UK National Physics Laboratory formula for penetration of RHA

I’ve made a spreadsheet calculator, so anyone can play with it:




Edit: Comparison with historical data:


Edit: I feel like, perhaps, there is some confusion in regards to what this formula is.
Probably as soon as people read “formula” they think of it as something distinct and separate from “hard” data from “real” penetration tests. But, as you can see in this snippet, the output of “formula” is very real and true to real life experimental data.

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@KillaKiwi The calculator is showing error because you put target thickness too high. This model is applicable only to plates up to 2 calibers thick.

Here is something interesting: if we compare experimental data and the NPL formula, we can see that it’s prediction that, on average, ballistic limit for this target does not appreciably change with BHN varying between 240 and 300, matches perfectly.



The amount of kinetic energy absorbed during perforation of the plate is directly related to it’s Navy ballistic limit, for example for 780kJ, its 1571 fps.

The value of R^2 next to 0 indicates that there is very likely no casual connection between the two variables.