Abstract: A fuel system for a gas turbine engine configured to combust hydrogen fuel is disclosed. The fuel system comprises a main fuel conduit and a fuel pump configured to operate on liquid hydrogen within the fuel conduit to provide pressurised fuel to a combustor of the gas turbine engine. A fuel metering unit is configured to control fuel flow delivered to the combustor. The fuel pump is configured to provide hydrogen at an outlet above a critical temperature and pressure, to thereby provide supercritical hydrogen fuel downstream. The fuel metering unit is configured to provide a variable flow area downstream of the pump, to deliver fuel at required flow parameters.

Abstract: A fuel system for a gas turbine engine includes a fuel offtake configured to divert a portion of hydrogen fuel from a main fuel conduit, a burner configured to burn the portion of hydrogen fuel diverted from the main fuel conduit and at least first and second heat exchangers. The first heat exchanger is configured to transfer heat from exhaust gasses produced by the burner to hydrogen fuel in the main fuel conduit and the second heat exchanger is provided upstream in hydrogen flow of the first heat exchanger and is configured to transfer heat from a further heat exchange fluid to hydrogen fuel in the main fuel conduit. In an embodiment, the further heat exchange fluid is compressor bleed air bled from a core compressor of the gas turbine engine.

Abstract: An aircraft propulsion system comprises a core gas turbine engine (201) comprising a core compressor (202, 204) configured to provide core air to a core combustor (206) and a core turbine (208, 209) in fluid flow series. An auxiliary compressor (220) is provided, which is separate to the core compressor (202, 204), and configured to provide air to an auxiliary air system (218). A heat exchanger (218) is provided, which is configured to transfer heat from air from the auxiliary compressor (220) to fuel in the main fuel conduit (217) prior to provision to the core combustor (206).

Abstract: A hydrogen fuel delivery system (300) comprises a fuel line (312) having an inlet (315) and an outlet (316), a liquid fuel pump (307) configured to provide a flow of liquid hydrogen fuel from a hydrogen fuel storage tank (308) to the fuel line inlet (315), a heat exchanger (306) having first and second fluid paths (313, 314), the fuel line (312) passing through the first fluid path (313), a pre-heater line (317) having an inlet (318) connected to the fuel line (312) between the fuel line inlet (315) and the heat exchanger (306), the pre-heater line (317) comprising a first control valve (301) and a burner (305) between the pre-heater line inlet (318) and the heat exchanger (306), the pre-heater line (317) passing through the second fluid path (314) of the heat exchanger (306) towards a pre-heater line outlet (319), a second control valve (302) in the fuel line (312) between the heat exchanger (306) and the fuel line outlet (316), a first temperature sensor (321) configured to measure a first fuel temperature

Abstract: A computer-implemented method of enabling optimisation of trajectory for a vehicle, the method comprising: determining a trajectory for the vehicle using: an algorithm; a vehicle model defining path constraints for the vehicle through space; a propulsion system model defining parameters of a propulsion system of the vehicle; an objective function defining one or more objectives; and controlling output of the determined trajectory.

Abstract: The present disclosure relates to an apparatus (e.g., a data processing apparatus) for planning a route of a vehicle. The apparatus is configured to: determine a trajectory solution TS1, TS2 for the vehicle based on: one or more objective parameters; at least one scenario SN, S1, S2 defined by one or more constraint parameters relating to the vehicle and/or to a journey the vehicle is to make; and at least one situation N, ET, ER which the vehicle could experience while making the journey. The present disclosure also relates to a computer-implemented method for planning a route of a vehicle.

Abstract: A fuel system for a gas turbine engine includes a fuel offtake configured to divert a portion of hydrogen fuel from a main fuel conduit, a burner configured to burn the portion of hydrogen fuel diverted from the main fuel conduit and at least first and second heat exchangers. The first heat exchanger is configured to transfer heat from exhaust gasses produced by the burner to hydrogen fuel in the main fuel conduit and the second heat exchanger is provided upstream in hydrogen flow of the first heat exchanger and is configured to transfer heat from a further heat exchange fluid to hydrogen fuel in the main fuel conduit. In an embodiment, the further heat exchange fluid is compressor bleed air bled from a core compressor of the gas turbine engine.

Abstract: A method of controlling a vapour-compression system for circulating a working fluid. The vapour-compression system comprises a compressor, an expansion device and an evaporator configured to facilitate heat transfer from a thermal source into the working fluid. The method comprises: determining or receiving a cooling demand, the cooling demand being associated with a demand to cool the thermal source; determining a preliminary thermofluidic property objective value based on the cooling demand; determining a final thermofluidic property objective value based on the preliminary thermofluidic property objective value and one or more thermofluidic property objective value thresholds, wherein the final thermofluidic property objective value relates to a target thermofluidic property of the working fluid at a control location within the vapour-compression system; and controlling at least one of the compressor and the expansion device based on the final thermofluidic property objective value.

Abstract: An aircraft propulsion system fuel system comprises a fuel line configured to receive liquid hydrogen fuel from a fuel tank, a vaporizer configured to vaporize liquid hydrogen fuel from the fuel line to generate a supercritical or gaseous fuel, a main fuel pump configured to receive and to pump the gaseous or supercritical fuel from the vaporizer during operation of the propulsion system, and a heater provided downstream in fuel flow to the main fuel pump, and configured to raise the temperature of the gaseous or supercritical fuel to a propulsion system delivery temperature.

