Ki-27 vs Ki-43: Why is the Nate tougher?

[JtD]

The in game toughness values seem to be the same for both planes.

I don't know about the construction IRL, but the Ki-43 is known for structural failures while the Ki-27 is not. Well, that is as far as I am concerned. The Ki-43 did not have self sealing fuel tanks, the Ki-43II did get some sort of fuel tank protection.

It could be noted that the Ki-43 is sleeker than the Ki-27, which would make the structure higher stressed.

All in all I wouldn't be surprised if the Ki-27 was a bit tougher, or maybe "less fragile", than the Ki-43 in real life, but I don't think it is that way in game.