I have found this thread very interesting.
I would like to bring up two factors which have not(?) been stressed in this thread so far.
The first is purely operational at a strategic level and revolves around who is on the offensive. At the start of the war the IJN and USN were on a rough parity in ability to fight large scale naval battles and amphibious warfare. The Japanese were on the offensive at sea in an organized and largely pre-planned way until about the end of 1942 or beginning of 1943. The tie(?) at Coral Sea and Japanese loss at Midway put a serious crimp in the IJN's offensive plan and ability. The US quickly gained the offensive in 1943.
A general rule of warfare is that in a maneuver war whoever is on the offensive has an advantage, at least temporarily.
Examples of this are common in the PTO, ETO, MTO, and Eastern Front. In the ETO we saw the successful German attack on France, and the initially successful attack on the Eastern Front against the Russians. In the MTO we saw the see-saw war in the desert between the UK and the Italians or Germans. In the PTO we saw the Japanese successes in the Philipines, Indonesia, Malaysia, Dutch East Indies, etc. In most of these cases the attacking forces accomplished the objectives against equal or superior numbers of enemy - mostly because of superior planning and the fact that the enemy was not given time to recover once the attack began. Once the offense was stopped, if the enemy could go on the offensive the advantage switched to the enemy.
The other factor is the ratio of forces. I figure most of the readers of this thread are at least generally aware of the change in ratio of IJN to USN carriers beginning in 1942 after Midway, and the start of the deployment of large number of land based USAAF and Marine aircraft into the PTO.
In the intital engagements between the F4F and the Zero, the F4F faired poorly in kill-to-loss ratio. Once the USN was on the offensive, where the numbers were equal or in favor of the F4F, the kill-to-loss ratio improved. I do not remember the exact numbers claimed/comfirmed kill-to-loss ratio but I believe it was approximately 2:1 overall. (I am seperating the F4F/FM-1 stats from the later war FM-2 stats. The FM-2 was a much better performing model operating in a very different operational environment from that of the early-war model F4F/FM-1.)
In the current(?) subject of the thread, ie Japanese airpower and what was the reason for the apparent drastic change in capability in late-1942 thru 1943, I believe the answer lies mainly in a combination of the above two factors. The introduction of the P-38, F4U, F6F, etc. simply magnified the effect.
Of interest perhaps is the following:
There is a common myth in US tribal lore that the 'Thatch Weave' was some amazingly new method of aerial combat that turned the tide of war in the air, or at least allowed the F4F pilots to survive when outnumbered against the Zero. Neither of these statements is true.
Maybe it was a new tactic to the US, but the concept of mutual support between wing men - or at least members of the same flight/squadron - was not new to the IJN/IJA, Luftwaffe, or RAF/FAA (I would assume it was not new to the French, Italian, or Russians either but I do not know enough about their training and experience early-war to venture any categorical statement). The value of the 'Thatch Weave' (ie mutual support) really only became broadly evident when the US began to outnumber the IJA/IJN during engagements.
Compared to the F4F the Zero was as fast or faster in level flight, had a superior climb rate, a hugely superior turn rate, a higher roll rate at dog-fight speeds, and better visibility from the cockpit. The only area of maneuver the F4F had an advantage in was in dive speed. (I leave out the marginal superior speed at very high altitudes over about 20,000 ft as ther was almost no combat at those heights in the early war.)
The F4F was also less likely to catch fire after the -4 model entered service with self-sealing FTs in late(?)-1942, and the pilot was perhaps more likely to survive hits due to armor being fitted.
When facing equal numbers of enemy aircraft that are that superior in maneuver to yours, the 'Thatch Weave' would simply have ended in two Zeroes tailing two F4Fs and shooting them down. The 'Thatch Weave' primarily worked when two F4F were being tailed by one Zero, the second F4F having a chance to interfere with the Zero safely getting a shot on the first F4F.
