[Juha]

Thanks Graham, I suspected that, so Smith's graph is identical to that of NACA. Do You Know what was appr. IAS equivalents for 109F 's 500kmh (TAS) and 600 kmh (TAS) at 3000m? Or other way around what were appr. TAS equivalents for Spit V's 310mph (IAS) and 375mph (IAS) at 10000ft?

Also 109E could achieve 400mph only in dive and I think same was true for F-4 at 3000m.

Juha

I should have first look my archives, so for 109F-1 and -2 at 3000m 469kmh (IAS) = 553kmh (TAS) and 486kmh(IAS) = 573kmh (TAS). Source Kennblatt for Bf 109F-1 and F-2. Berlin 1941.

To be honest I was thinking that the difference between IAS and TAS in this case was appr. 50 kmh but it seems to have been appr. 85kmh.