Abstract: The heat exchanger comprises an intermediate portion (14) of refractory composite material, e.g. of C/C composite material, in which fluid circulation channels (16) are formed, and which is interposed between a portion of refractory composite material, e.g. having a ceramic matrix, such as C/SiC composite material, forming a heat shield (12) and a portion of thermostructural composite material, e.g. C/C composite material, forming a heat exchanger support structure (18), the component portions of the heat exchanger being assembled together by brazing. The heat exchanger can be used as a wall element exposed to an intense heat flux, in particular in a nuclear fusion reactor or in a ram jet combustion chamber.

Abstract: A fiber structure is made by superposing plies of fiber fabric and bonding the plies together by needling, so that the fibers of the superposed plies extend essentially in a first direction (X) and in a second direction (Y) orthogonal thereto, the plies being bonded together by fibers that are moved by the needling in a third direction (Z) extending transversely relative to the plies, and a piston preform is cut out from the needled fiber structure so that one of the first and second directions (X, Y) is parallel to the generator lines of the surface of the preform that corresponds to the cylindrical side surface of the piston. The preform is densified at least in part by the substance that constitutes the matrix of the composite material, and the piston is machined from the densified preform.

Abstract: The combined propulsion engine comprises an air-breathing jet engine and a non-air-breathing rocket engine, the jet engine comprising an air inlet device and an external nozzle which, in association with a central body, defines an air-breathing combustion chamber, while the rocket engine comprises a non-air-breathing annular combustion chamber and at least one turbo pump for feeding it with propellant. The combustion chamber of the rocket engine is disposed inside a central body towards the rear thereof and is situated at the downstream end of the air-breathing combustion chamber, the rocket engine combustion chamber being itself delimited by a streamlined portion extending the central body and constituting a spike which penetrates into the throat of the external nozzle while ensuring aerodynamic continuity for the stream of combustion gases leaving the air-breathing combustion chamber.

Abstract: The stator blades (10) are made of a thermostructural composite material and have asymmetric inner and outer roots (14, 16) such that at least one of the roots of an a blade presses against the outer side (12b) or inner side (12b) of a neighboring blade. Also, each root (14, 16) of each blade presses against the adjacent ring by a part only of its external surface, thereby allowing some flexing of the root under the effect of differential expansion between the blade and the ring.