Hybrid propulsion systems

A method of propelling an aircraft using an aircraft propulsion system, the aircraft propulsion system comprising:

• one or more parallel propulsion units, each of the parallel propulsion units comprising:
• a propulsor of a first set of propulsors;
• a gas turbine engine configured to drive the propulsor;
• and
• an electrical machine selectively configurable to:
• generate, for output via one or more electrical busses, electrical energy using mechanical energy derived from the propulsor of the first set of propulsors or the gas turbine engine;
• and
• drive the propulsor of the first set of propulsors using electrical energy received via the one or more electrical busses;
• one or more series propulsion units, each of the series propulsion units comprising:
• a propulsor of a second set of propulsors;
• and
• an electrical machine selectively configurable to:
• generate, for output via the one or more electrical busses, electrical energy using mechanical energy derived from the propulsor of the second set of propulsors;
• and
• drive the propulsor of the second set of propulsors using electrical energy received from the one or more electrical busses;
• one or more power units configured to generate and output electrical energy via at least one of the one or more electrical busses;
• and
• one or more electronic controllers programmed to operate in a dual source mode by at least simultaneously causing the one or more parallel propulsion units to drive the first set of propulsors using fuel, causing the one or more power units to output electrical energy via the one or more electrical busses, causing the electrical storage system to discharge to output electrical energy via the one or more electrical busses, and causing the one or more series propulsion units to drive the second set of propulsors using electrical energy received via the one or more electrical busses;
• the method comprising:
• driving, by the one or more parallel propulsion units of the aircraft, the one or more propulsors of the first set of propulsors;
• outputting, by the one or more parallel propulsion units of the aircraft, electrical energy onto the one or more electrical busses;
• and
• driving, by the one or more series propulsion units of the aircraft and using electrical energy received via the one or more electrical busses, the one or more propulsors of the second set of propulsors that is different than the first set of propulsors.

An aircraft propulsion system comprising:

• one or more parallel propulsion units, each of the parallel propulsion units comprising:
• a propulsor of a first set of propulsors;
• a gas turbine engine configured to drive the propulsor;
• and
• an electrical machine selectively configurable to:
• generate, for output via one or more electrical busses, electrical energy using mechanical energy derived from the propulsor of the first set of propulsors or the gas turbine engine;
• and
• drive the propulsor of the first set of propulsors using electrical energy received via the one or more electrical busses;
• one or more series propulsion units, each of the series propulsion units comprising:
• a propulsor of a second set of propulsors;
• and
• an electrical machine selectively configurable to:
• generate, for output via the one or more electrical busses, electrical energy using mechanical energy derived from the propulsor of the second set of propulsors;
• and
• drive the propulsor of the second set of propulsors using electrical energy received from the one or more electrical busses;
• one or more power units configured to generate and output electrical energy via at least one of the one or more electrical busses;
• and
• one or more power units configured to generate and output electrical energy via at least one of the one or more electrical busses;
• and
• one or more electronic controllers programmed to operate in a dual source electric-only mode by at least simultaneously causing the parallel propulsion units to drive the first set of propulsors using electrical energy received via the one or more electrical busses without each gas turbine engine of the one or more parallel propulsion units using fuel, causing the power units to output electrical energy via the one or more electrical busses, causing the electrical storage system to discharge to output electrical energy via the one or more electrical busses, and causing the series propulsion units to drive the second set of propulsors using electrical energy received via the one or more electrical busses.