Actually down low from 0-15 000 ft is where the Bf 109F-4 has the advantage over the Spitfire Vc, as it both outspeeds and outclimbs the Spit at low altitude. Up high the Messerschmitt struggles with it's small penguin-wings in the thin air, and the Spitfire Vc will outclimb it slightly, meaning it can also hold a turn better vs the Bf 109F at high alt. Speed is also quite even at high altitude. (This is why the British later added extra wing area to their high altitude Spitfire IXe's, while clipping the wings for their low altitude IXe's, as it increased the roll rate without really decreasing the low alt performance). I will post a full comparison in a few hours
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/Robert