The X-47B Unmanned Combat Air System (UCAS) demonstrator taxies on the flight deck of the aircraft carrier USS Harry S. Truman in the Atlantic Ocean in this handout photo

 
The X-47B Unmanned Combat Air System (UCAS) demonstrator taxies on the flight deck of the aircraft carrier USS Harry S. Truman in the Atlantic Ocean in this handout photo
The X-47B Unmanned Combat Air System (UCAS) demonstrator taxies on the flight deck of the aircraft carrier USS Harry S. Truman in the Atlantic Ocean in this December 9, 2012 handout photo obtained by Reuters December 10, 2012. REUTERS/U.S. Navy/Mass Communication Specialist 3rd Class Kristina Young/Handout