Combustible charges adhering to the inner wall of a combustible structure containing a propellant charge

Abstract

The invention relates to a munition containing, in a cellulose ester-based combustible structure, a propellant charge of powder grains and an ignition device, a munition in which at least one cellulose ester-based combustible charge is deposited in the form of a solid geometric volume pattern adhering to the internal wall of the cellulose ester-based combustible structure.

Description

Title of the invention: Combustible charges adhering to the internal wall of a combustible structure containing a propellant charge Field of invention

[0001] The technical field is that of additional combustible charges to a propellant charge of powder of a munition of the shell or mortar type. These additional combustible charges ensure the function of ignition relay, delivery of functional additives (for example an anti-glow, anti-copper or anti-erosion additive), or of propellant energy supply. According to the present invention, these combustible charges are arranged in adherence to the internal wall of the combustible structure, in particular the combustible case, containing the propellant charge of a munition. These combustible charges are particularly suitable for munitions with large internal bulk, for example those in which the tail of the projectile is integrated into the heart of the propellant charge, of the arrow shell type. State of the art

[0002] The propellant charge of a munition is initiated by combustion by an ignition device. This ignition device, which initiates the combustion of the munition, is composed of a primer and possibly a pyrotechnic charge. This ignition device can be coupled with one or more ignition relays ensuring uniform ignition of the propellant charge.

[0003] On a first level, the prior art describes ignition relays inserted into the case containing the propellant charge of an arrow shell. These ignition relays make it possible to optimize the ignition for modern munitions which have a significant length and / or a volume of powder which is difficult to access by the flame of a conventional ignition device, composed of a primer, an igniter and an igniter tube forming the primer tube (TPA). Increasing the performance of the ignition means is also sought due to the use of low-vulnerability composite propellant powders which are difficult to ignite, for example of the LOVA or HE LOVA type.

[0004] These ignition relays are connected to the TPA and they ensure better distributed ignition of the propellant charge.

[0005] 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 for example a pyrotechnic composition, such as black powder or a composition combining Boron / potassium nitrate or aluminum / potassium perchlorate or Magnesium / Teflon® or Viton®. Depending on the ammunition, the ignition cords are arranged in the mass of the load and / or are fixed on the internal surface of the case and / or on a rear part of the projectile inserted into the load.

[0006] Patent application WO 93 / 12400 describes, for example, this type of device. The ignition cords [figures 10 and 11, ref. 32], connected to the igniter, are distributed in the mass of the propellant charge. Patent US5129324 also describes this type of architecture using ignition cords in a single munition and also in a staged munition.

[0007] Patent application FR2799832 describes a device of the same type as that of patent application WO93 / 12400 but also including ignition cords (ref 8a) glued or applied with adhesive tape to the internal wall of the case and to the tail of the projectile.

[0008] In the usual ammunition of the arrow shell type (see the principle representation of figures 3a and 3b below), a first part of the propellant charge is first of all placed in the case equipped with its base supporting the TPA. A space is left free in the upper part of the case. This space has the function of receiving the tail of the arrow supporting around it a cylindrical cage enclosing a second part of the charge. The tailed arrow (projectile) equipped with the cage on its tail is secured to the upper part of the case by means of a connecting piece. The upper part of the case then contains, above the first part of the charge, the tail and its cage enclosing the second part of the propellant charge. The connecting piece, made of plastic or fibrous fuel material, is riveted and / or glued to the upper part of the case.The ammunition is therefore made of two assembled parts, each including a part of the propellant charge. It is also possible, according to another method, to load the powder grains via orifices on the rear base of the pre-made ammunition with its case and projectile. The base of the ammunition is then put in place and ensures the closing of the loading orifices. For this type of ammunition, for example, it is understood that the ignition relays made of cords, proposed by the prior art, make the operations of assembling the ammunition complex. It is necessary to take precautions so as to avoid moving / damaging the cords arranged in the heart of the case and / or on the wall of the case and / or the 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 piece.Generally, the cords distribute the ignition of the propellant charge locally on their operating line and / or in only a part of the . height of the charge. The distribution of the ignition of the propellant charge is therefore not uniform and is likely to generate pressure waves on ignition between the rear and the front of the munition. The modularity of the cords in positioning and number is also limited. Their installation requires complex adaptations to each new munition architecture.

