Abstract: A rotary actuator device having an annular piston rod, the device comprising at least one piston held provided with sealing means and co-operating with an annular piston rod mounted so as to be capable of moving in an annular chamber, together with means for selectively applying a fluid under pressure in said annular chamber, wherein the piston head co-operates with the piston rod via a hinge having one degree of freedom in rotation and one degree of freedom in translation, said hinge comprising a piece in the form of a knife whose edge co-operates with a V-groove in a female portion of triangular profile, the knife edge and the V-groove being parallel to the axis of rotation of the piston rod. This disposition enables the forces exerted on the sealing means to be brought back into balance, thereby increasing sealing even under high pressures.

Abstract: The method of manufacturing a combustion chamber wall, in particular for a rocket engine, includes the following steps:[a] making a corrugated metal inner shell by deforming a first plane or tubular sheet;[b] making a metal outer shell from a second plane or tubular sheet;[c] assembling the corrugated inner shell and the outer shell together and welding them together locally;[d] forming an inner coating on the inside face of the corrugated inner shell by the technique of powder metallurgy using a container for the material that is to constitute the inner coating, the outside face of said container being constituted directly by the inside face of said corrugated inner shell and the inside face of said container being made using removable non-consumable sections or a soluble core that is removed by selective chemical dissolving after the inner coating has been formed by applying a hot isostatic compacting cycle; and[e] forming an outer coating on the outside face of the outer shell.

Abstract: The rotary machine includes an automatically-retracting axial abutment system mounted between the rotary shaft of the machine and its case, the abutment system having a displaceable abutment portion that is prevented from rotating, a rotary abutment portion mounted on the displaceable abutment portion by means of a bearing suitable for transmitting axial forces to the displaceable abutment portion, a very stiff flexible device connecting the displaceable abutment portion to the case in such a manner as to enable the displaceable abutment portion to move through a small amplitude in translation along the axis of the rotary shaft, and an axial thrust transmission member for transmitting thrust from the rotary shaft to the rotary abutment portion, the thrust transmission member being shaped to be in contact between the rotary shaft and the displaceable abutment portion when the machine is at rest, and to drive the rotary abutment portion via purely static friction when the machine is rotating and is exerting axi

Abstract: The resistive elements are made up of strips of carbon/carbon composite material that are interconnected by connection pieces that are likewise made of carbon/carbon composite material and that serve both for making electrical connections and for making mechanical connections between the strips. The strips and the connection pieces are assembled together at least in part by means of their shapes. The resistive elements may be coated in a layer of pyrocarbon.

Abstract: Inside a single casing the turbopump comprises a main shaft driven by a turbine, a secondary shaft coaxial with the main shaft, a low pressure impeller mounted on the secondary shaft to create a medium pressure flow which is brought back to flow parallel to the axis of the turbopump by a baffle and which is deflected through 180.degree. in a return channel so as to come back parallel to the axis of the turbopump towards a high pressure impeller mounted on the main shaft inside the secondary shaft. The entire HP flow formed by the HP impeller is output via the insides of curved hollow blades forming a portion of the LP impeller, this HP centrifugal flow thus establishes a driving torque for the LP impeller.

Abstract: A microwave antenna capable of operating at high temperature comprises at least one waveguide opening to the outside through an opening in a covering panel and including a tubular portion integrally formed with the panel, projecting inwards therefrom, and connected to the remainder of the panel around the opening, the panel and the integrated waveguide being made of a refractory composite material capable of ensuring microwave propagation and constituting a structural element capable of being raised to high temperature. The waveguide is filled with a refractory dielectric material such as an alumina-alumina type composite material.

Abstract: A fibrous preform is formed from a yarn composed of long discontinuous fibers made of a refractory material or its precursor. The discontinuous fibers are disposed parallel to one another without twist, and the integrity of the yarn is achieved by a covering yarn made of a fugitive material. The fibrous preform is intended to be densified by a matrix material for the manufacture of a composite material article. The covering yarn is eliminated before the preform is densified by the matrix material.

Abstract: The installation comprises support tooling having a shape that corresponds to that of the preform to be made and on which superposed layers of a two-dimensional fiber fabric can be draped; a needling head comprising a group of needles, a device for driving the needles lengthwise with reciprocating translation motion, and a bearing plate provided with perforations to pass the needles and suitable for being pressed against a layer draped over the support tooling; an arm carrying the needling head and possessing a plurality of degrees of freedom; and a control device for automatically controlling the displacement of the arm to move the needling head within the range of the arm along predetermined trajectories and with predetermined orientations.

Abstract: Inside a single casing the turbopump comprises a main shaft driven by a turbine, a secondary shaft coaxial with the main shaft, a low pressure impeller mounted on the secondary shaft to create a medium pressure flow which is brought back to flow parallel to the axis of the turbopump by a baffle and which is deflected through 180.degree. in a return channel so as to come back parallel to the axis of the turbopump towards a high pressure impeller mounted on the main shaft inside the secondary shaft. The entire HP centrifugal flow formed by the HP impeller is output via the insides of fixed hollow blades forming a portion of the baffle towards a delivery channel secured to the casing and collecting the high pressure fluid after it has passed through the fixed hollow blades. A shunt channel is taken from the delivery channel to apply a high pressure centripetal flow through the insides of the curved hollow blades forming a portion of the LP impeller, thereby establishing driving torque for the LP impeller.

