Modular length fuel container and its ignition relay for propellant charge.

Abstract

This disclosure relates to a propellant fuel container, which includes at least two tubular stages superimposed by circumferential juxtaposition with a base stage having a bottom with a tubular neck in its central part.

Description

Title of the invention: Modular length fuel container and its ignition relay for propellant charge. Scope of the invention

[0001] The technical field of the invention is that of propellant charges for tube-type weapons, more particularly that of fuel containers holding a charge of propellant powder(s) to form propellant charges. Prior art

[0002] Propellant charges consisting of pouches (also called cartridges), each containing a charge of propellant powder, stacked and housed in a combustible container (also called a fuel casing, fuel box, or fuel pouch), are known. This type of propellant charge is described in patent application FR-A-1 514 293. The number and combination of pouches to be stacked in the fuel container are chosen according to the desired firing range. The pouches, with their flexible textile-type covering, are cylindrical in shape and have a central channel allowing for the placement of an ignition relay along the propellant charge. The fuel container has a base and a disc for securing the stack of pouches at one end and a lid at the other end.An open neck at the bottom and a stabilizer disc opening onto the central channel of the bag stack allow the ignition relay to pass along the central part of the propellant charge. This packaging in a flexible textile, besides being impractical to handle under operational conditions, does not guarantee the integrity of the propellant charge. Furthermore, the flexible-wrapped bags within the propellant charge do not form a perfectly aligned geometric stack. Consequently, positioning the ignition relay at the center of the bag stack via the bottom of the fuel container is complex and geometrically imprecise. Therefore, the alignment of the ignition charge along the center of the propellant charge is not guaranteed, and ignition defects, such as negative pressure waves, are observed in these propellant charges.

[0003] To date, propellant charges for tube-type weapons conventionally consist of one or more cylindrical solid combustible containers holding a propellant powder charge. Patent application EP-A-0 646 762 describes compositions and a method for obtaining combustible containers. The combustible container is initially obtained by felting an aqueous suspension / emulsion consisting mainly of nitrocellulose fibers onto a liquid-permeable metal filter serving as a mold (also called a felting grid). Cellulose fibers (kraft paper) and a thermosetting resin are used to create a first rough shape of the element. This rough shape is then pressed twice and then hot-cured (resin cross-linking). The aqueous suspension may also contain additives to address erosion control or the migration of nitrated oils. Similarly, the finished combustible container elements can be coated with various types of materials (including adhesive strips containing a copper-blocking agent) or a protective film-forming nitrocellulose varnish against external agents.

[0004] The process for obtaining combustible containers therefore requires the use of molds and tooling adapted to each of the four phases of object formation (felting, wringing, dehumidification, and curing). The dimensions, particularly the length, of the combustible containers are thus standardized to correspond with those of the molds and tooling. It is easy to understand that the longer the container, the more complex and expensive the tooling (molding and demolding phases at each stage of transformation). The combustible container has a central tube housing an ignition relay that ensures homogeneous ignition of the propellant charge. These propellant charges, when intended to be assembled by fitting into the tube-mounted weapon, are commonly called modular (propellant) charges.For a large-caliber round (typically 155 mm), the propellant charge consists of a series of modular charges, each containing a propellant charge and its associated ignition relay. The modular charges are cylindrical with a diameter calibrated for the tube-mounted weapon and a length approximately equal to their diameter. In the remainder of this document, the term "bottom" refers to the portion of the container located on the breech side of the tube-mounted weapon, and "top" refers to the portion of the container located on the projectile side. The propellant containers of the modular charges have a neck at their bottom that extends into a central tube (shorter than the length of the cylindrical wall of the container). Their cylindrical wall has a rounded end that narrows in diameter to meet the bottom wall.After the container is loaded with propellant powder, the top is sealed with a combustible lid attached to the wall and the top of the container's central tube. The lid's positioning leaves a cylindrical wall protruding above the lid. This wall allows the container to be nested with the bottom of another container. (See patent application GB-A-2 194 024 and the patent.) US 6,457,603 describes modular cargo containers whose interlocking sections are secured by connecting elements on their walls. The central tube is designed to contain a live-burn ignition charge. This tube, containing said ignition charge, is referred to in the remainder of this document as the ignition tube. The tube can be multi-perforated to promote the rapid propagation of the ignition heat flux to the propellant charge. It can be bonded to the tube, both inside and on its external surface. According to one variant, as described in patent application FR-A-3 106 401, the tube can receive an ignition charge by depositing nitrocellulose collodion loaded with ignition powder onto its internal surface. After the collodion has dried, the tube is coated with the ignition charge, which adheres to its internal surface. The container, fitted with its ignition tube, is sealed with a combustible lid after being loaded with a propellant charge (grains, sticks, or bundles).

