US Patent 7891603 Differential thrust control system

A system allowing for the controlled propulsion of aircraft, especially buoyant and semi-buoyant airships designed as a symmetric body of revolution, without the need for or use of aerodynamic control surfaces, comprised of a plurality of ducted fan thrusters placed both fore and aft, designed to ingest air flowing at less than free stream velocity. Fans are arranged such that when at standard orientation, the thrust from each is directed tangentially to an arc drawn along the hull from bow to stem. By defining multiple sets of thrusters based upon their location, differential thrust may be applied based upon set membership in order to affect translational and rotational maneuvering of the aircraft.