Ah, so thats what your problem is... "I want a Western Front game with US planes! Why did you go and make a game forcing these planes down our throat which I had to buy because you are an uber communist with the KGB in control of my money!" If you weren't interested in that theater, why in the hell would you even bother with it then? I mean, damn, would you buy a Ford when you know you won't be happy with it and really want a Chevy?!
I still don't see how this "data" was extracted from the game, since the flight model data is in an encrypted file.
The P39D was cast off from the US because of its poor high altitude performance. Information break through: The plane featured in Il2 and FB is the P39N which was vastly improved over the D models the US and Britain used, AND it is ONLY good at mid to low altitudes in the game.
The Brewster was cast off in favor of the F4F because, tah dah!, the F4F had wings that could fold up and was just a little bit faster. Britain used the Brewster quite extensively and were successful with it. Just because the US cast them off does not make them poor planes, they didn't fit in with the high altitude desires the USAAF and USN had.
Guess what? Take that P47 up to high altitude, where it belongs, and you'll have no problems with anything. It belongs above 6000meters in the game.
No, the FMs aren't perfect and many of them aren't right. But each patch has brought advantages to one side or the other. Atleast if you understand some very simple things, you'll see that while some planes are screwy, the majority still rule in their respective performance envelopes.
All German airplanes and the P47 (P51 when it gets added in) belong above 5500 - 6000meters to really be good. All Russian planes, except the MiG 3 (all variants except the AM-38) are great BELOW 3000meters. Mediocre at 4000meters, and SUCK above that. MiG3 great above 6000meters, SUCKS below 4000meters. Hurricanes, SUCK above 4000meters. Pretty good 2500-3500meters. Okay below that when matched against Russian planes.
As for your comprehensive tests done by Il2compare, it only tested the AI variants of the flight models using closed radiators. Not exactly a worthwhile test on the more modelled versions the humans control.
-SW