A series of flight tests were completed to demonstrate the ability of two unmanned aircraft to refuel in flight. The tests, which did not involve any fuel transfer, were conducted by Northrop Grumman, the Defense Advanced Research Projects Agency and NASA using two NASA Global Hawks, one configured as a tanker and the other as a receiver. The tests at Edwards Air Force Base, Calif., were done between January and May. Among other things, the tests show the tanker could extend and retract its refueling hose, and the two Global Hawks were able to fly as close as 30 feet. The $33 million DARPA program aims to demonstrate autonomous fuel transfer between two Global Hawks, enabling flights of up to one week endurance. Northrop Grumman is also developing the technology to help extend the operating range and flight duration of future carrier-based unmanned systems like the X-47B unmanned demonstrator aircraft. (Source: Globe Newswire, 10/05/12) Gulf Coast note: Global Hawks are built in part in Moss Point, Miss.