Abstract: An apparatus for winding a filament onto a former includes one or more filament supply bobbins mounted on an annular carrier for rotation about a first axis for receiving a plurality of windings of the filament, and a translation device for moving the former relative to the carrier along a path which passes through the carrier thereby enabling the filament to be wrapped around the former. A guide member guides the filament from a respective bobbin to the former, the guide member defining a radially outward facing cylindrical surface. The apparatus reduces bending of the filament as it is wound onto the former.

Abstract: A power turbine suitable for a gas turbine engine which a blade of one array of turbine blades has a fan propulsion blade attached to its radially outer extent. A drum member is further provided which carries at least one further annular array of turbine blades and is coaxially interposed between the arrays of turbine blades and fan propulsion blades to rotate with the same in operation. Aperatures are defined through the drum member to accommodate the attachment structure provided between the turbine blade and the fan propulsion blades such that relative radial movement is permitted between the turbine blade and the drum.

Abstract: A cooled vane suitable for a gas turbine engine is provided with an internal chamber which is fed with cooling air from the radially inner and outer ends of the vane. Cooling air supplied to the radially inner end of the vane is at a higher pressure than that supplied to the radially outer end. In order to ensure effective cooling of the vane a chordwise extending baffle is provided within the chamber to divide the chamber into radially inner and outer portions. The baffle is so configured as to permit a limited flow of cooling air from the radially inner chamber to the radially outer chamber. This facilitates effective cooling of the aerofoil of the vane in the region of the baffle.

Abstract: Monitor signals are produced which are qualitative or quantitative measures of the shape, size or position of a light spot on an optical head relative to fibre-optic receptors in the optical head. One pair or two pairs of receptors may be used. Production of the monitor signals involves modulating the incident light forming the light spot at a predetermined frequency, delaying the light signals in one or more of the fibre-optic receptors relative to the light signals in one or more of the other receptors by, say half a wavelength of the predetermined frequency, combining the outputs of the fibre-optic receptors to produce a compound light signal, producing an equivalent compound electrical signal by means of a photodiode, and processing the compound electrical signal in electronic processors to extract one or more of its components to act as the monitor signals.

Abstract: The present invention is particularly concerned with the supply of fuel to fuel servos of gas turbine engines. A check valve (62) is positioned in a return pipe (40, 24, 22, 26) from a fuel spill valve (12) to the upstream low pressure side of a high pressure pump (10). An aperture (32) in a piston (30) of the check valve (62) produces a predetermined pressure drop across the check valve (62) when the flow of excess fuel reaches a predetermined value. A fuel servo shut off valve (64) is positioned in a pipe (42, 58) connecting a fuel flow regulator (14) to a fuel servo (80). A piston (46) of the fuel servo shut off valve (64) initially closes a chamber (56) to prevent fuel being supplied to the fuel servo (80), from the fuel flow regulator (14). The piston (46) of the fuel servo shut off valve (64) is moved against a spring (48) when the predetermined pressure drop is formed across the check valve (62) to allow fuel to be supplied from the fuel flow regulator (14) to the fuel servo (80) via chamber (56).

Abstract: Known methods of controlling inertia welding and friction welding processes fail to control metal upset, and so require post machining of the welded components. The invention pre-determines the ideal rates of relative rotation, force applied and metal upset rates for a given material to be welded, enters those rates in a microprocessor memory and then connects the microprocessor to the apparatus on which the weld is to be effected. The microprocessor monitors the actual rates, compares them with the ideal rates and, should differences occur, generates signals from those differences with which to adjust operation of the apparatus.

Abstract: A brush seal operationally located between a rotatable shaft and static structure comprises a number of stages. The seal stage adjacent a region of low fluid pressure and its adjacent stage are spaced apart by an apertured ring. The apertures in the ring being so dimensioned as to vent pressurized fluid from the chamber and thereby reduce the magnitude of the pressure differential across the seal stage adjacent the region of low fluid pressure.

Abstract: A load transference structure between a core engine and power turbine comprises a plurality of circumferentially spaced apart radially extending spoke members, each of which is attached at its radially inner extent to first and second axially spaced apart support panels. Each of the spoke members is provided with a circumferentially extending portion positioned adjacent the panels which are adapted to cooperate with a circumferentially adjacent spoke member in such a manner that radial but not circumferential load transfer is permitted to take place between them. The load transfer structure permits load transfer to take place between the core engine casing and the power turbine.

Abstract: An improved arrangement of a turbofan engine comprises a core engine, an upstream fan, a downstream fan and a booster compressor. The upstream fan and downstream fan are both positioned upstream of the core engine, and are arranged to be driven in opposite directions by a gear assembly. The gear assembly is positioned axially between the upstream fan and downstream fan. The booster compressor is positioned upstream of the upstream fan and downstream fan, and comprises a first rotor carrying blades and a second rotor carrying blades. The first rotor is driven with the upstream fan and the second rotor is driven by the turbine of the core engine in opposite direction to the first rotor.

Abstract: A compressor rotor assembly comprises a shaft and at least one disc having integral radially extending aerofoil blades which disc is integral with the shaft. The assembly comprises a matrix material in which a plurality of short reinforcing fibres are so disposed that the majority thereof within the shaft are generally axially aligned while the majority thereof within the aerofoil blades are generally radially aligned. At least one filament wound support ring provides radial support for the aerofoil blades.

