Abstract: A variable geometry nozzle for a gas turbine engine in which a circumferential array of flaps are pivotally connected to the engine by their upstream ends, the flaps comprising interdigitated flexible and rigid flaps. The geometry of the nozzle is varied by drawing together the side edges of adjacent flexible flaps which causes pivoting of both the rigid and flexible flaps and a change in the curvature of the flexible flaps. The rigid flaps seal the spaces between the side edges of adjacent flexible flaps. A modification is shown using auxiliary radially outwardly flared flaps to provide convergent divergent geometry.

Abstract: A nozzle guide vane structure for a gas turbine engine in which the vane comprises an aerofoil portion and inner and outer platforms. The non gas-contacting surfaces of the platforms are provided with forward and rearward sealing flanges sealed to adjacent engine structure to provide spaces sealed against ingress of working fluid between each pair of forward and rearward flanges. The mounting means for the vane projects into these spaces from the non gas-contacting surface.

Abstract: A turbine blade for a gas turbine engine has a hollow aerofoil and a root. A first insert for the distribution of cooling air in the aerofoil is inserted thereinto through an opening in the root but due to the relatively high camber of the blade the insert is such that it has to be displaced laterally after insertion. A second insert, also inserted through the opening, is provided to secure the first insert in position and to guide the cooling air from the opening to the first insert.

Abstract: A mounting arrangement for the fan rotor of a ducted fan engine includes a first drive which supports and rotates the fan under normal operating conditions but which includes a frangible connection which breaks when an excessive out-of-balance force is applied to the fan rotor for example after loss of one or more blades. A second supporting and driving structure is provided which has built-in transverse flexibility but which can transmit torque. This structure is redundant during normal operation of the engine but comes into use when the frangible connection is broken and allows the fan rotor to rotate eccentrically around a new axis in an inverted condition.

Abstract: A method of insulating a shell mould for investment casting by adhering a particulate or fibrous insulator such as perlite, vermiculite or ceramic fibres to a shell mould by an adherent coating. In a preferred process the shell mould is first dipped into the adherent coating and the particulate insulator is applied to the mould through a stuccoing process. Multiple layers of insulation can be applied to the mould to vary the thickness of insulation as required.

Abstract: The production of passages in workpieces is described by an electrical method which simultaneously utilizes electrochemical and electrical discharge machining with a single electrode and dilute electrolytes. The method overcomes the metallurgical defects inherent in the recast layer left by electrical discharge machining which is removed by electrochemical machining. The method is particularly suited to producing cooling passages in the turbine blades of gas turbine engines and can be used to produce venturi shaped holes with rounded edges.

Abstract: A probe for determining at what point in space contact is made between an object and a stylus. The stylus is located in an accurately defined rest position relative to a housing and slight deflection of the stylus away from this rest position is detected preferably by electrical switches.

Abstract: Cold neutron radiation of energy less that 0.025 eV having a flux greater than 1.times.10.sup.3 neutrons/square centimeter/second is used to diagnose temporal information about the spatial distribution of hydrocarbon fuel and lubrication oils in internal combustion engines, gas turbine engines and fuel systems.Images of the movement of fuel or oil are recorded by directing a beam of neutrons through an engine and using an image intensifier responsive to low light levels to intensify an image formed by neutrons which have been directed through the engine onto a fluorescent screen. The output image from the intensifier is recorded by a video or cine camera.

Abstract: A dual cycle vectored thrust engine has a flow control valve for changing the cycle from a pure jet for supersonic operation to by-pass cycle for vertical take-off. The valve has two separate inlets, two separate outlets and passageways within the valve which provide flow communication between the inlets and the outlets, one part of the valve being rotatable relative to the other to change the direction of flow through one of the inlets from communication with one of the outlets to communication with the other of the outlets. The passageways leading to one of the outlets are shaped to turn the flow through up to 180.degree. to enable the flow to be passed to front vectorable nozzles upstream of the valve.

Abstract: A convergent divergent exhaust nozzle for a jet engine, in which a circumferential array of interdigitated master and slave petals are axially movable along an arcuate track. Each petal is divided by a hinge into upstream and downstream portions and the downstream portions are pivotable about the hinges to vary the divergent flare angle of the nozzle. The master petals are supported on the arcuate tracks by means of a pair of axially spaced apart rollers bearing on opposite surfaces of the tracks. Gas pressure on the petals is used to reduce the force necessary to operate the nozzle.

