Front View of McDonald XP-85 Plan Model. Parasite Airplane designed to be carried in the B-36 bombay (never built) At the time it was the smallest Jet powered airplane. The McDonnell XF-85 Goblin was an American prototype fighter aircraft conceived during World War II by McDonnell Aircraft. It was intended to be deployed from the bomb bay of the giant Convair B-36 bomber as a parasite fighter. The XF-85's intended role was to defend bombers from hostile interceptor aircraft, a need demonstrated during World War II