Abstract: Apparatus for controlling a power generation system, the apparatus comprising a controller configured to: identify a trigger indicative of a future change in electrical power output by the power generation system to a first power level; control the power generation system to change electrical power output to a second power level in response to the trigger, the second power level being equal to, or different to the first power level; and control supply of at least a portion of the electrical power output from the power generation system at the second power level to an electrical energy storage system to charge the electrical energy storage system.

Abstract: Apparatus for controlling a power generation system, the apparatus comprising a controller configured to: identify a trigger indicative of a future change in electrical power output by the power generation system to a first power level; control the power generation system to change electrical power output to a second power level in response to the trigger, the second power level being equal to, or different to the first power level; and control supply of at least a portion of the electrical power output from the power generation system at the second power level to an electrical energy storage system to charge the electrical energy storage system

Abstract: Apparatus for controlling a power generation system, the apparatus comprising a controller configured to: identify a trigger indicative of a future change in electrical power output by the power generation system to a first power level; control the power generation system to change electrical power output to a second power level in response to the trigger, the second power level being equal to, or different from the first power level; and control supply of at least a portion of the electrical power output from the power generation system at the second power level to an electrical energy storage system to charge the electrical energy storage system.

Abstract: An aircraft propulsion system. The system comprises an internal combustion engine configured to drive a first propulsor and an electric generator. The system further comprises an electric motor or motors each configured to be powered by electric power provided by the generator, and configured to drive the first propulsor and/or a second propulsor. An electrical energy storage unit is provided, and is configured to store electrical energy supplied from the generator and supply electrical power to the electric motor. At maximum take-off power, the electric motor provides between 5% and 20% of total maximum aircraft propulsive take-off power.

Abstract: A method of assembling a rotor stack comprising a plurality of component parts, the method comprising: determining swash measurements for interfacing surfaces of the plurality of parts; calculating a runout estimate for a plurality of relative orientations of the parts; applying an optimization algorithm to identify an optimal orientation from the plurality of relative orientations based on the runout estimates; and assembling the parts in the optimal orientation.

Abstract: Apparatus for controlling a power generation system, the apparatus comprising a controller configured to: identify a trigger indicative of a future change in electrical power output by the power generation system to a first power level; control the power generation system to change electrical power output to a second power level in response to the trigger, the second power level being equal to, or different to the first power level; and control supply of at least a portion of the electrical power output from the power generation system at the second power level to an electrical energy storage system to charge the electrical energy storage system

Abstract: An air duct arrangement (58) for an aircraft (40). The arrangement (58) comprises an environmental control system (ECS) (50). The ECS (50) comprises an air inlet (60) arranged to ingest a low velocity portion of a boundary layer flow adjacent the aircraft fuselage (44), and to deliver a flow of air to an environmental control system air intake (66). The arrangement (58) further comprises an ejector (70) arranged to receive an ECS exhaust (76), and boundary layer air from an aft region of the aircraft (40), and to exhaust air to the ambient airstream at an aft portion of the aircraft (40).

Abstract: A method of assembling a rotor stack comprising a plurality of component parts, the method comprising: determining swash measurements for interfacing surfaces of the plurality of parts; calculating a runout estimate for a plurality of relative orientations of the parts; applying an optimisation algorithm to identify an optimal orientation from the plurality of relative orientations based on the runout estimates; and assembling the parts in the optimal orientation.

Abstract: An air duct arrangement (58) for an aircraft (40). The arrangement (58) comprises an environmental control system (ECS) (50). The ECS (50) comprises an air inlet (60) arranged to ingest a low velocity portion of a boundary layer flow adjacent the aircraft fuselage (44), and to deliver a flow of air to an environmental control system air intake (66). The arrangement (58) further comprises an ejector (70) arranged to receive an ECS exhaust (76), and boundary layer air from an aft region of the aircraft (40), and to exhaust air to the ambient airstream at an aft portion of the aircraft (40).

Abstract: This invention relates to an aircraft comprising: a first propulsive unit having a first fan with an axis of rotation; and a second propulsive unit local to the first propulsive unit, the second propulsive unit having a second fan with an axis of rotation, wherein the rotational axis of the first fan is proximate to the surface of the aircraft relative to the rotational axis of the second fan such that the first fan ingests boundary layer air when in use.

Abstract: This invention relates to a propulsive unit for an aircraft, comprising: a nacelle which defines a duct for channeling an airflow when in use and which provides an outwardly facing surface of the propulsive unit, the outwardly facing surface having an aerodynamic shape; a fan unit for accelerating the airflow within the duct when in use; wherein the duct has an inlet and an outlet and the nacelle is operable to adjust the either or both of the area of the inlet and outlet while substantially retaining the aerodynamic shape of the outwardly facing surface.