Quote from “Gun Button to Fire” (Tom Neil – passage refers to May 1940…so Mk1)
“I forced down the nose and watched the speed rise rapidly – 300, then 350, finally 400. Everything tight and the starboard wing dropping. Hard left aileron now – it must be the radiator under one wing. I trimmed forward…..more, then more, working the rudder bias at the same time. God, I had never been so fast! 430!”
Interesting! This was his first flight in a Spitfire.
Nicholaiovitch
Edit:- Dive was started at 8000ft.