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Detail Page: Armour Angles


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The_Chieftain #1 Posted Sep 20 2013 - 19:02

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Armour is measured with respect to two main factors: The raw thickness of the armour plate, and also the slope of the armour. (Another is the hardness factor, but this is not modelled). This latter is important for two reasons: Firstly, it increases the chance of a ricochet, and more importantly, it effectively makes the armour thicker.
Here’s a pictorial example:
Posted Image
(Note that different countries measure slope differently. In this example, the measurement is from the vertical. Some statistics measure from the horizontal, so instead of ‘0’ read ’90.’ When comparing sources, be sure to verify their reference plane)
The actual effect is a little more complicated, due to the tendency of AP shells to turn into the plate upon impact (“Normalisation”), but you can see the gist of it. The more a plate is sloped compared to the trajectory of the shell, the harder it is for the shell to penetrate, and this effect increases exponentially the more it is sloped.
The mathematical equation for this is as follows: Thickness of the plate divided by the co-sin of the angle from impact trajectory. So, the example for the case of a 100mm piece of plate at a 20° slope from vertical with the shell trajectory being parallel to the ground: 100\cos(20) = 106.4
The practical result of all this is that a gun capable of penetrating a tank without notable sloped armour (eg Pzkfpw III with 70mm) may not be capable of penetrating a tank which has less armour, but is sloped (eg T-34 with 45mm)
Now that you know the effect of slope on armour, you can use this information both offensively, and defensively.
In the defense, use inclines found on the terrain to artificially induce slope. For example, if you can position yourself on a 20° ramp or hillside, your vertical, unsloped armour suddenly has a 20° angle to enemies which are at the same elevation to you. If you already had armour sloped at 30°, that 20° just dramatically increased the effective slope to 50°, with the accompanying exponential increase in effective armour thickness.
Here’s an example by the numbers.
Posted Image
Let’s say we have a tank whose glacis (Upper front slope) is 45mm, steeply sloped at 60 degrees. Our formula gives an effective armour equivalence of 90mm. The tank driver finds a hill which has a slope of 10 degrees. Relative to the enemy vehicle, this armour plate is now sloped at 70 degrees. Plugging into the calculator, that gives us an effective thickness of 131mm.  The benefit of the mere ten degree slope in this situation should be obvious.
What if you find yourself on a piece of flat terrain where you cannot find a ramp to increase your vertical slope? All is not lost. You may not be able to affect the vertical angle of incidence, but you can affect the horizontal angle of incidence. Or, in plain English, if you can’t point your tank up or down, point it sideways.
  No horizontal slope____________Induced horizontal slope
Posted Image
There’s usually not much you can do about your turret: You will obviously be forced to point your cannon at your target, so the target will similarly have a good perpendicular angle on the front of your turret. (If you have a long reload time, consider traversing a little until reload is nearly complete)
However, if your hull is visible to the target, rotate it a small bit. Not too much, as you don’t want to make vulnerable your weak side hull armour, maybe 15-20 degrees or so at the most for a typical engagement, unless you are firing around cover and the hull is protected. This will increase the effective armour thickness in the exact same armour as slope from the vertical does as described above. Remember that although your effective front hull armour thickness will increase exponentially the more you rotate the hull, your effective side armour thickness will decrease exponentially, plus it becomes an easier target.
If you have far too much time on your hands, it is possible to estimate the theoretical ‘sweet angle’ for your tank. Taking the example of a Pzkpfw IV which has 80mm of front hull armour and 30mm to the side, most of which has no vertical slope to speak of, if you rotated the hull 10 degrees, you would have an effective armour thickness of the front hull of 81mm and the side hull, in the unlikely event of a hit, of 172mm. Rotate to 30 degrees, though, and the front hull armour has gone to 92mm equivalence and the side hull has dropped to 60mm, due to the decreased angle. 20 degrees of rotation, however works out as the ‘sweet angle’, with about 86mm of armour equivalence regardless of if the front or side is hit
.
The exact angle for any tank will depend on the ratio of front to side hull armour. Pzkpfw VI has a much lower ratio, with 100mm of front hull armour, and 80mm of side hull armour, all of which, for purposes of this experiment, are pretty much vertical. As a result, the Tiger can ‘afford’ to make the side armour more vulnerable. The ‘sweet angle’ for this tank is some 39 degrees, providing both front and side effective armour values of about 127mm. Most tanks cannot afford to rotate that far, however, before the sides become unacceptably vulnerable.
It is, of course, possible to combine the effects of inducing both vertical and horizontal slope. Place yourself on a ramp or hillside –and- rotate the hull a bit and gain the cumulative benefits of both angles.
So that’s the defensive aspect. A lot of people seem to forget, however, that the maths work the other way as well. You can artificially reduce the effect of your enemy’s armour by positioning your tank accordingly. Usually this means taking the high ground.
Reducing angle of impact
Posted Image
Let’s take a fairly extreme example. This happy-looking Marine is in the driver’s hole of an M1A1 tank, one of the best protected vehicles in the world today.
Posted Image
You can eyeball the thickness of the glacis armour for yourself, but it’s somewhere just over 2”, let’s say 60mm. Doesn’t seem like much, until you realize that the armour is sloped at about 82 degrees from the vertical, making it equivalent to some 430mm of armour from a shell impacting from a trajectory parallel to the ground. An enemy tank positioned on the high ground which applies a mere ten degrees of relative angle which fires and hits the Abrams on the glacis will instead encounter effectively only 194mm of armour equivalent, less than half.
Such relatively shallow elevation advantages may not prove particularly useful in engaging an enemy’s roof or engine deck, as they are still going to have high chances of ricochet and high relative thickness values, but they do mean that front armour plate which was nominally impervious to your cannon may suddenly prove vulnerable. That seemingly invulnerable IS-3 with the sloped thick front hull can be penetrated much more easily in that front hull by shooting at it from an angle a little above and to one side than if you were trying to slug it out on an equal basis from the front.
So use the angles! Just don’t whip out your scientific calculator in the middle of a battle, it’s probably not worth it.
Further information with even greater detail on the game mechanics is available on the Wiki.

