No, there are 6 of them, and I believe that is the one remaining (of 2 built) XB70's, a funky cobra snake looking bomber from back in the 1960's, at the Wright Pat AF Museum last time I saw it.
It has 6 big-butt afterburner engines! Yummy!
Oh, the other one crashed during test flights, that's why there were no more built!

Here's "The rest of the story" http://xb70.interceptor.com/

So...I guess the only sailboat remotely similar would be the Volvo X 70's?