Abstract: In pulsed X-ray fluoroscopy in which the fluoroscopic screen receiving the X-rays is subsequently observed by a video recording system incorporating an image intensifier, the quality of the video image is impaired because of electrical noise and phosphor flare. The image quality is improved by reducing the gain of the video system synchronously with the occurrence of each X-ray pulse. In addition, the residual disturbance left on the video output is stabilized by synchronizing the video framing cycle frequency with the X-ray pulse frequency.

Abstract: Induction heating apparatus for a dieless drawing operation includes a flexible induction coil made from a flexible metallic strip contained within an elastomeric sleeve which also defines a cooling fluid passage. The coil is sufficiently flexible to be capable of being formed into a shape which substantially conforms to that of a workpiece being heated at any point along the length of the workpiece. The apparatus of the invention also includes cam followers connected to the coil and cams which represent the shape of the workpiece over which the followers move during the heating operation to change the shape of the coil as required to maintain the coil at a substantially constant distance from the surface of the workpiece.

Abstract: A gas turbine powerplant includes an attitude control nozzle comprising an aperture in a duct wall of the powerplant for discharging a propulsive stream from the powerplant. One or more flaps are each pivoted to the side edges of the aperture and pivotally movable into different positions relative to the duct. In one position the flaps co-operate to close the aperture and in further positions the free ends of the flap or flaps co-operate to define variously directed discharge orifices of variable area.

Abstract: Apparatus for taking spatial measurements from recorded radiographic or photographic films includes a co-ordinate measuring framework on which are statically mounted a video camera and light source, and on which can be placed the film. The camera scans a small area of the film which is illuminated by the light source and the film is movable beneath the camera to enable any part thereof to be scanned. The information produced by the camera is passed to a video-microdensitometer which displays on its output screen an image of the area of the film being scanned. Measurement is achieved by lining features on the displayed image against a datum line by movement of the film below the camera in the framework and noting the co-ordinates of the new positions of the film on the frameworks.

Abstract: The passage of foreign objects such as bullets or stones through a gas turbine engine compressor is observed by directing beams of x-radiation through the engine, receiving the beams on fluorescent screens, to form fluorescent images, intensifying the fluorescent images by respective image intensifiers and recording the intensified images with respective high speed cine cameras.

Abstract: A fuel system for a gas turbine engine has in flow series a low pressure pump, a filter and a high pressure pump, latter being connected to a delivery duct leading to the engine. The low pressure pump is a jet pump wherein the jet is produced by spill flow from the delivery duct. The spill flow is heated to prevent ice formation in the filter.

Abstract: A by-pass gas turbine engine capable of producing an unmixed exhaust stream which comprises a core of hot turbine exhaust gases surrounded by an annular layer of by-pass air, is combined with a target thrust reverser. The ratio of the total pressure of the by-pass air to the total pressure of the turbine exhaust gases is arranged to be greater than unity to a significant extent, and the buckets are made from lightweight materials such as titanium, light alloys or even fiber re-inforced composite materials.

Abstract: A composite casing for a gas turbine engine comprises an inner wall which may be an integrally formed drum or a plurality of separate rings, and which is overwound with carbon fibers in a cross-weave and resin bonded to the inner wall. Honeycomb material is used to increase the outside diameter of the inner wall to provide continuous surface over which to wind the fibers.

Abstract: The useful life of rotating machines is used up depending upon the load which the machine has to bear. In some machines it is necessary to measure the usage of the machine life and the present invention provides a device for doing this. In the described embodiment the device is applied to a gas turbine engine in which measurement of speed changes between certain speed levels is used to indicate the life usage.

Abstract: A method of manufacture of an annular seal element comprises the steps of providing an apertured backing ring with closely packed bristles extending radially outwardly from the circumference thereof, clamping the free ends of the bristle between a pair of co-axial rings and welding the rings and the outermost tips of the bristles into a unitary structure and subsequently machining away the original backing ring to leave the rings with radially inwardly extending bristles.The invention also includes a sealing element made by the method.