Disclosed herein is a propulsion system, which may be implemented in an air-vehicle, such as a ducted-fan organic air-vehicle. The propulsion system comprises (a) a power source, (b) a fan located within a duct and powered by the power source, (c) a plurality of vanes arranged in an x-clocked configuration and configured to produce control moments from the flow generated by the fan. The maximum control moments, which can be created by the vanes in the x-clocked configuration, are substantially oriented along the flight axes of the air-vehicle or the principle axis of the maximum moment of inertia.