The Global Hawk unmanned aerial vehicle (UAV), which is already changing the way the U.S. Air Force does business, could undergo an evolutionary leap in endurance, or the time the aircraft can stay in the air, in the next few years.

Global Hawk, produced by Northrop Grumman Corp., can fly autonomously for up to 35 hours at a time, at an altitude of 60,000 feet or higher, while scanning an area of some 40,000 square miles, according to the company. ...