[0009] Patent application WO 2009 / 043876 describes an ignition relay consisting of at least one ring (ref. 4) integral with the internal face of the case. This ring comprises a flexible surface supporting a firing pin (ref. 4e) on the side of the propellant charge. This ring contains a charge of priming composition (ref. 8) capable of igniting by impact of the firing pin (following the deformation of the flexible surface during pressurization of the ammunition). The ignition of the propellant charge takes place in two stages:

[0010] - partial ignition of the propellant charge and rapid pressurization of the ammunition following operation of the main ignition device (ref.6),

[0011] - the rapid deformation of the flexible surface (ref. 4d) of the rings causing the percussion and ignition of the charge in the ring priming composition. The operation of the annular ignition relays thus helps to accelerate and complete the ignition of the propellant charge.

[0012] This embodiment therefore requires annular relays comprising a charge in priming composition with firing pin inducing safety and handling constraints, in particular when placing the load. The two-stage ignition of the propellant charge lengthens the pressurization time of the ammunition. The reproducibility of the operation of the firing pins may depend on the arrangement of the bulk propellant charge in the case. Finally, the complementary ignition effects are located in the areas where the rings are arranged in the charge.

[0013] The person skilled in the art is therefore always looking for a device acting as an ignition relay in an ammunition case, easily positionable in the case (even with an ammunition fin flush with the ignition device), not requiring an additional fixing or connecting member, not interfering with the installation of the propellant charge consisting of loose powder grains, with positioning and quantity that can be adjusted depending on the type of ammunition and leading to a distributed and homogeneous ignition over the entire propellant charge.

[0014] On a second level, the functional additives, for example anti-glow or anti-copper or anti-erosive, are incorporated into the propellant powder or into the fibrous matrix of the combustible case of the ammunition. They can also be provided via bags / sleeves arranged in the structure of the ammunition. Patent application FR2374278 thus describes a weapon powder composed of grains containing the anti-glow additive K2SO4. Patent US1963116 describes powder grains coated with a tin-based compound as an anti-coppering additive. Patent application FR2802918 presents a propellant charge for a munition or a combustible case incorporating a charge comprising a metal oxide with a wax, polyurethane or cellulose binder as an anti-erosion additive. Patent US4098193 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 propellant performance of the munition. Their incorporation into the matrix of the combustible case or into sachets / sleeves arranged in the case does not allow for optimal delivery during operation of the munition.In addition, the positioning of bags or sleeves in large ammunition is impossible or adds a complex operation to the constitution of the ammunition.

[0015] The person skilled in the art therefore seeks to incorporate functional additives into the ammunition:

[0016] - without degrading the energy performance of the ammunition,

[0017] - by ensuring their delivery progressively according to the gas flow rate of combustion of the propellant charge, and

[0018] - according to an installation compatible with munitions with large internal dimensions.

[0019] On a third level, the person skilled in the art knows that the rate of energy charges (of the octogen or hexogen type for example) in a grain of powder is limited (typically < 75% by mass) in order to maintain sufficient mechanical resistance properties, particularly at low temperatures. Too high a charge rate also leads to low combustion speeds at low pressure, which also degrade the ignition properties of the charge.

[0020] The person skilled in the art therefore seeks to increase the mass rate of energetic charges in the munition above conventional values ​​without degrading the mechanical or ignition properties of the propellant charge, while maintaining a progressive delivery of this charge added during operation of the munition.

