The work of Steve D. Gage and Rick R. Dobson Jr. Technology of Black OP. propulsion and perhaps that of Alien vehicle propulsion as well? Centrifugal [centrifical] force is used in a way that loopholes around Newton's third law of motion.
Source-See video description for description of parts and workings of Rick's functional prototype:
Source-International Space Agency: http://www.youtube.com/user/worldspacenews
International Space Agency-Official Site: http://www.isa-hq.com/
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