Abstract: An aircraft extending between a forward end and an aft end is provided. The aircraft includes an auxiliary power unit positioned proximate the aft end of the aircraft, the auxiliary power unit having an auxiliary power unit inlet duct and an auxiliary power unit exhaust duct, and a boundary layer ingestion fan positioned proximate the aft end of the aircraft, the boundary layer ingestion fan having a support shaft, wherein the auxiliary power unit exhaust duct extends through a portion of the support shaft of the boundary layer ingestion fan.

Abstract: An aircraft includes an electric power source having a combustion engine and an electric generator. The electric generator is powered by the combustion engine. The aircraft also includes a propulsion assembly including a propulsor and an electric motor, the electric motor configured for rotating the propulsor. The aircraft also includes an electrical outlet configured for connection with an outside power sink. The electrical outlet and the propulsion assembly are selectively in electrical communication with the electric power source such that the electric power source selectively provides electrical power to one of the electrical outlet or the propulsion assembly.

Abstract: A propulsion system includes a propulsor having a driveshaft, an electric machine coupled to the driveshaft of the propulsor, and a combustion engine having an output shaft. The propulsion system additionally includes a one-way clutch operable with at least one of the driveshaft of the propulsor and the output shaft of the combustion engine. The one-way clutch allows for a differential angular velocity of the driveshaft relative to the output shaft in a first circumferential direction and prevents a differential angular velocity of the driveshaft relative to the output shaft in a second circumferential direction.

Abstract: An aircraft includes a fuselage; a wing coupled to, and extending from, the fuselage; and a hybrid-electric propulsion system. The hybrid-electric propulsion system includes a power source including a combustion engine and an electric generator; a plurality of vertical thrust electric fans integrated into the wing and oriented to generate thrust along the vertical direction, the plurality of vertical thrust electric fans arranged along a length of the wing and driven by the power source; and a forward thrust propulsor. The forward thrust propulsor it is selectively or permanently mechanically coupled to the combustion engine.

Abstract: A planet gear train for an engine casing includes a sun gear rotatable by a shaft, a ring gear, a plurality of planet gears rotatably mounted in a planet carrier and meshing with the sun gear and the ring gear, and a damping system. The damping system includes a soft mount disposed about the shaft and coupling the planet carrier the engine casing. The soft mount includes a flexible inner sleeve and a flexible outer sleeve. The flexible inner sleeve and the flexible outer sleeve are fixedly coupled together at respective central portions thereof near the shaft. The damping system further includes a plurality of damping couplers disposed about an outer flange of the planet carrier. The plurality of damping couplers is configured to flexibly couple the flexible inner sleeve to the flexible outer sleeve.

Abstract: A propulsion system for an aircraft having an aft end is provided herein. The propulsion system can include an electric propulsion engine defining a central axis. The electric propulsion engine can include an electric motor, a fan rotatable about the central axis of the electric propulsion engine by the electric motor, a bearing supporting rotation of the fan, and a thermal management system. The thermal management system can include a lubrication oil circulation assembly for providing the bearing with lubrication oil. The lubrication oil circulation assembly can be driven independently of a shaft of the electric propulsion engine.

Abstract: A propulsion system for an includes a combustion engine, a propulsor, and an electric machine configured to either be driven by the combustion engine or configured to drive the propulsor. The electric machine defines an axis. The electric machine includes a rotor extending along and rotatable about the axis, and a stator having a plurality of winding assemblies, the plurality of winding assemblies spaced along the axis of the electric machine, each winding assembly operable with the rotor independently of an adjacent winding assembly during operation of the electric machine.

Abstract: A propulsion system for an aircraft can include an electric power source and an electric propulsion assembly having an electric motor and a propulsor. The propulsor can be powered by the electric motor. An electric power bus can electrically connect the electric power source to the electric propulsion assembly. The electric power source can be configured to provide electrical power to the electric power bus. An inverter converter controller can be positioned along the electric power bus and can be electrically connected to the electric power source at a location downstream of the electric power source and upstream of the electric propulsion assembly.

Abstract: A propulsion system for an aircraft includes a gas turbine engine and an electric propulsion engine defining a central axis. The electric propulsion engine includes an electric motor and a fan rotatable about the central axis of the electric propulsion engine by the electric motor. The electric propulsion engine additionally includes a bearing supporting rotation of the fan and a thermal management system including a thermal fluid circulation assembly. The thermal fluid circulation assembly is in thermal communication with at least one of the electric motor or the bearing and is further in thermal communication with a heat exchanger of a thermal management system of the gas turbine engine.