[0021] The present invention relates to combustible loads providing an ignition relay, and / or the delivery of functional additives and / or a doping energy supply, said combustible loads being capable of being implanted with a large latitude of positioning in a munition with a large internal size, thus overcoming the limitations and constraints of the prior art. Summary of the invention

[0022] The invention relates to combustible charges adhering to the internal 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. Said combustible charges can provide an ignition relay function and / or a function of delivering one or more functional additives and / or a function of providing additional energy (doping) to that of the propellant charge. The combustible structure, in particular a combustible case, can therefore receive one or more combustible charges of the same function or different functions. Although mainly relating to the combustible case of the munition, the invention also finds its application to any additional combustible element of the structure containing the propellant charge of the munition.The subject of the invention is more particularly devoted to munitions of the 120 mm tank shell type, explosive shell or large bulk shell for example an arrow shell, but can also be implemented in any type of munition with a combustible structure, for example munitions of other calibers such as a large caliber 155 mm munition with monolithic loading or modular loading, or mortar munitions in particular those of caliber 60 mm, 81 mm or 120 mm. Brief description of the figures

[0023] [Fig-1] shows different types of patterns of a combustible load on a case fuel.

[0024] [Fig.2a] shows the rear part of an arrow shell type ammunition comprising a combustible loading on its combustible structure formed by the case.

[0025] [Fig.2b] shows the front part of an arrow shell type ammunition comprising a combustible loading on its combustible structure formed by the connecting piece.

[0026] [Fig.3a] shows the assembly of the rear part and the front part of a munition of the arrow shell type comprising a combustible charge on their combustible structure.

[0027] [Fig.3b] shows an assembled arrow shell type ammunition comprising a combustible loading on its combustible structure. Description of the invention

[0028] It will be noted that within the scope of the present disclosure, the different embodiments described may be combined with each other.

[0029] According to one aspect, the invention relates to a munition 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 internal wall of the combustible structure.

[0030] The aforementioned combustible charge can perform the following functions:

[0031] - it can serve as an ignition relay for the propellant charge (said charge com fuel is then also called in the rest of the document relay loading),

[0032] - it can allow the delivery of functional additives (said fuel loading is then also called additive loading in the rest of the document),

[0033] - it can contribute to a doping energy supply (said combustible loading is then also called in the rest of the document energy loading).

[0034] The cellulose ester-based combustible charge has the advantage of being able to be implanted directly on a combustible structure containing the propellant charge, independently of the propellant charge. Said combustible structure containing the propellant charge comprises in particular a combustible case but also any other additional combustible structures, such as connecting or closing elements of the munition. It is also entirely possible to implant said combustible charge on any other combustible structure subsequently added constituting the architecture of the munition.

[0035] The cellulose ester-based combustible charge is obtained from a cellulose ester-based collodion loaded with either ignition powder for relay charging, or at least one functional additive for additive charging, or with at least one energetic charge for energetic charging. The collodion, in the form of a paste, is deposited on the surface of the combustible structure and then dried.

[0036] The collodion used in the context of the invention is of the cellulose ester base + solvent(s) type. In one embodiment, the collodion base is made up of a cellulose ester (for approximately 70% to approximately 90% by mass) and generally contains in addition, conventionally, at least one plasticizer (approximately 1% to approximately 20% by mass, preferably approximately 10% by mass) and at least one stabilizer of the cellulose ester (approximately 0.5% to approximately 5% by mass). It is likely to contain a residual quantity of solvent(s), in particular phlegmatization solvent(s) or (and) solvent(s) for dissolving the cellulose ester used during its manufacture.

[0037] Advantageously, the cellulose ester used as the major component is chosen from cellulose nitrate, cellulose acetate or nitrocellulose, the latter being preferred. The nitrogen mass content of the nitrocellulose is suitably 10.5% to 13.5%, an example being grade E nitrocellulose with a nitrogen mass content of 11.8% to 12.3%, advantageously equal to 12%.

[0038] The plasticizer used to prepare the collodion may be in particular 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).

[0039] The stabilizer used to prepare the collodion may in particular be a compound whose chemical formula includes aromatic nuclei (opportunely two aromatic nuclei), capable of fixing the nitrogen oxides from the decomposition of nitric esters (presently nitrocellulose). Examples of stabilizers include 2-nitrodiphenylamine (2-NDPA), 1,3-diethyl-1,3-diphenyl urea (centrality I), 1,3-dimethyl-1,3-diphenyl urea (centrality II), and 1-methyl-3-ethyl-1,3-diphenyl urea (centrality III).

