Drones that stay airborne forever

JUNJI KUROKAWA / THE ASSOCIATED PRESS 2010
With minimal modification, Northrop Grumman's plan is

to give the Global Hawk the capability to autonomously

refuel other drones and also to receive fuel itself.

February 27, 2011 by Rikki Mitchell Arizona Daily

Raytheon working on a system letting one UAV refuel another

Unmanned aircraft are flying every day on missions that call for them to collect data and images for hours on end. Soon, they may never have to come down. Tucson-based Raytheon Missile Systems is part of a larger effort to develop technology to keep these drones in the air indefinitely. A U.S. patent was issued to Raytheon recently for a system that would allow one unmanned aerial vehicle to communicate in order to safely refuel another drone in flight. The patent says a typical flight for unmanned aircraft includes being launched from its base, flying to the area of operation, "loitering" in that area to perform its mission and then flying back to the base and landing, all while carrying spare fuel in case of weather delays. Flying to the intended area of operation, and also flying back to the base, uses just as much fuel as the most important part of the aircraft's mission - the loitering. If an unmanned aircraft could be refueled in the air, it could remain in the air for much longer periods, Raytheon said in its patent application. The technology explained in the patent would allow the two unmanned aircraft to fly within close proximity of each other and then connect a cord between the two drones to refuel.