At the time of its first flight, Dec. 17, 1947, the B-47 Stratojet represented a radical departure from traditional design, and it set the design standards for all large jet aircraft until the present time. The six-engine Boeing B-47 was America's first multiengine swept-wing jet bomber. Its thin 116-foot wing was extraordinarily flexible and swept back at a 35-degree angle. Once airborne, the graceful jet broke speed and distance records; in 1949 it crossed the United States in under four hours at an average 608 mph. The B-47 needed defensive armament only in the rear because no fighter was fast enough to attack from any other angle.Eighteen small rocket units in the fuselage provided jet-assisted takeoff (JATO), and parachutes cut its landing speeds. Later models were powered by 5,200-pound-thrust axial-flow jet engines, and top speeds were 600 mph. A total of 2,032 B-47s in all versions were built.