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, 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.

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, which may be implemented on a Flight Management System (FMS) of the aircraft, comprises: obtaining flight path data for the aircraft, the flight path defining a three-dimensional path from an origin to a destination; receiving weather data indicative of weather conditions along the flight path; and determining an amount of energy required to fly the aircraft along the flight path. The determination uses an aircraft energy usage model whose inputs include the flight path data and the weather data. Based on the determination and a comparison with an amount of stored energy available to the aircraft, the FMS may validate the flight path for flight or reject the flight path.

Abstract: A method of actively controlling torsional resonance of a rotating shaft of an engine is provided. The shaft has a rotational velocity characterised by a low frequency, rotational velocity term and a high frequency, oscillatory term superimposed on the low frequency term, the oscillatory term being caused by torsional resonance. The method including: measuring the rotational velocity of the shaft; extracting the oscillatory term from the measured rotational velocity; and on the basis of the extracted oscillatory term, applying a torque component to the shaft, the torque component being modulated at the same frequency as the torsional resonance to counteract the torsional resonance.

Abstract: The present disclosure concerns control a hybrid electric gas turbine system (300) for an aircraft. The system comprises an electric generator (308) and a gas turbine (309) to form a generator system, an electric motor (303) and a fan (302) to form a propulsor (301), a controller (306) and an electric storage unit (307). After receiving a command for a change in demand for thrust, the controller (306) determines an operational profile that minimises a function comprising a measure of fuel supplied to the gas turbine (309), a transfer of electric power from or to the electric storage unit (307) and a difference between measures of current and demanded thrust over a time period. The controller then operates the electric motor (303), gas turbine (309) and electric storage unit (307) according to the determined operational profile over the time period.

Abstract: A method of determining a flight trajectory of a vertical take-off aircraft (10) having vectorable propulsion (30, 32). The method comprises: 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 (10) to 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: A control system for use in controlling a cabin blower system. The cabin blower system includes a gas turbine engine spool, a cabin blower compressor powered by the spool and arranged in use to compress fluid used in a cabin of an aircraft, and one or more control mechanisms via which the control system controls the power extracted by the cabin blower compressor from the spool. The control system is arranged in use to control the power extracted from the spool by the cabin blower compressor in accordance with one or more primary control parameters. The control system is arranged in use to alter the spool power extracted by the cabin blower compressor by comparison with the power that would have been extracted in accordance with the primary control parameters alone, in response to modifications in a secondary control parameter indicative of the commencement or occurrence of an engine transient.

Abstract: A method of controlling turbine tip clearance includes measuring turbine speed; measuring turbine temperature; measuring parameters indicative of current operating conditions; determining limits for the turbine speed and turbine temperature; calculating target tip clearance from the turbine speed, turbine temperature and parameters, to optimise turbine efficiency within the turbine speed and turbine temperature limits; and controlling turbine tip clearance apparatus to the calculated target tip clearance.

Abstract: A method of actively controlling torsional resonance of a rotating shaft of an engine is provided. The shaft has a rotational velocity characterised by a low frequency, rotational velocity term and a high frequency, oscillatory term superimposed on the low frequency term, the oscillatory term being caused by torsional resonance. The method including: measuring the rotational velocity of the shaft; extracting the oscillatory term from the measured rotational velocity; and on the basis of the extracted oscillatory term, applying a torque component to the shaft, the torque component being modulated at the same frequency as the torsional resonance to counteract the torsional resonance.

Abstract: A fluidic device for providing analogue output control includes a main channel, a first control channel, a second control channel, a comparator which receives respective input fluid flows from the main, the first and the second control channels. The first control channel is configured such that the input fluid flow therefrom carries an oscillating pressure wave signal, the second control channel includes a flow regulator controllable to vary the mass flow rate of the input fluid flow from the second control channel, and the main channel is configured such that the input fluid flow therefrom is at a reference mass flow rate. The comparator is configured such that the input fluid flows from the first control and the second control channels act in combination on the input fluid flow from the main channel to produce an output fluid flow from the comparator having a PWM mass flow rate characteristic.

Abstract: A gas turbine engine is disclosed having a tip clearance control system. The tip clearance control system has a cabin blower system, a casing arranged in use about a rotor of a gas turbine engine and a fluid delivery passage. The cabin blower system having a cabin blower compressor arranged in use to compress fluid used in a cabin of an aircraft and to compress fluid conducted via the fluid delivery passage into heat exchange with the casing.

Abstract: An aircraft defining longitudinal, lateral and vertical directions the aircraft comprising: a main wing and a tail, each being pivotable about the lateral direction (B); a plurality of main propellers mounted to the main wing, and configured to pivot with the main wing; at least one cruise propeller mounted to the tail, and configured to pivot with the tail; each main propeller being stowable from a deployed position to a stowed position; wherein each main propeller has a fixed pitch, and each cruise propeller has a variable pitch.

Abstract: The present disclosure concerns control a hybrid electric gas turbine system (300) for an aircraft. The system comprises an electric generator (308) and a gas turbine (309) to form a generator system, an electric motor (303) and a fan (302) to form a propulsor (301), a controller (306) and an electric storage unit (307). After receiving a command for a change in demand for thrust, the controller (306) determines an operational profile that minimises a function comprising a measure of fuel supplied to the gas turbine (309), a transfer of electric power from or to the electric storage unit (307) and a difference between measures of current and demanded thrust over a time period. The controller then operates the electric motor (303), gas turbine (309) and electric storage unit (307) according to the determined operational profile over the time period.