The Northrop YB-49 was a prototype jet-powered medium bomber, a development of the piston-engined YB-35. The two YB-49s built were both converted YB-35 test aircraft. However it was never to enter production,being passed over in favour of the more conventional Convair B-36.
Courtesy USAF
The day the "Flying Wing" bombed the Martians .....
http://it.youtube.com/watch?v=zaIbvIdex04&feature=related