The Spiteful and Naval version named Seafang were the ultimate derivatives of the Spitfire. These planes were under development during WWII but were not ready for service before the war ended. They were brand-new designs with lots of Spitfire influence. Important innovations included laminar flow wings, low-drag wide/slim radiators under the wings, and wide-track inwardly retracting landing gear. The plane first flew in June 1944, but crashed soon after that flight, setting the program back. Only a small number were built, first equipped with single propeller Griffon 65's, soon upgraded to 85 contra-rotating propellers, and finally the ultimate 100 series Griffon. A 100 series equipped Spiteful XVI was able to achieve a level speed in full combat trim of 494 Mph
