One could also compare the strength of the G4M Betty and Ki-21 Sally. One is a Zippo, the other seems to be a tank. I also wonder about the apparent fragility of the Pe-2 compared to the Bf-110, Ju-88 or A-20.

Indeed there are some DM's that just don't seem to make sense... I know generally how the DM's work in theory but in practice there seems to be some interesting results.

If the Ki-27 and Ki-43-I are so similar... they should go down similarly but they don't. Even if the wing tanks are smaller... fire a dozen .303 rounds in that general area and you should get a light... but you rarely do.

Another ultra strong plane is I-16.
Even newer soviet planes are more fragile than it.P-40 (later models) are also strong,but propeller stops at any reason.

IJN and IJA planes looks quite fragile,but USN fighters are too stronger than them.

You may be remembering back in the 1.1 days but the I-16 isn't really that strong anymore. A few good shots to the fuselage and they light right up.

Back in the old days they used to shrug off everything and keep on fighting.

Actually if you compare I-16 versus Ki-27 which is a Khalkin Gol matchup there is a major problem because the Ki-27 is nearly immune to the I-16's machine guns but the reverse is not true so the Ki-27 wins most fights on DM alone.

The P11.c used to be a ram monster ... rip the wings off 109's and spits in collisions and fly away intact.

Really annoyed people online when you did that :P

idk about tough but nates can turn on a pinhead....I have tried to dogfight them in my Spitfire and had them out turn me.....same thing with a Buffalo and some early war french plane...things seemed to turn around right in place like a tank

That is probably because the Hurricane has a lot of "empty space" (particularly in the fuselage) where a bullet would simply pencil through without hitting anything of consequence. The Spitfire was a lot more "packed", and the skin was a part of the weight bearing structure, unlike the fabric parts on the Hurricane.

i have noticed that, both the p40 and p39 seem to have engine fires or stoppages much more than anything else.

This part doesn't surprise me. It's regarded as one of the quickest turning monoplanes which isn't surprising given Japan's Army Air Force doctrine of turn fighting. When the Ki-43 was introduced even it was regarded by pilots as too slow in the turn compared to what they were used to.

The Ki-61 and Ki-44 were real shocks to these pilots no doubt!