Your AA math is wrong.You obviously did not follow in the point of these runs: If I build AA, I build it in every Run. Because it's not only about maximizing industry, but finding the best way to do it. If you don't want to build AA, that's fine, but shouldn't affect my findings.
And the AA Investment costs 3.47 MIC, to be exact, which won't produce a lot of fighters in late 1939.
2x7x2500 = 35000 cic
AA doesnt benefit from infrastructure, not from autarky and not from war economy, MIC does. so the same civs do more then double the cic output on a mic then on aa.
cic output on 39 tech for aa is 120cic for 15 civs, 2500/120 = 21 days to produce 1 AA *14 = 294 production days.
Cic output in MIC is in a lvl 6! province is 240cic * 294days = 70560 / 7200 = 9,8 mic
my first estimated guess was even to low...
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