[0005] The modular charges are arranged in standardized logistical or tactical containers. This type of container is described, for example, in patent application FR-A-2 840 979. The gunner on the firing range then retrieves the modular charges from the containers to be stacked by interlocking them in the tube-mounted weapon for the desired firing range. The modular charges are sized to allow the gunner to assemble a combination that covers all desired firing ranges. Generally, two types of modular charges of the same dimensions but containing different propellant charges are available: the first for short-range propellant assemblies ("Low Zone," typically 4 km to 13 km), and the second for long-range propellant assemblies ("High Zone," typically 8 km to 40 km).

[0006] Each combustible container for current modular loading is equipped with a bottom wall and a combustible lid on its top. These two elements have, in particular, the following disadvantages: - occupy a volume which, combined with the number of modular charges in the chamber of the tube-mounted weapon, is less than the volume that could be occupied by the additional propellant powder charge, - increase, given their cumulative mass, the risk of incandescent residues after firing.

[0007] Furthermore, each modular charge has a tube containing an ignition charge. Their discontinuous stacking leads to a staged ignition of the propellant charge in the tube-based weapon. This results in longer ignition delays (particularly for cold firing) and the possible production of negative pressure waves (particularly for hot firing).

[0008] Also, an artilleryman in fixed operational conditions may only use a repeated and identical combination of modular charges for a desired firing range. It is then also possible that modular charges are taken from different containers and that the modular charges remaining in the containers no longer correspond to the desired combination. The containers must then be reconditioned while still containing unused modular charges. Under fixed operational conditions (fixed ranges), the handling of the tube-driven weapon's charges could therefore be optimized by using a propellant charge of a suitable length for repeated firing ranges. However, manufacturing modular charges with optimized and adjustable dimensions cannot be considered without additional costs, requiring the use of new molds and tooling to produce fuel containers of non-standard lengths (either shorter or longer). Current technology therefore does not allow for the production of propellant charges of adjustable length without significant investment and time (design, plans, tooling, assembly and disassembly, maintenance, etc.). Summary of the invention

[0009] This disclosure relates to a propellant charge of variable length. More particularly, it concerns a tubular fuel container of variable length and its ignition relay. The fuel container, equipped with its ignition relay, is loaded with propellant powder(s) to constitute the propellant charge.

[0010] The propellant charge fuel container of this disclosure comprises tubular stages arranged circumferentially with a base stage having a bottom with a central tubular neck. Adhesive strips are arranged on the inner wall of the circumferential interstage seams, and textile strips are integrated into the outer wall of the circumferential interstage seams. In one embodiment, a single textile strip is integrated into the outer wall in a spiral winding along the entire length of the fuel container. The fuel container further contains an ignition relay consisting of nested flanged tubes with an ignition charge adhered to their inner face. The ignition relay is embedded in said central tubular neck of the fuel container.The fuel container and the flanged tubes are made of fibrous combustible material containing a cellulosic ester, advantageously nitrocellulose.

[0011] This disclosure also relates to a method for obtaining said fuel container equipped with its ignition relay. This method has the advantage of using as manufacturing technological building blocks prior art modular fuel charge containers (for example of the type described in patent application EP-A-0 646 762), of standard length, and therefore prior art manufacturing tooling.

[0012] The invention overcomes the constraints and drawbacks of prior art propellant charges by proposing propellant charges of variable length equipped with high-performance ignition relays. The propellant charges of this disclosure are suitable for the combustion chamber volumes of current and future improved-performance tube-type weapons (with reference to their caliber and tube length). Their functional performance (ignition, projectile velocity, etc.) is enhanced compared to that of prior art propellant charges. Brief description of the figures

[0013] [Fig.la] represents the constituent elements of a prior art combustible container.

