So, What is a “Penetration”

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Thanks to CaptianNemo for sending me the data required.

Hello everyone,

when playing World of Tanks, have you ever asked yourself, what is a shell “penetration”? The natural answer would of course be “a situation, where the shell goes through the armor”. True, of course, that is the essence of the entire thing, but it is not all. In order to estabilish a penetration at certain distance, you have to know four basic things:

- obviously, the distance
- the type of gun (shell) you are shooting
- the type of armor you are shooting at
- what exactly counts as a “penetrating hit”

Especially the last part leads to a lot of confusion, because it’s absolutely possible that using different methods, the very same gun with the very same shell can have WILDLY different penetration values.

So, what counts as penetration? Well, everyone counts it differently. The most blatant case of this is the different performance of German and Soviet guns according to German/Soviet tables. Let’s have a look at some of the methods first. It’s all very technical, so I will try to skip the mumbo jumbo and explain it in layman’s terms.

Americans

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This is the American basic table, showing the penetration methods of various US military branches with various purposes. The important part for us is the army branch. As you can see, there are two categories – complete and partial penetration. Complete penetration according to the American methodology is acquired, whenever a shell punctures the armor enough for light to shine through, once the shell is removed. In other words, it’s enough for the shell to have just a tip inside the armor and you have achieved a complete penetrating hit. This led to the situations, where the guns had WILDLY higher penetration values when tested by the Americans then when tested by for example the Soviets.

The situation is also complicated by the fact that wartime American firing tests were messy, it was for example not clear as to what targets were shot at, the testing armor was standardized only after the war.

Germans

Germany tested the shells so that the shell (usually focusing on APHE rounds) had to penetrate the armor in such a condition that it was not too deformed to detonate. If it was, even a “penetrating” hit would count as non-penetration during the tests if the shell was incapable of doing so. In order for the penetration at such a distance to be defined for the type of the shell round, two thirds of shells, strinking that respective armor thickness, must be able to explode after penetrating with 100 percent of the shell doing so (no partial explosions). The issue of course comes with various sources claiming various things (other sources claim it was only half of the shells, or even count five or three consecutive shots into the armor), but that’s the general method. As you can see, this method is much stricter than the American one, it practically means intact shells have to pass through the armor itself.

Soviet

Soviet method of penetration recognizes several categories. A penetration is achieved when 75 percent of the shell mass has passed through the armor (notice the word mass, it means that the penetration is achieved even if the shell splinters to pieces within the armor). From there, two categories are defined:

- Certified penetration is when 80 percent of hits result in penetration
- Initial penetration is when 20 percent of hits result in penetration

Of the three methods, the German one is possibly the strictest, at least in this sense. However, as written above, this is just one part of the puzzle. This post is not intended to explain exactly why (theoretically) the same gun has different values, when tested by Soviets and Germans (especially wartime tests are really problematic), there are far too many variables in that. It is here to show you that when someone says “that gun penetrated more in real life, OMG WG BUFF” and uses one (even reputable) source as reference, it does not mean that he is right and someone else is wrong. Both can be right.

Typical example is the 88mm L/71 Tiger II gun. According to Soviet data, it penetrates 160mm of armor at 90 degrees at 500 meters. German number is (Spielberger) is 185mm or even 205mm (two different tests), at the same distance. What shells exactly did both parties use (that actually differed as well – Americans took whatever German shells they got, the Germans tended to pick the best shells for the testing)? What armor were they firing at? Under what conditions? We don’t know. So, in a way, in World of Tanks, penetration is a balance parameter as well, because various test results can be used (according to balance needs), while some guns (Soviet D-25 for example) have unhistorically buffed penetration (165mm at 100 meters, but that’s according to the same tests, that give 88mm L/71 168mm, so be careful what you wish for).

Unfortunately, no such things as common firing tests of all wartime guns exist. The thing that come the closest are the Yugoslavian post-war trials from early 60′s, which are quite interesting, but are more like “practical”, along the lines of “88mm L/71 Panzergranate 43 can penetrate the frontal armor of the T-54A medium tank at 600 meters”.

