An axial flow turbomachine (102) for producing thrust to propel an aircraft is shown. The turbomachine has an inner duct (202) and an outer duct (204), both of which are annular and concentric with one another. An inner fan (206) is located in the inner duct, and is configured to produce a primary pressurised flow (P). An outer fan (207) is located in an outer duct, and is configured to produce a secondary pressurised flow (S). The outer fan has a hollow hub (208) through which the inner duct passes. The outer fan has a diameter of from 2.5 to 3.5 times a diameter of the inner fan.

An axial flow turbomachine (102) for producing thrust to propel an aircraft is shown. The turbomachine has an inner duct (202) and an outer duct (204), both of which are annular and concentric with one another. An inner fan (206) is located in the inner duct, and is configured to produce a primary pressurised flow (P). An outer fan (207) is located in an outer duct, and is configured to produce a secondary pressurised flow (S). The outer fan has a hollow hub (208) through which the inner duct passes. A hub-tip ratio of the outer fan is from 1.6 to 2.2 times a hub-tip ratio of the inner fan.

An axial flow turbomachine (102) for producing thrust to propel an aircraft is shown. The turbomachine has an inner duct (202) and an outer duct (204), both of which are annular and concentric with one another. An inner fan (206) is located in the inner duct, and is configured to produce a primary pressurised flow (P). An outer fan (207) is located in an outer duct, and is configured to produce a secondary pressurised flow (S). The outer fan has a hollow hub (208) through which the inner duct passes. The inner fan is configured to have, in operation, a rate of rotation of from 3 to 8 times that of the outer fan.

An axial flow turbomachine (102) for producing thrust to propel an aircraft is shown. The turbomachine has an inner duct (202) and an outer duct (204), both of which are annular and concentric with one another. An inner fan (206) is located in the inner duct, and is configured to produce a primary pressurised flow (P). An outer fan (207) is located in an outer duct, and is configured to produce a secondary pressurised flow (S). The outer fan has a hollow hub (208) through which the inner duct passes. The inner fan is configured to have, in operation, a tip speed of from 1 to 3 times that of the outer fan.

An axial flow turbomachine (102) for producing thrust to propel an aircraft is shown. The turbomachine has an inner duct (202) and an outer duct (204), both of which are annular and concentric with one another. An inner fan (206) is located in the inner duct, and is configured to produce a primary pressurised flow (P). An outer fan (207) is located in an outer duct, and is configured to produce a secondary pressurised flow (S). The outer fan has a hollow hub (208) through which the inner duct passes. A swept area of the outer fan is from 2 to 20 times greater than a swept area of the inner fan.

Methods and systems to electrically assist an internal combustion engine of an aircraft may be provided. A first bladed rotor may be rotated by a first internal combustion engine. Electricity may be generated from a first motor generator by rotating a first shaft of the first motor generator with the first internal combustion engine. In response to a predetermined event, such as an engine failure, mechanical power may be generated from the first motor generator instead of electricity. The mechanical power may be transferred to the first bladed rotor. The mechanical power may be generated by applying electricity to the first motor generator. The electricity applied is received from a second motor generator, where the electricity received from the second motor generator is generated by rotating a second shaft of the second motor generator with a second internal combustion engine that powers a second bladed rotor.

Disclosed is a system for a gas turbine engine, the gas turbine engine comprising a primary shaft, the system including a rotor shaft; a plurality of components connected to the rotor shaft, including a wound field synchronous main machine (MM) and a permanent magnet generator (PMG); and wherein the PMG, alone or with the MM provide torque to change rotational speed of the rotor shaft, thereby changing rotational speed of the primary shaft.

An aircraft having a vertical takeoff and landing flight mode and a forward flight mode. The aircraft includes a fuselage and a dual tiltwing assembly having a vertical lift orientation and a forward thrust orientation relative to the fuselage. The dual tiltwing assembly includes a forward wing and an aft wing coupled together and to the fuselage by a quadrilateral linkage. A distributed propulsion system is coupled to the dual tiltwing assembly and includes a plurality of forward propulsion assemblies coupled to the forward wing and a plurality of aft propulsion assemblies coupled to the aft wing. A flight control system is operably associated with the distributed propulsion system and the dual tiltwing assembly. The flight control system is operable to independently control each of the propulsion assemblies and is operable to transition the dual tiltwing assembly between the vertical lift orientation and the forward thrust orientation.

An electric machine including a stator having a fully non-magnetic core and stator windings formed of a non-superconducting transposed conductor to reduce eddy current losses. It further includes a rotor having a fully non-magnetic core and superconducting windings or superconducting magnets which produce a magnetic field for interaction with the stator windings. A cryogenic cooling system is arranged to cool the stator windings to reduce conduction losses in the stator windings.

A method for operating a propulsion system of an aircraft includes moving a plurality of forward and aft propulsors to a vertical thrust position. While in the vertical thrust positions, the method also includes providing a first forward to aft ratio of electric power to the plurality of forward and aft propulsors. The method also includes moving the plurality of forward and aft propulsors to a forward thrust position. While in the forward thrust positions, the method also includes providing a second forward to aft ratio of electric power to the plurality of forward and aft propulsors. The first forward to aft ratio of electric power is different than the second forward to aft ratio of electric power to provide certain efficiencies for the aircraft.