FSX/P3D v3,v4,v5 Spitfire Mk9 Longwing. The Supermarine Spitfire Mk IX was originally developed as a stopgap measure as a response to the appearance of the Focke-Wulf FW 190A. It used the Merlin 60/70 series engines in a slightly modified Mark Vc fuselage. Native P3D/FSX models by A.F. Scrub.