Aircraft propulsion system and aircraft powered by such a propulsion system built into the rear of an aircraft fuselage

1. An aircraft propulsion system intended for being integrated into the rear of an aircraft fuselage, the propulsion system comprising, from upstream to downstream in the direction of a gas flow in the propulsion system, at least two gas generators supplying a power turbine having two counter-rotating turbine rotors for driving two fans disposed downstream of the gas generators, and separate air inlets for supplying each gas generator, characterised in that it comprises an electrical drive device configured to rotate at least one of the turbine rotors and comprising at least one electrical generator configured to transform part of the energy of the flow coming from the gas generators into electrical power and an electric motor supplied by said electrical generator and capable of rotating at least one of the turbine rotors, said electrical generator being installed on one of said gas generators, and in that said turbine rotor is capable of being rotated simultaneously by a flow coming from said gas generators and by the electrical drive device.

2. The propulsion system according to claim 1 , wherein the electrical drive device comprises electric energy storage means supplied by said electrical generator and configured to supply said electric motor.

3. The propulsion system according to claim 2 , wherein said storage means are configured to supply said electric motor for at least three successive full propulsive power flight phases, such as during take-off or climb of the aircraft.

4. The propulsion system according to claim 2 , wherein said storage means are configured to supply said electric motor during a reduced power flight phase, such as idle, super-idle or ground, and wherein at least one of the turbine rotors is capable of being rotated solely by the electrical drive device during a reduced power flight phase.

5. The propulsion system according to claim 2 , wherein said gas generators are configured to provide between 80% and 95% of the main primary power to the turbine rotors during a full propulsive power flight phase, such as during take-off, and said storage means and said electric motor are configured to provide between 5% and 20% of the main primary power to the turbine rotors during a full propulsive power flight phase.

6. The propulsion system according to claim 2 , wherein said storage means are configured to discharge and supply the electric motor during a full propulsive power flight phase, such as during take-off or climb of the aircraft, and to recharge during an intermediate propulsive power flight phase, such as a cruise flight.

7. The propulsion system according to claim 1 , wherein the electrical drive device comprises a reduction gear connected to said electric motor and to the turbine rotors and configured to transform electrical power from said electric motor to mechanical power on said turbine rotors.

8. The propulsion system according to claim 7 , wherein the reduction gear is a differential reduction gear.

9. The propulsion system according to claim 1 , wherein the gas generators and the turbine rotors are mechanically independent.

10. The propulsion system according to claim 1 , in which the turbine rotors are configured to directly rotate the fans.

11. An aircraft powered by a propulsion system according to claim 1 , the propulsion system being integrated into the rear of a fuselage of the aircraft.

12. A method of using an aircraft propulsion system according to claim 1 , comprising the rotating of at least one of the turbine rotors simultaneously by a flow coming from said gas generators and by the electrical drive device.