Abstract: A gas turbine engine for an aircraft comprises, in axial flow sequence, a compressor module, a combustor module, and a turbine module. The gas turbine engine further comprises a first electric machine that is rotationally connected to the turbine module, and an electrical energy storage unit. The gas turbine engine is configured to generate a maximum dry thrust T (N). The first electric machine is configured to generate a maximum electrical power PEM1 (W). The electrical energy storage unit has an energy storage capacity E (Wh), a maximum charge rate C (h?1), and a maximum discharge rate D (h?1). The electrical energy storage unit is configured to store electrical energy that may be generated by the first electric machine.

Abstract: Aircraft power and propulsion systems and methods of operating the systems, one method includes: operating electric machines of gas turbine engines as generators to extract mechanical power from spools and generating electrical power therefrom; meeting an electrical power demand of a plurality of electrical loads connected with an electrical system by supplying the plurality of electrical loads with electrical power generated by the electric machines; determining when there is an electrical system and/or the gas turbine engine fault and an amount of electrical power generated by the power and propulsion system is reduced to a lower level; and responsive to the determination: during a time period ?T, controlling the plurality of electrical loads reducing the electrical power demand; and during the time period ?T, meeting at least part of the electrical power demand of the plurality of electrical loads by discharging the electrical energy storage system.

Abstract: Aircraft power and propulsion systems, aircraft comprising such power and propulsion systems, and methods of restarting a gas turbine engine of such power and propulsion systems during flight are provided. One such aircraft power and propulsion system comprises: a propulsive gas turbine engine comprising a plurality of spools, combustion equipment, one or more electric machines mechanically coupled with one or more of the spools and an electrically-powered fuel pump for delivering fuel to the combustion equipment; an electrical system connected with the one or more electric machines and the electrically-powered fuel pump, the electrical system comprising an energy storage system; and a control system configured to: responsive to a determination to the effect that a flame in the combustion equipment has been extinguished, control the electrical system to supply electrical power from the energy storage system to the fuel pump during an engine restart attempt.

Abstract: A blower assembly for providing air to an airframe system, including a rotor configured to be mechanically coupled to a spool of a gas turbine engine and a flow modifier configured to receive and/or direct flow to the rotor; wherein the blower assembly is configured to permit relative movement between the rotor and the flow modifier to move between: a compressor configuration in which the rotor is configured to be driven to rotate by the spool and to receive and compress air from the gas turbine engine, and discharge the compressed air for supply to the airframe system; and a turbine configuration in which the rotor is configured to receive air from an external air source to drive the spool to rotate.

Abstract: A twin-engine aircraft power and propulsion system including first and second propulsive gas turbine engines, each having combustion equipment and a first and second spool; first, second, third, and fourth electrical power generation sub-systems including electric machines respectively mechanically coupled with the first spool of the first propulsive gas turbine engine, the second spool of the first propulsive gas turbine engine, the first spool of the second propulsive gas turbine engine, and the second spool of the second propulsive gas turbine engine; and first, second, third, and fourth power channels respectively connected with distribution sides of the first electric machine, second electric machine, third electric machine, and fourth electric machine.

Abstract: An aircraft propulsion system comprises first and second thrust producing gas turbine engines. The system comprises a controller configured to determine a required overall propulsion system thrust level, and determine an engine core power level contribution from each aircraft gas turbine engine such that the overall propulsion system produces a minimum overall noise level and meets the required overall propulsion system thrust level. In meeting the minimum overall noise level, at least the first and second gas turbine engines are operated at different engine core power settings.

Abstract: Multi-engine aircraft power and propulsion systems and methods of starting the engines of multi-engine aircraft disclosed, including supplying electrical power from an electrical power source to electric machines of the a first gas turbine engine and operating electric machines as motors to drive rotation of spools of the first gas turbine engine; starting the first gas turbine engine by lighting combustion equipment of the first gas turbine engine; operating the electric machines of the first gas turbine engine as generators to extract mechanical power and generate electrical power from spools of the first gas turbine engine; transferring the electrical power to electric machines of a second gas turbine engine and operating the electric machines as motors to drive rotation of spools of the second gas turbine engine; and starting the second gas turbine engine by lighting combustion equipment of the second gas turbine engine.

Abstract: A bearing arrangement includes a shaft, at least one contact bearing and at least one non-contact bearing and a controller. The controller is configured to control a magnitude of a restoring force applied to the shaft by the non-contact bearing in accordance with a sensed parameter such that a stiffness of the shaft is modified such that one or more resonance frequencies of the shaft are moved away from one or more external forcing frequencies.

Abstract: A fuel control system for a gas turbine engine includes a fuel metering valve, a pressure raising and shut-off valve (PRSOV), and a shutoff effector including a first stage unit that is electrically powered and a second stage unit that is controlled by the first stage unit. The second stage unit actuates a valve member of the PRSOV between an open position that allows supply of a fuel to burners of the gas turbine engine and a closed position that prevents supply of the fuel to the burners. Upon loss of electrical power to the first stage unit during operation of the gas turbine engine, the first stage unit is configured to: control the second stage unit to actuate the valve member of the PRSOV to the closed position after a predetermined time duration; or retain the valve member of the PRSOV in the open position.

Abstract: A sensor assembly is shown for sensing a crossing of the critical point in a system utilising a working fluid in a transcritical cycle passing through the critical point. A first broadband acoustic sensor is located upstream of a component and a second broadband acoustic sensor is located downstream of the component, each of which are arranged to detect high-frequency and low-frequency sounds caused by the crossing of the critical point. A flow regulation device regulates flow of working fluid through the component in response to the output of one or both of the first broadband acoustic sensor and the second broadband acoustic sensor, thereby adjusting the location of the crossing of the critical point.