[0040] The solvent(s) is(are) chosen from acetic esters (for example ethyl acetate, butyl acetate), carbonic esters (for example methyl carbonate, ethyl carbonate), propylene glycol ethers (for example Dowanol® PM), acetates (for example 1,3-dioxolane), ethyl esters (for example ethyl lactate).

[0041] The solvent is for example a double solvent of the acetone / butyl acetate (AB) type 50% / 50% by mass or a double solvent such as ethyl lactate for 35% to 60% by mass and butyl acetate for 40% to 65% by mass for a total of 100%.

[0042] The collodion is advantageously formulated to result in a dry extract (after evaporation of the solvent) of 10% to 40% by mass.

[0043] The composition of the cellulose ester base for forming the collodion is for example that of Table 1:

[0044] [Tables 1] Cellulosic base Nitrocellulose 84 Plasticizer 13 Stabilizer 3 Total 100

[0045] Table 2 below shows a formulation of collodion at 14% dry extract by mass using the cellulose base of Table 1.

[0046] [Tables2] Collodion Composition (% by mass) Cellulosic base Nitrocellulose 84 14 Plasticizer 13 Stabilizer 3 Total 100 Solvents Butyl acetate 43 Acetone 43 Total 100

[0047] In certain embodiments, the combustible charge (relay charge) is obtained after deposition and then drying of a paste (adhering to the surface of the combustible structure of the munition) consisting of a cellulose ester-based collodion charged with ignition powder (classified in risk division 1.1 within the meaning of the UN GHS classification (UN Globally Harmonized System of Classification and Labeling of Chemicals)) or with the ingredients forming the ignition powder.

[0048] The composition of the ignition powder is most frequently black powder (NP) consisting of an agglomerated mixture of potassium nitrate (saltpeter), charcoal and sulfur. There are also other compositions of agglomerated ignition powder, in particular of the type: Boron / KNO3, in a ratio generally of 70 / 30 (% by mass), a metal (for example iron, aluminum, zinc, magnesium), an oxidant of the perchlorate type (for example potassium perchlorate) or of the fluorinated polymer type (for example PTFE such as Teflon®).

[0049] In one embodiment, the collodion loaded with ignition powder(s) comprises about 50% to about 70% by mass of ignition powder(s), and the balance to 100% (i.e., about 30% to about 50% by mass) of collodion. Conventionally, the ignition powder(s), previously constituted, is (are) added to the collodion.

[0050] Table 3 below gives an example of the composition of collodion from Table 2, loaded with ignition powder to form the relay charge.

[0051] [Tables3] Raw materials Composition (% by mass) Black powder (or equivalent) 59 Collodion 41 Total 100

[0052] Collodion loaded with ignition powder is classified in hazard division 1.3 within the meaning of the UN GHS classification (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, which facilitates the operations of depositing the collodion on the tube.

[0053] After drying, a combustible charge useful as an ignition relay is formed, which adheres to the internal surface of the combustible structure and comprises approximately 88% to approximately 92% by mass of ignition powder(s), approximately 7% to approximately 10% by mass of cellulose ester, the remainder to 100% being provided by the plasticizer, the stabilizer and the residual solvent originating from the collodion. The residual solvent originating from the collodion generally represents less than 1% by mass of the total mass of the combustible charge. As an indication, the dry combustible charge obtained after drying (evaporation of the solvent) of the collodion of Table 3 contains the mass ratios indicated in Table 4 below.

[0054] [Tables4] Dry composition % by mass Black powder (or equivalent) 90.08 Nitrocellulose 8.35 Plasticizer 0.96 Stabilizer 0.35 Residues (water, solvent, etc.) 0.26 Total 100

[0055] In certain embodiments, the combustible charge (additive charge) is obtained after deposition and then drying of a paste (adhering to the surface of the combustible structure of the munition) consisting of a cellulose ester-based collodion loaded with at least one functional additive. These additives are either inert (for example calcium carbonate) or low-energy (for example potassium nitrate) and to guarantee the absence of residues after combustion, the paste can also, in addition, contain a combustible charge in a small mass proportion (<= 10%) in order to adjust the combustion properties of the additive charge after drying the paste. This combustible charge can be an ignition powder or a propellant powder.

