GE 93 turboprop has the air/gas flow from the the rear to the front of the engine. Air is sucked in rather than rammed in. Rather than the air compressor powered by a shaft from the exhaust gas turbines, it could be powered by an electric motor. Air and fuel could then be supplied solely on the basis of the exhaust gas flow required. An electric motor could be fitted on the turbine side of the planetary gears to provide power to the electric compressor and the aircraft. In an electric aircraft, the planetary gears could go and two electric motors provided. A large motor to drive the propeller to produce the desired short term power, and a smaller motor attached to the exhaust turbine to provide power to aircraft systems and to batteries to power the aircraft. The engine will be greatly simplified and its costs will fall. In a standard turbine engine, there is a fixed ratio. generally 1:1, shaft connection between the exhaust and air turbine to power the air turbine. The fixed ratio means some inefficiency in the engine. A simpler, cheaper, more efficient engine will justify an engine that is somewhat heavier in a plug-in hybrid aircraft.