Abstract: A fan drive system comprising a main drive shaft 13 which drives the fan through a frangible coupling 27 and an auxilliary drive shaft 30 which by-passes the coupling 27. The auxilliary shaft 30 is pre-twisted elastically in the opposite direction to the direction of rotation of the main shaft 13, and is held in the pre-twisted state by the coupling 27. When the coupling 27 disconnects the drive from the main shaft 13, for example when the fan becomes unbalanced and transverse loads exceed a predetermined magnitude, the auxilliary shaft 30 unwinds. Unwinding of the shaft 30 cushions the fan against suddenly applied loads when the coupling 27 breaks and also reduces the loads on the coupling 27 during normal balanced running.

Abstract: A blade assembly for use in an axial flow compressor or turbine. The blade assembly includes a disc provided with a circumferential blade root retaining channel in its periphery and an annular array of aerofoil blades having roots located in the channel so that gaps are defined between adjacent roots. Each root is provided with two circumferentially extending sealing skirts which are arranged so that they cooperate with the blade roots to define an annular sealing surface which is in operation in sealing engagement with an annular portion of the internal surface of the root retaining channel.

Abstract: A dovetail type circumferential slot fixing for retaining blades of a bladed rotor assembly of a turbomachine which requires no additional loading slot. The shape and dimensions of the dovetail roots of the blades and the dovetail blade-retaining slot are such as to allow the blades to be loaded by introducing a flank of each root dovetail into the slot and rolling the blades in an axial direction. The blades are held outwards against radially inward facing faces of the blade-retaining slot by a support means which may be a detachable plate, flange member or nose bullet that engages the blade platforms.

Abstract: The airflow from the compressor of a gas turbine engine into the combustion chamber or chambers principally comprises combustion air which enters the upstream end of the combustion chamber and dilution air which enters the combustion chamber at some point downstream of the combustion chamber inlet, the combustion air being made up of primary and secondary air entering the combustion chamber primary and secondary zones.In order to cope with the control of emissions from the combustion chambers, it is desirable to control the combustion air fuel ratio over the engine operating range by controlling air mass flow to the combustion and dilution zones of the combustion chamber. The invention proposes that this control can be achieved by providing a variable rate diffuser upstream of the primary, secondary and dilution air inlets, the variable rate diffuser comprising vortex generator having an associated variable air bleed.

Abstract: Air is bled from the compressor of a gas turbine engine and it is led to holes in the shanks of turbine blades, so as to cool the interiors of the blades during operation of the engine. Some of the air leaks radially outwards, to seal the gas annulus against hot gas leaks onto the face of the turbine disc. A reduced flow of cooling air is enabled at conditions other than engine full throttle. This however, starves the gas sealing air. The invention provides a back up supply, by putting the air through a plenum chamber and dividing it so that when cooling airflow is reduced, a further sealing air flow is provided in compensation therefore.

Abstract: A bladed rotor turning tool comprising a rotatable shaft (1), a finger (7) articulated on the end of the shaft about an axis substantially perpendicular to the shaft axis, the inclination of the finger relative to the shaft axis being controlled by cam means (10,11,12 and 14) so that the finger varies between being substantially perpendicular to the shaft axis and being substantially parallel to the shaft axis at diametrically opposed shaft positions. The cam means may comprise a cam surface (14) at the end of a sleeve (13) in which the shaft is positioned and means (10,11,12) for urging the finger into contact with the cam surface. Two such fingers may be provided to improve turning.

Abstract: A cooled wall structure for a gas turbine engine comprises a perforated and an inner wall in which the walls are capable of relative movement to cope with the thermal strains experienced by the combustion chamber during operation of the engine. The inner wall comprises a number of wall elements attached to the outer wall in the manner of overlapping tiles. Each wall element is immovably secured to the outer wall at the mid-point of its downstream end and the sides of each wall element are movably attached to the outer wall adjacent the sides of the downstream end of the wall element.The upstream end of each wall element is located between the outer wall and an adjacent flow in either an upstream or a downstream direction between the walls.The wall elements can have a plurality of raised lands to increase the surface area of the elements and to protect the incoming cooling air against the cross-flow of cooling air already flowing in the wall structure.

Abstract: A method of manufacturing a composite material in which layers of reinforcing filaments are stitched across with filaments of a thermoplastic polymer and then interposed between sheets of the same thermoplastic polymer as that used to stitch across the reinforcing filaments. The resultant stack is then heated under pressure for sufficient time for the thermoplastic polymer to impregnate the reinforcing filaments whereupon the thus formed composite is cooled under compression in order to avoid any distortion thereof.

Abstract: A method of sealing a flame sprayed metal or metal containing coating on a metal substrate in which the deposited coating is saturated with an anaerobically curable sealant such as a polymethacrylic ester with an amine catalyst which has a viscosity of up to 25 centipoises. After the sealant has been applied to the coating, excess sealant is wiped off the coating surface and the sealant is cured. The sealant prevents the absorption of water by the flame sprayed coating and hence corrosion of the metal substrate.

Abstract: A fuel control system for a gas turbine engine comprises a main fuel controller which varies the fuel flow to the engine in accordance with the engine pressure ratio and an idling fuel control arrangement. Control of idling fuel flow on a pressure ratio basis is somewhat wasteful of fuel. Therefore in the present invention the idling fuel control arrangement is arranged to control to a constant value of engine HP rotor speed. In the embodiment a variable bleed orifice is allowed to reduce the control pressure which operates the main fuel valve.

