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 and system for distributed power generation is provided. The method includes determining an operational cycle for the system; determining an average energy requirement of the system based on the operational cycle; configuring a plurality of energy sources each corresponding to the load device to produce a peak efficiency corresponding to the average energy requirement of the system; and coupling the energy source to provide energy to the load device.

Abstract: A turbomachine and method for operating a turbomachine comprising a first rotatable component and a second rotatable component each defining a rotatable speed mechanically independent of one another, and an electric machine electrically coupled to the first rotatable component and the second rotatable component such that a load level relative to the first rotatable component and the second rotatable component is adjustable is generally provided.

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: An aircraft includes a fuselage extending between a forward end and an aft end. An aft engine is mounted to the aft end of the fuselage, the aft engine defining a centerline. The aft engine further includes a nacelle having a bottom section, the bottom section having a forward lip. The forward lip of the bottom section defines a camber line. The camber line, in turn, defines an angle relative to the centerline of the aft engine greater than or equal to at least about five degrees.

Abstract: An aircraft including a fuselage and an aft engine is provided. The fuselage extends from a forward end of the aircraft towards an aft end of the aircraft. The aft engine is mounted to the fuselage proximate the aft end of the aircraft and includes a fan and a nacelle. The fan is rotatable about a central axis of the aft engine and includes a plurality of fan blades. The nacelle of the aft engine surrounds the plurality of fan blades and defines a bottom portion having a forward end. Additionally, the nacelle defines a curved surface at the forward end of the bottom portion, the curved surface including a reference point where the curved surface defines the smallest radius of curvature. The nacelle further defines a normal reference line extending normal from the reference point. The normal reference line defines an angle with the central axis of the aft engine greater than zero to, e.g., allow for a maximum amount of airflow into the aft 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 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 propulsion system for an aircraft is provided having a propulsion engine configured to be mounted to the aircraft. The propulsion engine includes an electric machine defining an electric machine tip speed during operation. The propulsion system additionally includes a fan rotatable about a central axis of the electric propulsion engine with the electric machine. The fan defines a fan pressure ratio, RFP, and includes a plurality of fan blades, each fan blade defining a fan blade tip speed. The electric propulsion engine defines a ratio of the fan blade tip speed to electric machine tip speed that is within twenty percent of the equation, 1.68×RFP?0.518, such that the propulsion engine may operate at a desired efficiency.

Abstract: An aircraft includes a boundary layer ingestion fan defining a centerline and including a plurality of fan blades rotatable about the centerline. The aircraft also includes a fuselage extending between a forward end and an aft end along a longitudinal direction, the boundary layer ingestion fan positioned within the fuselage at the aft end of the fuselage, the fuselage defining an inlet upstream of the boundary layer ingestion fan extending at least about 180 degrees around the centerline of the boundary layer ingestion fan, the fuselage further defining an exhaust downstream of the boundary layer ingestion fan.

Abstract: An aircraft is provided including a fuselage and an aft engine. The fuselage defines a top side, a bottom side, and a frustum located proximate an aft end of the aircraft. The frustum defines a top reference line extending along the frustum at a top side of the fuselage, and a bottom reference line extending along the frustum at a bottom side of the fuselage. The top and bottom reference lines meet at a reference point aft of the frustum. The fuselage further defines a recessed portion located aft of the frustum and indented inwardly from the bottom reference line. The aft engine includes a nacelle extending adjacent to the recessed portion of the fuselage such that the aft engine may be included with the aircraft without interfering with, e.g., a takeoff angle of the aircraft.

Abstract: A turbomachine and method for operating a turbomachine comprising a first rotatable component and a second rotatable component each defining a rotatable speed mechanically independent of one another, and an electric machine electrically coupled to the first rotatable component and the second rotatable component such that a load level relative to the first rotatable component and the second rotatable component is adjustable is generally provided.

Abstract: A propulsion system for an aircraft is provided having a propulsion engine configured to be mounted to the aircraft. The propulsion engine includes an electric machine defining an electric machine tip speed during operation. The propulsion system additionally includes a fan rotatable about a central axis of the electric propulsion engine with the electric machine. The fan defines a fan pressure ratio, RFP, and includes a plurality of fan blades, each fan blade defining a fan blade tip speed. The electric propulsion engine defines a ratio of the fan blade tip speed to electric machine tip speed that is within twenty percent of the equation, 1.01×RFP?0.311, such that the propulsion engine may operate at a desired efficiency.