[0056] As functional additives that can be used in the context of the invention, examples that may be mentioned are anti-glare additives, anti-erosion additives, anti-coppering additives, and mixtures of one or more of these additives.

[0057] The anti-glare additive is, for example, chosen 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.

[0058] The anti-erosion additive is, for example, chosen from camphor, 2-4 dinitrotoluene, butyl phthalate, calcium carbonate, titanium dioxide, molybdenum trioxide, tungsten trioxide, silicon oxide, magnesium silicate (talc), preferably titanium dioxide. The additive can also be the centrality already possibly contained in very small quantity in the collodion as a stabilizer.

[0059] The anti-copper additive is, for example, chosen from tin, tin oxide, lead oxide, preferably tin oxide.

[0060] In some embodiments, the collodion loaded with functional additive(s) comprises about 30% to about 50% by mass of collodion and the balance to 100% by mass of at least one functional additive and optionally a combustible filler, for example about 40% to about 70% by mass of functional additive(s), and 0% to about 10% by mass of a combustible filler.

[0061] After drying, a combustible charge useful as an additive charge is formed, which adheres to the internal surface of the combustible structure and comprises about 70.3% to about 92% by mass of additive(s), 0% to about 17.6% of a combustible charge, about 7% to about 10% by mass of cellulose ester, the balance to 100% being provided by the plasticizer, the stabilizer and the residual solvent from the collodion. The residual solvent from the collodion generally represents less than 1% by mass of the total mass of the combustible charge.

[0062] An example of the composition of the dry material forming the additive charge after deposition is given in Table 5. This example is obtained with the use of 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 of the mass percentage of the charge of the at least one functional additive and of the possible combustible charge therefore represents 90.08% of the total of the dry composition.

[0063] [Tables5] Dry composition % by mass Additive charges 74.81 to 90.08 Fuel charge 0 to 15.27 Nitrocellulose 8.35 Plasticizer 0.96 Stabilizer 0.35 Residues (water, solvent, etc.) 0.26 Total 100

[0064] In certain embodiments, the combustible charge (energetic charge) is obtained after deposition and then drying of a paste (adherent 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 chosen from hexogen (RDX), octogen (HMX), FOX-7 (1,1-diamino-2,2-dinitroethene (DADNE)), FOX-12 (guanylurea dinitramide, GUDN), or even a composite powder composition (also called LOVA powder) comprising an energetic charge and a crosslinked binder, for example of the polyurethane, polyglycidyl azide (PAG) and / or thermoplastic type, for example PMMA or an ethylene / vinyl acetate copolymer (EAV).

[0065] In some embodiments, the energetically charged collodion comprises about 50% to about 70% by mass energetic charge, and the balance to 100% (i.e., about 30% to about 50% by mass) collodion.

[0066] The paste intended to form said energetic charge is classified in risk division 1.3 within the meaning of the UN GHS classification (UN Globally Harmonized System of Classification and Labeling of Chemicals). The danger zones to be taken into account for the handling of the charged collodion are therefore reduced, which facilitates the operations of depositing the collodion on the tube.

[0067] After drying, a combustible charge useful as an energetic charge is formed, which adheres to the internal surface of the combustible structure and comprises about 88% to about 92% by mass of the at least one energetic charge, about 7% to about 10% by mass of cellulose ester, the balance to 100% being provided by the plasticizer, the stabilizer and the residual solvent from the collodion. The residual solvent from the collodion generally represents less than 1% by mass of the total mass of the combustible charge.

[0068] An example of the composition of the dry material forming the combustible charge The energy content after deposition is given in Table 6. This example is obtained using the same collodion as given in Table 2 and the same ratio of the charge(s) added to the collodion as given in Table 3. In this example, the total mass percentage of the energy charge therefore represents 90.08% of the total dry composition.

