Abstract: A fibrous preform (1) is produced, provided with a sandwich structure comprising an intermediate flexible core (4) and two outer fibrous frames (2, 3), respectively arranged on opposing outer faces of said flexible core (4) and assembled by sections of wire (8, 9) passing through said fibrous frames (2, 3), said preform (1) being impregnated with resin. Said preform is then hardened and the core (4) is removed, preferably by pre-densification with chemical vapour infiltration, and the structure produced is then densified with liquid-phase infiltration.

Abstract: A fibrous preform (1) is produced, provided with a sandwich structure comprising an intermediate flexible core (4) and two outer fibrous frames (2, 3), respectively arranged on opposing outer faces of said flexible core (4) and assembled by sections of wire (8, 9) passing through said fibrous frames (2, 3), said preform (1) being impregnated with resin. Said preform is then hardened and the core (4) is removed, preferably by pre-densification with chemical vapour infiltration, and the structure produced is then densified with liquid-phase infiltration.

Abstract: A method for obtaining solutions that contain 1,2,4-triazole-5-one (OTA) in concentrated sulphuric acid, includes using 3-amino-1,2,4-triazole (ATA) as a precursor of OTA. There is also provided a method for preparing 3-nitro-1,2,4-triazole-5-one (4) (ONTA) from the solutions.

Abstract: A method for obtaining solutions that contain 1,2,4-triazole-5-one (OTA) in concentrated sulphuric acid, includes using 3-amino-1,2,4-triazole (ATA) as a precursor of OTA. There is also provided a method for preparing 3-nitro-1,2,4-triazole-5-one (4) (ONTA) from the solutions.

Abstract: The present invention relates to a method for crystallizing ammonium dinitramide (ADN), through spontaneous nucleation and crystal growth, from a solution containing said ammonium dinitramide (AND) dissolved in a solvent. Said solvent characteristically has a viscosity greater than or equal to 0.25 Pa s (250 cP) when said spontaneous nucleation is implemented. The ADN crystals obtained by said method have a median shape factor of 1 to 1.5 and are perfectly suitable for placement in the composition of energy materials.

Abstract: The present invention relates to a method for crystallizing ammonium dinitramide (ADN), through spontaneous nucleation and crystal growth, from a solution containing said ammonium dinitramide (AND) dissolved in a solvent. Said solvent characteristically has a viscosity greater than or equal to 0.25 Pa s (250 cP) when said spontaneous nucleation is implemented. The ADN crystals obtained by said method have a median shape factor of 1 to 1.5 and are perfectly suitable for placement in the composition of energy materials.

Abstract: A method of producing a double-walled thermo-structural composite monolith may include assembling, by stitching, a sandwich having a core and outer fibrous armors. The stitched sandwich structure is impregnated with a viscous resin. After the resin hardens, the core is removed from the sandwich structure.

Abstract: The invention concerns a combustion chamber whereof the inner wall (17)is made at least partly of a thermostructural composite material, which is porous to the fuel passing through the double wall (14); and the porosity of said inner wall (17) is adjusted so that the proportion of said fuel passing through said inner skin ranges between 5% and 15% of the total amount of fuel input in said ramjet engine.

Abstract: The invention concerns a combustion chamber whereof the inner wall (17)is made at least partly of a thermostructural composite material, which is porous to the fuel passing through the double wall (14); and the porosity of said inner wall (17) is adjusted so that the proportion of said fuel passing through said inner skin ranges between 5% and 15% of the total amount of fuel input in said ramjet engine.

Abstract: The invention concerns a method characterized in that it consists in assembling by stitching a sandwich consisting of a core and outer fibrous armors and impregnating the stitching thread during the impregnation process of said fibrous armours, and thereafter eliminating said core, said stitching fiber forming spacers (23) between the skins (21, 22).

Abstract: According to the invention, the wall (5) is mounted movably as one so as to be able to slide longitudinally in translation, bringing the joint line (14) closer to the fuel injector (9) so as progressively to modify the geometries of the oxidant inlet (16) and of the combustion chamber (15), said geometries passing progressively from a first state (I) in which, for a Mach number lying between 1.5 and 3, said oxidant inlet (16) constricts said oxidant flow only slightly and the combustion chamber (15) is long and divergent, to a second state (III) in which, for a Mach number lying between 8 and 12, said oxidant inlet (16) strongly constricts said oxidant flow and said combustion chamber (15) is shorter and exhibits a constant cross section.

Abstract: According to the invention, the wall (5) is mounted movably as one so as to be able to slide longitudinally in translation, bringing the joint line (14) closer to the fuel injector (9) so as progressively to modify the geometries of the oxidant inlet (16) and of the combustion chamber (15), said geometries passing progressively from a first state (I) in which, for a Mach number lying between 1.5 and 3, said oxidant inlet (16) constricts said oxidant flow only slightly and the combustion chamber (15) is long and divergent, to a second state (III) in which, for a Mach number lying between 8 and 12, said oxidant inlet (16) strongly constricts said oxidant flow and said combustion chamber (15) is shorter and exhibits a constant cross section.

