World of Tanks. Explaining Mechanics - Penetration, Part 1

Uploaded by WorldOfTanksCom on 05.11.2012

Greetings to you all, players!
This episode of “Explaining mechanics” will tell you about one of the most important aspects of the game: armor penetration.
Understanding armor penetration algorithms is essential for every player. In point of fact, it can help you inflict more damage to enemy vehicles and protect your
own vehicle against hostile fire more effectively.
That is why this episode will teach you to protect your tank, and the next one will tell about destroying enemy tanks.
Remember that “World of Tanks” is a game, not a training simulator.
We do our best to keep it aligned with real tank combat principles, but some artificiality is inevitable in order to make the battles more dynamic.
The actual processes calculating the effects of a shell hitting armor are too complex to be calculated “on-the-fly”, and the range of consequences is so broad that, in
comparison, Brownian motion looks simple.
For example, if a shell tries to penetrate armor head-on, it would seem to have its maximum penetration potential.
But in real battles, a shell can break apart due to severe internal stress, resulting in zero penetration potential.
Game physics allow for a 25 per cent fluctuation compared to the value in the description.
For example, if the penetration value of your MS-1’s main gun is 51 millimeter then its real value will range from 38 mm to 64 mm.
The Damage value range is calculated the same way.
Before we start discussing penetration mechanics and geometry theory, let’s explain some terms we are going to use.
Take a point on the armor and draw a tangent through it.
A straight line perpendicular to the tangent drawn through this point is the “normal axis”, or the perpendicular.
Now don’t you wish you had paid attention in geometry class in school?
Let’s move further and explain what “impact angle” is.
It is the angle between the normal axis and the shell path from the point of impact;
For example, if this angle is 0 degrees, the penetration probability is at its highest, and if it is 80 degrees, then the shell is more likely to ricochet.
It should also be noted that many players consider the impact angle to be the angle between the tangent and the shell path. For example, they’ll say that ricochet
chances are high if the impact angle is less than 30 degrees. However, we’ll stick to the terms used by our developers and the military, and compare the angle to the normal axis.
Another term is “Effective armor thickness”.
If the impact angle is large, the thickness of the armor is actually larger than the nominal armor thickness in the description.
This “effective armor thickness” you actually have to pierce can be calculated as the ratio of armor thickness to impact angle cosine. So now you’re also regretting
sleeping through algebra, right?
Of course, we don’t expect you to arm yourself with a protractor and calculator evaluating effective armor thickness. Just remember this simple and intuitive rule: the
greater the impact angle is, the thicker the actual armor you will have to penetrate.
To understand where and how you should aim to penetrate your opponent’s armor, you can use the penetration indicator on your reticle.
If the indicator is green and your shell hits the enemy armor on the normal axis, the enemy tank will likely be damaged.
If it is orange, the odds of penetrating the armor are fifty-fifty.
If it is red, don’t waste your shells – you’re not going to penetrate the armor.
But the color of the indicator isn’t what you should ultimately rely on.
The armor of a tank can be positioned at various unexpected angles, and your shell may deviate from the center of your reticle and hit the armor in a slightly different spot.
If you are trying to hit the glacis plate of a tank which is at an angle to you, like a diamond, you may fail to penetrate it.
Even if the nominal armor thickness of this tank is 50 mm, this angular position means that your shell has to deal with 60, 70, or 80 mm — or even more, but the
penetration marker color based on the actual armor thickness remains the same.
But don't get all worked up over that! Keep in mind that tank armor acts exactly the same in the real world. That is why tank engineers take this into consideration
and design their shells so that they tend to decrease impact angle and bring it closer to 0 degrees at the moment of hitting the armor.
This effect is called “shell normalization” and is around 4-5 degrees in World of Tanks starting with the 0.8.0 update.
This means we can adjust our effective armor thickness formula to take into consideration the normalization angle:
If your shell hits the enemy’s armor at an impact angle of 45 degrees, the final impact angle after normalization will be 40 degrees, which will make the whole
penetration process slightly easier.
Let’s calculate effective armor thickness with normalization for two well-known tanks: the PzKpfw VI Tiger and the PzKpfw VIB Tiger II.
For descriptive reasons we’ll shoot each tank from the front, 50 m away from them, and fire at their glacis plate with main guns that have a penetration potential
about the same as the thickness of the armor.
To make things simpler, we’ll assume that the shell’s path is parallel to the ground.