Abstract: The invention relates to fuel burners and to combustion equipment for use in gas turbine engines.A more uniform mixture of fuel and air can be obtained in an annular flame tube by ensuring that each fuel injector is maintained in a fixed position in relationship to the annular flame tube. The present invention provides a fuel burner and combustion equipment with means to locate the fuel injector in a fixed position in relationship to the annular flame tube.The fuel burner comprises a fuel feed arm and a fuel injector. The fuel injector is attached to the fuel feed arm, and a fuel passage extends coaxially through the fuel feed arm and supplies fuel to the fuel injector. The fuel from the fuel passage is supplied to a fuel chamber in a pintle positioned within a duct in the fuel injector. The fuel chamber supplies the fuel through a number of fuel passages into the duct.

Abstract: A rotor blade for a gas turbine engine is provided with an internal tip damper comprising a damper weight which rotates under centrifugal load to cam itself into engagement between two components of the aerofoil, in particular the interior surface of the hollow aerofoil and the tip of a cooling air entry tube. By altering the degree of offset between the center of gravity of the weight and its support the frictional engagement may be varied.

Abstract: An assembly comprising two components having different thermal coefficients of expansion. Each component is provided with means such as flanges and bolts for securing the components together. At least one of the components is provided with slots in the flange and end portion of the component to impart flexibility thereto. One of the components is provided with a bridging piece which covers the slots to prevent leakage of fluid through the slots, and the bridging piece has a seal that engages the other of the components to form an effective fluid seal.

Abstract: An annular seal for a gas turbine engine comprises a stacked plurality of Belleville washers with at least some of their abutting peripheries held together by U-section rings. If only those peripheries pointing toward a lower pressure area are retained together, gas pressure will hold the other peripheries together. Because the U-section rings do not prevent the washers from changing the angle of their section, relatively large axial motion between the sealed members may be tolerated.

Abstract: A cooled vane for a gas turbine engine has a hollow aerofoil with apertures at its trailing edge for cooling air ejection. In order to control the flow of cooling air out of these apertures a metering insert extends between the opposed internal faces of the aerofoil adjacent the trailing edge and accurately defines the required flow areas.In a preferred embodiment the insert is of `hairpin` cross section and defines the flow area as channels between projections from the limbs of the `hairpin` which abut with the internal faces of the aerofoil. A cooling air entry tube then engages with the concavity of the hairpin, and the flow down the two flanks of the tube may be controlled by the flow area provided by the projections on the respective limb.

Abstract: A fuel control system for a gas turbine engine comprises a main steady-state fuel control unit which adjusts the fuel flow to the engine to produce an approximation to a desired thrust and a trimmer device which trims the fuel flow demanded by the main unit to produce a closer approximation to the desired thrust. During transients such as accelerations a trimmer suitable for steady operation will apply zero trim until the desired thrust is almost attained, when an amount of trim may have to be applied rapidly. This can lead to overshoots.To mitigate the problem the trimmer is provided with a model of the main control unit which derives an approximation to the trim which will be required when the steady state is reached. This is applied to the main unit throughout the transients, and when the desired thrust is achieved only second-order changes need to be made.

Abstract: A signal processor for use in association with a frequency analyzer, can operate in the frequency translation mode or the filter mode.The signal processor comprises a first low pass filter, the signal from which is fed to two first parallel programmable gain amplifiers controlled by a first digital function controller. The signals then pass via two, second low pass filters to two second programmable gain amplifiers controlled by a second digital function controller. The signals from the second amplifiers are then added by an adder and filtered by a third low pass filter.The first controller is controlled by a frequency signal equal to the frequency in the middle of the bandwidth being translated and the first filter is controlled by a frequency which is a multiple of the control frequency to the first controller.

Abstract: A method of making at least the aerofoil of a blade for a gas turbine engine in which the cooling air exit passages, whether at the trailing edge or in other parts of the aerofoil, are cast rather than machined subsequently. In the method a disposable piece is formed with holes of the shape of the holes eventually required in the blade aerofoil. The piece is placed in a die and used to define part of the ceramic core required in the casting process, the die being arranged to produce a channel portion interconnecting the otherwise free ends of the parts of the core which will form the passages. The ceramic core thus formed in a lost-wax casting process to form the blade aerofoil, the channel portion being embedded in the shell mould to support the parts which define the passages.

Abstract: An anti-icing airflow temperature sensor (2) comprising a temperature sensitive element (4) and a casing (6) around the temperature sensitive element, the front (8) of the casing having apertures (10,12) of high perimeter/aspect ratio, the side of the casing having outwardly forwardly inclined apertures (20) adjacent the temperature sensitive element, the rear (14) of the casing having a substantial open area and the casing having a substantial unapertured portion between its front and the side aperture or apertures.

Abstract: An arrangement for effecting a seal between components 10,12 that rotate together and between which relative radial movement is tolerated while maintaining the seal. A conical, or Belleville, sealing ring 25 is located between the components 10,12 and means 19,22 are provided for clamping the components 10,12 together. The sealing ring 25 is so shaped and dimensioned that, in use, centrifugal forces acting on the ring 25 impart a turning moment to the ring 25 to cause it to twist and effect a seal with each of the components 10,12.