Hybrid electric propulsion systems are described. The systems include a gas turbine engine having a low speed spool and a high speed spool. The low speed spool includes a low pressure compressor and a low pressure turbine and the high speed spool includes a high pressure compressor and a high pressure turbine. An electric machine is configured to augment rotational power of at least one of the high speed spool and the low speed spool. A controller is configured to control the electric machine to one of add or subtract rotational energy to or from at least one of the high speed spool and the low speed spool during a transition to or from an idle state of operation of the gas turbine engine.

Hybrid electric propulsion systems are described. The systems include a gas turbine engine having a low speed spool and a high speed spool. The low speed spool includes a low pressure compressor and a low pressure turbine and the high speed spool includes a high pressure compressor and a high pressure turbine. An electric machine is configured to augment rotational power of at least one of the high speed spool and the low speed spool. A controller is configured to control the electric machine to one of add or subtract rotational energy to or from at least one of the high speed spool and the low speed spool during a transition to or from an idle state of operation of the gas turbine engine.

A fully compounding rotorcraft includes a fuselage having first and second wings extending therefrom and configured to provide lift compounding responsive to forward airspeed. A twin boom includes first and second tail boom members that extend aftward from the first and second wings. An empennage is coupled between the aft ends of the tail boom members. An anti-torque system includes a tail rotor that is rotatably coupled to the empennage. An engine is disposed within the fuselage and is configured to provide torque to a main rotor assembly via an output shaft and a main rotor gearbox. An auxiliary propulsive system is coupled to the fuselage and is configured to generate a propulsive thrust to offload at least a portion of a thrust requirement from the main rotor during forward flight, thereby providing propulsion compounding to increase the forward airspeed of the rotorcraft.

The electrical power generation system including a micro-turbine including a combustor, a first stage turbine configured to be driven by a combustor exhaust from the combustor, at least one compressor operably connected to the combustor to provide a compressed airflow to the combustor, a catalytic converter configured convert the combustor exhaust to a catalytic exhaust that includes at least exothermic heat, a second stage turbine configured to be driven by the catalytic exhaust from the catalytic converter, and one or more shafts connecting the first stage turbine and the second stage turbine to the at least one compressor such that rotation of the first stage turbine and the second stage turbine drives rotation of the at least one compressor.

A gas turbine engine is provided. The gas turbine engine includes a turbomachine having a low speed spool and a high speed spool; a rotor assembly coupled to the low speed spool; an electric machine rotatable with the low speed spool for extracting power from the low speed spool, for adding power to the low speed spool, or both; and an inter-spool clutch positioned between the low speed spool and the high speed spool for selectively coupling the low speed spool to the high speed spool.

A gas turbine engine is provided. The gas turbine engine includes a turbomachine having a low speed spool and a high speed spool; a rotor assembly coupled to the low speed spool; an electric machine rotatable with the low speed spool for extracting power from the low speed spool, for adding power to the low speed spool, or both; and an inter-spool clutch positioned between the low speed spool and the high speed spool for selectively coupling the low speed spool to the high speed spool.

There are describes methods and systems for operating an engine coupled to a fuel system having a fuel manifold configured to supply fuel to a combustor of the engine. The method comprises receiving a gaseous fuel flow request indicative of a change in demand for gaseous fuel to the engine; applying a fuel loss bias to the gaseous fuel flow request to obtain a biased fuel flow request, the fuel loss bias associated with a change in mass flow rate of the gaseous fuel from the fuel manifold to the combustor in response to the change in demand; and causing the gaseous fuel to flow into the combustor in accordance with the biased fuel flow request.

A turbofan engine is provided. The turbofan engine includes a fan comprising a plurality of fan blades; a turbomachine operably coupled to the fan for driving the fan, the turbomachine comprising a compressor section, a combustion section, and a turbine section in serial flow order and together defining a core air flowpath; a nacelle surrounding and at least partially enclosing the fan; an inlet pre-swirl feature located upstream of the plurality of fan blades, the inlet pre-swirl feature attached to or integrated into the nacelle; and a means for directing incoming objects towards an outer portion of the turbofan engine in communication with the inlet pre-swirl feature.

A turbofan engine is provided. The turbofan engine includes a fan comprising a plurality of fan blades; a turbomachine operably coupled to the fan for driving the fan, the turbomachine comprising a compressor section, a combustion section, and a turbine section in serial flow order and together defining a core air flowpath; a nacelle surrounding and at least partially enclosing the fan; an inlet pre-swirl feature located upstream of the plurality of fan blades, the inlet pre-swirl feature attached to or integrated into the nacelle; and a means for directing incoming objects towards an outer portion of the turbofan engine in communication with the inlet pre-swirl feature.

The disclosure relates to a hybrid-electrical drive system for an aircraft having two subsystems that are largely independent of each other. A stator winding of a common electrical machine is assigned to each of the subsystems such that both subsystems may be supplied with electrical energy from the common electrical machine. If a defect occurs in one of the subsystems, the drive system may be configured such that electrical energy from a battery of the non-defective subsystem may be transferred into the defective subsystem by utilizing the two stator winding systems.