Abstract: A hybrid electric aircraft equipped with gyroscopic stabilization control is provided. In one aspect, a hybrid electric aircraft includes a turbo-generator having a gas turbine engine and an electric generator operatively coupled thereto for generating electrical power. The turbo-generator defines a rotation axis. The aircraft also includes one or more electrically-driven propulsors for producing thrust for the aircraft. In addition, the aircraft includes a pivot mount operatively coupled with the turbo-generator. To provide gyroscopic stabilization control of the aircraft, the pivot mount is controlled to adjust the rotation axis of the turbo-generator relative to a prime stability axis of the aircraft. Additionally or alternatively, a rotational speed of the turbo-generator can be changed to provide gyroscopic stabilization control of the aircraft.

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: The present disclosure is directed to a gas turbine engine defining a radial direction, a longitudinal direction, and a circumferential direction, an upstream end and a downstream end along the longitudinal direction, and an axial centerline extended along the longitudinal direction. The gas turbine engine includes a fan assembly including a plurality of fan blades rotatably coupled to a fan rotor in which the fan blades define a maximum fan diameter and a fan pressure ratio. The gas turbine engine further includes a low pressure (LP) turbine defining a core flowpath therethrough generally along the longitudinal direction. The core flowpath defines a maximum outer flowpath diameter relative to the axial centerline. The gas turbine engine defines a fan to turbine diameter ratio of the maximum fan diameter to the maximum outer flowpath diameter. The fan to turbine diameter ratio over the fan pressure ratio is approximately 0.90 or greater.

Abstract: A gas turbine engine is provided. The gas turbine engine includes a turbomachine defining an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct; a primary fan driven by the turbomachine; and a secondary fan located downstream of the primary fan within the inlet duct. The gas turbine engine defines a thrust to power airflow ratio between 3.5 and 100 and a core bypass ratio between 0.1 and 10, wherein the thrust to power airflow ratio is a ratio of an airflow through a bypass passage over the turbomachine plus an airflow through the fan duct to an airflow through the core duct, and wherein the core bypass ratio is a ratio of the airflow through the fan duct to the airflow through the core duct.

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 gas turbine engine includes a compressor section and a turbine section together defining a core air flowpath. Additionally, a rotary component is rotatable with at least a portion of the compressor section and at least a portion of the turbine section. An electric machine is mounted coaxially with the rotary component and positioned at least partially inward of the core air flowpath along a radial direction of the gas turbine engine. A cavity wall defines at least in part a buffer cavity surrounding at least a portion of the electric machine to thermally insulate the electric machine, e.g., from the relatively high temperatures within the core air flowpath.

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 of an aircraft has at least one unducted fan and at least one ducted fan, the at least one unducted fan and the at least one ducted fan being powered by an electric power source and rotatable between a vertical thrust position and a forward thrust position, and a controller configured to distribute electrical power between the at least one unducted fan and the at least one ducted fan. During a first mode when the at least one unducted fan and the at least one ducted fan are in the vertical thrust position, the controller is configured to distribute the electrical power between the plurality of unducted fans and the plurality of ducted fans such that the at least one unducted fan is a primary source of thrust.

Abstract: A hybrid electric aircraft equipped with gyroscopic stabilization control is provided. In one aspect, a hybrid electric aircraft includes a turbo-generator having a gas turbine engine and an electric generator operatively coupled thereto for generating electrical power. The turbo-generator defines a rotation axis. The aircraft also includes one or more electrically-driven propulsors for producing thrust for the aircraft. In addition, the aircraft includes a pivot mount operatively coupled with the turbo-generator. To provide gyroscopic stabilization control of the aircraft, the pivot mount is controlled to adjust the rotation axis of the turbo-generator relative to a prime stability axis of the aircraft. Additionally or alternatively, a rotational speed of the turbo-generator can be changed to provide gyroscopic stabilization control of the aircraft.

Abstract: The present disclosure is directed to a gas turbine engine defining a radial direction, a longitudinal direction, and a circumferential direction, an upstream end and a downstream end along the longitudinal direction, and an axial centerline extended along the longitudinal direction. The gas turbine engine includes a fan assembly including a plurality of fan blades rotatably coupled to a fan rotor in which the fan blades define a maximum fan diameter and a fan pressure ratio. The gas turbine engine further includes a low pressure (LP) turbine defining a core flowpath therethrough generally along the longitudinal direction. The core flowpath defines a maximum outer flowpath diameter relative to the axial centerline. The gas turbine engine defines a fan to turbine diameter ratio of the maximum fan diameter to the maximum outer flowpath diameter. The fan to turbine diameter ratio over the fan pressure ratio is approximately 0.90 or greater.

Abstract: A gas turbine engine includes a compressor section and a turbine section together defining a core air flowpath. Additionally, a rotary component is rotatable with at least a portion of the compressor section and at least a portion of the turbine section. An electric machine is mounted coaxially with the rotary component and positioned at least partially inward of the core air flowpath along a radial direction of the gas turbine engine. A cavity wall defines at least in part a buffer cavity surrounding at least a portion of the electric machine to thermally insulate the electric machine, e.g., from the relatively high temperatures within the core air flowpath.

Abstract: The present disclosure is directed to a gas turbine engine defining a radial direction, a longitudinal direction, and a circumferential direction, an upstream end and a downstream end along the longitudinal direction, and an axial centerline extended along the longitudinal direction. The gas turbine engine includes a fan assembly including a plurality of fan blades rotatably coupled to a fan rotor in which the fan blades define a maximum fan diameter and a fan pressure ratio. The gas turbine engine further includes a low pressure (LP) turbine defining a core flowpath therethrough generally along the longitudinal direction. The core flowpath defines a maximum outer flowpath diameter relative to the axial centerline. The gas turbine engine defines a fan to turbine diameter ratio of the maximum fan diameter to the maximum outer flowpath diameter. The fan to turbine diameter ratio over the fan pressure ratio is approximately 0.90 or greater.

Abstract: A propulsion system of an aircraft has at least one unducted fan and at least one ducted fan, the at least one unducted fan and the at least one ducted fan being powered by an electric power source and rotatable between a vertical thrust position and a forward thrust position, and a controller configured to distribute electrical power between the at least one unducted fan and the at least one ducted fan. During a first mode when the at least one unducted fan and the at least one ducted fan are in the vertical thrust position, the controller is configured to distribute the electrical power between the plurality of unducted fans and the plurality of ducted fans such that the at least one unducted fan is a primary source of thrust.

Abstract: A gas turbine engine includes a compressor section and a turbine section together defining a core air flowpath. Additionally, a rotary component is rotatable with at least a portion of the compressor section and at least a portion of the turbine section. An electric machine is mounted coaxially with the rotary component and positioned at least partially inward of the core air flowpath along a radial direction of the gas turbine engine. A cavity wall defines at least in part a buffer cavity surrounding at least a portion of the electric machine to thermally insulate the electric machine, e.g., from the relatively high temperatures within the core air flowpath.

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 gas turbine engine includes a compressor section defining a compressor exit temperature, T3. The gas turbine engine also includes a combustion section and a turbine section, with the turbine section defining a turbine inlet temperature, T4. A ratio, T4:T3, of the turbine inlet temperature, T4, to compressor exit temperature, T3, during operation of the gas turbine engine at a rated speed is less than or equal to 1.85.

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 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 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: 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.