[0014] [Fig.lb] represents the dimensional elements of a prior art combustible container.

[0015] [Fig.2] shows a view of a flanged tube and its connection with another collared tube.

[0016] [Fig.3] shows the base stage of a fuel container of adjustable length.

[0017] [Fig.4] shows a schematic view of the assembly of the stages of a body of the fuel container with adjustable length.

[0018] [Fig.5] shows a schematic view of a fuel container assembly Adjustable length, equipped with an associated ignition relay and a cover.

[0019] [Fig.6] shows a view of a fuel container equipped with its ignition relay.

[0020] [Fig.7] shows a photograph of the internal part of a fuel container Adjustable length, equipped with its own ignition relay.

[0021] [Fig.8] shows photographs of the loading of propellant powder into a fuel container of adjustable length.

[0022] [Fig.9] shows a photograph of a propellant charge consisting of a container adjustable length fuel. Description of the invention

[0023] A standard fuel container (1), as shown in Figures 1a and 1b, comprises a cylindrical wall (2) of thickness e, diameter ¢1 and length L1. The cylindrical wall has a rounded end extending into a cylindrical bottom (3) of diameter ¢2, less than ¢1, and of length L2. A tubular neck (4) originates at the center of the cylindrical bottom and is extended by an annular fitting (5) of internal diameter ¢3. A central tube (6) of external diameter ¢3 extends from this annular fitting via a rounded end. The annular fitting of each fuel container is cut (along the dashed cutting lines shown in [Fig. 1b]) at its base to obtain a flanged tube (7) (of the type described in patent application FR-A-3 115 869), of length L5 with a male part (8) of length L3 and a flange (9) of length L4 (with L4 <L3) as shown in [Fig. 2]. The flanged tubes are reversible, meaning that the male end of one flanged tube can be inserted into the flange of another flanged tube. Each flanged tube can optionally be cut radially on its male end to adjust its length L5.

[0024] Such a standard fuel container, the annular joint of which has been cut off ([Fig. 3]), is used as the base stage (10) of the modular-length fuel container according to this disclosure. This base stage therefore comprises a cylindrical wall (11) and a bottom (12) with a tubular neck (13) in its central part. It is possible, if necessary, to reduce its length L1 by cutting off a portion of its cylindrical wall above the cylindrical bottom.

[0025] Tubular stages (14) of height H (H <L1-L2) souhaitées au-dessus de la hauteur du fond comme indiqué par les pointillés sur la [Fig.3]. Ces étages tubulaires (14) sont destinés à être assemblés par juxtaposition pour former avec l’étage de base le corps du conteneur combustible de longueur modulable.

[0026] This provides a base level and tubular levels with adjustable heights. Each tubular level can optionally be cut to adjust its height.

[0027] The container of adjustable length is assembled by circumferentially juxtaposing the first level onto the base level, and then successive levels until the desired total length is reached. The container thus comprises a base level (10) and at least two levels (14). Advantageously, the container comprises from 2 to 10 levels (14). An adhesive strip (15) is positioned to cover the inner wall of the circumferential joint area between levels (10, 14) or (14, 14). This adhesive strip thus provides a primary positioning function for the stacked levels, enabling handling of the assembly. This strip advantageously contains one or more functional agents, such as an anti-copper agent, an anti-erosion agent, or an anti-glare agent. The assembly of the juxtaposed levels is then reinforced by double-bonding a textile strip (16).This textile strip is placed on the outer wall of the circumferential joint between floors. To achieve this, the outer wall of the circumferential joint between two floors is coated with nitrocellulose collodion, extending slightly beyond the surface. This causes partial dissolution (gelatinization of the nitrocellulose by the action of solvents present in the collodion) of the fibrous structure on the surface. The textile strip is then wrapped around the previously coated wall. The textile strip is then impregnated on its outer surface with nitrocellulose collodion, which may be the same as, or different from, the one used to coat the outer wall. The textile strip impregnated with nitrocellulose collodion fuses with the fibrous structure of the wall. After the nitrocellulose collodion has dried by solvent evaporation, the textile strip becomes a structural part of the outer wall of the circumferential inter-story joint zone. The outer wall of the circumferential inter-story joint zone thus incorporates the textile strip. This stiffening process is therefore comparable to the conventional lamination process for obtaining composite structures. The layered composite structure of the outer walls of the circumferential inter-story joint zones ensures the mechanical rigidity of the assembly by forming a reinforcement. This results in the cylindrical body (17) of the modular-length fuel container of the invention, as shown in [Fig.4] (the relative thicknesses of the adhesive strips and textiles at the floor joints in relation to the container structure are greater than reality to ensure the legibility of the view). .