[0069] [Tableauxô] Dry composition % by mass Energy charge 90.08% Nitrocellulose 8.35 Plasticizer 0.96 Stabilizer 0.35 Residues (water, solvent, etc.) 0.26 Total 100

[0070] Said paste, containing either an ignition powder, or at least one functional additive, or an energy 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 press piston or a single screw extended by an extrusion channel and a nozzle to form patterns on a support (the internal surface of the combustible structure of the munition for the present invention), for example by means of a device of the type described in patent application WO 2021 / 144539.

[0071] In the context of the implementation of 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 collinear with the extrusion axis of the press piston or the single-screw. It is thus possible to carry out deposits on a curved support such as, for example, the rear bottom of an ammunition case.

[0072] The combustible structure of the ammunition is made of a cellulose ester-based combustible material (having the appearance of a felt). The combustible materials constituting the combustible structure and said combustible charge must be chemically compatible and have the property of adhesion to one another. For this purpose, 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 manner, in the remainder of the description.

[0073] In certain embodiments, the combustible structure is a fibrous structure, such as that marketed by the company Eurenco, consisting of 45% to 81% by mass of cellulose ester (fibers), 3.5% to 33.5% by mass of cellulose (fibers), 4% to 14% by mass of resin (binder), 0% to 1.6% by mass of a stabilizer, and 0% to 15.5% of additional acrylic or polyester fibers (the sum of these different constituents being equal to 100%). An example of the composition of the combustible structure is given in Table 7.

[0074] [Tables7] Composition % by mass Nitrocellulose 69 Cellulose 25 Resin 5 stabilizer 1

[0075] The deposition of the paste of said combustible charge in solvent(s) produces a localized dissolution of the surface of the combustible structure ensuring good adhesion of the combustible charge deposited after drying of the paste.

[0076] The paste is deposited on the internal wall of the combustible structure of the munition according to one or more patterns which, after drying, constitute(s) said combustible charge. The deposited patterns may be of linear, helical or curvilinear shapes, or of combined shapes so as to obtain a mesh according to the optimal configuration sought for the ignition of the munition or the delivery of at least one additive or an energy supply (dopant). Different patterns may also be deposited over the height of the combustible structure.

[0077] When the at least one combustible charge acts as an ignition relay (relay charge), it does not require a specific connection with the ignition device. Said at least one relay charge is for example a linear or curvilinear pattern of which at least one end is coupled (in contact or sufficiently close) with the ignition device to ensure its ignition and thus initiate its combustion. The spatial and mass distributions of the patterns of the relay charge can be adapted with great latitude according to the characteristics of the propellant charge and the ammunition, thus allowing rapid and homogeneous ignition of the propellant charge. Said at least one relay charge is suitable for ammunition with separate stages (for example of the type described in patent US5129324), with assembled stages (for example according to the usual method of assembling the combustible structure of arrow shells, see [Fig.3b]), with large internal space requirements.

[0078] When the at least one combustible load ensures the delivery of at least one functional additive (additive loading) or a doping energy input (energy loading), the objective sought with the combustible loading is not to provide upon ignition a quasi-instantaneous contribution to the propellant loading, as in the case of relay loading, but to distribute the contribution of additive(s) or energy during the combustion of the loading. For this, the at least one additive or energy loading is not generally coupled with the ignition device and is ignited by the propellant loading or a relay loading. Its combustion is therefore generally initiated by that of the propellant loading or by at least one relay loading. However, it is not excluded that said additive loading or said energy loading is 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 the ignition relays) or semi-continuous or punctual patterns on the wall of the combustible structure according to a geometric and mass distribution ensuring the continuous supply proportional to the gas flow generated by the combustion of the propellant charge. For firing from a tube weapon, this flow rate is intended to increase as the projectile advances in the tube in order to best maintain the constant gas pressure in the tube.

[0079] The patterns of the additive charges or the energetic combustible charges are themselves arranged on the combustible structure according to a configuration adapted to the operation of the propellant charge so as to deliver the at least one additive or the energetic supply according to an optimal and continuous mass flow rate during the combustion period of the propellant charge. For example, these patterns can be of circular or linear or point or combined shapes distributed regularly or not on the combustible structure.

