I saw this beast on a German aviation page a few years ago.
It looks like nothing I have ever heard of. X-24 or vertical-H engine, I would guess, and an enormous installation behind the cockpit - either a supercharger with its own engine (not a turbo, see exhaust stacks) or a Russian-type auxiliary-ramjet set-up, or the radiator.
I think it's probably a mock-up - just a guess from details like the ends of the wing stubs - but of what?
The photo is also blessedly free of cultural cues to where it was designed. http://www.aviationpics.de/myst/page_12.htm
Modified to reflect the fact that I forgot the pic, sorry Deltafan