Overhaul of Gaijin calculator

I thought that HE filler did not actually reduce penetration of a round at all in a direct sense. To my understanding, HE filler reduced the lower velocity threshold of a round shattering (“shatter gap”) and if the reduction put the shatter velocity in range of the round’s actual firing velocity, it would thus appear to be reducing penetration directly. Hence how you get weird cases like T33 penning only around 170mm vertical but still decking a Panther into next week frontally.

Regarding your issue with how caps and ballistic caps affected round masses, I remember KillaKiwi long ago saying how removing about 9% of shell mass gave pretty good results for all APC rounds, 3% of shell mass for ballistic windshields, and 12% for both.

Regardless of the semantic details, I think that your efforts are something that should get far more recognition than it currently does. I hope that changes like this also are coupled with postpen changes - we all know how badly sub-120mm APHE overperforms, how many solid AP rounds are rather iffy in postpen performance (75mm ROQF Mk.V and Comet 77mm full calibers for example), APCR and tungsten carbide APDS being rather meh in a lot of cases, HEAT & HEATFS being laser beams, HESH’s armor-penetrating component (not the overpressure) being downright pathetic, and HE lacking the entire kinetic component of its penetration.

We need your penetration changes, as well as undoing nonsense postpen changes alongside them.

Then obviously, BRs across the board need complete and total upending.


I’m not going to pretend to understand all the mechanics of AP vs APC vs APHE. I’m just trying to make something that gives reasonable results and requires limited changes to the game mechanics. Gaijin chose the Demarre system for their AP penetration. I think its overly simplistic but that’s their decision. My suggestions allow them to use their simple system but generate reasonable results.

There are other formulas and calculators but they are well beyond my understanding and my ability to replicate.

Might be interesting to some:






Source: https://apps.dtic.mil/sti/pdfs/AD0389304.pdf

It’s absurd this keeps getting passed over for suggestions with fraction of the votes or replies.

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To clarify the APCR adjustments, here is 76mm M93 using the tungsten carbide calculator.

This chart shows about 9.7” or 246mm of penetration for the M93 but it is likely using 220 BHN armor plate.


That spreadsheet is a converted form of this chart.


It’s a little complicated, but essentially the chart gives you the penetration against RHA ranging from 220 BHN to 330 BHN.

My understanding is the game uses 240 BHN as the standard. 247mm BNH at 220 would be about 241mm at 240 BHN.


The issue with the APCR chart is the values aren’t exactly linear, there is a slight curve to the chart. It works out to a few percent so I’m not sure if it’s worth trying to figure out how to account for the curve in the DeMarre version.

I’ve requested documents to confirm but the HVAP T29E15 (M321) and APBC-T T166 were tested with the 76mm gun. Here is how performance would look. This may be a reasonable upgrade for the late US 76mm armed tanks.


Compared to M93 and M79.


While not entirely related to how WW2-related shells function, Gaijin’s shell penetration calculator for APFSDS shells needs to be scrapped, it is inherently flawed in that a lot of shells are unnecessarily nerfed without explanation other than that Gaijin swapped to whatever the L-O equation is. Instead, Gaijin should swap to William Oddermat’s penetration calculator available at https://www.longrods.ch/perfcalc.php

The LO equation is the Lanz Odermatt formula.

I’d also like to draw attention to naval ammunitions, which suffer even more so than tank shells from the current system. While Gaijin seems to attempt to adjust their formula to match RL data of some tank shells, they completely spoil the naval shells as they work in a very different context. TLDR, the current formula is optimised for small-calibre (compared to naval shells, all tank shells are small calibre ofc) and high-velocity (600+ m/s) impact against homogenous plates, whilst naval shells IRL were optimised for relatively low impact velocities (400~600 m/s) and against face-hardened plates. Naval shells also had to passed stricter acceptance standards than tank shells IRL. The penalty from bursting charge made up by Gaijin was entirely based on tank shell performances and it severely deteriorates naval shells’ performance at low striking velocity. According to data of various navies I have, the Gaijin formula globally underestimate post WWI naval high-calibre shell’s performance by over 20%, and in some severe cases such as the British 15" APC, the formula underestimate the penetration by nearly 60% at 1400 ft/s (396 m/s) striking velocity.


The DeMarre formula was created to represent penetration against nickel steel ship armor in the 1890s. I don’t think the formula is a bad option, I just think Gaijin’s implementation is not great.


I’m not saying De Marre formula itself is a bad option either. The thing is, this formula IRL had been modified extensively over time to fit the new technologies and ofc different context, and gaijin made up their own version too but it’s entirely based on tank context. While navy shell is a very different category they insists to treat everything “equally”. One may argue that the mismatch of tank shell performance in game is somewhat within an acceptable margin but the error in calculating naval shells is way beyond the threshold to be considered as “acceptable” imo


That’s fair. I would work on changes for the naval version but I don’t have much data on naval guns. I have no problem with anyone using my information for a naval suggestion, or helping if there are any questions.

I just work with the information I have. This suggestion is not even all my work. There are multiple people I have worked with to gather this information and helped to get a workable solution.

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How hard would it be to have a separate calculator for naval rounds?

There is no way a one size fits all system like the calculator will be accurate for all rounds. Materials, design and quality control are not taken into account. Gaijin uses velocity, diameter, weight, HE filler and cap or no cap. That is too simplistic to produce results that match every round.

It wouldn’t be difficult to get the formula to match known performance for one round and use that as a basis but it would only be accurate for similar rounds.

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I’ve been looking into German ballistics data but haven’t found much. Here’s the long 88.


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The APCR shells need some love.

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Fixing APCR would be a major change. It would help with quite a few balance issues.


good advice, the American APBC in the game is too easy to ricochet, but the Soviet APBC ricochet angle is better than the American APBC

Could the APCR and APDS penetration of the Marder A1 20mm cannon be looked at?
For tungsten ammunition, they seem to me to penetrate quite little, apart from the fact that, for example, the APCR pierces extremely when faced with a slight angle.

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