A propulsion engine comprising at least a first propulsion unit including a first fan encased by a geared ring and a gas turbine engine driving a first shaft connected to the first fan, at least a second propulsion unit including a second fan encased by a geared ring connected to a second shaft operatively coupled to an electric machine and at least an electric storage device connected to the electric machine. The geared rings are configured to transmit torque between the fans so that they can rotate in conjunction (directly or through an intermediate gear) when they are driven by at least one of said first and second shafts. The propulsion engine is arranged for controlling the torque to be supplied to the assembly of the first and second fans by the gas turbine engine and/or by the electric machine acting as a motor or as a generator.