Helicopter starts in straight-level flight, completes a half-roll followed immediately by a half-loop, and resumes straight-level flight in the revers direction.

Researchers at the Massachusetts Institute of Technology rolled a model X-Cell 60 helicopter 180°, flew it upside down for a second, then completed a half loop to end up flying upright in the opposite direction, all by flipping a switch on a remote control. The maneuver, called split-S, lets an aircraft reverse direction quickly in a horizontally confined space. It's one of a variety of aggressive, agile maneuvers that the next generation of unmanned aerial vehicles (UAVs) will be expected to perform in military combat.

The technology developed by MIT researchers makes it possible for anyone to operate the aerobatic craft. Small, agile, autonomous helicopters like MIT's X-Cell 60 may provide a new tool for military reconnaissance or weapons delivery in mountainous or other challenging terrain that is off limits to larger aircraft and too dangerous for manned aircraft. Their small size, ease of operation, and potentially low cost compared with the current generation of UAVs, such as the Predator, make this option appealing not only to the military, but to the entertainment industry as well.