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 fuselage and a wing assembly attached to or formed integrally with the fuselage. The aircraft also includes a propulsion system having a port propulsor and a starboard propulsor. The port and starboard propulsors are each attached to the wing assembly on opposing sides of the fuselage and are rotatable between a forward thrust position and a vertical thrust position. The propulsion system also includes a supplemental propulsor mounted to the fuselage to provide certain efficiencies 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: 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 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 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: An aircraft includes a fuselage, a forward wing assembly, and aft wing assembly, and a propulsion system. The propulsion system includes a first primary thrust propulsor and a first secondary thrust propulsor, the first primary thrust propulsor being different than the first secondary thrust propulsor. Both the first primary thrust propulsor and the first secondary thrust propulsor are mounted to the same one of: a starboard side of the aft wing assembly, a port side of the aft wing assembly, a starboard side of the forward wing assembly, or a port side of the forward wing assembly.

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: A gas turbine engine comprises a fan, a compressor, a turbine having first stage blades and second stage blades, the first stage blades rotates in a first direction and the second stage blades rotates in a second direction opposite the first direction. The first stage blades are directly adjacent to one another, a drive in operable input connection with the fan and in operable output connection with the first stage blades and the second stage blades, the first stage blades and the second stage blades driving the fan through the drive.

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 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: 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 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: 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 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 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 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 includes an electric propulsor and a gas turbine engine. The propulsion system also includes an electric machine coupled to a rotary component of the gas turbine engine generating a voltage at a baseline voltage magnitude during operation of the gas turbine engine. An electric communication bus is provided electrically connecting the electric machine to the electric propulsor. The propulsion system additionally includes a means for providing a differential voltage to the electric propulsor equal to about twice the baseline voltage magnitude.

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.