Abstract: A superalloy which is to be solution heat treated is first coated with a vapor barrier, so as to reduce the loss of surface material during the heat treatment step. The advantage gained is the maintenance of an etchable surface for grain boundary inspection purposes.

Abstract: A Helicopter rotor and engine control apparatus in which the computers used to control the engines and the rotors are linked to exchange performance data and act together to improve the aircraft performance.

Abstract: A gas turbine includes a change-over valve having a rotatable part and a static part. The valve is disposed between upstream and downstream compressors of the engine for selectively directing flows from the upstream compressor and an auxiliary inlet to the downstream compressor or an auxiliary outlet, the downstream static part of the valve being formed as a structural element of the engine casing from which extends forwardly a support member which carries bearings for supporting the forward rotating part of the valve and the casing of the compressor.

Abstract: In a gas turbine engine the clearance between the tips of a row of rotor blades and the surrounding casing is maintained in a pre-determined range by providing supplies of relatively hot and cold air to passages in the casing. The amount of hot or cold air which is allowed to pass through the passages is controlled by exhausting the flow from the passages through a control clearance which varies in proportion to the size of the clearance to be controlled.

Abstract: An aircraft has a ducted fan gas turbine engine connected thereto by an underwing mounting arrangement. Links connect the engine to wing main beams and are connected only to that side of the engine which is inboard with respect to the fuselage of the aircraft. An aerodynamically shaped box structure surrounds the links and obviates the gap between engine and wing on the inboard side of the engine.

Abstract: An exhaust nozzle for a gas turbine engine comprises a substantially tubular duct structure to which is mounted flow directing flaps for varying the throat area of the nozzle. The duct structure is progressively shaped and deformed as it extends in a downstream direction to provide straight upper and lower lips to which respective upper and lower flaps are pivotally attached for selectively vectoring the exhaust flow. The opposing sidewalls extend vertically within the duct structure and protrude therefrom between which the flaps and exhaust orifice is thereby defined within an essentially tubular duct.

Abstract: A turbopropeller, or turbofan, gas turbine engine comprising a single spool core engine arranged to drive a propeller, or a fan, via gear means may be provided with a starter motor, and a clutch means.The clutch means disengages the propeller, or fan, from the gear means and core engine when the core engine is at rest or running below a predetermined speed to allow easy starting of the core engine by the starter motor. The clutch means engages the propeller, or fan, with the gear means and core engine when the core engine is running at or above the predetermined speed.An axially moveable piston may be provided to brake the propeller when the clutch means has disengaged the propeller from the core engine.

Abstract: Data processing methods and circuit arrangements are provided whereby out of a succession of data, some or most of which are false due to interference or noise, only those most likely to be true are selected for transmission to following stages of processing. Selection is achieved by comparing, according to a predetermined criterion, successive input data words with a data word already held in a data store and updating the store by discarding the stored data word and replacing it with an input data word whenever an input data word meets the predetermined criterion. A stored data word is utilised in further processing only when a predetermined number of input data words have been compared with the stored data word without updating having occurred. The invention has particular relevance to optical pyrometry systems.

Abstract: A locking member for insertion into a radial gap between radially inner and outer components 28,29 respectively which rotate together. The locking member is provided for preventing relative rotational movement between the components and exploits and centrifugal forces exerted on the ring due to the rotation of the components to ensure that frictional locking is maintained. The ring is shaped to form a plurality of "levers" 25 joined together the ring. Each lever 25 comprises two limbs 22,24 and has a fulcrum (b) which engages an inward facing circumferential surface of the outer component 29. The product of the mass of one of the limbs 22 of each lever 25 with its moment about the fulcrum is greater than the corresponding product for the other limb 24 so that the centrifugal forces on the limbs 22,24 cause each lever 25 to rock about its fulcrum (b) and thereby urge the limbs 24 into engagement with an outward facing circumferential surface of the inner component 28.

Abstract: The invention relates to intakes for turbopropeller gas turbine engines of the tractor type. A tractor turbopropeller gas turbine engine comprises a gas generator, an upstream propeller and a downstream propeller. The propellers are positioned upstream of the gas generator, and the propellers are driven via shaft means and gear means. An intake means supplies air to the gas generator, the intake means comprises an intake opening and an intake duct. The intake opening is positioned axially between the propellers, and a portion of the intake duct extends axially through the downstream propeller. This arrangement reduces the length of the shaft and the turbopropeller gas turbine engine, and reduces the weight accordingly. The intake opening is arranged to provide improved protection against ingestion of large foreign objects, such as birds, into the intake duct and gas generator.

Abstract: A circumferential array of aerofoil blades (11) comprising an aerofoil portion and a root portion is mounted on the periphery of a disc (14), sealed in place under vacuum and subsequently hot isostatically pressed to achieve diffusion bonding across the interface between the array (11) and the disc (14). Each of the root portion of the array (11) and the disc (14) is provided with axially extending flanges (12, 13, 15 and 16) at its axial ends. The flanges (12, 13, 15 and 16) are so dimensioned that when the array (11) is mounted on the disc (14) the flanges (12, 13, 15 and 16) engage each other in close fitting relationships in such a way that the array (11) and the disc (14) have an enclosed annular chamber radially spacing them apart. Annular chambers (18, 19) are provided at the interfaces of the confronting flanges (12, 13, 15 and 16), and the regions of the interfaces between the chambers (18) and the free axial ends of the flanges (12, 13, 15 and 16) are sealed by vacuum brazing.

