US Patent 8461704 Gas turbine engine apparatus

A gas turbine engine arrangement comprises a core engine, a power turbine and a propulsor. The core engine comprises at least one compressor and at least one turbine arranged to drive the at least one compressor and the core engine is arranged in a casing. The power turbine is positioned downstream of the at least one turbine and the power turbine is arranged to drive the propulsor. An electrical machine is arranged upstream of the at least one compressor. The electrical machine comprises a stator and a rotor and the electrical machine comprises a motor/generator. A first clutch selectively connects the rotor of the electrical machine to the power turbine and a second clutch selectively connects the rotor of the electrical machine to the at least one compressor of the core engine.