The fast monocock full metal low wing fighters started to appear in air forces in 1939/1940/1941.
Sorry to be annoying, I am NOT a spelling nazi, but please... monocoque. And it doesn't mean "1 wing." It means that the exterior is also the major stress-bearing element in the design. That element of design was common in some combat biplanes in the mid-1930s. The F3F, for example, was a monocoque biplane. The difference is primarily in the "skin." A fabric covered surface is not a monocoque design. An aluminum surface generally was.
Those designs were so radically new that all the knowledge that pilots gained from WWI and in post war years become practically obsolete.
Errr. No. Nothing terribly radical about the designs at all. If you look at the progression from biplane to monoplane it's not a "great leap forward." It's a series of incremental progressions from frame&fabric, low HP biplanes to aluminum-skinned, higher HP-engined monoplanes. Withing the general category of things 1-winged and monocoque there was a huge degree of variation in characteristics affected by things like weight and drag and of course especially by powerplant output.
Thus, saying that USN had extensive deflection shooting training from 1925 onwards means practically nothing because all that training and tactics were done in aircraft that were far far inferior to new hot fighters they all received before the war started (and practically useless because everything changed in meantime when new machines arrived).
That is just pure, off the cuff, taking off the top of your head speculation and it is nonsense. It's hard to imagine what sort of training cycle you think that the USN used. People did not transition from Wright Fliers to F4Fs 48 hours before being sent into combat, so this business about the 'new fighters being radically different' in whatever you think they differed in ... is just not applicable. F4F pilots trained extensively in F4Fs at deflection shooting and were very, very good at it. And the proof is in the performance. Thach, Flatley, other famous pilots at the time attributed USN pilots' ability to hold their own to good deflection shooting. Lundstrom's analyses prove that good deflection shooting was instrumental in obtaining victories over the A6M. So, you seem to have a "theory" with no good statement of why the theory ought to make sense that is not supported by extant information about training practices nor by extant information from combat.
Now I don't know what you imagine to be radically different. Airspeeds increased, but that happened at a pretty constant rate from 1914 through 1945. The only "great leap" in airspeed occurred with the transition to the jet age.
I also fail to see how this could matter in combat, because high rates of closure in deflection training could be obtained using almost any aircraft. Consider an AT6 Texan pilot training at aerial gunnery. His target is a banner towed by, perhaps, a Hudson or some other aircraft. In any quartering from behind to dead astern approach, the AT6's closing rate is on the order of anything from nil to 100 mph, depending on the AT6's pilots desires. This is certainly much greater than the speed differential of any F4F on a quartering approach on an A6M in a combat where, for example, both planes may have turned once. It's certainly a much greater difference than that for which F4F pilots would have compensated when and A6M making a stern approach pass on an F4F would dive under then zoom up in front of the F4F (a favored tactic of A6M pilots as a matter of training and doctrine).
Finally, there is the fact that the deflection shooting worked. You don't have to take my word for it. Read what Thach and Flatley said about it. You don't have to take their word for it, read what Lundstrom said about it. You don't have to take his word for it, read the detailed descriptions of a2a combat and see for yourself the numerous instances of Zekes falling to F4Fs in deflection shots. You don't have to beleive those are typical, but if you read any history of the aerial war the usual conclusion is that the dcotrinal emphasis on deflection shooting gave the USN the edge. Heck, if I remember right even the "usual suspects" Japanese pilot anecdotes credit the USN pilots with being crack shots.
You don't have to believe THEIR word for it either. Ask yourself how an a/c that was less maneuverable at slow speed than the Zero, with inferior acceleration, inferior climb, and slower maximum WEP speed at all altitudes managed to shoot down more Zekes in direct confrontations than they lost? It wasn't done by pounding one's fists on the controls and shouting harsh words at the Japanese.
Show me a fellow who rejects statistical analysis a priori and I'll show you a fellow who has no knowledge of statistics.
Didn't we have this conversation already?
Well,actually you can train in slower aircraft,and all air forces have been doing so since World War One..
