Plans of Spitfire Mk.IX
These plans show the Spitfire Mk.IX, an stopgap version designed to combat the Fw 190 but that ended up being produced in larger numbers than the more advanced Mk.VIII. It can be tell apart from the Mk.V by having an air intake under each wing while the Mk.V only had an intake under one wing.
How to cite this article:
Rickard, J (7 September 2019), Plans of Spitfire Mk.IX , http://www.historyofwar.org/Pictures/pictures_spitfire_IX_plan.html