Aircraft propulsion system with variable speed rotating structure

A propulsion system for an aircraft, comprising:

• a first propulsor rotor configured to generate propulsive thrust;
• a second propulsor rotor configured to generate propulsive lift;
• and
• a thrust control system comprising an engine controller and a gas turbine engine core, the gas turbine engine core comprising a compressor section, a combustor section, a turbine section and a rotating structure, the rotating structure comprising a turbine rotor within the turbine section, the engine controller including a processing device and a memory, and the engine controller configured to selectively control operation of the gas turbine engine core, such that the gas turbine engine core operates in a first mode of operation and a second mode of operation, and such that an engine pressure ratio of the propulsion system decreases from a first engine pressure ratio during the first mode of operation to a second engine pressure ratio during the second mode of operation, the second engine pressure ratio lower than the first engine pressure ratio, to reduce the propulsive thrust generated by the first propulsor rotor;
• the gas turbine engine core configured to rotate the rotating structure during the first mode of operation to drive the first propulsor rotor to generate the propulsive thrust, and
• the gas turbine engine core configured to rotate the rotating structure during the second mode of operation to drive the second propulsor rotor to generate the propulsive lift, and
• the gas turbine engine core configured to rotate the rotating structure such that the propulsive thrust generated by the first propulsor rotor during the first mode of operation is 1.5 to 5 times greater than the propulsive thrust generated by the first propulsor rotor during the second mode of operation.

An aircraft system, comprising:

• a first output configured to generate propulsive thrust;
• a second output configured to generate propulsive lift;
• and
• a thrust control system comprising an engine controller and a gas turbine engine core, the gas turbine engine core comprising a compressor section, a combustor section, a turbine section and a rotating structure, the rotating structure comprising a turbine rotor within the turbine section, the engine controller including a processing device and a memory, and the engine controller configured to selectively control operation of the gas turbine engine core, such that the gas turbine engine core comprises a first mode of operation and a second mode of operation;
• the gas turbine engine core configured to rotate the rotating structure at a first rotational speed during the first mode of operation to rotatably drive the first output, and the aircraft system having a first engine pressure ratio between 1.25 and 3.0 during the first mode;
• and
• the gas turbine engine core configured to rotate the rotating structure at a second rotational speed during the second mode of operation to rotatably drive the second output, the second rotational speed between fifty-five percent and seventy-five percent of the first rotational speed, and the aircraft system having a second engine pressure ratio between 1.01 and 1.06 during the second mode;
• wherein the engine controller selectively controls operation of the gas turbine engine core such that an engine pressure ratio of the aircraft system decreases from the first engine pressure ratio during the first mode of operation to the second engine pressure ratio during the second mode of operation to reduce the propulsive thrust generated by the first output.