Originally designed around a Pratt & Whitney X-1800 it had to modified when the X-1800 was cancaelled. The Allison V-1720 was not the engine that was the best choice. The stability issues IIRC had to do with spin problems, specifically inverted spin problems. One airframe still exists and is undergoing restoration at the Kalamazoo Air Zoo Museum. Like a number of other projects that died on the vine the P-55 represents some intruiging what ifs. What if Curtiss had been allowed to persue a jet powered version? What if the stability problems had been properly addressed? As to the XP-55's nickname it started as a joke by an unnamed Curtiss engineer and of course had to be cleaned up a bit for the public. Actually I've been using the P-55 in a number of short stories revolving around an idea put forward by a writers group on Yahoo
http://groups.yahoo.com/group/redtide-1945/ the looks at the idea that Joseph Stalin was actually more paraniod than he was and orders the Red Army west in summer 1945
http://home.att.net/~jbaugher1/p55.html
