Not sure how I stumbled onto this nifty X-B70 site, but I'm glad I did. Lots of little-known information on the wackiest of the airforce's wacky cold war-era projects. Spectacular and spectacularly expensive engineering in search of a mission, thy name is USAF!
I saw the X-B70 at Dayton, and to say it is impressive is an understatement. Actually, I pretty much stumbled over it... it was so huge and blended into the white-on-white of the museum's ceiling so well that at first it was just part of the scenery. I literally fell over the front gear tires, looked up, and I think I may have said "holy sh*t" out loud.