[0080] The combustible charge as described above is suitable for different types of ammunition, in particular for ammunition of the arrow shell or explosive shell type.

[0081] The invention is illustrated by the following examples given without limitation. Examples Example 1

[0082] [Fig.l] shows examples of patterns (linear, helical, mesh, combined shapes) that can be retained for a combustible charge on a planar view of the internal surface of the combustible structure. The combustible charge [1] adhered 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

[0083] This example concerns the implantation of combustible charges according to the invention in ammunition of the type of a large-volume arrow shell. It is an arrow shell [5] assembled according to the conventional method in two parts (figures 2a and 2b). The first rear part ([Fig.2a]) consists of a case [6] made of fibrous combustible material containing a first propellant charge [7a] and its ignition device. This ignition device forming a primer tube comprises an igniter and its primer inserted [8] in the base of the case [6] in connection with an igniter tube [9] in the center of the first propellant charge [7a]. A space

[10] is left free in the upper part of the combustible case [6]. The second front part ([Fig.2b]) consists of a feathered arrow

[11] (projectile) fitted with a sabot

[12] attached to a connecting piece

[13] and supporting around its rear feathered part a cylindrical cage

[14] .This cylindrical cage

[14] contains a second part of the propellant charge [7b]. The upper free part

[10] of the combustible case is intended to receive the tail of the arrow

[11] supporting around it the cylindrical cage

[14] . The tailed arrow

[11] equipped with the cage on its tail is secured to the upper part of the case by means of the combustible connecting piece

[13] . The connecting piece, also made of fibrous combustible material, is glued to the upper part of the case. The ammunition is therefore made of two assembled parts, each including a part of the propellant charge (figures 3a and 3b).

[0084] Relay charge patterns [15a and 15b] have been deposited on the internal face of the connecting piece

[13] and the case [6], the ends of which become joined after assembly (figures 3a and 3b). This ensures homogeneous ignition over the entire propellant charge (part contained in the case and front part in the area of ​​the connecting piece) of the munition. Similarly, at least one additive charge and / or at least one energetic combustible charge can also be deposited on the internal face of the connecting piece and / or the case, whether or not connected after assembly. The patterns of these combustible charges are adapted to ensure a supply of additive(s) or energy during the combustion of the propellant charge.

Claims

Claims

1. Munition (5) containing, in a cellulose ester-based combustible structure (6), a propellant charge of powder grains (7a, 7b) and an ignition device (8, 9), munition in which at least one cellulose ester-based combustible charge (15a, 15b) is deposited in the form of a solid geometric volume pattern adhering to the internal wall of the cellulose ester-based combustible structure.

2. Ammunition according to claim 1, wherein the combustible charge comprises from 88% to 92% by mass of ignition powder(s) and from 7% to 10% by mass of cellulose ester.

3. Ammunition according to claim 1, wherein the combustible charge comprises at least one functional additive selected from an anti-glow additive, an anti-erosion additive and an anti-coppering additive.

4. Ammunition according to claim 3 wherein the combustible charge comprises 70.3% to 92% by mass of functional additive(s), 0% to 17.6% of a combustible charge and 7% to 10% by mass of cellulose ester.

5. Ammunition according to claim 1, wherein the combustible charge comprises at least one energetic charge.

6. Ammunition according to claim 5, wherein the combustible charge comprises from 88% to 92% by mass of at least one energetic charge and from 7% to 10% by mass of cellulose ester.

7. Ammunition according to one of claims 2 to 6, wherein the at least one combustible charge deposited in the form of a solid geometric volume pattern is coupled with the ignition device.

8. Ammunition according to one of claims 3 to 6, wherein the at least one combustible charge deposited in the form of a solid geometric volumetric pattern is not coupled with the ignition device.

9. Ammunition according to one of claims 1 to 8, which is of the arrow shell or explosive shell type.

10. Ammunition according to claim 9, in which the combustible structure (6) is a case and comprises a connecting piece (13) separately supporting patterns of the at least one combustible load, the patterns of the case and the connecting piece being joined after assembly of the ammunition.

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