Adjustable-length combustible case and ignition relay thereof for propellant charge

Abstract

The present disclosure relates to a combustible case for a propellant charge, which comprises at least two tubular stages stacked by circumferential juxtaposition on a base stage having a bottom presenting a tubular neck in its central portion.

Description

[0001] Modular length fuel container and its ignition relay for propellant charge. Domain The invention relates to propellant charges for tube-type weapons, more particularly to fuel containers holding a charge of propellant powder(s) to form propellant charges. Prior art: Propellant charges consisting of pouches (also called cartridges), each containing a charge of propellant powder, stacked and housed in a fuel 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-1514293. 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 stabilizing disc for the stack of pouches at one end, and a lid at the other. An open neck in the base and stabilizing disc, leading to the central channel of the pouch stack, allows 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 powder charge. Furthermore, the flexible pouches in the propellant charge do not form a perfectly aligned geometric stack. Consequently, positioning the ignition relay in the center of the pouch stack via the base of the fuel container is complex and geometrically imprecise.The alignment of the ignition charge along the center of the propellant charge is therefore not guaranteed, and ignition defects, such as negative pressure waves, are observed in these propellant charges. 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 646762 describes compositions and a process for obtaining combustible containers. The combustible container is initially obtained by felting an aqueous suspension / emulsion, composed mainly of nitrocellulose fibers, cellulose fibers (kraft paper), and a thermosetting resin, onto a liquid-permeable metal filter serving as a mold (also called a felting grid). This process yields a first rough shape of the element, which is then pressed twice and then hot-cured (resin crosslinking).The aqueous suspension may also contain additives to address erosion reduction or the migration of nitrated oils. Similarly, the finished combustible container components can receive various types of coatings (including adhesive strips containing an anti-copper agent) or a film-forming nitrocellulose varnish for protection against external agents. The process of producing 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 becomes (molding and demolding phases at each stage of the process).The propellant container has a central tube housing an ignition relay that ensures homogeneous ignition of the propellant charge. These propellant charges, when designed to be assembled by nesting within the tube-mounted weapon, are commonly called modular (propellant) charges. For a large-caliber round (typically 155 mm), the propellant charge consists of nested 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 the term "top" refers to the portion of the container located on the projectile side.The fuel containers of modular charges have a neck at their base that extends into a central tube (shorter than the cylindrical wall of the container). Their cylindrical wall has a rounded end that narrows in diameter to meet the base wall. After the container is loaded with propellant powder, the top is closed with a combustible lid that is secured to the wall and the top of the central tube. The lid's positioning leaves a cylindrical wall protruding from the top. This wall, above the lid, allows the container to be nested with the base of another container. Patent application GB-A-2194024 and US patent 6457603 describe modular charge containers whose nesting is secured by connecting elements on their walls. The central tube is designed to contain a fast-burning ignition charge.This tube, containing the ignition charge, is referred to hereafter as the igniter tube. This tube may be multi-perforated to facilitate the rapid propagation of the ignition heat flux to the propellant charge. It may be bonded to the tube, both internally and externally. According to one variant, as described in patent application FR-A-3106401, the tube may 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 igniter tube, is sealed with a combustible lid after being loaded with a propellant charge (grains, sticks, or bundles).Patent application DE 10 2007 033832 describes an assembly of individual propellant charge modules, the first basic module of which is received in a case and connected to it. Each individual propellant charge module consists of a sealed container and a partial charge of propellant powder. The geometry of the containers is designed to allow them to be stacked in tiers to form the propellant charge of an artillery round. The assembled modular charges are placed in standardized logistical or tactical containers. This type of container is described, for example, in patent application FR-A-2840979. The gunner on the firing range then retrieves the modular charges from the containers to be stacked by nesting them in the gun barrel 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 (typically "Low Zone," 4 km to 13 km), and the second for long-range propellant assemblies (typically "High Zone," 8 km to 40 km). Each current modular charge fuel container has a base and a fuel lid on top. These two components have the following drawbacks: - they occupy a volume which, combined with the number of modular charges in the gun's chamber, reduces the space available for the additional propellant charge; - they increase, given their combined mass, the risk of incandescent residue after firing. Furthermore, each modular charge has a tube containing an ignition charge.Their discontinuous stacking leads to a staggered ignition of the propellant charge in the gun barrel. This results in longer ignition times (especially for cold firing) and the potential generation of negative pressure waves (especially for hot firing). Furthermore, a gunner operating under fixed conditions may only use a repeated and identical combination of modular charges for a desired firing range. It is also possible that modular charges may be taken from different containers, and that the remaining charges in the containers may no longer correspond to the desired combination. The containers must then be repackaged while still containing unused modular charges.Under fixed operational conditions (fixed ranges), the handling of propellant charges for tube-type weapons could be optimized by using a propellant charge of a suitable length for repeated firing ranges. However, manufacturing modular charges with optimized and adjustable dimensions is not feasible without additional costs, requiring the use of new molds and tooling to produce propellant 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.). This disclosure relates to a propellant charge of variable length. More specifically, 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. 