There are multiple possibilities that I have encountered. Such as the F4U's, you actually lose your aileron, not the entirety of the wing, yet it still handles as if you lost half a wing. And I noticed this on the P-38 too, once you lose half a wing, it doesn't seem to be gone. Another reason I encountered could be that at a distance of 300 feet or further away (At my graphics settings) the wing appears whole again, yet closer than 300 it's not there.