the recorded temperature of the trials was even lower (compare lower attachment).seppw wrote: ↑23 Nov 2018 04:03For those who are wondering, although the Tiger II was abandonned during some hot day in the summer, as far as I can remember - and correct me, if I'm wrong - the tests with the 122mm and 100mm guns were conducted during mid November 1944, when it was -2°C on average.critical mass wrote: ↑15 Nov 2018 11:20When comparing ductile and brittle types of failure one need to factor in and guard against yet another important bias: Every material, even the most ductile types of armor can show brittle behavior in very cool ambient conditions. That is because the ability of the steel to exhibit plastic deformation is dependent on the ambient temperature, too. Armor steel has a temperature, where the change from ductile to brittle behavior takes place. F.e. most 1920´s US armor was having this temperature -measured by Charpy impact notch tests- at approx. 0°C with 1950´s US armor averaging at -50°C. Armor steel which has a very low brittle temperature is thus preferable. This is important when one tries to compare, f.e. a test made under summer conditions (say TIGER I trials) with another one executed at subzero temperatures (say famous TIGER II trials).
The problems represents a unique bias for testing, though. That is because the engine isn´t running (steel is a good heat conductor).
Of course, the soviets didn´t pay that much attention to the issue in their own ballistic vehicle tests. Though we don´t know a lot about the ambient conditions in these cases, making direct comparison a very difficult project (like, f.e. IS2 with welded, RHA straight nose getting frontally penetrated by plugging by 88mm KWK43 at 450-600m through the glacis and at >4km through the nose plate, compare upper attachment).