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. In some embodiments, adhesive strips are placed on the inner wall of the circumferential jointing areas between stages, and textile strips are integrated into the outer wall of the circumferential jointing areas between stages. In one variant, 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 also contains an ignition relay consisting of nested flanged tubes with an ignition charge adhered to their inner face. The ignition relay is embedded in the central tubular neck of the fuel container. The fuel container and the flanged tubes are made of a fibrous combustible material containing a cellulosic ester, advantageously nitrocellulose. 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 building blocks, prior art modular fuel containers (for example, of the type described in patent application EP-A-0 646762), of standard length, and therefore prior art manufacturing tooling.The invention overcomes the constraints and drawbacks of prior art propellant charges by proposing variable-length propellant charges 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: Figure 1a shows the constituent elements of a prior art fuel container. Figure 1b shows the dimensional elements of a prior art fuel container. Figure 2 shows a view of a flanged tube and its connection to another flanged tube. Figure 3 shows the basic stage of a variable-length fuel container.Figure 4 shows a schematic view of the stage assembly of a modular-length fuel container body. Figure 5 shows a schematic view of a modular-length fuel container assembly equipped with an associated ignition relay and a lid. Figure 6 shows a view of a fuel container equipped with its ignition relay. Figure 7 shows a photograph of the internal part of a modular-length fuel container equipped with its ignition relay. Figure 8 shows photographs of the loading of propellant powder into a modular-length fuel container. Figure 9 shows a photograph of a propellant charge consisting of a modular-length fuel container. Description of the invention: A standard fuel container (1), as shown in Figures 1a and 1b, comprises a cylindrical wall (2) of thickness e, diameter F1, and length L1.The cylindrical wall has a rounded end extended by a cylindrical base (3) of diameter F2, smaller than F1, and of length L2. A tubular neck (4) originates in the center of the cylindrical base, extending into an annular fitting (5) of internal diameter F3. A central tube (6) of external diameter F3 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 Figure 1b) at its base to obtain a flanged tube (7) (of the type described in patent application FR-A-3115869), of length L5 with a male part (8) of length L3 and a flange (9) of length L4 (with L4 <L3) comme montré sur la figure 2. Les tubes à collerette sont réversibles, c’est-à-dire que l’extrémité de la partie mâle d’un tube à collerette peut s’emboiter dans la collerette d’un autre tube à collerette.Each flanged tube can optionally be cut radially along its male end to adjust its length L5. Such a standard fuel container, with its annular fitting cut (Figure 3), is used as the base stage (10) of the length-adjustable fuel container as described in this disclosure. This base stage comprises a cylindrical wall (11) and a bottom (12) with a tubular neck (13) in its central portion. Its length L1 can be reduced, if necessary, by cutting a portion of its cylindrical wall above the cylindrical bottom. Tubular stages (14) of desired heights H (H≤L1-L2) are cut from other standard fuel containers (whose tubular fittings (5) have been previously cut) above the height of the bottom, as indicated by the dashed lines in Figure 3.These tubular stages (14) are designed to be assembled by juxtaposition to form, together with the base stage, the body of the modularly lengthened fuel container. This provides a base stage and tubular stages with adjustable heights. Each tubular stage can optionally be cut to adjust its height. The modularly lengthed container is assembled by circumferentially juxtaposing the first stage onto the base stage, and then successive stages until the desired total length is reached. The container therefore comprises a base stage (10) and at least two stages (14). Advantageously, the container comprises from 2 to 10 stages (14). In some embodiments, an adhesive strip (15) is positioned to cover the inner wall of the circumferential joint area between stages (10, 14) or (14, 14). This adhesive strip thus provides an initial positioning function for the stacked stages, facilitating 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 layers is then reinforced by double-bonding a textile strip (16). This textile strip is placed on the outer surface of the circumferential joint zone between layers. To achieve this, the outer surface of the circumferential joint zone between two layers is coated with nitrocellulose collodion, extending slightly beyond the surface. This causes partial dissolution (gelatinization of the nitrocellulose by the action of the solvents present in the collodion) of the fibrous structure on the surface. The textile strip is then wrapped around the surface previously coated with the nitrocellulose collodion.The textile strip is then impregnated on its outer surface with nitrocellulose collodion, which may be the same as or different from that used to coat the outer wall. The collodion-impregnated textile strip fuses with the fibrous structure of the wall. After the nitrocellulose collodion dries through solvent evaporation, the textile strip becomes a structural component of the outer wall of the circumferential joint between floors. The outer wall of the circumferential joint between floors 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 