Abstract: A representation of oil flow in a gas turbine engine is obtained by injecting a compatible radioactive isotope label into the engine oil flow and detecting the radiation emitted from within the body with detectors mounted outside the body to produce signals representative of the quantity and direction of the radiation; the detector output signals are compensated for attenuation on passing through the engine in accordance with attenuation signals derived from a representation of the spatial distribution of the engine and of its materials, and signals from non-viable directions are discounted. The compensated detector output signals are used to generate a number of focal-plane tomograms from which an image in a desired plane may be re-constructed. The image may be formed on a background of the engine in the relevant plane generated from the representation thereof.

Abstract: A fuel vaporizer for a gas turbine engine combustion chamber comprises a hollow cylindrical stem open at one end and branching into two radial branch ducts at the other end which terminate in outlets facing towards the inlet end. In order to ensure more even cooling of the vaporizer stem, the fuel injector which lies inside the stem has two outlets which direct fuel onto those parts of the interior wall of the stem which lie between the branch passages, and a baffle divides the interior of the stem to ensure that each branch passage is fed with fuel from only one fuel injector, and each fuel injector supplies only one branch passage.

Abstract: A propeller module for an aero gas turbine engine comprising two contra-rotating propellers has a reduction gear train positioned axially between the propellers. Pitch change mechanism are provided to change the pitch of the blades of both propellers independently of the differential speed of the propellers. The pitch change mechanisms comprise two sets of hydraulic motors one set of which is mounted on a carrier member of the gear train within the planet gears, the other set is mounted on the hub of the second propeller. Pitch selector valves control the supply of hydraulic fluid to the hydraulic motors, and the pitch selector valves are operated by a pitch change power unit. The pitch selector valves are positioned coaxially of the propellers and a transfer tube extends coaxially between the pitch selector valves to transfer hydraulic fluid therebetween independently of differential speed of the propellers.

Abstract: A device for detecting axial movement of a rotating member, for example a compressor rotor of a gas turbine engine, comprises a conducting wire spaced radially from the rotating member, and a magnet carried by the rotating member passes in proximity to the conducting wire when the rotating member is rotating. The conducting wire has a first limb a second limb and a third limb extending with axial and circumferential components, the first and third limbs extending in the circumferentially opposite direction to the second limb to increase resolution between pulsed e.m.f.'s produced when the magnet crosses the limbs. The first, second and third limbs are each formed from a pair of parallel connected bars to produce positive and negative pulsed e.m.f.'s which form zero crossing points which are more easily detected. This enables operation at greater radial clearance or lower rotating speeds.

Abstract: A fan casing of a turbofan gas turbine engine has a slot which extends generally in a circumferential direction and which has an aerofoil section. A variable pitch fan blade may be removed from the turbofan by rotating the fan blade about its axis of rotation to fine pitch setting, and rotating the fan rotor so as to align the tip of the fan blade with the slot. The fan blade is detached from the fan rotor and the tip of the fan blade is inserted radially into the slot. The root portion of the fan blade is then moved in a radially outwards and axial direction to remove the fan blade. The slot in the casing allows the fan blade to be loaded by the reverse procedure. Loading/unloading of a fan blade is made possible without removing the fan casing.

Abstract: An apparatus for winding a filament onto a former includes one or more filament supply bobbins mounted on an annular carrier for rotation about a first axis for receiving a plurality of windings of the filament, and a translation device for moving the former relative to the carrier along a path which passes through the carrier thereby enabling the filament to be wrapped around the former. A pair of pinch rollers positioned at the mid span of each bobbin act to guide the filament onto a loading surface over which the filament passes from the pinch rollers to the former. The loading surface is formed by the radially innermost portion of the carrier and is arcuate in cross section. The apparatus reduces bending of the filament as it is wound onto the former.

Abstract: In a multi stage ducted fan or ducted propeller gas turbine engine, a fan flow exit path is provided in the cowl between axially adjacent stages of blades. The stage of blades downstream of the exit are each pivotable to attitudes which on continued rotation of the stage, induces a reverse flow of ambient air into the duct via the nozzle. The normal and reversed airflows meet under the exit path and pass therethrough to atmosphere. The need for blocker doors in the duct is obviated and energy is imported to the fan air passing through the exit by both stages of blades.

Abstract: The invention minimizes selected tones present in buzz-saw noise, otherwise known as multiple pure tone noise. This noise arises from the production of unequal shockwaves during the rotation at sonic or supersonic velocities of a bladed rotor, the dimensional characteristics of whose blades are subject to manufacturing tolerances. Minimization of selected buzz-saw noise tones is achieved by arranging the blades around the rotor in a sequence which minimizes selected Fourier coefficients of the shockwave strengths; alternatively, the blades are arranged to minimize selected Fourier coefficients of the dimensional characteristics of the blades, such as thickness, t, stagger angle .theta., and camber. The invention is particularly applicable to the fan propulsors of turbofan aeroengines.

Abstract: A ducted fan gas turbine engine is provided with a fan cowling member made up of a static portion and an axially translatable portion. A plurality of rails interconnect the first and second cowling member portions and carry a generally annular array of airflow deflector vanes. The deflector vanes are normally stowed in stacked relationship when the cowling portions are contiguous but are equally axially spaced apart to define a fan air flow thrust reverser when the second cowling portion has been translated to a position downstream of the first cowling portion.

Abstract: A propeller module for a gas turbine engine comprising two contra-rotating propellers has a reduction gear positioned axially between the propellers. Pitch change mechanisms are provided to change the pitch of the blades of both propellers independent of the differential speed of the propellers.