Let’s start with the Tiger. Its upper armor plate thickness is 100 mm and its deviation is only 9 degrees from vertical line.
The impact angle is the same, and normalization effect makes it 4 degrees.
Let’s try the KwK 40 L/48, which has an average penetration of 106 mm.
That’ll result in multiple armor penetration, before the 25% penetration variable is applied, as the effective armor thickness in this case is still 100 mm.
Now let’s take a look at the King Tiger. Its upper armor plate thickness is 150 mm.
We’ll test its toughness with the 90 mm Gun M3 that has a penetration potential of 160 mm.
Most shells don’t do significant damage to this tank, as its glacis’ deviation is around 50 degrees, and this means that its effective armor thickness is 212 mm, which is pretty impressive!
The maximum penetration of our main gun for AP is only 200 mm. This means that the “king” won’t even be disturbed by impacts of our AP shells on its upper armor plate.
The normalization effect we mentioned before won’t do any good if the impact angle is more than 70 degrees. Then the shell will certainly ricochet.
This is important: don’t take random shots. You must estimate the angle your shell will hit your enemy’s armor at before you shoot, so you don’t waste your ammo or expose your position.
Even after a shell ricochets, it can still cause damage to the target, but this is possible only within one vehicle.
Playing pool won’t work here though: don’t lay your account for hitting more than one tank with one shell using ricochets.
There is no ricochet if you use an armor-piercing or sabot shell and the shell's caliber is more than 3 times greater than the thickness of the armor: then it will try to
penetrate the armor irrespective of impact angle.
If a shell hits any external modules, such as the tracks, main gun, or observation devices, there will also be no ricochet regardless of impact angle.
Modules have their own damage model: every module has its own armor and hit points. Also, the rules for estimating armor thickness cannot be applied to modules
— the thickness of armor you must penetrate always stays the same.
If penetrated, the module loses hit points, and the shell continues moving and may yet damage the rest of the tank. But the penetration potential of the shell
decreases according to the armor thickness of the damaged module, so it may fail to penetrate the hull armor. The external modules can protect your hull armor, but
they may be damaged or destroyed.
Vehicle armor comes in two types:
solid armor and the so-called spaced armor.
Penetrating solid armor will decrease the hit points of the enemy tank. Penetrating spaced armor will decrease shell’s penetration potential.
Spaced armors are usually situated at a certain distance from solid armor and are rather thin, except for main gun mantlets.
It is important to understand that destroying spaced armor doesn’t damage the tank’s hit points.
This is one of the most common reasons for unexpected hits that do not do any damage to the target.
Don’t forget that penetration potential fluctuates.
If a shell manages to penetrate spaced armor, its penetration potential can be decreased so much that it fails to penetrate the underlying armor.
You must know by now that there are various types of shells. These shells have different effects when striking enemy armor:
Armor-piercing shells are subject to normalization and ricochet rules in full force and effect.
Sabot shells differ from armor-piercing shells only in their increased penetration potential.
High-explosive shells don’t ricochet and have lower penetration values, but can inflict damage even if exploding right on the armor or even near the vehicle.
HEAT shells have increased penetration and don’t ricochet, but their drawback is that they get no advantage from normalization rules.
Now it’s time to summarize armor penetration theory and move on to practical recommendations for armor penetration.
Take aim and fire!
Your shell hits the enemy vehicle on its spaced armor.
What processes take their place next?
The first step: the server calculates the path of the shell according to the ballistic formula, determines the point of impact of the shell and its speed vector at that moment.
Then the angle between the normal axis and the armor at the impact point is calculated.
If this angle exceeds 70 degrees, and the shell’s caliber is less than triple the armor thickness at that point, the shell will ricochet.
The second step: if the shell didn’t ricochet and its caliber exceeds the armor thickness by more than two times, then the normalization value is increased for AP and
sabot shells in proportion to the ratio of shell caliber to armor thickness according to the following formula:
As you see, if a shell is of much greater size, it will penetrate the armor easier.
The third step: at this stage, the penetration potential value of the shell is calculated.
This depends on firing distance — shooting from more than 100 m away decreases the shell’s penetration— and also on the random 25% fluctuation value.
The fourth step: After penetrating the spaced armor the shell keeps moving, but its penetration potential is reduced by the thickness of the spaced armor.
If the shell hits the primary armor after completing those steps, the whole algorithm gets repeated:
ricochet test, shell normalization, and calculation of final penetration.
