Abstract: A method of friction welding a first workpiece to a second workpiece, includes the first workpiece with a first faying surface having a first faying length, the second workpiece with a second faying surface having a second faying length, the second faying length greater than the first faying length; positioning the first workpiece adjacent the second workpiece; reciprocating the first workpiece and the second workpiece against one another, the first faying moves relative to the second faying by a sweep length, a temperature at the first and second faying surfaces increases to create a weld interface; each of the first and second workpieces are consumed into the weld interface, adjusting the sweep length the sweep length remains equal to a difference between the second and the first faying lengths; and stopping the reciprocating and allowing the first and second workpieces to cool to weld the first and second workpieces together.

Abstract: A gas turbine engine comprises a compressor having a plurality of blades mounted to a hollow, annular compressor drum. The compressor comprises an electric storage device mounted within the hollow compressor drum.

Abstract: The present disclosure relates to a metallic shaft for connecting components of a gas turbine engine. Example embodiments include a metallic shaft (400) for connecting components of a gas turbine engine, the shaft (400) having a longitudinal axis (410) and comprising: a first section (401) extending from a first end (403) of the shaft (400) to a joint (405), the first section (401) composed of a material having a first thermal expansion coefficient along the longitudinal axis (410); a second section (402) extending from a second opposing end (404) of the shaft to the joint (405), the second section (402) composed of a material having a second thermal expansion coefficient along the longitudinal axis (410) that is different to the first thermal expansion coefficient.

Abstract: A gas turbine engine comprises, in fluid flow series, a gas-generator compressor, a combustor, a gas-generator turbine, and a free power turbine. The gas-generator compressor is an axi-centrifugal compressor comprising a plurality of axial compression stages followed by a single centrifugal compression stage, wherein the International Standard Atmosphere, sea-level static (hereinafter ISA SLS) design point pressure ratio of the axi-centrifugal compressor is from 12 to 16, and a ratio of the ISA SLS pressure rise across the axial compression stages to the ISA SLS pressure rise across the centrifugal compression stage is from 0.75 to 1.

Abstract: A turboshaft gas turbine engine comprises, in fluid flow series, a gas-generator compressor, a combustor, a gas-generator turbine, and a free power turbine. The expansion ratios of the turbines are dependent upon an outlet temperature of the combustor, and an expansion relationship between the turbines is defined as the ratio of expansion ratios of the turbines over a running range of non-dimensional power outputs of the gas turbine engine. A second derivative of the expansion relationship is from 0.6 to 1.0.

Abstract: A gas turbine engine comprises a fan, a compressor, a low pressure turbine and a high pressure turbine. The fan diameter is greater than 250 cm and less than 381 cm; and the gas turbine engine has a first thrust at sea level static conditions and a second thrust at end of runway conditions; and a thrust take-off ratio greater than 1.32; wherein the thrust take-off ratio is the ratio of the first thrust to the second thrust.

Abstract: There is disclosed an exhaust nozzle for a gas turbine engine. The exhaust nozzle comprises a frame extending along a longitudinal axis, and a convergent petal pivotably attached at a convergent pivot point to the frame and extending axially downstream and radially inward from the frame. The exhaust nozzle comprises a follower roller fixed to the convergent petal on a radially outer side of the convergent petal, and a cam defining a working surface configured to engage the follower roller to react a force from the convergent petal. The cam is movable along a travel in an axial direction to actuate radial movement of the follower roller to pivot the convergent petal. The cam defines a convex working surface such that a contact angle between the follower roller and the cam varies along the travel to thereby vary an axial component of the force reacted by the cam.

Abstract: A gas turbine engine for an aircraft including an engine core including a turbine, compressor, and core shaft connecting the turbine and compressor; a fan located upstream of the engine core including a plurality of fan blades; a gearbox that can receive input from the core shaft and can output drive to the fan at a lower rotational speed than the core shaft, an epicyclic gearbox including a sun gear, planet gears, a ring gear, and a planet carrier on which the planet gears are mounted; and a gearbox support. A first gearbox support shear stress ratio: torsional ? ? shear ? ? stress ? ? of ? ? the ? ? gearbox ? ? support ? at ? ? maxiumum ? ? take ? ? off ? ? conditions radial ? ? bending ? ? stiffness ? ? of ? ? the ? ? gearbox ? ? support is less than or equal to 4.

Abstract: An Electronic Engine Controller (EEC) for a gas turbine engine. The EEC is configured to be connected to a solenoid valve, and configured to control the solenoid valve by providing a driving signal to either a first solenoid winding or a second solenoid winding of the solenoid valve, the first and second solenoid windings being magnetically coupled to one another by an armature of the solenoid valve. The armature is movable under the action of the driving signal to operate the solenoid valve. The solenoid winding of the first and second solenoid windings provided with the driving signal is a driving winding and the other solenoid winding of the first and second solenoid windings is a pick-up winding. When the EEC controls the solenoid valve via the driving winding by providing the driving signal thereto, it is further configured to sense a position of the solenoid valve via the pick-up winding by detecting a signal induced in the pick-up winding by the magnetic coupling.

Abstract: A gas turbine engine for an aircraft including: an engine core including a turbine, compressor, and core shaft connecting turbine to the compressor; a fan located upstream of engine core, the fan containing a plurality of fan blades mounted for rotation about an engine axis, each blade of the plurality of fan blades having a leading edge and trailing edge extending across a span of an airflow duct from blade root to tip; and a gearbox that receives an input from core shaft and outputs drive to fan so as to drive the fan at a lower rotational speed than the core shaft, wherein the trailing edge of each blade is characterized by a metric M defined as a rate of change of an angle of trailing edge between 0.4 and 0.8 of the span divided by an area averaged trailing edge angle, M being not less than around 4.