Abstract: A common mechanism enables both throat area change in either a fan duct or an exhaust gas duct and flow deflection at the nozzle of the duct.

Abstract: The invention relates to fluid outlet ducts particularly cooling air outlet ducts of a gas turbine engine. A fluid outlet duct for a gas turbine engine is divided across its width into a plurality of second plenum chambers, each of the second plenum chambers has an associated exit nozzle located in the casing of the gas turbine engine for discharging cooling air. The cooling air from a heat exchanger is supplied through a first plenum chamber to each of the second plenum chambers. Each of the second plenum chambers has a valve to vary the flow of cooling into the second plenum chambers so that the total flow area of the fluid outlet duct may be varied to obtain relatively high exit velocities for the cooling air to give good thrust recovery.

Abstract: A gas turbine engine disc having integral, radially extending aerofoil blades and an integral shroud interconnecting the radially outer extents of the blades is described. In the manufacture thereof continuous fibres are wound around an annular array of inserts provided in a dividable disc. The inserts define the spaces between adjacent blades on the disc. A mixture of chopped carbon fibre and an epoxy resin matrix material is then injected into the central portion of the die interior. Any part of the wound fibres which has not been impregnated by the chopped fibre/resin matrix material is subsequently impregnated by a matrix material whereupon the die is opened to release the thus produced bladed disc.

Abstract: One problem associated with aircraft using variable cycle engines is how to provide an air intake which is sufficiently large to be able to supply air to both the first and second compressors of the engine during the parallel flow mode and sufficiently small to minimize aerodynamic drag when the engines are operated in the tandom flow mode during supersonic forward flight. This invention overcomes this problem by providing an air intake which combines a blocker door covering a second portion of the duct which communicates with the second compressor and a means of varying the inlet area of the duct such that the area is maximize when the engines are required to operate in the parallel flow mode and minimized during series flow operation.

Abstract: A geared turbofan gas turbine engine has a fan rotor carrying a plurality of fan blades driven by a gas generator via a gear assembly. A fan casing which has an exterior surface is positioned coaxially with and encloses the fan rotor.A lubricant supply is provided to lubricate and cool the gear assembly and a heat exchanger is provided to cool the lubricant.An air scoop forms a first duct which supplies air to the heat exchanger to cool the lubricant. A second duct defined partially by the air scoop downstream of the heat exchanger and an annular chamber formed coaxially supplies air warmed in the fan casing by the heat exchanger to the exterior surface of the fan casing for deicing or anti-icing purposes.The air scoop and heat exchanger can be positioned on the fan casing, the gas generator casing or a pylon. A valve in the air scoop controls the flow of warmed air to the second duct.

Abstract: One problem associated with aircraft using variable cycle engines is how to provide an air intake which is sufficiently large to be able to supply air to both the first and second compressors of the engine during the parallel flow mode and sufficiently small to minimize aerodynamic drag when the engines are operated in the tandem flow mode during supersonic forward flight. This invention overcomes this problem by providing an air intake which combines a blocker door covering a second portion of the duct which communicates with the second compressor and a means of varying the inlet area of the duct such that the area is maximized when the engines are required to operate in the parallel flow mode and minimized during series flow operation.

Abstract: A radiation probe includes an optionally cooled tube 10 with a window 22 at one end, and can be traversed across a gas turbine engine combustion chamber 20 by drive means 26. A radiation detector 28 simultaneously measures radiation intensity at a plurality of wavelengths, at each of a succession of positions during the traverse. From this data, local values of radiation levels, grey and non grey absorption coefficients, local temperature and local gas composition and soot concentration are calculated, using a recurrence formula which relates intensities at neighboring positions.

Abstract: Known porous laminates of the kind wherein ambient atmosphere each side of the laminate is connected via holes and passageways, the latter lying within the laminate thickness in planes parallel with the faying faces, suffer from airflow energy loss which arises from the changes in direction undergone by the airflow while in transit from one side of the laminate to the other side thereof. The invention provides extra holes on the high pressure side of the laminate, over those points in the passages wherein the greatest change in direction of flow occurs, so as to re-energize the airflow which has reached those points via the relevant holes of the known arrangement.

Abstract: A rigid, non-metallic laminate suitable as a fire barrier, made by impregnating a layer of non-metallic fibers other than glass fibers with a resin, coating glass fibers with a refractory aluminum silicate to form a sheath, superimposing a layer of the thus alumina silicate coated glass fibers on the resin impregnated layer of non-metallic fibers and then subjecting the resulting laminate simultaneously to heat and pressure to squeeze resin from the non-metallic fibers into the interstices of the alumina silicate coated glass fibers and to cure the resin binder. A rigid multi-layer laminate in a common resin binder useful as a fire resistant panel or duct for a gas turbine engine results.