Abstract: The present disclosure is directed to a gas turbine engine including a housing circumferentially surrounding an electric machine. The electric machine is supported within the housing. The housing defines a cooling passage proximate to the electric machine. The cooling passage circumferentially surrounds the electric machine and is extended at least partially along a lengthwise direction of the electric machine. The cooling passage provides a flow of fluid therethrough.

Abstract: An aeronautical propulsion system includes a fan having a plurality of fan blades rotatable about a central axis and defining a fan pressure ratio, FPR. The propulsion system also includes an electric motor mechanically coupled to the fan for driving the fan, the electric motor including a number of poles, npoles, and defining a maximum power, P. The relationship between the fan pressure ratio, FPR, of the fan, the number of poles, npoles, of the electric motor, and the maximum power, P, of the electric motor is defined by an equation: n pole p = C 1 · e - 9.062 · FPR + C 2 · e - 1.2604 · FPR ; wherein C1 is a constant having a value between 22,000 and 52,000, wherein C2 is a constant having a value between 4.0 and 9.8, and wherein e is Euler's number.

Abstract: An aeronautical propulsion system includes a fan having a plurality of fan blades rotatable about a central axis and defining a fan pressure ratio, FPR. The propulsion system also includes an electric motor mechanically coupled to the fan for driving the fan, the electric motor including a number of poles, npoles, and defining a maximum power, P. The relationship between the fan pressure ratio, FPR, of the fan, the number of poles, npoles, of the electric motor, and the maximum power, P, of the electric motor is defined by an equation: n pole P = C 1 · e - 9.062 · FPR + C 2 · e - 1.2604 · FPR ; wherein C1 is a constant having a value between 22,000 and 52,000, wherein C2 is a constant having a value between 4.0 and 9.8, and wherein e is Euler's number.

Abstract: A turbofan engine is provided including a fan having a plurality of rotatable fan blades and defining a fan pressure ratio during operation of the turbofan engine. The turbofan engine also includes a turbomachine operably coupled to the fan for driving the fan, the turbomachine including a compressor section, a combustion section, and a turbine section in serial flow order and together defining a core air flowpath. The turbofan also includes an outer nacelle at least partially surrounding the fan and the turbomachine, the outer nacelle defining a bypass passage with the turbomachine. A bypass ratio of an amount of airflow through the bypass passage to an amount of airflow through the core air flowpath during operation of the turbofan is less than or equal to about 11 and wherein the fan pressure ratio is less than or equal to about 1.5.

Abstract: A propulsion system for an aircraft is provided having an aft engine configured to be mounted to the aircraft at an aft end of the aircraft. The aft engine includes a fan rotatable about a central axis of the aft engine having a plurality of fan blades attached to a fan shaft. The aft engine also includes a nacelle encircling the plurality of fan blades and a structural support system for mounting the aft engine to the aircraft. The structural support system extends from the fuselage of the aircraft, through the fan shaft, and to the nacelle when the aft engine is mounted to the aircraft. The aft engine may increase a net thrust of the aircraft when mounted to the aircraft.

Abstract: A propulsion system for an aircraft including a plurality of primary engines is provided. The plurality of primary engines includes at least a first primary engine and a second primary engine, each configured for mounting to a respective one of a pair of wings of the aircraft. The propulsion system additionally includes an aft engine configured for mounting at a tail section of the aircraft. The plurality of primary engines are sized to provide an amount of thrust sufficient for the aircraft to takeoff without use of the aft engine, such that the aft engine may be configured as a non-prime reliable engine.

Abstract: An aircraft includes a fuselage extending between a forward end and an aft end. An aft engine is mounted to the aft end of the fuselage, the aft engine defining a centerline. The aft engine further includes a nacelle having a bottom section, the bottom section having a forward lip. The forward lip of the bottom section defines a camber line. The camber line, in turn, defines an angle relative to the centerline of the aft engine greater than or equal to at least about five degrees.