Abstract: A turboprop propulsion system where there is a core engine driving a power turbine that is connected through a planetary drive transmission to first and second counterrotating propellers. One of the propellers is connected to the ring gear, while the other propeller is connected to the planetary carrier, the sun gear being driven from the power turbine. The apparatus is provided with a substantially continuous gaseous flow path from the inlet to the exhaust nozzle of the engine, with the planetary drive transmission being spaced radially from the flow path. In some embodiments, the planetary transmission is positioned radially inwardly of the flow path, while in other embodiments, it is positioned radially outwardly of the flow path. The propellers can be in either the pusher configuration or the tractor configuration.