[0028] According to one embodiment, the double collodion nitrocellulose lamination process of a textile strip is applied to the entire outer wall of the stack assembly. The textile strip is then spirally wound along the entire length of the outer wall of the container. The outer wall of the container thus incorporates the spirally wound textile strip along its entire length.

[0029] The nitrocellulosic collodion used in this disclosure consists of a nitrocellulosic base and a solvent. The nitrocellulosic base comprises nitrocellulose, a plasticizer, a solvent, and optionally one or more additives. Collodions of this type are described in patent application FR-A-3 117 399.

[0030] Examples of plasticizers include the following compounds: phthalates, centralities, diethyl succinate, adipates, triacetin, organic phosphates, citrates, triethylene glycol, glycol esters, castor oil, fusel oil, glycerol-based molecules, tetrahydrofurfuryl oleate, pentaerythrityl tetrabenzoate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, trioctanoate, methyldinitramine, camphor, sucrose acetate isobutyrate, sucrose benzoatesulfoamides, urea resin, acrylic resin, amphiphilic block copolymer polyethylene adipate-polyethylene glycol, epoxylated and ethoxylated plasticizer, trioctyl trimellitate, dioctyl malate or bis(2-ethylhexyl) malate, cardanol, dimethylacetamide, butylphthalimide, isopropylphthalimide, alkyl polyvinyl ethers, crosslinked polyesters, poly(E-caprolactone), methanes and their mixtures.

[0031] The solvent is conventional: alcohols, ethers, acetates, and ketones, for example acetone, an acetate, ether, ethanol, and mixtures thereof, for example a double solvent of the acetone / butyl acetate type or of the type ethyl lactate / butyl acetate, or ethyl acetate alone, or ethyl lactate alone.

[0032] The stabilizer is of a conventional type, it can be chosen for example from alpha tocopherol, alpha ionone, polybutadiene, akardyte, 2-nitrodiphenylamine (2NDPA), l,3-diethyl-l,3-diphenyl urea (centrality I), l,3-dimethyl-l,3-diphenyl urea (centrality II), and l-methyl-3-ethyl-l,3-diphenyl urea (centrality III), and mixtures thereof.

[0033] The additives are typically chosen from among anti-stick agents (of the silicone type, for example), anti-glare agents, antioxidants, colorants, surfactants, anti-caking agents, anti-UV agents (for example of the benzophenone or diamyl phenol type) and mixtures thereof.

[0034] Collodion is advantageously formulated to lead to a dry extract (after evaporation of the solvent) of 10% to 80% of the mass of collodion, preferably to a dry extract of 35% to 50%.

[0035] According to one embodiment, collodion contains the following constituents, expressed as mass percentages:

[0036] - approximately 8% to approximately 60% nitrocellulose,

[0037] - approximately 1% to approximately 40% of at least one plasticizer,

[0038] - approximately 0.2% to approximately 2% of at least one stabilizing additive,

[0039] - 0% to approximately 0.5% of at least one additive,

[0040] - approximately 20% to approximately 90% of at least one solvent,

[0041] the sum of the quantities of these constituents being equal to 100%.

