A recent Defense Tech article provides some interesting new info on Northrop Grumman's RQ-4 Global Hawk, a UAV used for surveillance. As production of the Global Hawk continues to ramp up, there are 17 of the new robot planes currently being built for the Air Force, in addition to the ones already in service for the Air Force and Navy. The Air Force expects to have 50 Global Hawks in service by 2015. The most interesting suggestion in the article is that the Global Hawk is both more effective and less expensive to operate than the old U-2 spy planes, 30 of which remain in service. The Air Force has requested to retire the manned U-2 in favor of the unmanned Global Hawk.