Well, I did a quick test of the P-39Q offline and found that Pyro's adjustments result in a vast improvement. Flap drag is now roughly the same as the P-40E, perhaps even a bit less.
A quick full flap turn radius test got me 466 feet vs 526 feet prior to the update. Another big improvement is in turn rate, which jumped from 17.2 dps to 18.2 dps. This puts in company with the La-5FN and 109G-2 in terms of radius, but inferior in turn rate.. That's significant in that in a prolonged circle fight, it will lose ground and equality after a few 360 turns.
Nonetheless, flaps use is at least now a real option.
Nice job Pyro, very much appreciated.

My regards,
Widewing