[0042] According to the process described in patent application FR-A-3 106 401, a nitrocellulose collodion loaded with ignition powder is deposited on the inner wall of the male end of the flanged tubes. After drying (evaporation of the solvents from the collodion), the ignition charge (18) adheres to the male end of the flanged tube. The flanged tubes, each with its ignition charge, are nested together to form a tubular ignition relay (19) with a length equal to that of the cylindrical body of the adjustable-length fuel container. The male end of one flanged tube fits into the flange of another flanged tube, as shown in Figure 2. If necessary, flanged tubes have been pre-cut to length along their male ends so that the final nesting corresponds to the total height of the adjustable-length fuel container.This provides a system of flanged tubes fitted with an ignition charge, designed to form the tubular ignition relay along the entire length of the modularly lengthened fuel container. To ensure good adhesion of the flanged tube joints, the contact surfaces between the male end and the flange are bonded after immersion in nitrocellulose collodion. The collodion... Nitrocellulosic collodion produces a local dissolution of the contacting surfaces and, after drying (evaporation of the solvent(s)), ensures structural adhesion of the joint. The ignition relay is then fitted by inserting its male end into the tubular neck of the base stage of the modular-length fuel container. Prior to insertion, the outer wall of the male end of the ignition relay and the inner surface of the tubular neck of the base stage are coated with nitrocellulosic collodion to ensure adhesion.

[0043] To obtain a propellant charge with adjustable length, the fuel container with adjustable length is loaded with one or more propellant powders and a fuel cover (20) is fixed on the last stage and the ignition relay (19).

[0044] Fig. 5 shows a schematic view of the assembly of the adjustable length fuel container (17) equipped with the associated ignition relay (19) and the cover (20).

[0045] The invention thus enables the manufacture of a variable-length fuel container with its ignition relay, using prior art standard-length fuel containers as basic technological building blocks. The ignition relay in the propellant charges of the invention is simple to assemble and ensures efficient ignition along the entire length of the variable-length fuel container. The available volume in the variable-length fuel container is greater than that of a conventional container of equivalent length, which provides an increase in the muzzle velocity of the munition compared to prior art propellant charges. A variable-length propellant charge, adapted to the length of the chamber of the tube-type weapon, is thus available and can replace, with a volume saving, an assembly of conventional modular propellant charges.

[0046] The length modulations are multiple, allowing the design of equivalents of conventional modular charge assemblies and can go beyond to complete the total available length of the combustion chamber (existing lengths for example of 39, 45, 52 calibers or future for example of 58 calibers and more).

[0047] As explained above, one aspect of this disclosure relates to a process for obtaining a combustible container as defined herein, which includes:

[0048] - obtaining the container tiers and flanged tubes by cutting of elements in a combustible container comprising (i) a cylindrical wall, (ii) a cylindrical bottom in the center of which a tubular neck originates, (iii) an annular fitting extending from the tubular neck, and (iv) a central tube extending via a rounded end of the annular fitting;

[0049] - the superposition of floors by circumferential juxtaposition.

[0050] In one embodiment of the aforementioned method, the container tiers are joined by coating the inner surface of the jointing area between tiers with an adhesive strip. The joined tiers can advantageously be stiffened by coating their outer wall with nitrocellulose collodion, covering the coated outer wall with a textile strip, and then impregnating the textile strip with nitrocellulose collodion. In this way, the outer wall of the circumferential jointing areas between tiers incorporates the textile strip.

[0051] The modular length propulsive charges of the invention are suitable: - as a single propulsive charge in simplifying the assemblies (bi-modular “Low Zone” & “High Zone”) of modular charges (for example equivalent in length to 1.2 or 1.5 modules or intermediate charge equivalent to 2 or even 3 modules); - as a unique long-range charge allowing a space saving of at least 10% for the main propellant element due to the disappearance of the bases and covers constituting the modular charges for existing (39, 45, 52 calibers) and future (58 calibers & more) tube-type weapons.

[0052] Thus, according to one aspect, the present disclosure relates to a propellant charge consisting of a fuel container as defined herein, said container containing a charge of propellant powder(s) and being closed with a lid.

[0053] According to another aspect, the present disclosure relates to the use of a propellant charge as defined above in a tube-gun munition.

[0054] This disclosure is illustrated by the example below, given for illustrative purposes only. Example

[0055] Standard combustible containers have been manufactured with a fibrous structure, such as that marketed by Eurenco, consisting of 45% to 81% by mass of cellulosic 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% by mass of additional acrylic or polyester fibers (the sum of these different constituents being equal to 100%). The composition of the combustible fibrous structure used in this example is given in Table 1.

