Among publicly traded defense companies, Northrop Grumman (NYSE:NOC) continues to dominate the market for large unmanned aerial vehicles -- as its latest contract win demonstrates.

On Friday, Northrop announced that it has received a $114 million advance procurement contract from the U.S. Air Force, funding preparations to build three of its high-altitude, unarmed spy drones, the RQ-4 Global Hawk.

Northrop's Global Hawk. Source: Northrop Grumman

The Air Force funds will be used to pay for acquisition of "long-lead" items such as sensor suites and airborne signals intelligence payloads, or ASIPs, as well as buying retrofit kits for two ASIP units installed in existing Air Force Global Hawks. Northrop expects to complete the required purchases under this contract by 2015.

The Global Hawk is capable of flying at altitudes of up to 60,000 feet, over distances as far as 12,300 nautical miles, for as long as 30 hours without refueling. The system has been used to support combat operations in Iraq, Afghanistan, and Libya, as well as on humanitarian missions surveying destruction in the wake of earthquakes in Haiti and Japan.