I can't comment on if its right or wrong, because there are instances of planes making it back from severe hits that should in normal cases dropped the plane. It's an extreme case, but one such intance would be Robert Johnson's P-47 after his tangle with Egon Meyer's Fw190.
Anyhow, there could be a number of reasons why the cannon hits to that Spitfire did not give off enough damage.
I've seen the pic in that other thread, and from that angle, I count two hits on the left wing, one on the portside rear section behind the cockpit, and two very close to the starbordside cockpit. However, the sprites themselves are sometimes misleading, as there hit places are not always accurately displayed. Another reason is may be that the rounds may have a basic level of damage, but it depends on the relative conditions of the fight.
Or, for some very unlucky reason, the hits may have been recorded at something like "1 point" before structural failure, but stopped just there. Two hits seem concentrated on the left wing, but it may not have been enough to snap it off. Since DrkBlue said he got a hole in his cockpit, it is pretty obvious some of the force of 20mm impact did penetrate through his cockpit glass and cracked it. However, the fact remains that it might not have been enough.
One thing I can comment though, is that the limitations of the current damage modelling might be the reason DrkBlue survived, as we can assume that a better, more sophisticated damage modelling might have caused lot more complications for him.
For instance;
1) if the angle of the screenshot you have on his Spitfire is the angle you fired at him, then the 20mm shells impacted almost 90 degrees to his left wing surface. Two cannon shells at that angle at close proximity, would have dealt a very destructive blow to the surface of his left wing and would have ripped open a very large hole - immediately effecting the performance of the Spitfire, despite the fact it wasn't enough to snap the wing off.
IF we assume a higher level of realism, one of the shells connected on his left wing might have been a AP or API round. It might have at least punctured his gearbox or with some luck, could have damaged the ammo box of his gun.
2) I do not observe any hits directly to the cockpit, and yet, DrkBlue said that he got a hole. This means there was a close impact of a 20mm HE shell to his cockpit glass(which, is pretty obvious from the screenshot). 20mm shells don't drill "holes" in the cockpit. It is entirely possible, that his cockpit glass held solid and did not cause any harm to the pilot - however, a close impact of a 20mm would have cracked the glass like a sledgehammer hit to a car windshield - a "web" like series of cracks that will immediately impair his rearward visibility, instead of the clear, simple, "hole".
3) despite your logical analysis in this thread, we still can't really confirm if those hits are really all 20mms or not.. I think your basic analysis is logical, but to tell you the truth, I really can't be too sure if those are indeed, all 20mms. If AH would have displayed AP impacts and HE impacts seperately for guns of 23mm calibre and under, it might have been a lot easier to determine things.
4) however, since all AH bulltes are 'generic' currently, it's impossible to depict 20mm HE impacts in the 'blasts' as we can see in 37 or 30mm guns - since 20mm cannons had mixed ammo belts of AP and HE shells, but AH doesn't have mixed ammo belts at all!
Thus, all in all, Wilbus, you were just unlucky. Some consolation may be found in that if AH had a better, more sophisticated form of showing damage, then the situation might have been a lot better to you. However, in the current AH, all damage to the cockpit glass is in "hole"s. There is no intermediate level of damage that effects performance - cannon shells don't rip surfaces, and AP shells can't hit cables or rods.
Let's hope AH can update its form of basic damage modelling and ammo belt soon enough.
