Abstract: A vectorable nozzle mounting for an engine installation in a VSTOL aircraft in which hot gas nozzles are mounted on the airframe is described. A swivelable nozzle is mounted by means of a bearing on an intermediate fixed member such as a mounting ring on the airframe. The hot exhaust gas is discharged into the nozzle through a stub duct carried by the engine casing. Misalignment and movement between the duct and the nozzle is accommodated by movable sealing rings carried in the intermediate member which engage the outer surface of the duct. The sealing rings are spaced apart to form an annular chamber which is supplied with cooling air at a higher pressure than the pressure in the exhaust duct. The cooling air is arranged to cool the nozzle bearing and leakage passed the seals is of cooling air into the nozzle thus excluding hot exhaust gas from the engine bay.

Abstract: A sealing ring for controlling gas leakage through the annular space between two rotating concentric members; for example engine shafts. The sealing ring 20 has a generally trapezoidal cross section and an overlapping scarf joint. The sealing ring improves sealing by providing continuous lines of contact at edges between inner and outer coaxial shaft members.

Abstract: An aircraft jet engine management system has a digital electronic control unit (DECU) which measures turbine blade temperature (TBT) and controls the engine in such a way as not normally to exceed a TBT normal datum, there being an over-ride facility which responds to special circumstances as represented by one or more pilot-independent inputs to the DECU to allow temporary over-ride of the TBT limitation program, at least cut-off of the over-ride being pilot-independent.

Abstract: The method controls gas flow in an axial flow compressor in which the flow at one or more chosen station in the direction of flow through the compressor is sensed at a series of circumferentially spaced positions. Flow variations above a predetermined limit are evaluated to initiate a response if a disturbance above a predetermined acceptable level is detected. When such a disturbance is detected, higher pressure gas bled from downstream is injected at a station to supplement the main gas flow. An incipient rotating stall cell will appear as a variation occurring sequentially at the circumferentially spaced positions. By responding to such a condition with a pressure injection, it is found possible to suppress both rotating stall and surge conditions in the compressor before this disturbance develops fully. The same method can be arranged to counter steady state distortion.

Abstract: Ni--Al--Ti alloys which are plastically deformable at room temperature and have good strength at high temperature include a structure of regions of a .beta. phase of ideal composition NiAl, a .beta.' phase of ideal composition Ni.sub.2 TiAl and a .gamma.' phase of ideal composition Ni.sub.3 Al, the regions being epitaxially related to one another and preferably the .beta. phase or the .gamma.' phase is continuous.

Abstract: Particles or inclusions are removed from a molten alloy by contacting the molten alloy with a material selected from the group consisting of aluminium silicate, magnesium silicate, zirconium oxide or a mixture of alumina-calcia and alumina-magnesia.

Abstract: The article together with the alumina core in situ is placed in a sealable vessel containing a concentrated aqueous potassium hydroxide leaching liquor at a temperature immediately below its normal atmospheric boiling point. The vessel is sealed and the pressure within the vessel is reduced to less than atmospheric pressure so as to induce boiling and agitation of the leaching liquor within the passage in the article. The pressure in the vessel is raised to atmospheric pressure and finally spent leaching liquor together with leached alumina core is removed from within the article.

Abstract: A nickel-base casting alloy for use in gas turbine components consists essentially of the composition (in weight percent): carbon 0.02-0.15, chromium 14-18, cobalt 8-12, aluminum 0.5-1.5, titanium 2.0-3.5, niobium 3.5-6.0, tantalum 1.0-2.0, tungsten 1.0-3.0, molybdenum 3.0-6.0, boron 0.002-0.05, zirconium 0.01-0.1, balance nickel and incidental impurities. The alloy is characterized by a volume fraction of gamma prime of about 32%, an ultimate tensile strength in the range 990-1010 MPa over the temperature range 550.degree.-750.degree. C., and a mean coefficient of linear thermal expansion in the range 11.5-15.0 alpha(*E-06/.degree.C.).

Abstract: In a gas turbine engine tip clearance between rotor blades and an encircling shroud liner is controlled by moving the shroud liner radially to match the thermal and centrifugal growth of the rotor assembly. The shroud liner segments are suspended between two axially displaced control rings located in a passageway carrying air ducted from the compressor. One control ring responds very quickly to changes in gas temperature corresponding to centrifugal growth and blade thermal growth. The other ring responds very much more slowly and corresponds to the thermal growth of the disc. The shroud liner segments are suspended from the control rings to adopt a position that constitutes the average between the growth positions of the two control rings.

Abstract: Reinforcement preform of knitted fibers for a carbon or the like component such as an airfoil guide vane. A junction between adjacent sections of the finished article of the preform is formed with a buttonhole. In assembly, the reinforcement for one of the sections is passed through the buttonhole. In this way stresses can be better transmitted to a base section with reduced risk of tearing or delamination.

Abstract: An aerofoil blade containment structure that is adapted to surround the low pressure turbine casing of a gas turbine engine includes an annular support member upon which is mounted a glass fiber knitted sleeve. The knitted sleeve is folded to define a plurality of interconnected secondary sleeves that are arranged in coaxial superposed relationship. Use of the containment structure obviates the use of thick, and therefore undesirably heavy, turbine casings.

