Abstract: A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine is provided that has high efficiency together with low noise, in particular from the fan and the turbine that drives the fan. Values are defined for a combined contribution of the turbine noise and the noise from the fan emanating from the front of the engine to the Effective Perceived Noise Level (EPNL) at take-off to be in the range of from 2 EPNdB and 15 EPNdB lower than the EPNL of the whole engine at take-off.

Abstract: A power system for an aircraft includes one or more gas turbine engines arranged to burn a fuel so as to provide power to the aircraft; a plurality of fuel tanks each arranged to contain a fuel to be used to provide power to the aircraft; and a fuel manager. At least two of the fuel tanks contain different fuels, which have different proportions of a sustainable aviation fuel. The fuel manager is arranged to store information on the fuel contained in each fuel tank; and to control fuel supply so as to select a specific fuel accordingly to power at least the majority of operations on the ground. The fuel manager may additionally identify which tank contains the fuel with the highest proportion of a sustainable aviation fuel; and that fuel may be used to power at least the majority of operations on the ground.

Abstract: An aircraft propulsion system includes first and second engines and first and second electrical machines coupled to the first and second engines respectively. The first electrical machine is arranged to be driven by electrical power in order to at least partially drive the first engine. The second electrical machine is arranged to be driven by the second engine to generate electrical power. An electrical network allows transmission of electrical power between the electrical machines. A controller is arranged to selectively reduce fuel flow to the first engine and provide electrical power from the second electrical machine to the first electrical machine to drive the first electrical machine, based on expected properties of contrails formed in an exhaust plume of the first engine and/or the second engine. The system allows the formation of contrails by the engines to be managed in order to mitigate climate-warming effects of the contrails.

Abstract: A method of operating a gas turbine engine includes an engine core with a turbine, compressor, fuel combustor, and core shaft; a fan upstream of the engine core; a gearbox that receives an input from the core shaft and outputs drive to the fan; an oil loop system supplying oil to the gearbox; and a heat exchange system including: air-oil and fuel-oil heat exchangers, and wherein the oil loop system branches such that part of the oil flows along each branch and the air-oil and fuel-oil heat exchangers are parallel on different branches; and a modulation valve allows the oil sent via each branch to be varied, the method including controlling the heat exchange system wherein, under cruise conditions, a heat transfer ratio of: rate ? of ? heat ? transfer ? from ? oil ? to ? air rate ? of ? heat ? transfer ? from ? oil ? to ? fuel is in the range from 0 to 0.67.

Abstract: A method of operating a gas turbine engine comprising an engine core comprising a turbine, a compressor, a combustor arranged to combust a fuel, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core; a gearbox that receives an input from the core shaft and outputs drive to the fan; an oil loop system arranged to supply oil to the gearbox; and a heat exchange system comprising an air-oil heat exchanger through which the oil flows, a fuel-oil heat exchanger through which the oil and the fuel flow; and a valve arranged to allow a proportion of the oil sent via at least one of the heat exchangers to be varied, is disclosed, the method comprising controlling the valve such that, under cruise conditions, an oil flow ratio of: rate ? of ? oil ? flow ? into ? air - oil ? heat ? exchanger rate ? of ? oil ? flow ? into ? fuel - oil ? heat ? exchanger is in the range from 0 to 0.59.

Abstract: A gas turbine engine comprising a variable geometry combustor having fuel injectors, a rich-burn zone, a quick-quench zone, and a lean-burn zone, and further comprising quench ports for admitting quench air to the quick-quench zone; a variable geometry airflow arrangement for the variable geometry combustor, which is configured to vary an airflow through the fuel injectors and/or the quench ports; and a control system configured to control the variable geometry airflow arrangement in dependence upon an airflow delivered to the combustor, a fuel flow to the fuel injectors, and a target index of soot emissions to control the quantity of soot produced by combustion.

Abstract: A method of determining at least one fuel characteristic of a fuel provided to a gas turbine engine of an aircraft includes making an operational change, the operational change being effected by a controllable component of a propulsion system of which the gas turbine engine forms a part, and being arranged to affect operation of the gas turbine engine, sensing a response to the operational change; and determining the at least one fuel characteristic based on the response to the operational change.

Abstract: A method of refuelling an aircraft comprising a gas turbine engine and a fuel tank arranged to provide fuel to the gas turbine engine comprises obtaining an amount of energy required for an intended flight profile; obtaining a calorific value of fuel available to the aircraft for refuelling; calculating the amount of the available fuel needed to provide the required energy; and refuelling the aircraft with the calculated amount of the available fuel. The calculating the amount of the available fuel needed to provide the required energy may comprise obtaining an energy content of fuel already in the fuel tank and subtracting that from the determined amount of energy required for the intended flight profile.

Abstract: A method of forming a protective coating. The method includes providing a substrate including at least one chemical element and a surface; forming a basecoat composition including an aluminium phase including aluminium; applying the basecoat composition on the surface of the substrate to form a basecoat layer; heating the basecoat layer to a first temperature for a predetermined period of time; applying a glow discharge plasma on the basecoat layer; and heating the basecoat layer to a second temperature greater than the first temperature, in order to activate an exothermic reaction between at least the aluminium phase of the basecoat layer and the at least one chemical element of the substrate, wherein the exothermic reaction forms the protective coating on the surface of the substrate.

