Abstract: A propulsor (101) for an aircraft is shown. The propulsor comprises a propulsive fan (106), and an electric machine (108) configured to drive the propulsive fan. The electric machine has a casing containing electrical and electromechanical components, a shaft which extends outside of the casing and which is connected to the propulsive fan, and a seal to seal the casing around the shaft. A depressurisation system depressurises the casing below an external pressure to prevent electrical breakdown within gas in the casing of the electric machine.

Abstract: A combined cycle heat engine (10). The engine (10) comprises a first gas turbine engine (11) comprising a first air compressor (14), a first combustion system (16, 20) and a first turbine system (18, 22), and a second gas turbine engine (32) comprising a second air compressor (36) and a second turbine system (40). The engine further comprises a heat exchanger (38) configured to transfer heat from an exhaust of the first turbine system (18, 22) to compressed air from the second air compressor (36). The first combustion system comprises a first combustor (16) provided downstream of the first air compressor (14) and upstream of the first turbine system (18, 22), and a second combustor (20) downstream of a first turbine section (18) of the first turbine system and upstream of a second turbine section (22) of the first turbine system.

Abstract: A method of controlling at least part of a start-up or re-light process of a gas turbine engine, the method comprising: determining when a flame in a combustion chamber of a gas turbine engine is extinguished, during a start-up process or re-light process or during operation; purging the combustion chamber by controlling rotation of a low pressure compressor using a first electrical machine, and controlling rotation of a high pressure compressor using a second electrical machine, the combustion chamber downstream of the low pressure compressor and high pressure compressor; and controlling rotation of the low pressure compressor using the first electrical machine, and controlling rotation of the high pressure compressor using the second electrical machine to restart the start-up process or perform the re-light process.

Abstract: A combined cycle heat engine (10). The engine (10) comprises a first gas turbine engine (11) comprising a first air compressor system (14), a first combustion system (16) and a first turbine system (18) and a second gas turbine engine (32) comprising a second air compression system (36), a second turbine system (40), and a heat exchanger (38) configured to transfer heat from an exhaust (24) of the first turbine system (18) to compressed air from the second air compressor (36). The second gas turbine engine (32) comprises a second combustion system (20) downstream of the heat exchanger (38) and upstream of the second turbine system (40).

Abstract: An apparatus measuring thrust of an aircraft gas turbine engine includes a core shaft connecting a turbine and compressor, a fan and gearbox with a sun gear driven by the core shaft, a plurality of planet gears, an annulus gear mounted in a static structure, and a planet carrier driven by the fan via fan shaft. The apparatus includes a sensor to measure force applied by the annulus gear on the static structure and first and second sensors to measure rotational speed of the core and fan shafts. A processor determines restoring torque on the annulus gear from measurement of force applied by the gear on the static structure, torque applied to the fan by the planet carrier using rotational speeds of core and fan shafts and restoring torque on the annulus gear, and thrust of the fan from torque applied to the fan and the fan's rotational speed.

Abstract: A method of controlling at least part of a start-up or re-light process of a gas turbine engine, the method comprising: increasing an angular velocity of a low pressure compressor; determining if an exit pressure of the low pressure compressor is equal to or greater than a first threshold pressure; in response to determining that the exit pressure of the low pressure compressor is equal to or greater than the first threshold pressure, controlling rotation of the low pressure compressor using a first electrical machine and controlling rotation of a high pressure compressor using a second electrical machine, to increase angular velocity of the high pressure compressor; determining if an exit pressure of the high pressure compressor is equal to or greater than a second threshold pressure.

Abstract: A method of controlling at least part of a start-up or re-light process of a gas turbine engine, the method comprising: controlling ignition within a combustion chamber of the gas turbine engine; controlling rotation of a low pressure compressor using a first electrical machine, and controlling rotation of a high pressure compressor using a second electrical machine, the combustion chamber downstream of the low pressure compressor and high pressure compressor; determining if an exit pressure of the high pressure compressor is equal to or greater than a self-sustaining threshold pressure; and in response to determining that the exit pressure of the high pressure compressor is equal to or greater than the self-sustaining threshold pressure, ceasing controlling rotation of the low pressure compressor using the first electrical machine, and/or the high pressure compressor using a second electrical machine.

Abstract: A hybrid aircraft propulsion system. The system comprises a gas turbine engine having a turbine system comprising first and second turbine sections. The gas turbine engine further comprises a first combustor provided upstream in core flow from the turbine system, and a second combustor provided between the first and second turbine sections. The hybrid aircraft propulsion system further comprises an energy storage system and an electric propulsion system electrically coupled to the energy storage system.

Abstract: A gas turbine engine may include a high pressure compressor coupled to a high pressure turbine by a high pressure shaft, a core combustor located downstream of the high pressure compressor and upstream of the high pressure turbine, and a low pressure compressor provided upstream of the high pressure compressor. The low pressure compressor may be configured to direct core airflow to the high pressure compressor and first bypass airflow which bypasses the high pressure compressor, core combustor and high pressure turbine through a first bypass duct. The engine may further include a mixer downstream of the high pressure turbine and low pressure compressor, the mixer being configured to mix the core and first bypass airflows. The engine also may include a re-heat combustor configured to combust fuel with both core airflow and first bypass airflow.

