Abstract: A leaktight seal includes plaquettes that are housed between platforms of “hammer legged” vanes and a periphery of a rotor disc. The plaquettes lie above a throat that receives legs between a collar. The plaquettes are completed with heels that also lie between the legs. Centrifugal forces distort the seal and produce excellent leaktightness between the disc and the platforms.

Abstract: A method of improving the oxidation and corrosion resistance of a superalloy article comprises providing a superalloy substrate having a sulphur content which is less than 0.8 ppm by weight, and depositing on the substrate a protective antioxidation coating having a sulphur content also less than 0.8 ppm by weight. A heat barrier layer may also be provided by depositing on the protective anti-oxidation coating a ceramic coating of columnar structure.

Abstract: A noise-absorption structure comprising a frame over which a gastight membrane is tensioned, the outside face of the membrane receiving soundwaves, a gas such as air filling the volume defined by the frame and the membrane, and energy-dissipation means housed in the volume, which means are of the laminar gas-flow type, of the electrostatic type, or of the electromagnetic type, and area adjustable or controllable to modify the acoustic impedance of the structure as a function of the characteristics of the noise to be absorbed. The invention is particularly applicable in the aviation industry.

Abstract: A device for machining a hole or a shape of varying profile in a mechanical workpiece using an excimer laser comprises a screen having an aperture of predetermined shape disposed between the excimer laser and a device for focussing the laser beam, the screen being movable in a plane perpendicular to the laser beam. Control means is provided for automatically controlling displacement of the screen in real time while the hole is being machined in the workpiece, the control being effected as a function of the number of pulses emitted by the excimer laser. As an alternative, the screen may be replaced by a diaphragm comprising variable-aperture shutters.

Abstract: A cooled turbine blade comprising a platform and an aerofoil portion has a rebate formed in the aerofoil portion near the trailing edge on the pressure face side. This rebate extends from the platform to the blade tip, and slots for the escape of cooling air from an internal cavity of the aerofoil portion open into the rebate.

Abstract: In order to obtain sheets made of a nickel-based superalloy of type 718 having properties of superplasticity, the sheets are manufactured with a final cycle comprising the steps of: a) solution treatment at 1060° C. for 15 minutes; b) precipitation at 730° C. to 800° C. for 1 to 2 hours; c) cold rolling at a ratio greater than 60%, and d) recrystallization at 900° C. for 30 minutes. Superplastic deformation of such sheets is carried out at about 970±10° C. and under pressures inducing stresses between 45 and 60 MPa.

Abstract: A single flexible strip of strands or brush fibers is contained within a body constituted by an inner crown and an outer crown. The crowns are U-shaped such that they can be used to position the two ends of the flexible strip against an outer surface of revolving shaft. Preferably, the arms of the two crowns are of different lengths and face each other.

Abstract: To make an annular fiber structure, a strip-shaped fabric (50), is used which is made up of two superposed unidirectional sheets, with the directions of the sheets forming opposite angles relative to the longitudinal direction of the strip, the two sheets being bonded together so as to form deformable elementary meshes, the fabric being wound while being deformed so as to transform it into a flat helix, the elementary meshes deforming in such a manner that variation in mass per unit area between the inside and outside diameters of the turns remains small, and the flat turns are pressed against one another.

Abstract: The loader device is made of a thermostructural composite material and comprises a base (20), a loading pole (30) secured to the base and extending at least over the full height of the loader device, and a plurality of loading trays (40) each provided with a central passage through which the loading pole can pass. Each loading tray carries a plurality of spacers (50) enabling the trays to be mounted in succession at predetermined intervals, each tray carrying the same number of spacers which are in alignment so that after the trays have been assembled the spacers make up load-carrying columns extending over the height of the loader device, and at least one of the spacers carried by each tray has a disposition and/or a size that differs from the other spacers carried by the same tray so as to enable the trays to be indexed during assembly. Each tray (40) has means (45) for positioning parts at predetermined locations.

Abstract: In order to compensate non-linearity in the zero drift of the bridge at very low temperatures, a strain gauge in at least one of the arms of the bridge is in series with a resistor, e.g., a connection lead, of resistance that is much less than that of the strain gauge, and a compensation circuit is connected in parallel with the resistor. The compensation circuit includes a resistive element, e.g., a platinum probe, whose resistance varies as a function of temperature in such a manner as to influence, in the very low temperature range, the resistance of the parallel circuit of which it forms a part, and to do so in a manner that is sensitive to temperature and that increases with decreasing temperature.