joint between floors provides the mechanical rigidity of the assembly by forming a reinforcement.This yields the cylindrical body (17) of the modular-length combustible container of the invention, as shown in Figure 4 (the relative thicknesses of the adhesive strips and textiles at the tier joints with respect to the container structure are greater than actual thicknesses to ensure clarity). According to one embodiment, the double-coating process of nitrocellulose collodion on a textile strip is applied to the entire outer wall of the tier assembly. The textile strip is then spirally wound along the entire length of the container's outer wall. The outer wall of the container thus incorporates the spirally wound textile strip along its entire length. The nitrocellulose collodion used in this disclosure consists of a nitrocellulose base and a solvent. The nitrocellulose base comprises nitrocellulose, a plasticizer, a solvent, and optionally one or more additives.Collodions of this type are described in patent application FR-A-3117399. Examples of plasticizers include the following compounds: phthalates, centralites, 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), urethanes and their mixtures.The solvent is conventional: alcohols, ethers, acetates, and ketones, for example, acetone, an acetate, ether, ethanol, and mixtures thereof, such as a double solvent like acetone / butyl acetate or ethyl lactate / butyl acetate, or even ethyl acetate alone or ethyl lactate alone. The stabilizer is also conventional; it can be chosen, for example, from alpha-tocopherol, alpha-ionone, polybutadiene, akardyte, 2-nitrodiphenylamine (2NDPA), 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), and mixtures thereof.Additives are typically chosen from among anti-stick agents (such as silicone), anti-glare agents, antioxidants, colorants, surfactants, anti-caking agents, UV stabilizers (such as benzophenones or damylphenol), and mixtures thereof. Collodion is advantageously formulated to yield a dry extract (after solvent evaporation) of 10% to 80% of the collodion mass, preferably 35% to 50%. According to one embodiment, collodion contains the following constituents, expressed as mass percentages: - about 8% to about 60% nitrocellulose, - about 1% to about 40% of at least one plasticizer, - about 0.2% to about 2% of at least one stabilizing additive, - 0% to about 0.5% of at least one additive, - about 20% to about 90% of at least one solvent, the sum of the quantities of these constituents being equal to 100%.According to the process described in patent application FR-A-3106401, 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 collodion solvents), 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 system consists of a flanged tube assembly equipped with an ignition charge, forming the tubular ignition relay along the entire length of the modular-length fuel container. To ensure a secure fit, the contact surfaces between the male end and the flange are bonded after immersion in nitrocellulose collodion. The nitrocellulose collodion causes a local dissolution of the contact surfaces and, after drying (evaporation of the solvent(s)), ensures structural adhesion of the joint. The ignition relay is then inserted by fitting 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 nitrocellulose collodion to ensure adhesion.To obtain a variable-length propellant charge, the variable-length fuel container is loaded with propellant powder(s), and a fuel lid (20) is attached to the final stage and the ignition relay (19). Figure 5 shows a schematic view of the assembly of the variable-length fuel container (17) equipped with the associated ignition relay (19) and the lid (20). The invention thus enables the manufacture of a variable-length fuel container with its ignition relay, using standard-length fuel containers of the prior art 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 modular-length propellant container is greater than that of a conventional container of equivalent length, resulting in an increased muzzle velocity compared to prior art propellant charges. This provides a modular-length propellant charge, adapted to the length of the chamber of the tube-type weapon, which can replace, with a volume saving, an assembly of conventional modular propellant charges. Multiple length modulations are possible, allowing for the design of equivalents to conventional modular charge assemblies and even exceeding them to complete the full available length of the combustion chamber (existing lengths, for example, 39, 45, and 52 calibers, or future lengths, for example, 58 calibers and above).As explained above, one aspect of this disclosure relates to a method for obtaining a combustible container as defined herein, which includes: - 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 extending from the tubular neck, and (iv) a central tube extending from the annular fitting via a rounded end; - stacking the stages by circumferential juxtaposition. In one embodiment of the aforementioned method, the container stages are juxtaposed by applying adhesive tape to the internal surface of the jointing area between the stages.Adjacent floors can be advantageously stiffened by coating their outer surface with nitrocellulose collodion, covering the coated outer surface with a textile strip, and then impregnating the textile strip with nitrocellulose collodion. In this way, the outer surface of the circumferential jointing areas between floors incorporates the textile strip.The variable-length propellant charges of the invention are suitable: - as a single propellant charge to simplify the assemblies (bi-modular "Low Zone" & "High Zone") of modular charges (for example, equivalent in length to 1.2 or 1.5 modules or an intermediate charge equivalent to 2 or even 3 modules); - as a single long-range charge allowing a space saving of at least 10% for the main propellant element due to the elimination of the bases and covers constituting modular charges for existing (39, 45, 52 calibers) and future (58 calibers & above) tube-type weapons. Thus, in 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.In another respect, this disclosure relates to the use of a propellant charge as defined above in a tube-fire weapon round. This disclosure is illustrated by the example below, which is provided for illustrative purposes only. Example: Standard fuel containers have been manufactured using 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 constituents being equal to 100%). The composition of the combustible fibrous structure used in this example is given in Table 1.Table 1 Composition % by mass Nitrocellulose(s) - NC 69 Cellulose(s) - Kraft 25 Latex or acrylic resin 5 Stabilizer for NC 1 The dimensions of the standard containers (1) are given in Table 2 with reference to Figure 1b. Table 2 Standard fuel container Dimensions mm e 2.5 L1 / F1 181 / 153 L2 / F2 23 / 149 F3 30 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 Figure 2. Table 3 Flanged tube Dimensions mm L5 / F3 126 / 30 L4 10 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-3106401. The geometry of the standard containers (17) after cutting the flanged tube (7) is shown in Figure 3. One of them is kept as is to form the base stage (11).As shown in Figure 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. The adjustable-length fuel container (17) of this example consists of a base stage (10) and six juxtaposed stages (14), and its ignition relay (19) consists of eight nested flanged tubes (7) equipped with their ignition charge. A first stage (14) is placed edge-to-edge on the front part of the base stage (10). An adhesive strip (15) containing an anti-copper agent, ensuring the joint and positioning of this first assembly, is placed on the inner wall of the circumferential jointing area. This adhesive tape (15) is obtained by co-lamining a tin-based metal tape and a polyester tape 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 other layers (14) are then placed side by side on top of the first layer (14) by applying the adhesive strip (15) to the inner wall of each layer joint. Each outer wall of the inter-layer joint is then coated to a height of approximately 80 mm with nitrocellulose collodion. A strip of fabric (16) is then placed around the circumference of each nitrocellulose collodion-coated joint wall. The fabric is, for example, 17 decitex Nylon 6, approximately 0.15 mm thick and 60 mm wide. The fabric strip (16) is then covered with the same collodion that was previously applied in excess to the joint wall.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 stage assembly. 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 the gluing collodion has dried for approximately 1 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 modular length fuel container (17) thus constituted is equipped along its entire central length with a continuous ignition relay (19) as shown in figure 4.For this example, the length of the modular-length container after assembly of the 7 stages (1 base stage (10) and 6 stages (14) placed side by side) is 960 mm. The container in this 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 fuel 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. For the same overall length of 960 mm, the propellant charge obtained with the modular-length fuel container in this example is compared with a prior art propellant charge consisting of a stack of 6 modular charge containers of the same overall length (of the type shown in Figure 1).The ignition charge of each modular charge is identical to that of each igniter tube of the ignition relay included in the modular-length fuel container. Comparative dimensional characteristics: 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 the propellant charge of 16.45 liters, greater than that of the prior art stack of 6 modular charges, which is 15.6 liters. For a propellant composition of multibase composition and conventional geometry, known as 19T in a rosette configuration, the mass of the propellant charge arranged loose in the modular-length fuel container in this 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.Table 4 Fuel Container Overall Length Volume Density of the Geometry Mass of all (mm) free powder of powder grains in (litres) propellant bulk powder (g / cm3) contained (kg) Stack of 6 containers 15.6 2.4 x 6 = standard fuels 960 1.65 Rosette 14.4 Fuel container at 16.45 19 T 17 adjustable length Comparative functional characteristics 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 shots are carried out with a standard inert 155 HEE R BB type projectile including a base drag reducer in a 155 mm caliber barrel of 52 calibers in length 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.Negative pressure waves are related to the difference between the pressure at the breech and that at the base of the projectile. Table 5 Propellant Charges Ignition Time at +21°C Pressure Waves Negative Muzzle Velocity (MPa) (m / s) Stack of 6 containers < 50 ms < 30,940 standard propellants Fuel container at < 20 ms < 10 >1000 adjustable length The performance of the propellant charge in this 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

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

2. A fuel container according to claim 1, wherein the inner wall of the circumferential jointing areas between stages (10, 14) is coated with an adhesive strip (15).

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

4. A fuel container according to any one of claims 1 to 3, wherein the outer wall of the circumferential jointing areas between stages incorporates a textile strip (16). 5.

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

2. A combustible container according to any one of claims 1 to 5, further comprising an ignition relay (19) consisting of nested flanged tubes (7) having an ignition charge (18) adhered to their inner face.

3. A 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).

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

9. A 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 tiers 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 extending from the tubular neck, and (iv) a central tube extending via a rounded end of the annular fitting; - superimposing the tiers by circumferential juxtaposition.

11. A method according to claim 10, wherein the tiers are juxtaposed by coating the internal surface of the jointing zone between tiers with an adhesive strip. 12.A method according to claim 11, further comprising stiffening the juxtaposed stages 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.

13. A propellant 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 round for a tube-type weapon.

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