Abstract: A turboshaft gas turbine engine comprises, in fluid flow series, a gas-generator compressor, a combustor, a gas-generator turbine, and a free power turbine. The gas-generator turbine is a single stage turbine having a specific work of from 200 to 350 kilojoules per kilogram, said specific work being the power output of the turbine per unit mass flow therethrough.

Abstract: A gas turbine engine includes a main gas flow exhaust nozzle having an annular inner surface which, in use, bounds a flow of exhaust gas. The gas turbine engine further includes cooling passages having respective outlets therefrom to provide a flow of cooling air over a surface of the engine or an adjacent airframe component, thereby protecting the cooled surface from the exhaust gas flow. Adjacent cooling passages of the or each pair of the nested cooling passages are separated from each other by a respective dividing wall. The outlets from the nested cooling passages are staggered in the axial direction of the exhaust nozzle such that cooling air flowing out of an inner one of the adjacent cooling passages of the or each pair of the nested cooling passages flows over the dividing wall separating the adjacent passages.

Abstract: A powder deposition apparatus has a build plate, a powder source, a recoater arm, and an energy beam. The recoater arm is formed from ferromagnetic material. The recoater arm is arranged to deliver a layer of powder from the powder source across the working surface of the build plate prior to the energy beam fusing a predetermined portion of the delivered powder layer. The recoater arm comprises a magnetic portion.

Abstract: An aircraft gas turbine engine includes an engine core including a turbine, a compressor, a core shaft connecting the turbine to compressor, and a core casing surrounding the engine core. A fan is located upstream of the engine core and fan casing surrounds the fan. A gearbox receives input from the core shaft and outputs drive to rotate the fan. A single plane support structure connects the core and fan casing. The support structure includes an inner ring, outer ring and plurality of circumferentially spaced radially extending struts connecting the inner and outer ring. The inner ring including a torsion box and a gearbox and fan support structure is connected to the torsion box. A front and rear mount are configured to connect the gas turbine engine to the aircraft, wherein the front mount is coupled to the torque box and the rear mount is coupled to the core casing.

Abstract: An igniter seal arrangement for a combustion chamber. The combustion chamber has a wall having first surface and second surfaces. A boss projects from the first surface, and has a platform on its remote end. The platform has an inner surface spaced from the first surface of the wall to define a chamber between the first surface of the wall and the inner surface of the platform. The platform has an outer surface facing away from the first surface of the wall and an aperture extends through the wall from the outer surface of the platform of the boss to the second surface. First and second L-shape rails extend from the platform and a sealing member has a first edge and a second edge locatable between the outer surface of the platform and the first and second L-shape rails and the sealing member has an aperture to receive an igniter.

Abstract: A gas turbine engine comprises a fan mounted to rotate about a main longitudinal axis; an engine core, comprising in axial flow series a compressor, a combustor, and a turbine coupled to the compressor through a shaft; a reduction gearbox that receives an input from the shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the shaft; wherein the compressor comprises a first stage at an inlet and a second stage, downstream of the first stage, comprising respectively a first rotor with a row of first blades and a second rotor with a row of second blades, the first and second blades comprising respective leading edges, trailing edges and tips, and wherein the ratio of a maximum leading edge radius of the first blades to a maximum leading edge radius of the second blades is greater than 2.8.

Abstract: An aircraft propulsion system includes at least first and second electrical generators, each being configured to provide electrical power to a respective first and second AC electrical network. The system further comprises at least first and second AC electrical motors directly electrically coupled to a respective AC network and coupled to a respective propulsor, and a DC electrical network electrically coupled to the first and second AC networks via respective first and second AC to DC converters, and to a further electrical motor, the further electrical motor being coupled to a propulsor.

Abstract: An automated peening method comprising: providing, adjacent a surface of a workpiece, a robotic arm having a peening tool attached thereto; defining a peening area of the surface of the workpiece; calculating a peening path for the peening tool over the peening area, the peening path substantially covering the peening area and comprising a sequence of movement patterns, wherein a geometric variable of one or more of the movement patterns is modified using an output of a random number generator; and controlling the robotic arm to move the peening tool over the surface of the workpiece to follow the peening path.

Abstract: An electrical converter (203) having an active diode-clamped multilevel topology is shown. Each clamping diode is connected in antiparallel with a switch (S5A, S5B). The converter comprises polyphase supply phases (A, B, C) each of which are connected via a respective phase leg (401, 402, 403) to dc rails (301, 302) and a dc-link capacitor. The dc-link capacitor includes a plurality of series-connected capacitors (404, 405). A controller is configured to, in response to an event signal, for each phase leg, activate a combination of switches therein to form a pair of parallel conduction paths to a midpoint (406) between two capacitors in the dc-link capacitor, thereby connecting each phase to the same node.

Abstract: A method of forming a protective sheath for an aerofoil component includes: providing a first sheath portion and a second sheath portion, the first sheath portion and the second sheath portion each comprising an inner surface, an outer surface and an end surface between the inner and outer surfaces and having a sacrificial flange at its distal end; positioning the first sheath portion and second sheath portion so that the inner surface of the first sheath portion abuts against the inner surface of the second sheath portion with the end surfaces of the first and second sheath portions aligned to form a mating edge; and joining the first sheath portion to the second sheath portion by welding along the mating edge, wherein the sacrificial flanges are completely consumed and a curved outer profile is formed.