Abstract: A gas turbine engine for an aircraft, including: staged combustion system having pilot fuel injectors and main fuel injectors, staged combustion system being operable in pilot-only range of operation and pilot-and-main range of operation; and fuel delivery regulator arranged to control delivery of fuel to pilot and main fuel injectors. Fuel delivery regulator arranged to receive fuel from a first fuel source containing a first fuel having a first fuel characteristic and a second fuel source containing a second fuel having a different second fuel characteristic. The fuel delivery regulator is arranged to deliver fuel to the pilot fuel injectors during at least part of the pilot-only range of operation having a different fuel characteristic from fuel delivered to one or both of the pilot and main fuel injectors during at least part of the pilot-and-main range of operation. A method of operating a gas turbine engine is also disclosed.

Abstract: A decoking cleaning system for cleaning at least one component in-situ within a combustion engine system, the decoking system including at least one ultrasonic transducer with a means of connecting the at least one ultrasonic transducer to a component to be cleaned within the combustion engine system, the at least one ultrasonic transducer being connected to a power and voltage supply.

Abstract: A method of manufacturing a composite article precursor, e.g. from which to make an aerofoil. The method of manufacturing involves: laying down a first grouping of at least one layer of composite material upon a substantially upwardly-facing first surface of a preform of the composite article precursor; disposing a first deformable support over the first grouping of at least one layer of composite material; securing the first deformable support to the preform via a first securing fixing; rotating the preform about an axis such the first surface is no longer substantially upwardly-facing and a second surface of the preform is substantially upwardly-facing; laying down a second grouping of at least one layer of composite material upon the second surface of the preform; and vacuum debulking an assembly comprising the first grouping composite material, the second grouping of composite material, the first deformable support and the preform.

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: A gas turbine engine for an aircraft including: an engine core including a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan including a plurality of fan blades; a gearbox that can receive an input from the core shaft, and can output drive to a fan shaft via an output of the gearbox so as to drive the fan at a lower rotational speed than the core shaft; and a fan shaft mounting structure arranged to mount the fan shaft within the engine, the fan shaft mounting structure including at least two supporting bearings connected to the fan shaft.

Abstract: A highly efficient gas turbine engine is provided. The fan of the gas turbine engine is driven from a turbine via a gearbox, such that the fan has a lower rotational speed than the driving turbine, thereby providing efficiency gains. The efficient fan system is mated to a core that has low cooling flow requirements and/or high temperature capability, and which may have particularly low mass for a given power.

Abstract: An aerospace battery may include a housing and a battery pack core. The housing may include a thin dual layer casing. The battery pack core is disposed in the housing and may include at least one cell district that includes a plurality of pouch cell batteries. A ceramic material may surround the at least one cell district and a closed cell foam may fill open space between the ceramic material and the housing.

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: The disclosure relates to an electrical power system for connecting an electrical machine to first and second DC networks operating at different voltages. In an embodiment, an electrical power system comprises: an electrical machine having first, second, third and fourth windings; first, second, third and fourth AC:DC power electronics converters each connected to receive an input AC supply from the respective first, second, third and fourth windings, each AC:DC power electronics converter having first and second DC output terminals connecting the AC:DC power electronics converters to first, second and third DC supply output terminals, wherein the first and second windings are arranged to provide an AC supply to the respective first and second AC:DC power electronics converters in quadrature to each other and the third and fourth windings are arranged to provide an AC supply to the respective third and fourth AC:DC power electronics converters in quadrature to each other.

Abstract: There is provided a blower system for providing air to an airframe system, comprising a rotor configured to be mechanically coupled to a spool 440 of a gas turbine engine, wherein the rotor is configured to: in a blower mode, be driven to rotate by the spool to discharge air to an airframe discharge port for supply to an airframe system; and, in an engine drive mode, receive air from an external air source via an impingement port that is configured to direct the received air onto the rotor and thereby drive the rotor to rotate to drive the spool to.

Abstract: An electrical system includes: a battery; a fuel-cell pack; a load electrically coupled to the fuel-cell pack; a switching arrangement electrically coupled to the battery, the fuel-cell pack and the load; a DC-DC converter; and a control system. The switching arrangement configures the electrical system in at least one of a battery-charge mode and a combined-drive mode. In the battery-charge mode the battery is coupled in series to the fuel-cell pack and the load via the DC-DC converter for simultaneous charging of the battery and driving of the load by the fuel-cell pack. In the combined-drive mode, the battery is coupled in series to the fuel-cell pack and the load via the DC-DC converter for driving of the load by both the battery and the fuel-cell pack. The control system is configured to: monitor a parameter of an electrical power provided to the load; and control the DC-DC converter.

Abstract: A power routing circuit having first and second input nodes VIN1, VIN2 for connection to first and second power supplies and output node VOUT1 for load connection; and includes a first main switching circuit connected between the first input node VIN1 and output node VOUT1 and conductively connects the first input node VIN1 to the output node VOUT1 if a voltage at the first input node VIN1 is higher than a voltage at the output node VOUT1, and a first auxiliary switching circuit connected between the second input node VIN2 and output node VOUT1 and conductively connects the second input node VIN2 to output node VOUT1 if a voltage at the second input node VIN2 is higher than the voltage at the output node VOUT1 and the voltage at the first input node VIN1 is at least a threshold amount lower than the voltage at the second input node VIN2.

