Ever since the dawn of powered flight, it has been necessary for all aircraft to carry onboard fuel - whether in the form of batteries, fuel, solar cells, or even a human "engine" - in order to stay aloft. But a team of researchers from NASA's Marshall Space Flight Center in Huntsville, Ala., NASA's Dryden Flight Research Center at Edwards, Calif., and the University of Alabama in Huntsville is trying to change that. They have now chalked up a major accomplishment... and a "first." The team has developed and demonstrated a small-scale aircraft that flies solely by means of propulsive...