pochnof #2 Posted Oct 19 2013 - 18:13

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nice job sir but please i want to now some thing a bout the ratte p 1000 when we can see it on the game ?

KampfenKaze #3 Posted Oct 19 2013 - 18:14

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Greetings World of Tanks!
I am a mechanical engineer working for the development of military equipment. Something to throw on this topic, which I hoped that the information should have been disclosed sooner, is that the effect of angling can be multiplied and compounded. If the angle of your sloped armor is 60 degrees from the vertical, your effective armor would be doubled. However, if you angle your tank 60 degrees from your target, your armor would be doubled again, therefore you would experience an armor equivalent of quadruple your original.
It is quite obvious, if you look in to details of close-combat vehicles, the Russian Heavy Tank, Is7, has a front that is angled back at 60 degrees from the vertical, and then angled back at 60 degrees again, from the horizontal.
There we have the famous pike-nose design...x4 the armor of the original.

Edited by KampfenKaze, Oct 19 2013 - 18:16.


lallau #4 Posted Oct 19 2013 - 18:17

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humm i feel so badass when i increase even more the slope in my jgpanther and become a rubber armor :p

Azyur #5 Posted Oct 19 2013 - 18:19

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I love the Chieftain articles. They are almost always entertaining and, often, informative. What they are not, however, is a guide to solid WoT gameplay. Vehicle, armor and gun values are altered so frequently in WoT that it makes a mockery of any attempt to legitimize them with pseudo-scientific, psycho-babble.

WoT parameters are entirely subjective and  totally dependent upon the  whims and opinions of the development team, at any given time. As such, the best advice is to know your preffered vehicles' current patch values to determine which areas of coded performance are an asset, or deficit against its most likely opponents.

Also, every vehicle has coded weakspots. Learning those areas  can make a huge impact (no pun intended...okay maybe just a bit). Many of those weak zones can be penned regardless of attack vector, or defensive angling.

WoT is a simple game which, like most pvp mmo gaming, boils down to simple dps. Working with team mates and concentrating fire is far more effective in game than finding a good shoot down angle, or cubby hole from which to peekaboo. Although, situationally, all of those skills can be applied to improve upon a solid tactical foundation within the game.

Erich2142 #6 Posted Oct 19 2013 - 18:43

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Some useful information for the new comers. I just wish it was there when i joined 2 years ago.

Ekorus #7 Posted Oct 19 2013 - 18:50

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You need no excess of free time to calculate the sweet angle, it's simply
angle = arctg(lateral armor / front armor)

FaustianQ #8 Posted Oct 19 2013 - 19:06

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I'd like to point out that shells do normalize in the real world, but deflection forces overcome this significantly, the magnitude of which is determined primarily by shell diameter and plate thickness (caveat, this is for full bore, non-CE shells). This is absent in world of tanks to a large degree, so the article gives me the impression it's more about ingame game mechanics.

