....I think your memory is playing tricks. The Decathlon I remember in FUI was the same one in your shots. I don't think there ever was a biplane version.
Sorry Doug...!
Just peered at the case through my dusty bi-focals....
It's a Pitts S-2A, bi-plane....

By the way...
Has anyone managed to get this "DOS" version of FU 1 to work with "modern, Windows" computer set-ups, 'cos I can't.
I get "Page Errors" in memory...

Cheers...
Paul.