Abstract: A turbofan gas turbine engine comprises, in axial flow sequence, a heat exchanger module, an inlet duct, a fan assembly, a compressor module, and a turbine module. The fan assembly comprises a plurality of fan blades defining a fan diameter D, and the heat exchanger module comprises a plurality of heat transfer elements for transfer of heat from a first fluid contained within the heat transfer elements to an airflow passing over a surface of the heat transfer elements prior to entry of the airflow into the fan assembly. In use, the first fluid has a maximum temperature of 80° C., and the heat exchanger module transfers at least 300 kW of heat energy from the first fluid to the airflow.

Abstract: Electrical power distribution systems and methods of operating electrical power distribution systems are provided. One electrical power distribution system comprises: an electrical power storage unit; a transformer; a first bidirectional converter circuit connected between the electrical power storage unit and a first winding of the transformer; a first DC bus; a second DC bus; a second bidirectional converter circuit connected between the first DC bus and a second winding of the transformer; a third bidirectional converter circuit connected between the second DC bus and a third winding of the transformer; and a controller connected for control of the first, second and third converter circuits to distribute electrical power between the electrical power storage unit, the first DC bus and the second DC bus.

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 aircraft gas turbine engine includes a heat exchanger module, and a core engine. The core engine includes an intermediate-pressure compressor, high-pressure compressor, and high and low-pressure turbines. The high-pressure compressor rotationally connects to the high-pressure turbine by a first shaft, and the intermediate-pressure compressor rotationally connects to the low-pressure turbine by a second shaft. The heat exchanger module fluidly communicates with the core engine by an inlet duct. The heat exchanger module includes a central hub and multiple heat transfer elements extending radially from the hub and spaced in a circumferential array, for heat energy transfer from a first fluid within the elements to an inlet airflow passing over a surface of the elements prior to airflow entry into an inlet to the core engine. The gas turbine engine further includes a first electric machine rotationally connected to the first shaft, and positioned downstream of the heat exchanger module.

Abstract: A cooling system for an aircraft comprises an apparatus, a heat exchanger, and a vapour cycle machine. The apparatus comprises a first fluid being circulated to provide cooling to the apparatus, with the heat exchanger being configured to transfer waste heat energy from the first fluid to a second fluid. The second fluid has a temperature T2 (°C), and the vapour cycle machine is configured to increase a temperature T1 (°C) of the first fluid, to a temperature greater than T2 (°C).

Abstract: A gas turbine engine comprises, in axial flow sequence, a fan assembly, a compressor module, a turbine module, and an exhaust module. The gas turbine engine comprises first and second engine mount planes. The first and second engine mount planes are configured to support gas turbine engine in machine body. The gas turbine engine has axial length L, with axial length extending from inlet face of engine to exhaust face of engine. The first engine mount plane is positioned axially along gas turbine engine at first engine mount plane position, with first engine mount plane position within a range of between 0.24*L to 0.32*L from the inlet face of the engine. The second engine mount plane is positioned axially along gas turbine engine at second engine mount plane position, with second engine mount plane position within a range of between 0.73*L to 0.79*L from the inlet face of the engine.

Abstract: A gas turbine engine for an aircraft includes, in axial flow sequence, a compressor module, a combustor module, and a turbine module, with a first electric machine being rotationally connected to the turbine module. The first electrical machine is configured to generate a total electrical power PEM1 (W), and the gas turbine engine is configured to generate a total shaft power PSHAFT (W); and a ratio R of: R = Total Shaft Power = P S H A F T Total Electrical Power Generated = P E M 1 is in a range of between 0.005 and 0.020.

Abstract: A filter inductor for a power generation convertor; the filter inductor comprising a toroidal connector and a conductive winding having a first connector and a second connector positioned at each end of the winding, and wherein the conductive winding being formed from at least first and second winding segments which are connected to each other so as to form a continuous winding around the toroidal connector that extends form the first connector to the second connector.

Abstract: An aircraft gas turbine engine includes a heat exchanger module, and a core engine including an intermediate-pressure compressor, a high-pressure compressor, a high pressure turbine, and a low-pressure turbine. The high-pressure compressor is connected to the high-pressure turbine by a first shaft, and the intermediate-pressure compressor is connected to the low-pressure turbine by a second shaft. The heat exchanger module includes a central hub and heat transfer elements extending radially from the central hub and spaced in a circumferential array, for transferring heat energy from a fluid within the heat transfer elements to an inlet airflow passing over the heat transfer elements prior to entry of the airflow into an inlet to the core engine. The gas turbine engine further includes a first electric machine connected to the first shaft and positioned downstream of the heat exchanger module, and a second electric machines connected to the second shaft.

Abstract: An aircraft turbofan gas turbine engine includes a fan assembly, a compressor module, and a turbine module. An electric machine is positioned downstream of the fan assembly and is connected to the turbine module. The fan assembly includes a highest pressure fan stage having a plurality of fan blades defining a fan diameter. The turbine module includes a lowest pressure turbine stage having a row of rotor blades. The gas turbine engine has a fan tip axis that joins a radially outer tip of the leading edge of one of the plurality of fan blades of the highest pressure fan stage, and the radially outer tip of the trailing edge of one of the rotor blades of the lowest pressure turbine stage. The fan tip axis lies in a longitudinal plane which contains a centreline of the gas turbine engine. The fan axis angle is between 11 and 20 degrees.