Hi,
since the majority of japanese fighters was Ki-43´s and A6M´s, most of their problems get transferred to all japanese planes.
Afaik only the Ki-84 and specialy Ki-44 was similar heavy wingloaded like the allied fighters, but the Ki84 still was on the lower end of the scale(similar to the SpitfireIX).
Since the dragload is pretty important while a highspeed dive and the wingarea cause a main part of the drag, i guess even the Ki-84 wasnt able to dive with the P51 or P47 at highspeed, at least it must have had more problems than the FW190A, despite the structural problems.
I guess the initial diveacceleration of the Ki-84 must have been outstanding, but at highspeed the light weight, relative big wings and radial engine layout got to be a problem.
The structural and highspeed drag problems of the Ki-43-I and A6M2 also got fixed a bit by a shorter wingspan (smaler aspectratio) in the Ki-43-II+III and A6M3/5 . This have a shorter leverage as result and a better drag at highspeed(though they lost at medium/slow speed, what minimized the range), but this planes never got close to the dragload of the US planes.
Althought the thinking in the japanese HQ did change, it still wasnt consequent enough to provide the Vmax and divespeed of the P51´s and P47´s, but they got much closer to this performences and the climb and turnadvanatge made them to similar dangerus planes like the Zero vs the earlyer US planes.
What i always found to be strange is that the japanese HQ saw the advantage of the Me109E4 and Ki-44(the only more heavy wingloaded japanese fighter) that late or never in the needed way.
While fitting the more strong engine into the Ki-61´s they tried to increase the wingare, cause they thought the Ki-61 already was heavy wingloaded. Only after they got structural problems with the big wing they did use the old Ki-61 wing.
The Ki-44 made its maiden flight in 1940 and was available in 1942 and was for long time the only japanese fighter to be able to intercept the B29(with 4 heavy MGs, ouch ouch ouch).
Iam pretty sure, with the Ki-44 instead of Ki-43´s the AVG would have had more problems.
Are the following numbers right or do someone have better datas?
10.500 produced A6M´s, 8.209 was A6M2´s(2300 A6M3+5 sounds a bit few to me)
5,900 Ki-43´s, 716 Ki-43-I's
1200 Ki-44-II+III´s(smal number of Ki-44-I´s)
3.300 Ki-84-I's and Ki-84-II's
3.000 Ki-61-I's
1500 N1K1 + 2
And do someone know which was the main engine used in the Ki-84??
I have three different versions of the Ha-45 listed.
Ha-45-11(Nk9b), 1690HP/2900rpm/2000m, 1460HP/2900rpm/5700m
Ha-45-21(NK9H), 1860HP/3000rpm/1800m, 1620HP/3000rpm/6400m
Ha-45-21(no data), 1875HP/3000rpm/1800m, 1695HP/3000rpm/6100m
btw, at highspeed dives for now i dont had much problems to leave the AH Ki-84 behind, but of course if someone get slow, close to a Ki-84, the initial acceleration advantage of the Ki-84 will hinder you to get to highspeed without to get shot down.

Greetings, Knegel