Propulsion system for an aircraft

A hybrid propulsion system for an aircraft, comprising:

• a propulsor assembly including a first electric motor operably coupled with at least one propulsor;
• a first power assembly drivingly coupled to a first electric machine to produce a first amount of electric power, the first power assembly comprising a turbomachine including a fan;
• a second power assembly drivingly coupled to a second electric machine to produce a second amount of electric power, the second power assembly including one or more cylinders each configured to receive a piston, the piston operatively connected to a crankshaft, wherein the second power assembly is configured to generate electric power more efficiently than the first power assembly;
• power electronics operably coupled with the first electric machine and the second electric machine in parallel, the power electronics configured to enable power conversion operations from the first electric machine and the second electric machine and transfer power between the first electric machine and the second electric machine, wherein the power electronics are configured to combine at least a portion of the first amount of electrical power and the second amount of electrical power to supply the propulsor assembly;
• and
• a controller operably coupled to the first power assembly, the first electric machine, or both, and to the second power assembly, the second electric machine, or both, wherein the controller is further configured to direct electrical power from the first electric machine to the propulsor assembly in a first operating condition and from the second power assembly to the propulsor assembly in a second operating condition, wherein the controller is configured to throttle the first power assembly or the second power assembly while the other of the first power assembly or the second power assembly is brought up to speed during a power transition.