Aircraft powerplant with electric transmission(s)

1. A system for an aircraft, comprising:

a propulsor rotor; and

a powerplant configured to drive rotation of the propulsor rotor, the powerplant including a turbo-compounded intermittent internal combustion engine and a dual rotor electric machine;

the turbo-compounded intermittent internal combustion engine comprising a turbine rotor and an internal combustion engine, the turbine rotor operatively coupled to the propulsor rotor through the dual rotor electric machine, the internal combustion engine comprising an engine rotating assembly, and the turbine rotor operatively coupled to the engine rotating assembly through the dual rotor electric machine; and

the dual rotor electric machine including a first rotor, a second rotor, a first stator and a second stator, and the first stator and the second stator arranged radially between and axially aligned with the first rotor and the second rotor.

2. The system of claim 1 , wherein

the first rotor and the first stator form an electric motor; and

the second rotor and the second stator form an electric generator configured to generate electricity for powering the electric motor.

3. The system of claim 2 , wherein

the first rotor circumscribes the first stator;

the first stator circumscribes the second stator; and

the second stator circumscribes the second rotor.

4. The system of claim 2 , wherein

the second rotor circumscribes the second stator;

the second stator circumscribes the first stator; and

the first stator circumscribes the first rotor.

5. The system of claim 1 , wherein

the dual rotor electric machine is configured as a transmission between the turbine rotor and the engine rotating assembly during a first mode of operation; and

the dual rotor electric machine is configured as a starter motor for the internal combustion engine during a second mode of operation.

6. The system of claim 1 , wherein the internal combustion engine comprises a rotary engine.

7. The system of claim 1 , wherein

the powerplant further includes an electric gearbox; and

the engine rotating assembly is operatively coupled to the propulsor rotor through the electric gearbox.

8. The system of claim 7 , wherein the electric gearbox comprises a second dual rotor electric machine.

9. The system of claim 1 , wherein the engine rotating assembly is operatively coupled to the propulsor rotor through a second dual rotor electric machine.

10. The system of claim 9 , wherein

the second dual rotor electric machine is configured as a transmission between the engine rotating assembly and the propulsor rotor during a first mode of operation; and

the second dual rotor electric machine is configured as a starter motor for the internal combustion engine during a second mode of operation.

11. The system of claim 1 , wherein the propulsor rotor is an un-ducted propulsor rotor.

12. The system of claim 1 , wherein the propulsor rotor is a ducted propulsor rotor.

13. A system for an aircraft, comprising:

a propulsor rotor;

a powerplant configured to drive rotation of the propulsor rotor, the powerplant including a turbo-compounded intermittent internal combustion engine and a dual rotor electric machine;

the turbo-compounded intermittent internal combustion engine comprising a turbine rotor operatively coupled to the propulsor rotor through the dual rotor electric machine; and

the dual rotor electric machine including a first rotor, a second rotor, a first stator and a second stator, the first stator and the second stator arranged radially between and axially aligned with the first rotor and the second rotor, the first rotor and the first stator forming an electric motor, and the second rotor and the second stator forming an electric generator configured to generate electricity for powering the electric motor; and

a power source configured to selectively provide additional electricity to the electric motor to boost a mechanical power output of the electric motor.

14. A system for an aircraft, comprising:

a propulsor rotor; and

a powerplant configured to drive rotation of the propulsor rotor, the powerplant including an internal combustion engine and an electric machine;

the internal combustion engine comprising a rotary engine and a turbine rotor, the rotary engine comprising an engine rotating assembly, the turbine rotor operatively coupled to the engine rotating assembly through the electric machine, and the electric machine operatively coupled to the propulsor rotor through the engine rotating assembly; and

the electric machine including a first rotor, a second rotor, a first stator and a second stator, and the first stator and the second stator arranged radially between and axially aligned with the first rotor and the second rotor.

15. The system of claim 14 , wherein the propulsor rotor is an un-ducted propulsor rotor.

16. The system of claim 14 , wherein the propulsor rotor is a ducted propulsor rotor.

17. The system of claim 14 , wherein

the first rotor and the first stator form an electric motor; and

the second rotor and the second stator form an electric generator configured to generate electricity for powering the electric motor.

18. The system of claim 17 , wherein

the first rotor circumscribes the first stator;

the first stator circumscribes the second stator; and

the second stator circumscribes the second rotor.

19. The system of claim 17 , wherein

the second rotor circumscribes the second stator;

the second stator circumscribes the first stator; and

the first stator circumscribes the first rotor.