Hydrogen liquid oxygen combined cycle engine

An aircraft propulsion system comprising:

• a fan system including a fan rotatable about an engine axis and coupled to a fan drive electric motor configured to generate a fan discharge flow;
• an inlet movable between an open position allowing inlet airflow to the fan system and a closed position closing off inlet airflow to the fan system;
• a fuel system providing a flow of fuel;
• an augmentor configured to generate a propulsive gas flow from a mixture of fuel and the fan discharge airflow in a first engine operating configuration;
• a duct blocker movable between an open and a closed position for controlling the fan discharge flow to the augmentor;
• and a liquid oxygen system configured to provide oxygen to the augmentor to mix with the fuel and generate the propulsive gas flow in a second engine operating configuration, wherein in the second engine operating configuration, the duct blocker is in a closed position such that no fan discharge flow is communicated to the augmentor;
• and an electric power generation system includes a combustor for generating an exhaust gas flow by igniting a mixture of fuel and liquid oxygen, a free turbine section configured to be driven by the exhaust gas flow from the combustor, and an electric generator driven by the free turbine to provide electric power to the fan drive electric motor, wherein the fan drive electric motor is de-energized in the second engine operating configuration and the exhaust gas flow is exhausted through nozzle to supplement the propulsive gas flow.

A method of operating an aircraft propulsion system comprising:

• generating electric power with a free turbine driven generator rotatable about an engine axis;
• driving a fan about the engine axis with an electric motor to generate a fan discharge flow in a first engine operating configuration, wherein the electric motor is driven by the generated electric power from the generator;
• mixing the fan discharge airflow with fuel in an augmentor to generate a propulsive gas flow exhausted through a nozzle in the first engine operating configuration;
• closing off an inlet flow to the fan, closing off the fan discharge airflow to the augmentor, and communicating an oxygen flow to the augmentor for mixing with the fuel to generate the propulsive gas flow that is exhausted through the nozzle in a second engine operating configuration;
• and
• de-energizing the electric motor in the second engine operating configuration, wherein the electric power is generated by a power generation system that generates an exhaust gas flow that is exhausted through the nozzle to supplement the propulsive gas flow.