Abstract: The wheel comprises a central portion, or rim provided with blades at its peripheral portion and is made of a single piece of composite material formed by a fibrous reinforcement densified by a matrix. The fibrous reinforcement is formed from a helical fabric with radially oriented fibers and circumferentially oriented fibers. The density of fibers in a radial direction and the density of fibers in a circumferential direction varies along a radius of the wheel as a function of the variations of the radial stresses and circumferential stresses that are exerted on the wheel when it is in operation. At least part of the circumferentially oriented fibers in the rim are made of a material having high mechanical resistance, while at least part of circumferentially oriented fibers in the blades and at least part of the axially oriented fibers are made of a material having good resistance to high temperatures and chemical attacks.

Abstract: The armor for providing ballistic protection comprises an armor plate for stopping projectiles with an auxiliary plate disposed in front thereof at a determined spacing therefrom, the auxiliary plate being constituted by a ceramic plate pierced by a large number of cells distributed in a regular mesh and constituted by blind holes extending perpendicularly to the rear face of the auxiliary plate and opening out into the front face thereof. The effect of the auxiliary plate is to destabilize and to score the projectiles so as to enhance their tendency to shatter on striking the armor plate.

Abstract: A porous substrate is placed inside an enclosure and a gas flow is injected into the enclosure under predetermined conditions of temperature and pressure to form a solid deposit within the accessible pores inside the substrate. A wall that is permeable to the gas flow is interposed on the path of the flow between its inlet into the enclosure and the substrate, the wall not being in contact with the substrate, thereby forming around the substrate a region which is free from strong turbulence so that infiltration is performed essentially under diffusion conditions, thereby minimizing the deposition gradient within the volume of the substrate.

Abstract: The wheel (10), which is made from a composite material having a ceramic matrix comprises a hub that bears a drive gear (16) formed of teeth (20) that extend radially on one of the wheel's surfaces (10a). Each tooth is asymmetrical with respect to the meridian plane (21) that passes through its apex, and has first shoulder (20b) that subtends an angle a, preferably between 15.degree. and 45.degree., relative to that plane, and a second shoulder (20c) that subtends an angle b, preferably between 55.degree. and 85.degree., relative to that plane. Advantageously, the sum of the two angels is at least equal to 100.degree.. The turbine wheel has an improved resistance against inter-laminar shear stresses that result from tightening to a drive gear wheel.

Abstract: In a portion of the preform to be made in which the preform is to be of reduced thickness by having a recess formed therein, a mask is interposed between pairs of adjacent layers, the mask being made of a thin film of material through which the needles can pass during needling while opposing the passage of significant quantities of fiber taken by the needles, and after it has been needled, each layer is cut out around a line corresponding to the outline of the recess in the preform at the level where the layer is situated in the preform. A mask situated between two cutout layers occupies an area that is not less than the area between the cutout lines of the two layers, such that the portions of the layers that are delimited by the cutout lines are not securely connected to the remainder of the preform by the needling, thereby enabling the recess to be formed after all the layers have been needled by withdrawing the cutout portions of the layers and by peeling off the masks.

Abstract: Inside a single casing the turbopump comprises a main shaft driven by a turbine, a secondary shaft coaxial with the main shaft, at least one low pressure boost impeller mounted on the secondary shaft. The LP fluid flow is brought parallel to the axis of the turbopump by a baffle and after being deflected through 180.degree. in a return channel it is returned parallel to the axis of the turbopump toward a high pressure impeller mounted on the main shaft inside the secondary shaft. The entire HP flow formed by the HP impeller is delivered axially to a boost turbine secured to the secondary shaft and to the LP boost impeller and disposed between the main shaft and the secondary shaft. Through orifices and an axial channel are formed in the main shaft to pass the flow of HP fluid leaving the boost turbine inside the main shaft and then to exhaust the HP fluid to a delivery channel secured to the casing through the radial arms situated at the inlet to the turbopump.

Abstract: A composite material containing carbon is protected against oxidation by forming, on the composite material, an inner layer, an intermediate layer containing boron or a boron compound, and an outer layer of silicon carbide. The inner layer formed on the composite material before the intermediate layer is formed, is made of a refractory carbide that does not contain boron and that is at least 60 microns thick, said inner layer insulating the intermediate layer from the carbon contained in the composite material.

Abstract: The structure consists of a composite material having a reinforcement texture and a matrix. The composition of the matrix varies practically without discontinuity, in the structure's thickness direction, from an essentially refractory material (13) in the region of the front face intended to be exposed to very high temperatures, up to a material that is essentially heat conductive (16). Cooling fluid circulation conduits (15) can be arranged within the structure at a portion where the matrix is essentially heat conductive.

Abstract: The seat comprises panels made of ceramic matrix composite and assembled to one another by shape and by adhesion, either by interposition of an adhesive or else by condensification using the ceramic matrix material. The invention is particularly suitable for armored seats for helicopters.

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: A fibrous preform (10) of the component to be manufactured is conformed in the desired shape with the desired degree of compacting, prior to densification by chemical vapor deposition. The conformation is achieved by linking the preform (10) onto a rigid shaping device (12) by threads (30) that traverse the preform (10) and pass through holes (14) in the shaping device. The linking threads (30) are made of carbon or ceramic. Prior to the linking, a covering layer (16) may be arranged on the face of the preform (10) opposite to the one turned towards the shaping device.