Friday, 1 March 2013

Accuracy

Popular history is generally of the opinion that German tanks were superior snipers. You hear many tales of Tiger tanks effortlessly destroying their targets from miles away, while Allied tanks had to close to a very short range. This range will depend on who you ask, but many agree: German guns were much more precise than those of the Allies.

However, engineers should not be satisfied with hearsay! Let's take a look at some test results of the D-25T gun mounted on the Soviet IS-2 tank.

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The caption for the first picture reads: "Figure #2: Graphical depiction of shooting results during a D-25 accuracy test, from a distance of 1000 m." The small circle, marking the 5 most accurate shots, is 24 cm in radius. The large circle, marking all shots, is 80 cm in radius.

The caption for the second figure reads: "Figure #3: Graphical depiction of shooting results during a D-25 accuracy test, from a distance of 1900 m." The small circle, marking the 5 most accurate shots, is marked 45 cm in radius. The large circle, marking all shots, is 120 cm in radius.

What does this all mean? The casual viewer might see that this accuracy is good, but "good" has no place in engineering. Let us compare these results to contemporary German guns, the Tiger and Tiger II (often erroneously referred to as King Tiger). 

According to Jentz' Germany's Tiger Tanks - Tiger I and II: Combat Tactics, the KwK 36 8.8L/56 gun had 100% accuracy against a 2.5 meter by 2 meter target in training conditions (known range). The KwK 43 8.8L/71 gun on the Tiger II also has 100% accuracy at this range. Since the maximum deviation of the IS-2's D-25T is 80 cm at that range, it is safe to say that it can achieve 100% accuracy at that range as well.

Now, let's go up to 2000m. The accuracy of German tanks decreases slightly: 87% for the Tiger and 85% for the Tiger II. To see how the IS-2 measures up, let's hold up an imaginary 2.5 meter by 2 meter target to the distribution, like the Germans would be testing against.


As you can see all shells fall within the target's surface! By German metrics, the IS-2 has 100% accuracy at this range, even higher than the accuracy of the Tiger and Tiger II. Now, this is only one 10 shell trial, and the Soviet distance is 1900 m instead of 2000 m, so I cannot readily say that the IS-2 is more accurate than either of the German Tigers, but the reader can clearly see that the accuracy of the Soviet D-25T gun is at least comparable. According to a table of penetrations that will be the topic of a later post, the D-25T's armour piercing shells could defeat 129 mm of flat armour or 105 mm of armour angled at 60 degrees, enough to penetrate all armour of German tanks, aside from the upper glacis plate of the King Tiger. 

Let's take a look at another Soviet tank gun, the ML-20S howitzer that was mounted on the SU-152 and ISU-152 tank destroyers. This test uses a reduced propellant charge, the variable #6 one.

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The ML-20S was a howitzer, which are characterized by a larger caliber to barrel length ratio. This leads to a round that is not as accurate as one fired from a gun. Let's take a look at the results. 

At a distance of 1000m, the ISU-152 fired 10 HE-fragmentation shots towards the target. 50% of the shells landed within a circle with a 32 cm radius, and 100% of the shells landed within 96 cm. Obviously, not quite as good as the IS-2, but still respectable, and still a 100% accuracy metric by German standards. At this distance, an AP shell penetrated 124 mm of armour, which was enough for any German tank that was not a Tiger II. However, it did not have to penetrate. The 152 mm howitzer often shot HE rounds only, which was enough to literally tear any tank unlucky enough to be hit by them apart

In conclusion, despite what the popular history might have told you, Soviet tanks were very dangerous to German tanks, even at a large distance!

Edit: a few people were questioning why the distributions are circular, instead of oval. They're really not, which I explain here, along with data for a lot more guns.

20 comments:

  1. This comment has been removed by the author.

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  2. hi, this test says nothing about the quality of the sighting devices used to aim the guns. I'd expect a test site to use the best instruments on a clear day with no distracting noise or smoke to simulate a tank gunners environment. Russian glass optics were low quality, greenish glass sometimes with bubbles making fuzzier dark images . Compared to Zeiss optics, probably the worlds best in WW2, in scopes with a choice of different magnifications, the russian glass wasnt as good, so russian accuracy wasnt as good.
    Theres also the conditions inside the tanks to consider. German tanks were generally noted for their high crew comfort and well thought out controls, whereas russian tanks were rougher and needed greater crew effort. Fume extraction was better in german turrets. Communications were better in German tanks, useful for reporting target changes and fall-of-shot.

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    1. American reviews of Soviet optics call them "the best of those known worldwide". Blind devotion to mythical Zeiss quality is not based on any actual historical evidence.

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    2. Hello, could you please send me or post that American reviews? I just want to read more about it :P

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    3. Look up the Aberdeen report on the T-34, it's a pretty well known document.