If the underlying armor is penetrated, the vehicle is damaged by the shell using its average value plus or minus 25%.
It is also interesting to note that in real combat the shell changes its path as a result of the normalization effect; but in the game,
it just continues along its normalized flight path into the vehicle.
This algorithm is used in sequence —
first for spaced armor and external modules, then for regular armor.
As can be easily understood, a shell may penetrate several layers of armor, as it penetrates one layer after another.
In the next episode, we will talk about how the shell moves around inside the tank, some peculiarities of HEAT shells, and the effects of high-explosive shells.
Now it’s time for the most interesting part of our program. We’ll tell you some tactical techniques that can help you protect your tank in battle.
Can we use mathematical theory for that? Of course we can! Now we’ll explain several basic techniques that are based on this information.
So let’s go!
Technique #1: parking your tank at an angle. This is the so-called “invincibility position”.
You should position your tank so it is diagonal to enemy tanks, so their shells will hit your armor at an angle and the effective armor thickness will be at its peak.
To do this right, you should be familiar with your tank’s armor. If you do it just right, the enemy will have considerable difficulties trying to penetrate your armor.
Here’s an example using two well-known vehicles: the Soviet heavy tank IS-7 is armored so heavily in the front and poorly on its sides, that it’s better to face the
enemy head-on than diagonally. On the other hand, the German PzKpfw VI Tiger is more resistant when parked at an angle, due to its massive, flat frontal armor.
Technique #2: peeking around the corner.
You should always drive “cutting corners” so as to protect your vulnerable hull side and your tank’s tracks.
You should also keep in mind the composition of your vehicle armor so that enemy shells hit only the most protected parts of it.
You should expose your tracks only in case if your enemy has just taken a shot or doesn’t see you.
Don’t forget this basic rule of tank construction: almost every vehicle is protected better on its front than on its sides, and it is protected better on its sides
than from behind or from above.
This is why you should keep your front and frontal angles turned toward your most dangerous opponents.
Technique #3: Making use of horizontal rocking.
You can perform this common technique by driving your vehicle from left to right and back in short dashes.
With this trick, your enemy won’t be able to aim at your weak spots accurately and fire at your vertical armor gaps.
This is especially helpful when your armor is relatively flat. While reloading, you can rotate your turret. We warrant you that the enemy will have major difficulties aiming at its sides.
Technique #4: “Becoming a bait fish”.
Now that’s a challenge. You have to be a real pro to do this right!
Let your enemy fire at your hull side and then quickly turn into diagonal position.
This way the shell will ricochet. As a result, your tank won't get damaged.
Sudden, surprising movements are always useful in an engagement if you can manage to keep you crosshairs on the target.
Nevertheless, don’t forget that rotating the hull also decreases its speed.
Technique #5: Try dueling with your enemy from behind cover.
A tank’s turret armor is usually thicker than its hull armor. This means you should try to hide your vulnerable glacis plate behind some cover.
Indestructible obstacles, for example, a disabled tank or a hill, are perfect for a “hull down” position.
However, “single-shot obstacles” like a car, a stone fence, or a shaky barn can also be used for this purpose.
They will only protect you against one or two shots.
Your enemy will have to aim at sides or running gear: the most protected parts of your tank. What is more, the impact angle of the enemy’s shells will be very large.
You can get a ricochet — or one of your external modules might get damaged — but you won’t lose any hit points.
If you are going to attack, you can turn or roll away a bit and then return to your basic position after you have fired.
If you do everything right, this will make it hard for the enemy to aim at your weak spots.
Technique #6: Using ground cover and shooting suddenly from unexpected places.
Buildings may have windows and doors you can shoot through; ruins may have gaps that can also help. Fences and rock walls are a good opportunity to blaze away
at your enemy with only a tiny part of your turret exposed.
Use these places, study the maps, and try to remember any advantageous positions you’ve found!
That’s it for now!
We hope this episode and the information provided in it will be effective for keeping your enemy in view longer — and keeping you out of the Garage.
You are always welcome to visit our official World of Tanks forums to get relevant information, especially in the “You Ask — We Answer” and “Game Mechanics” forums, etc.
In our next episode, we are going to tell you about many other useful things. You’ll learn how to destroy the enemy, how exactly the damage value is calculated, and what is “right to the last shot”!
Good luck — and good-bye until next time! �