Abstract: A propulsion system for an aircraft includes a turbomachine having a first turbine, a primary fan mechanically driven by the first turbine of the turbomachine, and an electric generator mechanically driven by the first turbine of the turbomachine. The propulsion system also includes an electric fan assembly, the electric generator electrically connected to the electric fan assembly for powering the electric fan assembly.

Abstract: A propulsion system for an aircraft includes an electric power source and an electric propulsion assembly having an electric motor and a propulsor, the propulsor powered by the electric motor. The propulsion system also includes an electric power bus electrically connecting the electric power source to the electric propulsion assembly. The electric power source is configured to provide electrical power to the electric power bus, and the electric power bus is configured to transfer the electric power to the electric propulsion assembly at a voltage exceeding 800 volts.

Abstract: A propulsion system for an aircraft includes an electric propulsion engine. The electric propulsion engine includes an electric motor and a fan rotatable about a central axis of the electric propulsion engine by the electric motor. The electric propulsion engine also includes a bearing supporting rotation of the fan and a thermal management system. The thermal management system includes a lubrication oil circulation assembly and a heat exchanger thermally connected to the lubrication oil circulation assembly. The lubrication oil circulation assembly is configured for providing the bearing with lubrication oil. Such an electric propulsion engine may be a relatively self-sufficient engine.

Abstract: 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.

Abstract: A method for operating an electric fan of an aircraft propulsion system includes driving a plurality of fan blades of the electric fan with an electric machine to generate thrust for the aircraft; and driving the electric machine with the plurality of fan blades of the electric fan to generate electrical power subsequent to driving the plurality of fan blades of the electric fan with the electric machine to generate thrust for the aircraft.

Abstract: A method is provided for maintaining a gas turbine engine installed on an aircraft, the gas turbine engine including an electric machine mounted at least partially inward of a core air flowpath of the gas turbine engine. The method includes removing a rotor mount connecting a rotor of the electric machine to a rotary component of the gas turbine engine; removing a stator mount connecting a stator of the electric machine to a stationary component of the gas turbine engine; and removing in situ the electric machine.

Abstract: A propulsion system for an aircraft includes an electric power source, an electric propulsor assembly having an electric motor and a propulsor configured to generate thrust for the aircraft, and a power bus electrically connecting the electric power source to the electric propulsor assembly such that the electric power source powers the electric propulsor assembly. The power bus includes an electric line and a fluid cooling system, the fluid cooling system extending along at least a portion of a length of the electric line. The fluid cooling system is in thermal communication with the electric line for cooling the electric line during operation and is further in thermal communication with the electric motor of the electric propulsor assembly for cooling the electric motor of the electric propulsor assembly.

Abstract: A gas turbine engine includes a compressor section and a turbine section together defining a core air flowpath. The rotary component is rotatable with the compressor section and the turbine section. The gas turbine engine additionally includes an electric machine rotatable with the rotary component and positioned coaxially with the rotary component at least partially inward of the core air flowpath. The electric machine is flexibly mounted to a static frame member, or flexibly coupled to the rotary component, or both, such that the electric machine is mechanically isolated or insulated from various internal and external forces on the gas turbine engine.

Abstract: A propulsion system for an aircraft includes an electric propulsion engine configured to be mounted to the aircraft at an aft end of the aircraft. The electric propulsion engine includes a power gearbox mechanically coupled to an electric motor. The electric propulsion engine further includes a fan rotatable about a central axis of the electric propulsion engine by the electric motor through the power gearbox. Moreover, the electric propulsion engine includes an attachment assembly for mounting at least one of the electric motor or the power gearbox. The attachment assembly includes a torsional damper for accommodating a torsional vibration of the electric motor or the power gearbox.

Abstract: A gas turbine engine includes a core and a tie shaft. The tie shaft is rotatable about an axial direction of the gas turbine engine by the core of the gas turbine engine. The gas turbine engine additionally includes a modular fan having a plurality of fan blades and a frame. The plurality fan blades are attached to the frame and the frame is slidably received on the tie shaft of the gas turbine engine. The modular fan additionally includes an attachment member removably attaching the frame to the tie shaft of the gas turbine engine to removably install the modular fan in the gas turbine engine.

Abstract: An aircraft includes a fuselage, a forward wing assembly, and aft wing assembly, and a propulsion system. The propulsion system includes a port forward propulsor and a starboard forward propulsor, each of which rotatable between a forward thrust position and a vertical thrust position and together defining a maximum forward thrust capability. The propulsion system also includes a port aft propulsor and a starboard aft propulsor, each of which also rotatable between a forward thrust position and a vertical thrust position, and together defining a maximum aft thrust capability. The maximum forward thrust capability is different than the maximum aft thrust capability to achieve certain efficiencies.