A DARPA press release (PDF format) reports that the A160T Hummingbird UAV has set a new world record for unrefueled rotorcraft endurance by staying aloft for 18.7 hours during phase I test demonstrations. It also set a new endurance record for UAVs in the 1,102 lbs to 5,511 lbs weight class. The flying robot, built by Boeing, is powered by a gas-turbine engine. During the tests it carried a 300lbs payload. The test flight was fully autonomous. The eventual goal is to achieve flight times in excess of 24 hours. For more info on the robot, see the Wikipedia Boeing A160 Hummingbird article.