Ok, then I'll tell you.
I have to admit that it was pretty hard and I bet I'd given up way earlier if I had to find out.
It's a Sukhoj S-84.
I found it
here. Unfortunately this page is in German and I cannot link to the article directly, but I have holidays coming up, if anyone is interested, I might just translate it and post it here or something.
to all who kept on looking, especially Gil