Abstract: There is provided a method of operating a gas turbine engine including a combustor. The combustor includes a combustion chamber and a plurality of fuel spray nozzles configured to inject fuel into the chamber. The nozzles include a first and second subset of fuel spray nozzles. The combustor is operable in a condition wherein the first subset is supplied with more fuel than the second. A ratio of the number of nozzles in the first subset to the second is 1:2 to 1:5. The method includes operating the engine so a reduction of 20-80% in an average of particles/kg of nvPM in the exhaust when the engine is operating at 85% available thrust for given operating conditions and when the engine is operating at 30% is obtained when fuel provided to the nozzles is a sustainable aviation fuel instead of a fossil-based hydrocarbon fuel. Also provided is a gas turbine engine for an aircraft.

Abstract: An apparatus for determining the health of a battery including a plurality N of series-connected cells. The apparatus includes an AC signal source operable to cause an AC current to flow through one or more cells of the plurality of series-connected cells, a current measurement unit operable to measure the AC current, a voltage measurement unit operable to measure an AC voltage induced across the one or more cells by the AC current, and a health determination unit operable to determine a measurement of the health of the battery based on the measured AC current and the measured AC voltage.

Abstract: This invention concerns a fuel delivery system for an aircraft engine, comprising a fuel delivery regulator configured to receive fuel from a plurality of fuel sources for supply to the engine. An engine operating condition sensor reading is received by a control unit configured to control operation of the regulator. The control unit is configured to actuate the regulator based on a received signal from the engine operating condition sensor in order to vary the volume of fuels from the plurality of fuel sources supplied to the engine during at least a portion of a cruise phase relative to a further portion of an aircraft flight. The different fuels may comprise kerosene and an alternative fuel, such as a biofuel.

Abstract: A fixture for removably securing a plurality of components includes a hollow body including a plurality of channels and a plurality of sets of holes. The fixture further includes a plurality of hollow wedges and a plurality of sets of balls. Upon an axial movement of an elongate member in a first direction, the elongate member axially moves a first hollow wedge, thereby causing one or more elastic members to be sequentially compressed and move the subsequent hollow wedges. Upon the axial movement, a frustoconical surface portion of each hollow wedge moves the corresponding set of balls radially outwards within the corresponding set of holes, such that each ball extends partially into the corresponding channel, thereby moving the corresponding component into locking engagement with the corresponding channel.

Abstract: An electrical system includes: a battery; a fuel-cell pack; a load; a switching arrangement; and a control system. The switching arrangement selectively configures the electrical system in a battery-isolation mode and at least one of a battery-charge mode and a combined-drive mode. In the battery-isolation mode, the battery is decoupled from the fuel-cell pack and the load, and the fuel-cell pack is coupled to the load for driving of the load by the fuel-cell pack. In the battery-charge mode, the battery is coupled in series to the fuel-cell pack and the load for simultaneous charging of the battery and driving of the load by the fuel-cell pack. In the combined-drive mode, the battery is coupled in series to the fuel-cell pack and the load for driving of the load by both the battery and the fuel-cell pack.

Abstract: The disclosure relates to fault protection in a DC-DC electric power converter. The converter comprises first, second, third and fourth switches connected either side of an inductor. Fifth and sixth switches are connected between respective input and output terminals and a common line, the fifth and sixth switches providing protection in a fault event.

Abstract: A method of operating a gas turbine engine having a combustor having a combustion chamber and a plurality of fuel spray nozzles configured to inject fuel into the combustion chamber. The fuel spray nozzles have a first subset of fuel spray nozzles and a second subset of fuel spray nozzles. The combustor is operable in a condition in which the first subset of fuel spray nozzles are supplied with more fuel than the second subset of fuel spray nozzles. A ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:2 to 1:5. The method includes providing a fuel to the plurality of fuel spray nozzles having a calorific value of at least 43.5 MJ/kg. A gas turbine engine can be for an aircraft.

Abstract: A method of operating a gas turbine engine is disclosed, the gas turbine engine comprising a fuel delivery system arranged to provide fuel; a combustor arranged to combust at least a proportion of the fuel; a primary fuel-oil heat exchanger arranged to have up to 100% of the fuel provided by the fuel delivery system flow therethrough; and a secondary fuel-oil heat exchanger arranged to have a proportion of the fuel from the primary fuel-oil heat exchanger flow therethrough. Fuel is arranged to flow from the primary fuel-oil heat exchanger to the secondary fuel-oil heat exchanger and oil is arranged to flow from the secondary fuel-oil heat exchanger to the primary fuel-oil heat exchanger. The method comprises transferring 200-600 KJ/m3 of heat to the fuel from the oil in the primary fuel-oil heat exchanger at cruise conditions.