Abstract: An aircraft includes a turbofan engine, a cabin blower system and a PEM fuel cell stack. The cabin blower system includes a cabin blower compressor arranged to be driven by mechanical power derived from a shaft of the turbofan engine. A ducting system delivers respective portions of the mass flow rate of compressed air output by the cabin blower system to a cabin space of the aircraft via an air-conditioning unit and to the cathode input of the fuel cell stack. An electric motor receives electrical power from the fuel cell stack and provides mechanical power to the compressor via a drive arrangement of the cabin blower system. Power associated with excess capacity of the cabin blower system is recovered to the cabin blower compressor, thereby mitigating or eliminating the fuel consumption penalty on the turbofan engine associated with the excess capacity.

Abstract: A computer-implemented method of enabling optimisation of derate for a propulsion system of a vehicle, the method comprising: determining a derate for the propulsion system of the vehicle using: an algorithm; a vehicle model defining path constraints for the vehicle through space; a propulsion system model defining parameters of the propulsion system; an objective function defining one or more objectives; and controlling output of the determined derate.

Abstract: An aircraft propulsion system fuel system comprises a fuel line configured to receive liquid hydrogen fuel from a fuel tank, a vaporizer configured to vaporize liquid hydrogen fuel from the fuel line to generate a supercritical or gaseous fuel, a main fuel pump configured to receive and to pump the gaseous or supercritical fuel from the vaporizer during operation of the propulsion system, and a heater provided downstream in fuel flow to the main fuel pump, and configured to raise the temperature of the gaseous or supercritical fuel to a propulsion system delivery temperature.

Abstract: An aircraft propulsion system fuel system comprises a fuel line configured to receive liquid hydrogen fuel from a fuel tank, a vaporizer configured to vaporize liquid hydrogen fuel from the fuel line to generate a supercritical or gaseous fuel, a main fuel pump configured to receive and to pump the gaseous or supercritical fuel from the vaporizer during operation of the propulsion system, and a heater provided downstream in fuel flow to the main fuel pump, and configured to raise the temperature of the gaseous or supercritical fuel to a propulsion system delivery temperature.

Abstract: A gas turbine engine system includes a hydrogen-burning gas turbine engine and a fuel system including a fuel line arranged to receive gaseous hydrogen at an input thereof and provide the gaseous hydrogen to combustion apparatus of the hydrogen-burning gas turbine engine and a vent line including a vent valve and having a first end coupled to the fuel line and a second end disposed remotely from the hydrogen-burning gas turbine engine. A controller is arranged to switch the vent valve from a closed state to an open state upon detection of an engine shaft-break or similar condition, thus providing rapid evacuation of gaseous hydrogen from the fuel line and hence rapid shut-down of the engine. The engine may be shut down more rapidly than is possible by means of a shut-off valve within the fuel line.

Abstract: A computer-implemented method of enabling optimisation of trajectory for a vehicle, the method comprising: determining a trajectory for the vehicle using: an algorithm; a vehicle model defining path constraints for the vehicle through space; a propulsion system model defining parameters of a propulsion system of the vehicle; an objective function defining one or more objectives; and controlling output of the determined trajectory.

Abstract: A computer-implemented method of enabling optimisation of derate for a propulsion system of a vehicle, the method comprising: determining a derate for the propulsion system of the vehicle using: an algorithm; a vehicle model defining path constraints for the vehicle through space; a propulsion system model defining parameters of the propulsion system; an objective function defining one or more objectives; and controlling output of the determined derate.

Abstract: A method of automatically determining a flight trajectory of a vertical take-off and landing aircraft having vectorable propulsion can be used to improve flight efficiency. The method includes receiving one or more aircraft flight constraints, inputting the aircraft flight constraints to a trajectory planning algorithm to determine a minimum energy aircraft transition trajectory, and outputting a control schedule to fly the aircraft to along the flight trajectory.

Abstract: A method of controlling a gas turbine engine including receiving an instantaneous thrust demand for current operation of the engine, determining the inlet flow rate and/or the pressure ratio within the compressor of the engine and determining whether the inlet flow rate and/or the pressure ratio match the working line for the compressor. The angle of one or more vane of the compressor is adjusted according to a closed control loop if the inlet flow rate and/or pressure ratio lie outside said desired range in order to adjust the inlet inflow rate and/or pressure ratio to meet the working line. The fuel flow to the engine combustor is adjusted concurrently in order to meet the thrust demand.

Abstract: Computer-implemented methods for controlling the operation of aircraft, particularly electric or hybrid electric aircraft, are described. One such method, which may be implemented on a Flight Management System of the aircraft, comprises: receiving weather data indicative of weather conditions between a flight origin and a flight destination of the aircraft; and determining, using a constrained optimization method and a weather data dependent aircraft energy usage model, a three-dimensional flight path for the aircraft from the origin to the destination. The constrained optimization method may determine a flight path constrained by, amongst other things the energy required by an Environmental Control System of the aircraft.

Abstract: Computer-implemented methods for controlling the operation of aircraft, particularly electric or hybrid electric aircraft, are described. One such method, implemented on a Flight Management System (FMS) of an aircraft, comprises: receiving, by the FMS, weather data indicative of weather conditions around the aircraft; and selecting, by the FMS, based on the received weather data, one of a plurality of different pre-defined FMS profiles, each FMS profile corresponding to a different range of weather conditions and defining a different set of aircraft operating parameters. The aircraft may be flown under the control of the FMS using the selected FMS profile.