Abstract: A low thermal conductivity heat barrier coating deposited on a superalloy substrate is characterised in that it comprises a homogeneous mixture of oxides and has a composition containing a zirconia base, a zirconia-stabilizing oxide, and from 0.5 to 12 weight % of an additional metal element selected from nickel, cobalt, iron and mixtures thereof. The additional metal element may be added in an oxidised form, and the coating may also contain from 0.01 to 1 weight % of carbon.

Abstract: The invention relates to the inspection of an object (105) by radiography, this object possessing a crystal lattice. It consists of submitting the object (105) to electromagnetic radiation (103) to obtain a radiographic image of the object on receptor means (114) the radiographic image obtained, corresponding to one exposure, being a composed image resulting from a relative displacement of the object (105) which makes it possible to substantially reproduce the object while significantly attenuating the parasitic elements produced by diffraction of the electromagnetic radiation on the crystal lattice of the object.

Abstract: The material comprises fiber reinforcement made of fibers that are essentially constituted by silicon carbide, and an interphase layer between the fibers of the reinforcement and the matrix. The reinforcing fibers are long fibers containing less than 5% atomic residual oxygen and they have a modulus greater than 250 GPa, and the interphase layer is strongly bonded to the fibers and to the matrix such that the shear breaking strengths within the interphase layer and at the fiber-interphase bonds and at the interphase-matrix bonds are greater than the shear breaking strengths encountered within the matrix.

Abstract: A process for producing a hollow article made of a composite material of reinforcing fibers embedded in a matrix of hot-polymerized resin includes a step in which at least one core made of a silicone elastomer is draped with at least one layer of resin-impregnated reinforcing fibers. A resultant assembly is moulded to shape the internal and external surfaces of the hollow article by simultaneous inward and outward compression of at least one resin-impregnated fiber layer caused by movement of mould walls towards each other and by thermal expansion of at least one core.

Abstract: A process for the manufacture of a thin ceramic core involves casting a band of uniform thickness on a support from a solution of a ceramic material based on silica and zircon in a binder, drying the band, shaping the band in a mold and carrying out preheating and pressing of the band in the mold, baking the component thus obtained in a ceramic preform, and then carrying out an impregnation. The thin core obtained can be assembled together with another thin core and/or on a conventional thick central core, and can be used in precision casting such as in the production of turbine blades.

Abstract: A system for cooling the lubricant of the speed reducer of an aircraft turboshaft-engine during high-speed flight and during low-speed taxying. The cooling system includes a radiator through which the lubricant flows. An air supply duct delivers cooling air over the radiator. An air discharge duct discharges the air into the exhaust nozzle of the engine. The air supply duct is fed by an arcuate air take-off slot disposed in the air intake of the engine. The air discharge duct is provided with a flap for slowing air flow through the cooling system, and with an ejector-mixer, which is fed by compressed air, taken from the engine compressor, for creating a Venturi effect to increase air flow through the cooling system when required.

Abstract: The present invention provides: fiber preforms sheathed in a boron nitride coating, said coating (generated on said previously-prepared fiber preforms) having a structure that is original: microporous and granular; thermostructural composite materials in which the reinforcing fabric is constituted by said fiber preforms; and methods of preparing said fiber preforms and said thermostructural composite materials, respectively. The composites of the invention have their fiber preforms, based on fibers (F), sheathed in an original interphase (IBN) and embedded in the densification matrix (M).

Abstract: The closed electron drift plasma thruster uses a magnetic circuit to create a magnetic field in a main annular channel for ionization and acceleration, said magnetic circuit comprises: an essentially radial first outer pole piece; a conical second outer pole piece; an essentially radial first inner pole piece; a conical second inner pole piece; a plurality of outer magnetic cores surrounded by outer coils to interconnect the first and second outer pole pieces; an axial magnetic core surrounded by a first inner coil and connected to the first inner pole piece; and a second inner coil placed upstream from the outer coils. The thruster also comprises a plurality of radial arms included in the magnetic circuit, and a structural base which is separate from the magnetic circuit and which serves, amongst other things, to cool the coils.

Abstract: The drive system of a propeller driven transport aircraft has first and second propeller doublets mounted in the plane of the aircraft wings, each propeller doublet including two propellers disposed symmetrically on opposite sides of the central longitudinal axis of the aircraft. The first and second propeller doublets are driven independently of one another by first and second engine units via first and second independent drive trains respectively, the first and second engine units being disposed side by side in the aircraft fuselage.

Abstract: The thruster comprises, on a common plate, a plurality of main annular ionization and acceleration channels having axes that are not parallel and that converge in the outlet direction of the channels. A magnetic circuit sets up a magnetic field in the annular channels. The thruster also has a hollow cathode, a device for regulating the ionizable gas feed rate to each annular channel, and a device for controlling the ion discharge acceleration current in the channels. The direction of the thrust vector of the thruster can be controlled without significantly increasing the mass of the thruster.