An example system includes an electrical machine electrically configured to generate electrical energy used by one or more components of a gas-turbine engine; an energy storage system; and a controller electrically connected to the energy storage system and configured to receive electrical energy from the energy storage system, wherein, in response to the gas-turbine engine being shut off, the controller is configured to cause the electrical machine to rotate a rotor of the gas-turbine engine using the energy received from the energy storage system.

A propulsion assembly for aircraft includes a single-shaft engine turbomachine including a combustion chamber and a rotatably mounted shaft that turns at a turbomachine rating; an electrical generator coupled to the shaft; and a control system. The control system includes a fuel pump that brings fuel into the combustion chamber at a fuel flow rate which is a direct function of an ambient pressure and of the turbomachine rating, and power electronics that are coupled to the electrical generator and that control an electrical power drawn off the electrical generator so as to attain a target turbomachine rating.

A hybrid propulsion system for a multi-rotor rotary-wing aircraft, including: an internal combustion engine, an electric machine coupled to the internal combustion engine, a rectifier connected to the electric machine, a converter, an electric network connecting the rectifier to the converter, electric motors connected to the converter, rotary-blade assemblies coupled to the electric motors, wherein the system includes: a detector configured to detect a reduction in a demand for electrical power within the system to below a predetermined value, a bypass circuit configured to bypass the electric machine when the detector detects a reduction in the demand for electrical power.

An aircraft includes a fuselage extending along a first x-axis and a wing assembly including a first wing an a second wing. A first power assembly of the aircraft includes a first propulsion element and a first electric motor while a second power assembly includes a second propulsion element and a second electric motor. The aircraft further includes a third power assembly positioned aft of the first power assembly and the second power assembly. The third power assembly includes a third propulsion element and an internal combustion engine.

A method of operating an aircraft hybrid gas turbofan during an idle mode of operation includes reducing a fuel flow to a primary gas turbine engine and boosting a high spool of the primary gas turbine engine using a secondary gas turbine engine via a first power linkage connecting the primary and secondary gas turbine engines, such that a net fuel reduction is achieved. The net fuel reduction accounts for fuel flow to the primary gas turbine engine and fuel flow to the secondary gas turbine engine.

A power electronics converter comprising: first and second input terminals; first and second DC output terminals; a branch comprising first and second semiconductor switches connected in series between the first and second DC output terminals, the first input terminal connected to a node between the first and second semiconductor switches; a DC link capacitor connected between the first and second DC output terminals; and a reverse biased DC link diode connected across the DC link capacitor.

An aircraft comprises a fuselage, first and second wing segments each having a leading edge and a trailing edge, a plurality of spokes coupling the fuselage to the first and second wing segments, one or more motors disposed within or attached to the plurality of spokes, and three or more propellers proximate to a leading edge of the plurality of spokes, distributed along the plurality of spokes, and operably connected to the motors to provide lift whenever the aircraft is in vertical takeoff and landing and stationary flight and provide thrust whenever the aircraft is in forward flight. When the aircraft is in vertical takeoff and landing and stationary flight, the fuselage is approximately vertical. When the aircraft is in forward flight, the fuselage is approximately in the direction of the forward flight and extends forward beyond the leading edges of the first wing segment and the second wing segment.

Hybrid-electric powertrains for aircraft are disclosed herein. An example hybrid-electric powertrain includes a gas turbine propulsion engine including a first propulsor and a gas turbine engine to drive the first propulsor to produce thrust, a generator operably coupled to a drive shaft of the gas turbine engine, and an electric propulsion unit including a second propulsor and an electric motor to drive the second propulsor to produce thrust. During a first mode of operation, the gas turbine propulsion engine and the electric propulsion unit are activated to produce thrust, and the generator is driven by the gas turbine engine to produce electrical power to power the electric propulsion unit. During a second mode of operation, the gas turbine propulsion engine is activated to produce thrust and the electric propulsion unit is deactivated.

An aircraft propulsion system including at least first airmover, an electric motor configured to at least partially power the at least first airmover, wherein the first airmover includes a propeller having at least a first position configured to provide thrust to the aircraft and a second position configured to recharge a power source, wherein the second position is a reverse windmilling position, and a heat engine configured to at least partially power the first air mover or a second air mover.

Hybrid electric propulsion systems includes a combustion engine and an electric motor. The hybrid electric propulsion systems may include or utilize a non-transitory computer-readable medium comprising computer-executable instructions, which when executed by a processor associated with the hybrid electric propulsion system, cause the processor to perform a method that includes determining an occurrence of a thrust asymmetry in the hybrid electric propulsion system, and controlling the electric motor to decrease an efficiency of the electric motor for a transient time period sufficient to reduce a torque output of the combustion engine to match an electrical load on the combustion engine.