This new airframe later formed the basis for the Rolls - Royce Griffon powered Spitfires .
In a second stream of development Supermarine was working on an improved , reinforced , Spitfire airframe which incorporated several new features and was designed for the Merlin 60 and 70 series engines .
This new airframe later formed the basis for the Rolls - Royce Griffon powered Spitfire .
In a second stream of development Supermarine was working on an improved , reinforced , Spitfire airframe which incorporated several new features and was designed for the Merlin 60 and 70 series engines .