By the way, jet biplanes - it has been done for real. The Poles built one in the '70s: the PZL-Mielec M-15 "Belphegor", with 175 built. Not the biggest success in aviation ever, though.
Yeah, but I want it to look like Me-262 if it was build in 1920s Basically a Spad with Me-262 jet engines, makeshift cockpit and some other adds. I chose it a name, R-XI Polonez, because I got really interested in R-XIII Lublin recently.