Abstract: An aircraft including an aft-mounted boundary layer energisation system is shown. The system comprises a nacelle arranged around a tailcone of the aircraft which thereby defines a duct, the duct having, in axial flow series, an intake, a heat exchanger, and a nozzle, and no turbomachinery therein, whereby the system energises a boundary layer of the aircraft by means of Meredith effect.

Abstract: A method of controlling at least part of a start-up or re-light process of a gas turbine engine, the method comprising: increasing an angular velocity of a low pressure compressor; determining if an exit pressure of the low pressure compressor is equal to or greater than a first threshold pressure; in response to determining that the exit pressure of the low pressure compressor is equal to or greater than the first threshold pressure, controlling rotation of the low pressure compressor using a first electrical machine and controlling rotation of a high pressure compressor using a second electrical machine, to increase angular velocity of the high pressure compressor; determining if an exit pressure of the high pressure compressor is equal to or greater than a second threshold pressure.

Abstract: A combined cycle heat engine (10). The engine (10) comprises a first gas turbine engine (11) comprising a first air compressor system (14), a first combustion system (16) and a first turbine system (18) and a second gas turbine engine (32) comprising a second air compression system (36), a second turbine system (40), and a heat exchanger (38) configured to transfer heat from an exhaust (24) of the first turbine system (18) to compressed air from the second air compressor (36). The second gas turbine engine (32) comprises a second combustion system (20) downstream of the heat exchanger (38) and upstream of the second turbine system (40).

Abstract: A method of controlling at least part of a start-up or re-light process of a gas turbine engine, the method comprising: controlling ignition within a combustion chamber of the gas turbine engine; controlling rotation of a low pressure compressor using a first electrical machine, and controlling rotation of a high pressure compressor using a second electrical machine, the combustion chamber downstream of the low pressure compressor and high pressure compressor; determining if an exit pressure of the high pressure compressor is equal to or greater than a self-sustaining threshold pressure; and in response to determining that the exit pressure of the high pressure compressor is equal to or greater than the self-sustaining threshold pressure, ceasing controlling rotation of the low pressure compressor using the first electrical machine, and/or the high pressure compressor using a second electrical machine.

Abstract: A method of controlling at least part of a start-up or re-light process of a gas turbine engine, the method comprising: determining when a flame in a combustion chamber of a gas turbine engine is extinguished, during a start-up process or re-light process or during operation; purging the combustion chamber by controlling rotation of a low pressure compressor using a first electrical machine, and controlling rotation of a high pressure compressor using a second electrical machine, the combustion chamber downstream of the low pressure compressor and high pressure compressor; and controlling rotation of the low pressure compressor using the first electrical machine, and controlling rotation of the high pressure compressor using the second electrical machine to restart the start-up process or perform the re-light process.

Abstract: A combined cycle heat engine (10). The engine (10) comprises a first gas turbine engine (11) comprising a first air compressor (14), a first combustion system (16, 20) and a first turbine system (18, 22), and a second gas turbine engine (32) comprising a second air compressor (36) and a second turbine system (40). The engine further comprises a heat exchanger (38) configured to transfer heat from an exhaust of the first turbine system (18, 22) to compressed air from the second air compressor (36). The first combustion system comprises a first combustor (16) provided downstream of the first air compressor (14) and upstream of the first turbine system (18, 22), and a second combustor (20) downstream of a first turbine section (18) of the first turbine system and upstream of a second turbine section (22) of the first turbine system.

Abstract: An apparatus measuring thrust of an aircraft gas turbine engine includes a core shaft connecting a turbine and compressor, a fan and gearbox with a sun gear driven by the core shaft, a plurality of planet gears, an annulus gear mounted in a static structure, and a planet carrier driven by the fan via fan shaft. The apparatus includes a sensor to measure force applied by the annulus gear on the static structure and first and second sensors to measure rotational speed of the core and fan shafts. A processor determines restoring torque on the annulus gear from measurement of force applied by the gear on the static structure, torque applied to the fan by the planet carrier using rotational speeds of core and fan shafts and restoring torque on the annulus gear, and thrust of the fan from torque applied to the fan and the fan's rotational speed.

Abstract: A gas turbine engine may include a high pressure compressor coupled to a high pressure turbine by a high pressure shaft, a core combustor located downstream of the high pressure compressor and upstream of the high pressure turbine, and a low pressure compressor provided upstream of the high pressure compressor. The low pressure compressor may be configured to direct core airflow to the high pressure compressor and first bypass airflow which bypasses the high pressure compressor, core combustor and high pressure turbine through a first bypass duct. The engine may further include a mixer downstream of the high pressure turbine and low pressure compressor, the mixer being configured to mix the core and first bypass airflows. The engine also may include a re-heat combustor configured to combust fuel with both core airflow and first bypass airflow.