Encyclopedia Britannica editions are seen at the New York Public Library on March 14, 2012 in New York City. Encyclopedia Britannica announced it will be ceasing its print edition of reference books for the first time in its 244-year history to focus solely on digital versions. (Photo by Mario Tama/Getty Images)

Members of the American Civil War Society take part in a mock battle in the grounds of Cusworth Hall, South Yorkshire on July 2, 2011 in Doncaster, United Kingdom. Enthusiasts from all walks of life are taking part in re-enacting scenes from the American Civil War and in 'living history' events which are as authentic as possible. (Photo by Christopher Furlong/Getty Images)

The X-47B prototype on Tuesday flew off an aircraft carrier and into the history books. Today's achievement, the first-ever catapult launch of an unmanned aircraft from the flight deck of a carrier, promises to open up a new chapter in the annals of naval aviation. Photo: An X-47B pilot-less drone combat aircraft is launched for the first time off an aircraft carrier, the USS George H. W. Bush, in the Atlantic Ocean off the coast of Virginia, May 14, 2013. The U.S. Navy made aviation history on Tuesday by catapulting an unmanned jet off an aircraft carrier for the first time, testing a long-range, stealthy, bat-winged plane that represents a jump forward in drone technology. (Photo by Jason Reed/Reuters)