Abstract: A subject-matter of the present invention is novel polyglycidyl azides of general formula (I): in which: R1 represents an alkylene chain comprising 2 to 4 carbon atoms, R2 represents an alkyl chain comprising 1 to 4 carbon atoms, x represents an integer such that 4≦x≦10. These compounds are not detonatable and are of use in particular as energetic plasticizers in solid pyrotechnic compositions. They can be obtained according to a 3-stage process starting from epichlorohydrin by preliminary synthesis of polyepichlorohydrin with a hydroxyl terminal group of formula (II): then acylation of this compound in order to obtain a polyepichlorohydrin with an acyloxy terminal group of formula (IV): and then azidation of this compound.

Abstract: A fuel injection strut for a ramjet adapted to operate at high Mach numbers includes a combustion chamber into which a flow of combustion-supporting gas is introduced. A first end of the strut includes a stem having a leading edge with a dihedral shaped wall for defining a chamber on a concave side for receiving the flow of combustion supporting gas. An injection member generates a plurality of jets impinging cooling fluid on the concave side of the wall to cool the strut. The leading edge provides two-way permeability so that at lower speeds, air permeates through the leading edge to facilitate pilot combustion in the combustion chamber, and a higher speeds, the cooling fluid permeates through the leading edge to cool the strut.

Abstract: The present invention relates to a hybrid engine capable of employing a ramjet mode and a super ramjet mode and comprising a main engine system (3, 4, 5, 8) which burns fuel and which comprises at least one air inlet (3) for an air stream (F), a combustion chamber (8) and a jetpipe (4). According to the invention, said engine (1) additionally comprises first means (10) for storing, in ramjet mode, air diverted from the air stream (F), and second means (11) for burning, in super ramjet mode, some of a fuel of the engine (1) with the air stored by the first means (10), before injecting it into the main engine system (3, 4, 5, 8).

Abstract: The present invention concerns a fuel injection device for ramjets for supersonic and/or hypersonic aircraft, said ramjet comprising a combustion supporting gas inlet and, downstream thereof, a combustion chamber and a nozzle adapted to channel gases leaving the combustion chamber. In accordance with the invention, the injection device includes at least one injector having a structure with a plurality of spaced walls extending generally along the longitudinal axis of the ramjet body, fuel being injected into each space formed by two adjacent walls of said plurality of walls and at the downstream end of said structure.

Abstract: A fuel injection stub (6) for a ramjet is intended to operate at a high Mach number. According to the invention, the nose of the stub is formed by a thermally conductive thin wall (11) having at least approximately the shape of a dihedron, the angle of said dihedron being at most equal to 15.degree. and the radius of the leading edge (11A) of said nose being at most equal to 2 mm, and said stub includes means (23, 27) for injecting a coolant into the sealed chamber (18), said injection means producing a number of jets of pressurized coolant striking the concave face of said thin wall.

Abstract: A ramjet for supersonic and/or hypersonic aircraft, designed to operate over a wide range of speeds, includes an inlet for a combustion supporting gas; a fuel injection device; and a ramjet body. The ramjet body has a combustion chamber in which the combustion supporting gas is mixed with a fuel to be burned and an exhaust nozzle to channel gases leaving the combustion chamber and which has, at least in a transition area between the combustion chamber and the exhaust nozzle, a variable geometry enabling its longitudinal section to be progressively modified. The ramjet body has at least one controllable opening adapted to establish communication between the combustion chamber and the exterior to enable the introduction of an exterior air stream into the transition area.

Abstract: The present invention relates to an aircraft ram jet engine for supersonic and/or hypersonic flight, intended to operate over a wide range of speeds.According to the invention, the ram jet engine comprises a ram jet engine body (5) including a combustion cheer portion (6) and a jet pipe portion (7), and, in the vicinity of the transition region (8) between the combustion chamber (6) and the jet pipe (7), having a changing geometry passing progressively from a convergent then divergent longitudinal section, for speeds corresponding to a low Mach number, to an at least substantially constant then divergent longitudinal section for speeds corresponding to a high Mach number.

Abstract: An aircraft ram jet engine for supersonic and/or hypersonic flight, intended to operate over a wide range of speeds, of the type including: (a) an oxidant inlet; (b) at least one fuel injector; (c) a body in which the oxidant and fuel intended to be burned are mixed and the gases resulting from this combustion are channeled; and (d) at least one wall of the body consisting, at least partially, of plates (12) linked together by articulations. The ram jet engine comprises first fluid blowing means (19, 22), mounted in the region of the articulations (13), in order to cool them.