[0056] [Tables 1] Composition % by mass Nitrocellulose(s) - NC 69 Cellulose(s) - Kraft 25 Latex or acrylic resin 5 Stabilizer for NC 1

[0057] The dimensions of the standard containers (1) are given in Table 2 with reference to [Fig.lb].

[0058] [Tables2] Standard combustible container Dimensions mm e 2.5 L1 / 0>l 181 / 153 L2 / O2 23 / 149 ¢3 30

[0059] For each standard container (1), the flanged tube (7) was cut and extracted. The dimensions of the cut flanged tubes are given in Table 3 with reference to [Fig. 2].

[0060] [Tables3] Flanged tube Dimensions mm L5 / O3 126 / 30 L4 10

[0061] Each male part (8) of the flanged tubes (7) receives an ignition charge which adheres to its inner wall according to the process described in patent application FR-A-3 106 401.

[0062] The geometry of the standard containers (17) after cutting the flanged tube (7) is shown in [Fig. 3]. One of them is retained as is to form the base stage (11). As shown in [Fig. 4], the cylindrical wall of the other containers is cut above the height of the bottom (3) to obtain cylindrical stages (14) with a height of 154 mm and a diameter of 153 mm.

[0063] The modular length fuel container (17) of this example consists of a base stage (10) and 6 juxtaposed stages (14) and its ignition relay (19) consists of 8 nested flanged tubes (7) equipped with their ignition charge.

[0064] A first stage (14) is arranged by edge-to-edge juxtaposition on the front part of the base stage (10). An adhesive strip (15) containing an anti-copper agent, ensuring the joining and positioning of this first assembly, is disposed on the inner wall of the circumferential jointing area. This adhesive strip (15) is obtained by co-lamining a tin-based metallic strip and a A polyester strip coated on one side with a high-performance acrylic adhesive. Its thickness is approximately 0.1 mm and its width approximately 36 mm. The five remaining floors (14) are then placed side by side above the first floor (14) by positioning the adhesive strip (15) on the inner wall of each floor joint. Each outer wall of the joint between floors is then coated to a height of approximately 80 mm with nitrocellulose collodion. A textile strip (16) is then placed around the circumference of each joint wall coated with nitrocellulose collodion. The textile is, for example, type Nylon 6, 17 decitex, approximately 0.15 mm thick and 60 mm wide. The textile strip (16) is then covered with the same collodion that was previously applied in excess to the wall of the joint.After drying (evaporation of the solvent from the double collodion coating) for approximately 1 hour at 80°C, the textile strip (16) is integrated into the fibrous structure of the container and ensures the rigidity of the container tier assembly.

[0065] The interlocking surfaces of the eight flanged tubes (7), each containing its ignition charge (18), are coated with nitrocellulose collodion before being joined by interlocking. After drying the collodion for approximately one hour at 80°C, the assembly forming the ignition relay (19) is perfectly rigid. The male end (8) of the ignition relay (19) and the inner surface of the tubular neck (13) of the base stage (10) are then similarly coated with collodion before being joined. The resulting variable-length fuel container (17) is fitted along its entire central length with a continuous ignition relay (19) as shown in [Fig. 4]. For this example, the length of the modular-length container after assembly of the 7 levels (1 base level (10) and 6 levels (14) juxtaposed) is 960 mm.The container in the example is loaded with a propellant charge (21) composed of powder grains arranged loose (then vibrated to compact them) (Figure 8a) or arranged radially in superimposed layers (Figure 8b). The container is then closed with a combustible lid (20) that fits onto the circular edge of the last stage and onto the end of the ignition relay (19). Figure 9 shows a photograph of the resulting propellant charge.

[0066] For the same overall length of 960 mm, the propellant charge obtained with the modular-length fuel container of the example is compared with a prior art propellant charge consisting of a stack of 6 modular-length containers of the same overall length (of the type shown in Figure 1). The ignition charge of each of the modular charges is identical to that of each igniter tube of the ignition relay included in the modular-length fuel container. Comparative dimensional characteristics

[0067] The modular-length fuel container, with an overall length of 960 mm, due to the absence of an intermediate bottom and lid between stages, has a free volume for loading propellant powder of 16.45 liters, greater than that of the prior art stack of 6 modular charges, which is 15.6 liters. For a propellant powder composition in a multibase composition and conventional geometry, known as 19T in a rosette configuration, the mass of the propellant powder charge arranged loose in the modular-length fuel container of the example is 17 kg, greater than that contained in the stack of 6 modular charges, which is 14.4 kg. These comparative structural data are summarized in Table 4.

