Warthunder uses the NATO derived flat penetration equivalent protection to display protection of a vehicle. The soviet union used a Line of sight value. And a nominal defeat value in line of sight. I can prove this.

Heres a simple example though.

3BM4 is a homogenous steel monobloc long rod penetrator with 285mm flat pen, and 162mm thickness of plate perforated at 60 degrees, or 324mm LOS penetration.

Take this round and aim it at T-62s ufp woth an impact angle of 60 degrees. The protection equivalent will only show ~176mm. But T-62s ufp we know to be a 100mm steel plate sloped at 60 degrees. This provides a LOS protection value of 200mm RHA.

So what you can do, is convert the 176 the T62 is showing you to a true RHA LOS protection value.

You take the 176 T62 provides and divide it by the flat penetration of 3bm4 which is 285. This gives a percentage of penetration against 3BM4s flat pen. Now take this value and multiply it by 3bm4s angled performance at 60 degrees and it gives you exactly 200mm. This is the T-62s true LOS protection.

You can only do this with monobloc long rod penetrators that you have the ammo data for using lanz odermatt to calculate the performance, or AP rounds using the slope tables and the equations for that. You cannot use composite penetrators like 3bm22, or M735 to calculate protection because they act differently and cant be calculated using lanz and you also cannot use steel penetrators you do not know the hardness (BHN) for.

And this is how gaijin fucked up the 13 t series tanks. They took the Soviets LOS protection values and applied them at flat penetration equivalents. Only the T-72As (60-105-50) T-64A (80-105-20), T-80B (60-105-45), and T-64B (60-35-30-35-50) have the correct (within about 25mm) LOS protection and flat pen protection. They were corrected before. I can also prove this with some source material.

So they took a 530mm LOS protection value for T-72B and applied it as a flat pen protection of 530mm, which converted to LOS is 661mm. Which is erroneous.

Like Look at T64Bs array. Which is very similar to obj 292 or T-80Us arrays.

How the fuck does about 1cm total more steel and a tiny bit less textolite increase the t80us armor performance by over 100mm LOS? Its completely impossible. Even with the hardness plate differences it cant possibly achieve that.

I basically wrote a 50+ page paper on how and why gaijin fucked up and can completely prove anything i have stated here if youre interested.