The fact is, turning ability is next to useless in WW2 air combat.
I don't mean the kind of flying we do in the MA, I mean in actual air battles, many planes fighting many planes. While a lot of fun, the kind of flying done by most of us in the MA is not representative of "standard" WW2 air battles.
Why don't you turn in WW2 air combat like we do in the AH MA? If you slow down to turn with one guy, some other guy will kill you. Fly in a scenario sometime and you should see this point demonstrated very, very well. 80-90% of scenario deaths typically come from a guy who doesn't see his attacker until it's too late. It even happens to the "aces". You think keeping track of 5-6 enemy planes in the MA is tough? Try keeping track of 20! And remember, it only got harder in the real deal. It was much, much safer to just keep your speed up and not "dogfight" at all.
The fact that the F6F could turn reasonably well has NOTHING to do with the Zero. It can turn well because its designers wanted it to have a low stall speed and really docile stall characteristics (remember this is a plane designed to land on carriers) without sacrificing things like range or payload. So, they put a really big wing on it (this huge wing is a part of why the F6F is so slow compared to other US fighters, too). The good turning ability was essentially a by-product. The F6F was first and foremost designed to be the "perfect" carrier fighter, which by WW2 standards it was. I think the "designed to beat the zero" part is just a myth, or good PR from Grumman.
In this light the Zero is a total piece of junk compared to the F6F. The F6F can outrun, outclimb, outdive, and outrange the Zero. It accelerates quicker in a dive, holds that speed longer in a zoom, has a better weapon set with more ammo, is much tougher, and will easily outmaneuver the Zero at higher (read: combat) speeds. Add the declining average skill of the Japanese pilots and you have a recipie for slaughter.
J_A_B