Fishu, I don't buy that "2 seconds" argument at all. By the same token I've read that 2 seconds of fire from 8 .303s would be enough to down a German fighter. Considering that the M2 50 cal has almost 2 times the KE of the .303 round, that tells me that it should down a German fighter with less than 1 second concentrated fire. The 109 was easily the most fragile fighter in the ETO, the tail plane, O2, and engine were all EXTREMELY vulnerable to any type of fire. (Remember the 109E even required a braced tail and that more 109s were written off in landing accidents than were shot down during the BOB.) I've seen numerous gun camera films showing a 109 going into flames with little more than a quick burst across it.
For the sake of argument lets assume you are correct and that 2 seconds of continuous, concentrated fire is needed to bring down a fighter. Assume a low ROF for the M2 of, 750 Rounds per minute. That is equal to 4500 rounds per minute from all 6 guns, or 75 rounds per second. Are you saying that a 109 could take up to 150 concentrated rounds to a single area before damage would occur??? (I've read that the Germans considered the 50 cal to be in the same class as cannons.) Now please remember that the 50 cal bullets fired by American fighters were not simple lead shells. They were usually mainly API rounds. Even so the rounds had an average muzzle velocity of 870m/s and a weight of 48.5 grams. I calculate KE at the muzzle to be 1/2*.0485kg*870^2. (Formula for KE for non-relativistic speeds is .5MV^2.) I get 18354.8 Joules per round. Now consider a ROF of 75 rps, giving a total E of 2.75322*10^6 J delivered in 2 seconds as you have stated to be necessary to kill a fighter on average.
Now consider the HS MarkII. Looking at various sources I get a projectile weight of 130g at 880m/s. There are 4 cannons on the F4u-1c (wow, imagine that) For the sake of argument, lets consider the HS rounds to be AP. (Not a bad assumption given the ability of the HS MkII to kill tanks.) By the same calculations I get .5*.13*880^2 Joules per round or 50336 J per round. The HS MkII has a stated ROF of 600 RPM or 10 rps per gun, equal to 80 rounds in a 2 second period. By the same calculation as above this is 4.02688*10^6 J in 2 seconds. Again I will assume all rounds hit. The KE delivered by the HS 20mm AP is 1.46261 times the KE delivered by the 50 cal. Now here's the kicker; if the 50 cal takes 2 seconds to down a fighter, than the HS AP should take 1.36742 seconds of fire to deliver the same KE to a target. (2/1.46261 seconds)
Now here's the interesting part.
By your own post you claim (I do to) that 3 rounds of HS delivers lethal damage to the p51 drones. Extrapolating from the ROF of 40 rps from all 4 HS gives a total firing time of ONLY .075 seconds of fire needed to hit the target to cause lethal damage. Since the combined fire of 6 50 calibers takes 2 seconds, this leads to the conclusion that the HS in AH is 26.6666 times more lethal than the 50 cal. (2/0.75)
You are in effect saying that every round of HS is equal to 26 2/3 rounds of M2 50 caliber. Even if the HS was HE, do you think each round should deliver some 27 times the energy of a 50 caliber round?
I'd say a more realistic value would be on the order of up to 8 rounds of 50 cal API for each round of HS 20mm HE. Since the HS can deliver a lethal amount of damage in .075 seconds
by your own admission (I agree), would it be incorrect to assume that .075*8=.6 seconds of 50 caliber fire should deliver the same amount of energy? Why is there a 3.33 difference between this and 2 seconds as you claim necessary?
At the least, one must conclude that something is not right with the 50 cal as it is modelled right now. (I'm not even taking into account the fact that a 50 cal bullet is MUCH superior ballistically speaking to a 20mm HS and thus easier to hit with.)
Please do your own calculations if you doubt me. (I would be most appreciative if Pyro would do the same.
)
Fishu, I don't mean to pick on you in particular, you just hit a nerve here.
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bloom25
THUNDERBIRDS
