I've never played the game, only admired the aircraft designs. Some of them could be kitbashed from conventional aircraft kits. A few were made to resemble other "paper" aircraft designs. The Curtiss-Wright P2 Warhawk is closely patterned after a Blohm and Voss attack aircraft:
http://www.luft46.com/bv/bvp170.html
The FB14 Vampire is, in my view, more evocative of the A-10, what with the twin pusher props:
http://www.wizkidsgames.com/crimsonskies/figuregallery.asp?unitid=3547
My personal fave is this one:
http://www.wizkidsgames.com/crimsonskies/figuregallery.asp?unitid=3540
It's got several of my favorite elements: biplane wing arrangement, pusher prop, big cannon armament.