Ajatcho #9 Posted Oct 19 2013 - 19:14

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this way better than my trigonometry class :teethhappy:

FireAnt333 #10 Posted Oct 19 2013 - 20:01

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View PostAjatcho, on Oct 19 2013 - 19:14, said:

this way better than my trigonometry class :teethhappy:

Indeed! Now I feel as if all these years spent in school are actually valuable for something!  :teethhappy:

Heroilx #11 Posted Oct 19 2013 - 20:40

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Here is the current case with the IS-4:
With Zero horizontal angling, the following calculations are true:
______________________________________________________________________________________________________________________
Incorrect current angle at 59 degrees: which is (140/Cosine59)                     = 271 mm effective armor
For ap rounds its: -5 off the angle for normalization which is (140/Cosine54) = 238 mm effective armor against ap rounds
______________________________________________________________________________________________________________________
The so called bug fix which makes it the correct 61 degrees which is: (140/Cosine(61)) = 288mm effective armor
And for ap rounds its: (140/Cosine 56)                                                                            = 250mm effective armor against ap rounds
______________________________________________________________________________________________________________________
So theoretically, that "Bug fix" will make the IS-4M's UFG better protected against being penetrated so easily by almost 17mm overall, and by almost 12mm vs Ap rounds

GoodGameXXX #12 Posted Oct 19 2013 - 20:46

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View PostFaustianQ, on Oct 19 2013 - 19:06, said:

I'd like to point out that shells do normalize in the real world, but deflection forces overcome this significantly, the magnitude of which is determined primarily by shell diameter and plate thickness (caveat, this is for full bore, non-CE shells). This is absent in world of tanks to a large degree, so the article gives me the impression it's more about ingame game mechanics.
I thought there was some consideration for shell diameter and penetration, at least I think there was at some time.  Seems like they reworked it a few times in patch notes though.

Edited by GoodGameXXX, Oct 19 2013 - 20:46.


the_moidart #13 Posted Oct 19 2013 - 21:10

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You should have mentioned pausing while coming down a hillside makes you much more vulnerable to those below, if theyre far enough away to be sufficiently above your middle line, relatively speaking. I've seen T95's picked off frontally due to this.

Snrub_MC #14 Posted Oct 19 2013 - 21:13

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View PostAzyur, on Oct 19 2013 - 18:19, said:

I love the Chieftain articles. They are almost always entertaining and, often, informative. What they are not, however, is a guide to solid WoT gameplay. Vehicle, armor and gun values are altered so frequently in WoT that it makes a mockery of any attempt to legitimize them with pseudo-scientific, psycho-babble.

WoT parameters are entirely subjective and  totally dependent upon the  whims and opinions of the development team, at any given time. As such, the best advice is to know your preffered vehicles' current patch values to determine which areas of coded performance are an asset, or deficit against its most likely opponents.

Also, every vehicle has coded weakspots. Learning those areas  can make a huge impact (no pun intended...okay maybe just a bit). Many of those weak zones can be penned regardless of attack vector, or defensive angling.

WoT is a simple game which, like most pvp mmo gaming, boils down to simple dps. Working with team mates and concentrating fire is far more effective in game than finding a good shoot down angle, or cubby hole from which to peekaboo. Although, situationally, all of those skills can be applied to improve upon a solid tactical foundation within the game.

None of what you said makes learning about angling any less important. "pseudo-scientific, psycho-babble" wtf?

1)Doesn't matter how much armor changes or how often, angling to improve your armor is always better than not.

2)"coded weakspots" you make it sound like those are in at the whim of the Devs (some of it is but mostly they reflect RL weakspots).  The_Chieftain is teaching general WoT basics and focusing in on 1 specific topic each article.  You need to know how best to position every tank in the game as well as what their individual weakpoints are and how to hide them.

3)Obviously team work is important, but while you are concentrating your fire, maybe being in the right position to consistanly pen a tank is good? or not get damaged in the process?

CBR08 #15 Posted Oct 19 2013 - 21:14

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In the first example with the T-34-85, the enemy would just shoot the lower plate.

Chrysblade #16 Posted Oct 19 2013 - 21:18

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I clicked the linky thing and found myself in World of Smater-than-you-people... :hiding:

Veo #17 Posted Oct 19 2013 - 21:26

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Here's an excel sheet i whipped up a while ago.
the thickness of the armor is on the left, while the angle of the armor is on the top. intersection is the effective armor rating.
Posted Image
page 2-
Spoiler                     

Edited by Veo, Oct 19 2013 - 23:15.


Ignii #18 Posted Oct 19 2013 - 21:41

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How would you calculate the effective armor thickness of plates that are angled in two or more axes (e.g. the pike-nose on the is3 which is angled both back and to the sides)?

Poinciana #19 Posted Oct 19 2013 - 21:47

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What is co-sin? How do I find it's value?

Ignii #20 Posted Oct 19 2013 - 22:05

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View PostPoinciana, on Oct 19 2013 - 21:47, said:

What is co-sin? How do I find it's value?
It's a trigonometric function. Just type "cos A degrees" into google or wolfram alpha, where A is the angle of the armor plate.




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