Source:
www.panzer-war.com/page33.html
www.battlefield.ru
www.tank-net.com
wwww.valka.cz
EU forums (Tuccy’s post)

26 thoughts on “So, What is a “Penetration””

  1. ” The thing that come the closest are the Yugoslavian post-war trials from early 60′s, which are quite interesting, but are more like “practical”, along the lines of “88mm L/71 Panzergranate 43 can penetrate the frontal armor of the T-54A medium tank at 600 meters”.”

    Didnt they use refitted american 90mm shells to simulate real 88mm shells (because they had none)?

  3. So the German standard would result in a knocked out tank and the US standard would result in the army buying the shells even if they did not knock out tanks. Corporate Military Complex working as intended.

    • a buried shell will weaken the armor, most likely ensuring a 2nd shell penetrating
      also, a buried shell creates spalling, resulting in crew injury or even death

  4. Damn nice article.

    Of course there is one other potential way of comparing the guns. Use one countries tests on the guns!

      • Yes and no. The German data for most shells is available. OF course this means they only tested for guns they captured, and other weapons wouldn’t be featured, which is a problem.

        • I’m not sure what projectile the Russians had when they tested 88mm/L71. That could be an early model. Later German shells improved as they changed to blunt harder AP caps because the Germans saw the Russian blunt nosed shells did well against sloped armor.

          And you are welcome for visiting panzer war site.

  5. Good Morning SS,

    Actually there is quite a good source for compareable penetration values. It lists all well known guns from the war, at the US criteria. The book is “ww2 ballistics: armor and gunnery”, by Rexford.

    • But what the Americans counted as a Penetration, The Germans would say its a failed shot as the shell is too deformed to cause any post-armor effect on the crew or for the APHE (German defination) round to detonate and the Russians would say it is a penetration because 80% of the shell mass entered the tank.

      • American armor tests criteria changed when this happened.

        Also, US tests were better in ways as stated they just used ammo off the line, not chosen ammo that was perfect or handloaded.

        US testing of rounds by far was the most scientific in coldwar times. They used sloped plates and built mock ups rather than plates so the structures were reinforced.

        But the USSR I think did the most test firing of all nations.

        I dont think for a second that the long 88mm was only 165mm though. No way it was 205mm either. I`ll go with 185mm as a standard round.

      • wow rude…should i write an email to SS about it? Also you momma is so fat i can’t even penetrate with JgpzE100 HEAT.

          • If only your tiny brain could comprehend simple sarcasm such as “wow rude” expression. Yea, that would be great.

  7. “So, in a way, in World of Tanks, penetration is a balance parameter as well”

    Someone should inform WG? Maybe one day they figure out they can buff some terrible premiums(T23E3&T26E4 I looking at you). Working as intended.

    • Yeah, the long 90mm had very similar pen to the long 88mm. So Spershing should be whatever 88mm 71 is or within 5mm.

      Also, t23 should get Hvap as standard round.

      In wot Calibre often= Penetration but many many smaller calibers had more pen just less DMG.

      I would like an overhaul on Pen v DMG so we could get really cool niche guns. Thats why things like 57mm is so cool at low tier. High pen 85 DMG :)

  9. The description on the American test standards is a bit lax, Naval Criteria and Protection Criteria were both used by US Armed forces, so you’d get wildly varying performance reports about a gun depending on the testing standards used. Naval Criteria is probably the strictest out of these standards since a complete penetration requires an intact round to pass through plate and usual testing is done in excess of 6 rounds, preferably more, to establish ballistic limits of the projectile. If the round breaks up at all, it’s a partial penetration.

    German criteria is pretty similar but they used rounds that were specially made for testing, and it’s 10 shots for 50mm or less and 5 shots for 75mm or greater, while for Naval Criteria caliber was irrelevant until the BL was favorably established and rounds were roundly selected from a production batch.

    US Army and Protection criteria are fairly similar in checking for when a plate “fails” to protect the crew, Naval is more useful in determining if a gun is capable of penetrating and effectively destroying something.