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I've been reading Warrior to Dreadnought recently, and at one point in the footnotes D.K.Brown mentions a formula to compare the impact of guns of different types. That is, that the impact and damage of a shell is theoretically the cube of the shell weight but in practice more like the square of the shell weight.



It sounds like this is a useful parameter for comparing different kinds of ships across different countries - among other things, it reflects the generally understood case that a heavy slow shell is better than a small fast shell even for the same gun type.




So for gun effectiveness, might I suggest that this is at least a reasonable approximation:


Number of salvoes/shells per minute (use mid value) times square of shell weight times shell muzzle velocity.

Of course for very large ships with lots of armour then the penetration table approach works somewhat better. But this could be useful for comparing DDs and CLs, as well as MGBs.




For example:


Tribal class DD
8 4.7" mk IX
10-12 rounds per minute (use 11)
Shell weight 22.7 kg
Muzzle velocity 808 mps

Per-gun effectiveness value
4.58 million
Ship effectiveness value
36.6 million


1936-class DD

Main battery:
5 5" guns


15-18 rounds per minute (use 17)
Shell weight 28 kg
Muzzle velocity 830 mps


Per-gun effectiveness value
11 million
Ship effectiveness value
55 million


From this we get that the 1936 class is somewhat better than a Tribal - but that if they had the same ROF they'd not be much different.

I'd be interested to see if this actually works out.
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