Abstract: A vectorable nozzle for directing the thrust produced by a gas turbine engine includes a duct, at least one toroidal nozzle segment, and a carrier ring for mounting the nozzle segment to the duct. The nozzle segment is hinged to the outer circumferential surface of the carrier ring about its toroidal axis. The carrier ring is rotatably mounted to the external surface of the duct at the downstream end thereof by means of a roller element bearing. The arrangement is such that the nozzle segment is moveable between a stowed location within the airframe space envelope and a deployed location. Once deployed the carrier ring is able to rotate the nozzle segment relative to the duct in order to vector the thrust produced by the engine.

Abstract: A compressed gas storage tank comprises a multi-layer sheet metal sandwich structure with a predetermined pattern of solid state diffusion bonds between all the neighburing layers. After the sheets have been solid state diffusion bonded together in the flat condition, the tank is blow formed between dies under superplastic forming conditions to produce at least one superplastically expanded core layer for containing the compressed gas. The configuration of the core layer is determined by the diffusion bond pattern. The expanded core layer provided internal bracing for the tank to give in rigidity and enable it to withstand the high internal pressures.

Abstract: A plurality of workpieces are assembled into a stack. Two of the workpieces are machined on one surface at predetermined positions from the edges of the workpieces. The workpieces are stacked so that the machined surfaces of the workpieces face away from each other. Two workpieces are provided with a stop off material on one of their surfaces to prevent diffusion bonding at predetermined positions. The edges of the workpieces are welded together and a pipe is welded to the stack to interconnect with the stop off material to form a sealed assembly. The workpieces are diffusion bonded together. The integral structure formed is heated and opposite ends of the integral structure are twisted relatively to contour the integral structure to a predetermined shape. The integral structure is heated and the machined portions on the workpieces are isothermally forged and then the twisted integral structure is internally pressurised to superplastically form one workpiece to produce an article, eg a fan blade.

Abstract: A ducted fan gas turbine engine has a fan duct across which extends an aerodynamically configured fairing. The fairing has a leading edge region which is defined by a pair of doors. The doors pivot between a first position in which they define the fairing leading edge region and a second position in which they define an inlet for the flow of air into the fairing. The air flow into the fairing serves to provide cooling of components within the fairing.

Abstract: Gas turbine engine combustion chamber has staged combustion to reduce nitrous oxides and includes a first radial flow swirler and a second radial flow swirler located axially of an annular mixing zone with each swirler having vanes for rotating the incoming air in substantially opposite directions relative to each other; first and second fuel injectors are provided with a first fuel injectors located in one of the passages of each of the first and second swirlers and with the second fuel injectors located upstream of the passages of the first and second swirlers.

Abstract: A changeover valve for a tandem fan type of engine is located in a duct between fan stages at either end. The valve arrangement has a butterfly flap valve to selectively obstruct flow along the cut, a drop-down chute to eject front fan flow and secondary inlet means to induct air to the second fan stage to supply the core engine. The secondary inlet means comprises drop-in doors hinged to pivot into the duct behind the flap valve. A tertiary airflow in a space defined by the duct and an engine nacelle is admitted to the region at the second fan entry face which is shadowed by the secondary inlet doors.

Abstract: Conventionally gas turbine engine compressors have fixed inlet guide vanes to give a predetermined swirl to incoming air at an engine design speed, so that air enters the compressor at an optimum angle. At speeds much lower, for example, than the design speed the guide vane is less efficient. The guide vanes are thereby made variable in camber. Each vane comprises a number of spanwise hinged members which can be moved relative one to another to vary the vane camber.

Abstract: A method of electrochemically machining a workpiece made of electrically conductive material so as to provide a radius on an edge of the workpiece comprises, (a) providing a cathodic tool comprising a cathode section sandwiched between two anode sections and separated therefrom by insulation, (b) locating the tool adjacent to but separate from the workpiece so that the cathode section is positioned centrally over the edge of the workpiece to be radiused and the anode sections lie facing opposite sides of the edge, (c) causing electrolyte to flow between the tool and the workpiece, (d) applying a cathodic voltage to the cathode section, (e) applying preselected anodic voltages simultaneously to the workpiece and the anode sections so that electrical field null points between the cathodic tool and the workpiece lie either side of the edge to be radiused, and (f) varying the electrical field between the tool and the workpiece so as to cause the null points in the electrical field to move with respect to each oth

Abstract: A ceramic fibre reinforced metal rotor with integral rotor blades is manufactured using a continuous strip of unidirectional ceramic fibres in a metal matrix. The continuous strip of ceramic fibres in a metal matrix is cut into a plurality of separate pieces of predetermined length. The separate pieces of ceramic fibres in the metal matrix are arranged alternately in a spiral, with separate pieces of unreinforced metal matrix in adjacent abutting relationship to form a ring which has a plurality of laminations. The ring of laminations of metal matrix composite pieces and unreinforced metal matrix pieces are arranged between an inner and an outer metal ring to form an assembly. The assembly is consolidated by hot isostatic pressing using radially applied pressure. The separate pieces of metal matrix composite provide compliance to reduce breaking or buckling of the fibres, and the pieces of unreinforced metal matrix prevents damage spreading between laminations.