Wind tunnel tests were conducted to investi gate t he effect of placing a propulsion fan behind the tip of a li.tting ring for the purpose of recovering the energy in the trailing vortex. Results indicated tha~ significant increase of thrust could be obtained as a result of vortex energy recovery. In addition, the pre-swirling effect provided b.r the vortex allowed the tan to absorb more power and develop more thrust at a lower rotational speed.