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  3. Wow what a full crap of bias shit. I mean who on earth can believe this Russian crap? Every Russian site tells totally different stories to all none Russian. This is nothing more than for the time period, propaganda in favour of the useless Russian guns. Everyone who got atleast a clue about guns can realize that the Soviet 152, 122mm guns were performing accuracy wise somewhere at 1/2 to 1/4 of the accuracy of the German 88 l71. In terms of penetration, 124 pen is not enough to penetrate the Tiger II anywhere as even the lower glacis has over 160 armour when slope is taken into account. Also Panther tank's weakest spot is about 113 so the only part of a Panther it could penetrate was also lower glacis plate. So, in total. Of the germans 2 best armoured tanks, 1 couldn't be penetrated and the other could be penetrated almost from underneath, aka, it would occur maybe something like 1/6-1/10 shots aiming frontally. Not to forget ofcourse that already at a 30 degree angle, the shot couldnt penetrate the Panther's front armour anywhere at all.

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    1. "Anyone with a clue about guns" is not a primary source, I'm afraid. And if you click around the site, you will see that the ML-20 could wreck a Tiger II or a Panther pretty conclusively. A Ferdinand, even! Here you go: http://tankarchives.blogspot.ca/2013/03/suisu-152-vs-german-big-cats.html

      It is my most popular article for a reason.

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    2. lol @ this Biased BS blog

      so funny

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    3. lol @ pathetic little ignorant boys that were raised by a consumer society of self centered children

      not funny, it's sad, really, really sad.

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    4. lol @ stupid wehraboos

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    5. All you german fanboys are rediculous, you have just been filled with german propaganda, the D25T was probably better than the german 88's because it was just about as accurate except it had much more destructive power. And for all you saying that soviet optics were bad, well they were either just as good or better. And final thing the IS2 beats the Tiger2 anyday, for soo many reasons.

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    6. Yeah, USSR actually bought a German factory and equipment for making optics... That's why Russian optics in WW2 was comparable in quality.

      IIRC what makes german optics "special" is that they offered an extra level of magnification, which helped in acquiring target.

      But that does not mean Russian guns or optics are straight up worse like wehraboos thought(or rather, didn't think).

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  4. It's always fun watching people think that accuracy is just a matter of optics and nothing else. The shell doesn't come out of the sight, it comes out of the gun. Properly designed optics (magnification, clearness, and sight clutter, just to name a few) are a result of many features and can help to better identify and range targets, but they do not affect what the shell does.

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  5. I find some interesting discussion at https://forum.warthunder.ru/index.php?/topic/132350-o-kuchnosti-tankovykh-pushek/#entry4001870
    I not good at russian, but he says that soviet's accuracy is DIAMETER of circle with 50% and german's is RADIUS of this circle. Please anybody translate his post

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    1. sorry, i write with mistake. Must be: soviet's accuracy is RADIUS of circle with 50% shots and german's is DIAMETER of this circle

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    2. Gunnery tables discuss deviation, not radius. In addition, practical trials showed that this assertion is incorrect http://tankarchives.blogspot.ca/2015/03/tiger-ii-trials-gunnery.html

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  6. You say that it is erronous to call the Tiger II "King Tiger". That is not so. In German it is called "Königstiger". That's what the Germans call bengal tigers. You might say that the correct name then would be "Bengal Tiger", but the litteral translation of "Königstiger" IS "King Tiger". Things have diffrent names in diffrent languages and the Germans call the bengal tigers "king tigers" and since Tiger II is a German tank the German name should be used, which would be "King Tiger" if said in English.

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  7. Statistically speaking, the single, ten shell trials are not representing a sufficiently large sample size to base anything on.
    What is required to determine mean dispersion and standart deviation is a sample of at least 100, better 200 aimed shots.

    the conclusions drawn are made from too thin data. It´s certainly not safe to jump from a single case observation to a generalization.

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  8. Hello guys,
    I'm from Russia, let me explain these numbers.

    It is co-called "technical" grouping, not accuracy. It tells us only about quality of barrel. You know, like 1 MOA for rifles and so on. It totally undependends on crew traning and other real life parameters.

    Unlike this, german guide tells exactly about integral parameter of accuracy, wich includes crew traning, stress etc. Cheers!

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  9. It seems important to note the word "RADIUS".
    In german sources, 50% deviations are given as ZONES "Streuung in 50%", not radii.

    This means, f.e. 88mmL71 Pgr.39 width: 30cm, height: 50cm at 1000m
    This zone is not similar to radius but equals more it´s diameter (not actually, since the calculation frame was a rectangle in german sources, not a circle). 50% Radius to conform with SU defintioons would be for the same gun at 1000m: width 15cm, height: 25cm.
    At 1900m: 35cm x 45cm

    Tighter than with 122mm D25T -as could be expected.

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