I find the urge to bring up this debate again.
This is NOT a slight on the folks running Rangoon, but I noticed the FM-2 is being used to sub for the Brewster (again...).
Even the early version of the Brewster Buffalo, the A1, without all of the weight gain of the A3 And the heavily upgraded armor on the B-339E versions, still weighed 5040 lbs loaded. It had a short stubby wingspan of 35' and a wing area of about 209 square feet. It had a single-row 950 hp engine. It had 1x .30cal and 1x .50cal in the cowling and 1x .50cal in each wing.
The F4F-3 and -4 had 38' wingspans, wing area around 260 square feet (more lift), a double rowed 1,200 hp engine. They weighed (not sure on this, just quoting wiki -- but this does NOT seem right) 7000 lbs for the F4F-3 and 7950 for the -4. The -3 had 4x .50cals and the -4 had 2 more optional outboard of those (bringing the total to 6x .50cal).
Performance:
The weight of the F4F is higher than the F2A, but the wing is considerably larger, producing much more lift, and the wing loading is almost dead even (24 lbs per square foot for the Brewster, 26 lbs per square foot for the F4F-3). That brings us to the horsepower and other areas. The wing loading is one indicator of turn performance, but that means nothing if you don't have the horses to pull you around a turn.
The F4F4 has 250hp more than the F2a. Even the Finnish Brewsters that folks like to talk about only had 1000hp engines. This means a LOT of extra power. Much improved climb rate and the ability to haul the nose around in a turn. Granted the F4F has more weight and inertia, but the spit9 has less weight than the spit8, but the spit8's extra power means it actually tuns better. The airframe is almost identical, but the greater horsepower gives it an edge. (See Gonzo's charts)
So the F4F4 has much higher horsepower. This also means climb and acceleration will be different. The brewster would have less climb rate (smaller wing, less horsepower to pull upward), perhaps turn worse than the Grumman design, and then there's the other thing.
Speed.
The Buffalo's top speed was 311mph at 18000 feet.
The F4F is 320mph at about the same alt, however the F4F has 2 additional supercharger peaks on its speed chart. I believe the Buffalo's engine is a predecessor to the FM-2s, which has only 1 supercharger peak. Supposing this is engine-specific (I don't know) the Buffalo might have 1 or might have no other power peaks.
That means that while the F4F has just over 280mph on the deck, the Brewster would be closer to 250 (or less).
That's not even counting the FM-2.
The FM-2 has the same wingspan wing area and armament as the F4F-3, weighs 7400 lbs according to AH's homepage, but it's got one major consideration that the F4F-3 doesn't have.
It has a 1,350 hp engine.
That's right. Stock F2A1 (before all the weight, the nimble version) has only 950 hp. The later versions had more hp, but performed even worse because all the weight gain nullified it. The Finnish version was re-engined and still only had 1000hp. Where the Brewster's deck speed may be around 250, the FM-2 easily breaks 300mph with its WEP rating on the deck. That's a helluva performance difference. Climb rate also jumps almost 1000fpm over the F4F3 with "just" 150 extra horsepower. Acceleration is significantly improved over the similar-framed F4F3, and the climb, speed, acceleration all translate into a performance package that would only beg the question: Why is this even remotely being used for the Buffalo stand-in?
So, as much as the F4F is better than the Brewster, the FM-2 is better than the F4F.
That's not just a bad match-up for a Brewster stand-in, it's just wrong!
Might as well use a Ju-88 to stand in for a He-70!
In the past when I've brought this very large performance discrepency up, the main defense is that the FM-2 has 4 50cal guns, which is close to what the Brewster had.
Well the P-51D has weapons "close to" the P-40E, but you wouldn't sub one for the other, would you?? Weapons are not the ONLY reason to use a stand-in. Performance makes up a far better match.
F4F4 is far better than the FM-2 [EDIT: as a Brewster stand-in], performance wise, but it's still not a very good match, outperforming the Brewster in most areas. It's the horsepower.
Just looking at weapons alone, if the F4F4 had to be used, it could be. That is to say in a scenario there is much better discipline than in the AvA or the MA or what-have-you. You can set a rule and it will be enforced down the line by squadron leaders.
We flew an entire FSO in P-39Ds, and we were forbidden to use the 37mm (20mm only) and we did so. There were no major violations, mass-rule-breakings, or any anarchy of that sort. The same will hold true for the scenarios. On the other hand, IF a rogue pilot takes the extra pair of guns they will be considerably heavier, and any turn and climb and acceleration performance will be worse off than without them. If a shot lands, it will have a greater impact, but will the shot land in the first place? Or will said pilot have handicapped himself into being shot down?
I'm just saying we have the discipline to follow orders if they say "ONLY use the 4-gun package!" We've proven this before in several FSOs (non-specific to the F4F, I mean in regards to weapons options).
So, for the purpose of debate, there are better options than the FM-2 for the Brewster.
In fact, some pilots are so used to flying the FM-2 and shouting for the Brewster, they will probably be sorely disappointed if we ever get it in-game, because it doesn't perform at all like they were used to.
It's like flying a spit16 pretending it's a spit5, and then when the spit5 arrives it flies more like a spit1, and you wonder why you're not getting the same performance as the spit16 (hehe, that kind of a rambling example, ignore it if you don't understand)