Open rotor aircraft propulsion system with multi- gear system geartrain

An assembly for an aircraft, comprising:

• an open propulsor rotor configured to rotate about an axis;
• an engine core including a flowpath, a compressor section, a combustor section, a turbine section and a rotating structure, the flowpath extending through the compressor section, the combustor section and the turbine section from an inlet into the flowpath to an exhaust from the flowpath, the rotating structure including a compressor rotor in the compressor section and a turbine rotor in the turbine section, and the rotating structure configured to rotate about the axis and drive rotation of the open propulsor rotor;
• a geartrain disposed axially between and operatively coupling the rotating structure and the open propulsor rotor, the geartrain including a first star gear system and a second star gear system;
• and
• a propulsor module including the open propulsor rotor and the geartrain, the propulsor module removably coupled to the engine core.

An assembly for an aircraft, comprising:

• an aircraft fuselage extending longitudinally between a nose end of the aircraft fuselage and a tail end of the aircraft fuselage, the aircraft fuselage extending laterally between a first side of the aircraft fuselage and a second side of the aircraft fuselage;
• a first open rotor propulsion system disposed to the first side of the aircraft fuselage, the first open rotor propulsion system including a first open propulsor rotor, a first engine core and a first geartrain, the first open propulsor rotor configured to rotate about a first axis, the first engine core comprising a first rotating structure configured to rotate about the first axis and configured to drive rotation of the first open propulsor rotor through the first geartrain, the first rotating structure comprising a first turbine rotor, and the first geartrain comprising a first star gear system and a first planetary gear system;
• and
• a second open rotor propulsion system disposed to the second side of the aircraft fuselage, the second open rotor propulsion system including a second open propulsor rotor, a second engine core and a second geartrain, the second open propulsor rotor configured to rotate about a second axis, the second engine core comprising a second rotating structure configured to rotate about the second axis and configured to drive rotation of the second open propulsor rotor through the second geartrain, the second rotating structure comprising a second turbine rotor, and the second geartrain comprising a second star gear system and a third star gear system.