[0068] [Tables4] Fuel Container Overall Length (mm) Volume (liters) Propellant Powder Density (g / cm³) Powder Grain Geometry Bulk Powder Mass (kg) Stack of 6 Standard Fuel Containers 960 15.6 1.65 Rosette 19 T 2.4 x 6 = 1 4.4 Adjustable Length Fuel Container 16.45 17 Comparative functional characteristics

[0069] Table 5 gives the comparative functional characteristics between the propellant charge of the example and the prior art propellant charge with the propellant powder charge of Table 4. The firings are carried out with a standard inert 155 HEE R BB type projectile including a base drag reducer in a 155 mm caliber barrel, 52 calibers long, at a temperature of 21°C. The ignition time indicated in the table corresponds to the time required for a pressure increase from 0 to 25 MPa after ignition. The negative pressure waves are related to the difference between the pressure at the breech and that at the base of the projectile.

[0070] [Tables5] Propulsive charges Ignition time at +21°C Negative pressure waves (MPa) Seal velocity (m / s) Stack of 6 standard fuel containers < 50 ms <30,940 Modular ion fuel container < 20 ms < 10 >1000

[0071] The performance of the propellant charge in the example is therefore improved compared to that of a prior art propellant charge. Under the conditions indicated in Tables 4 and 5, the calculated gain in projectile range is approximately 10%, increasing from approximately 40 km to approximately 44 km.

Claims

Demands

1. Fuel container for propellant charge, which includes at least two tubular stages (14) superimposed by circumferential juxtaposition with a base stage (10) having a bottom (12) with a tubular central neck (13).

2. Combustible container according to claim 1, in which the inner wall of the circumferential jointing areas between floors (10,14) is coated with an adhesive strip (15).

3. Combustible container according to any one of claims 1 and 2, in which the adhesive strip (15) contains a functional agent such as an anti-coppering agent, an anti-erosion agent, an anti-glare agent.

4. Combustible container according to any one of claims 1 to 3, wherein the outer wall of the circumferential inter-story jointing areas incorporates a textile strip (16).

5. Combustible container according to any one of claims 1 to 3, wherein the outer wall of the container incorporates a strip of textile (16) spirally wound along the entire length of the container.

6. Combustible container according to any one of claims 1 to 5, further containing an ignition relay (19) consisting of nested flanged tubes (7) provided with an ignition charge (18) adhered to their inner face.

7. Combustible container according to any one of claims 1 to 6, wherein the ignition relay (19) is embedded in the tubular neck (13) of the base stage (10).

8. Combustible container according to any one of claims 1 to 7, wherein the stages (10,14) and the flanged tubes (7) are made of fibrous combustible material containing a cellulosic ester.

9. Combustible container according to claim 8 characterized in that the cellulosic ester is nitrocellulose.

10. A method for obtaining a combustible container according to any one of claims 1 to 9, comprising: - obtaining the container stages and flanged tubes by cutting elements from a combustible container comprising (i) a cylindrical wall, (ii) a cylindrical bottom in the center of which a tubular neck originates, (iii) an annular fitting in extension of the tubular neck, and (iv) a central tube in extension via a rounding of the annular fitting; - the superposition of the stages by circumferential juxtaposition.

11. Method according to claim 10, wherein the floors are juxtaposed by coating the internal surface of the jointing area between floors with an adhesive strip.

12. A method according to claim 11, further comprising stiffening the juxtaposed floors by coating their outer wall with nitrocellulosic collodion, covering the coated outer wall with a textile strip, and then impregnating the textile strip with nitrocellulosic collodion.

13. Propulsive charge consisting of a fuel container according to claims 1 to 9, the fuel container containing a charge of propellant powder(s) and being closed with a lid.

14. Use of a propellant charge according to claim 13 in a munition for a tube-fired weapon.

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