Abstract: A fuel system for a hydrogen fueled gas turbine engine comprises a main hydrogen fuel storage unit configured to store liquid hydrogen. The main fuel storage unit comprises an ullage space configured to store ullage fluid comprising gaseous or supercritical hydrogen. The system further comprises a liquid hydrogen drain line configured to provide liquid hydrogen from the main hydrogen fuel storage unit to a fuel conduit, the fuel conduit being configured to supply hydrogen fuel to a combustor of the gas turbine engine. A priming line is provided, which is configured to provide ullage fluid to the fuel conduit, and a priming valve is configured to selectively control flow through the priming line.

Abstract: Gearboxes for aircraft gas turbine engines, in particular arrangements for journal bearings such gearboxes, and related methods of operating such gearboxes and gas turbine engines. A gearbox for an aircraft gas turbine engine includes: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin.

Abstract: A tile for a gas turbine engine combustor. The tile has a base that has a hot-side surface, a cold-side surface, a first circumferential extremity, a second circumferential extremity and a local radial axis. The tile also has a plurality of cooling channels that have inlets on the cold-side surface and outlets on the hot-side surface, and one or more rail structure attached to the cold-side surface of the base.

Abstract: There is provided an air pressurisation system for an aircraft, the air pressurisation system comprising: a transmission for driving a rotor of a blower compressor for the air pressurisation system, wherein the transmission comprises: a first input configured to receive drive from a spool of a gas turbine engine; a second input; and an output configured to drive to the rotor of the blower compressor, wherein a speed of the output is determined by a function of speeds of the first and second inputs; and a brake coupled to the second input, wherein the brake is operable to engage and brake the transmission at the second input, in order to fix a transmission ratio of the transmission between the first input and the output.

Abstract: An inflatable probe for testing a component. The inflatable probe has a balloon formed of a dielectric material, the balloon having a neck and at least one electrode pair comprising an inner electrode and an outer electrode, the inner electrode being positioned on an internal surface of the balloon and the outer electrode being positioned on an external surface of the balloon. The inflatable probe also has a sealing plug that forms an air tight seal with neck of the balloon to retain a fluid within the balloon, the sealing plug at least having a seal electrode to connect to the inner electrode within the balloon, the sealing plug supporting a first wire to connect to a first seal electrode. The inflatable probe also has at least one tool that is connected to the balloon.

Abstract: There is disclosed a gas turbine engine comprising: an electrically-powered motor configured to rotate a driven spool of the gas turbine engine; a primary controller configured to conduct a primary function using the motor; and a bow controller configured to selectively control the motor to perform a rotor bow mitigation operation in which the motor drives the driven spool to rotate to mitigate a non-uniform thermal distribution in a rotor of a spool of the gas turbine engine.

Abstract: A techniques for improved guiding of hyper-redundant manipulator probes into a constrained space which make use of the known characteristics of the space into which the probe is being inserted to increase the efficiency of the computation of the path of the probe. Embodiments of the invention achieve this through an optimisation function which determined a new orientation which minimises the deviation between each of: a) the point on the probe where the probe starts to follow a defined curve within the constrained space and a predetermined initial point, and b) the distal end of the probe and said defined curve.

Abstract: A system includes a plurality of forming roller sets comprising an inner forming roller and an outer forming roller, each inner forming roller rotatable about an inner forming roller axis, each outer forming roller rotatable about an outer forming roller axis, each forming roller set being adjustable between an engagement configuration and a disengagement configuration, each forming roller set forming a profile on the ring component based on a forming roller set profile of the forming roller set, the system also including an actuating unit which controls the engagement and a disengagement of the forming roller sets with the ring component.

Abstract: A method of using computer implemented neural network for simulation of aerodynamic performance of technical object having geometry, method includes: training neural network using plurality of sets of pre-computed computational fluid dynamics encodings, CFD, outputs, wherein training is generated using inputs including: geometry of at least one training technical object; spatial locations of neural network input nodes as node attributes; relationship between geometry of at least one training technical object and neural network input node locations; associated boundary conditions; operating conditions; and computed outputs including flow fields and aerodynamic performance parameters; training using loss function evaluating error between neural network and pre-computed CFD outputs to produce trained neural network; using trained neural network with new inputs to generate as output predicted aerodynamic performance of technical object, wherein relationship between geometry of at least one training technical obje

Abstract: A method for gathering inflight data during operation of an electric or hybrid-electric aircraft. The aircraft includes: a swappable battery pack, connected to an electrical system of the aircraft, the swappable battery pack including a data storage module accessible via a data interface of the swappable battery pack; and a control unit, connected to the swappable battery pack via the data interface. The method includes, while the aircraft is in flight, gathering, by the control unit, the inflight data from the aircraft and saving the gathered inflight data to the data storage module of the swappable battery pack.

Abstract: A gas turbine engine for an aircraft includes a staged combustion system having pilot fuel injectors and main fuel injectors. The gas turbine engine further includes a fuel delivery regulator arranged to control delivery of fuel to the pilot and main fuel injectors, and a fuel characteristic determination module configured to determine one or more fuel characteristics of the fuel being supplied to the staged combustion system. A controller is configured to determine a staging point defining the point at which the staged combustion system is switched between pilot-only operation and pilot-and-main operation, the staging point being determined based on the determined one or more fuel characteristics, the controller being configured to control the staged combustion system according to the determined staging point.