Good point, I forgot to take this into account.critical mass wrote: ↑25 Nov 2019 08:59I think the differences are attributable to the different Charakter of the data and their reference in regard to performance.
Miles curves (Sollkurve and Abnahmebschusskurve) are minimum service acceptance references for service acceptance of armor plate. For a plate to be worse than the numbers, then the whole lot will have to be rejected (if failing retest). This by definition means that in general, acceptable plate quality such as procured for AFV armor is same or better than the reference. By how much is unknown.
The US data on the other hand are explorative trials, and record data as is obtained.
The two datasets are therefore not directly comparable.
Remember our conversation about how the slope effect changes with striking velocity? Well I've found the same phenomena in the US data. While struggling to describe the behavior of the shell/armour at the full range of variables, with an acceptable margin of error, I've noticed that the K constants seem to form rough groups based on striking velocity, so I've divided the data in two groups, one for shots with between 2100-2600fps approx, and another between 2800-3150fps approx. and was able to narrow down the K for each to within +-5%.
Are you sure about this? Because, from what I know, the scaling effect works in completely opposite fashion, reducing the energy requirements with absolute size of the projectile/armour combination, according to this publication:There are some other aspects involved but I don’t know their actual effect yet. The nose shape at 0.8 t/D and high obliquely is irrelevant, as the projectile will effect base first penetration regularly at such acute angle. But larger cal projectiles require somewhat more energy for obtaining holing and perforation at high obliquity than smaller caliber projectiles. It’s not a big difference but it’s measurable. I have it in datasets for US 8in, 14in and 16in APCBC, in German navy APCBC and German 75mm and 88mm Army APCBC, and I strongly suspect that it’s true for 50mm vs 90mm, too. Perhaps worth investigating further.