not require any specific connection to the ignition device. The at least one relay charge is, for example, a linear or curvilinear pattern, at least one end of which is coupled (in contact or sufficiently close) with the ignition device to ensure its ignition and thus initiate its combustion. The spatial and weight distributions of the relay charge patterns can be adapted with great latitude according to the characteristics of the propellant charge and the munition, thus enabling rapid and homogeneous ignition of the propellant charge. Said at least one relay charge is suitable for ammunition with separate stages (e.g. of the type described in U.S. Pat. No. 5,129,324), with assembled stages (e.g. according to the usual assembly mode of the combustible structure of arrow shells, see FIG. 3b), with large internal footprint.

When the at least one combustible charge delivers at least one functional additive (additive charge) or a doping energetic contribution (energetic charge), the aim of the combustible charge is not to make an almost instantaneous contribution to the propellant charge on ignition, as in the case of a relay charge, but to distribute the additive(s) or energetic contribution over the course of the charge's combustion. To achieve this, the at least one additive or energetic charge is generally not coupled to the ignition device and is ignited by the propellant charge or a relay charge. Its combustion is therefore generally initiated by that of the propellant charge or by at least one relay charge. However, it is possible for the additive or energetic charge to be coupled with the ignition device to ensure its ignition. The additive or energetic combustible charges can be deposited in continuous patterns (as previously described for ignition relays) or in semi-continuous or punctual patterns on the wall of the combustible structure, with a geometric and mass distribution ensuring a continuous supply proportional to the gas flow generated by the combustion of the propellant charge. When firing a tube weapon, this flow rate is designed to increase as the projectile advances through the tube, in order to maintain constant gas pressure in the tube. The patterns of the additive or energetic combustible charges are arranged on the combustible structure in a configuration adapted to the operation of the propellant charge, so as to deliver the at least one additive or energetic supply at an optimum and continuous mass flow rate during the combustion time of the propellant charge. For example, these patterns may be of circular or linear or punctual form or of combined forms, distributed regularly or irregularly over the combustible structure.

The combustible charge as described above is suitable for various types of ammunition, in particular ammunition of the arrow shell or explosive shell type.

The invention is illustrated by the following non-limiting examples.

EXAMPLES

Example 1

FIG. 1 shows examples of patterns (linear, helical, meshed, combined shapes) that can be selected for a combustible charge on a planar view of the inner surface of the combustible structure. The combustible charge [1] adhering to the combustible structure [2] is coupled by at least one of the ends of a pattern to the ignition device formed by an igniter [3] and an igniter tube [4] arranged in the rear bottom of the munition.

Example 2

This example relates to the installation of combustible charges according to the invention in a munition of the type of a high-capacity arrow shell. This is an arrow shell [5] assembled using the conventional two-part process (FIGS. 2a and 2b). The first, rear part (FIG. 2a) consists of a case [6] made of fibrous combustible material enclosing a first propellant charge [7a] and its ignition device. This ignition device, in the form of a primer tube, comprises an igniter and its primer [8] inserted into the base of the case [6] in conjunction with an igniter tube [9] at the center of the first propellant charge [7a]. A gap [10] is left free at the top of the combustible case [6]. The second front part (FIG. 2b) consists of a feathered arrow [11] (projectile) fitted with a clamp [12] integral with a connecting part [13] and supporting a cylindrical cage [14] around its rear feathered part. This cylindrical cage [14] contains a second part of the propellant charge [7b]. The upper free part [10] of the combustible case is designed to receive the tail of the arrow [11] supporting the cylindrical cage [14] around it. The feathered arrow [11], fitted with the cage on its tail, is secured to the upper part of the case by means of the combustible connecting part [13]. The connecting part, also made of combustible fibrous material, is glued to the upper part of the case. The ammunition is thus made in two assembled parts, each including part of the propellant charge (FIGS. 3a and 3b).

On the inside of the connecting part [13] and the case [6], relay charge patterns [15a and 15b] have been deposited, the ends of which become contiguous after assembly (FIGS. 3a and 3b). This ensures uniform ignition across the entire propellant charge (the part contained in the case and the front part in the area of the connecting part) of the munition. Similarly, at least one additive charge and/or at least one energetic combustible charge can also be deposited on the inside of the connecting part and/or of the case, in connection or not after assembly. The patterns of these combustible charges are adapted to ensure a supply of additive(s) or energy during combustion of the propellant charge.