Almost eight tons of German high-alloy steel!

A threat to any enemy!

The most powerful gun in World of Tanks!

Thousands dream of it!

Millions tremble before it!

But sometimes even this gun can't compensate

for the “outstanding” skills of a player.

To avoid this happening too often,

today we'll talk about armor penetration.

Explaining Mechanics Armor Penetration

Any gun has a standard set of characteristics:

damage, accuracy, aiming time, and rate of fire.

But all this is useless

if you're unable to penetrate the armor.

To fire effectively, you should learn

how penetration mechanics work, understand their principles.

Let's start with some theory from our confidential informant.

Every shell in the game has its penetration capability.

The documentation specifies its average value

when firing from 100 meters.

The actual penetration can be 25 percent higher or lower.

The damage caused is calculated in a similar manner.

Thanks, CI!

Let's go further and have a small experiment.

We'll take two T57 Heavy and two AMX tanks.

This choice is not accidental:

both vehicles feature 120-mm guns, equal average damage,

and almost the same penetration

with Armor-Piercing and High-Explosive shells.

The key difference is the type of Premium shells they have.

The AMX features Armor-Piercing Composite Rigid shells,

and the T57 Heavy can fire High-Explosive Anti-Tank shells.

The targets are placed not far from our vehicles.

I don't think any of the tanks will have problems

penetrating their armor, but let's see.

The first tank fires an AP shell;

the second shoots an APCR shell;

the third vehicle goes for a HEAT shell;

and the fourth firesan HE shell.

None of them had a problem.

Let's make the task more complicated:

we'll put the targets behind cover and repeat the experiment.

As you can see, the result is a bit different...

The HE shell dealt only splash damage,

and the HEAT shell got stuck in the fence.

But this isn't over yet.

Now we're going to remove the obstacles

and take the target a bit farther away.

The guns fire, and...

The result is different again.

Few people realize

that different shell types would be best

for firing at the same target in different situations.

To do this correctly, you need some theory.

As you know, there are four shell types,

each with its unique properties.

The main shell type used by most tanks

is the Armor-Piercing shell.

These shells fly quickly,

but their penetration capability slightly reduces with distance.

Their penetration capability also reduces

when they hit a destructible object, like a fence or a vehicle.

The fastest shells are APCR ones.

Only weekends pass by faster.

APCR shells can go through fences too,

but with distance they lose

their penetration capacity more than AP shells.

The HEAT shell is a different story.

Its penetration capability doesn't depend on the range

and remains the same along the entire trajectory.

But this comes at a price: this shell is the slowest one.

And if it hits a fence, it won't go any farther.

HE shells fly almost as fast as AP ones,

and they don't lose their penetration power with distance.

After hitting any object, an HE shell detonates,

and its fragments can damage a vehicle nearby.

In addition, these shells have the highest potential damage

and the lowest penetration capability.

And now let me give you some pieces of advice.

If you want to cause damage through fences,

fire AP shells or APCR shells.

To fire at a slow and well-armored vehicle

located far away, you'll hardly find

anything better than the HEAT shell.

If you take a shot at scouts from a long distance,

the ideal choice is the APCR shell.

And if your enemies are paper-thin,

send them some High-Explosive “parcels.”

And some more tips.

Any destructible building consists of sections.

If you want to destroy the building quickly,

fire an HE shell at the joint between these sections.

You can also use an HE shell to knock down a tree.

Or knock off the base capture

without exposing yourself to enemy fire.

With a large-caliber HE shell

you can even shoot down an airplane!

…That last one is a joke, of course, but the rest work!

…So, we already know how shells fly.

But what about all these hits,

ricochets, penetrations, and non-penetrations?

That's simple!

We have two parameters:

shell penetration capacity and armor thickness.

Both are measured in millimeters.

If the first number is higher than the second one,

the enemy receives damage.

Arithmetic, first grade!

However, this is true

when the shell hits the armor at a right angle.

In other cases,

the penetration power is calculated differently…

Let's take a point on the armor

and draw a tangent and a normal through it.

Speaking simply, a perpendicular line.

The shell's angle of entry

is an angle between the normal and the projectile's trajectory.

In this case,

the shell has to penetrate a much thicker layer of armor.

The relative armor is calculated

as the ratio of the nominal armor thickness

to the cosines of the entry angle.

The smaller this angle is,

the higher the chance of penetrating the armor.

Geometry, seventh grade!

That's why you shouldn't always fire rapidly.

Sometimes, it's better to wait a few seconds

and fire with certainty.

Each vehicle has its weak spots.

Normally, these are the cupola,

driver's hatch, and lower glacis plate.

However, if there isn't any chance to choose,

the theory will help you again.

To ensure higher shell effectiveness,

the design of shells allowed them to shift,

adjusting to the normal vector.

This resulted in thinner relative armor.

This effect is called “shell normalization.”

The normalization angle for AP shells is five degrees.

The normalization angle for APCR shells is two degrees.

HEAT shells are not subject to normalization at all,

neither are HE shells.

That's how it looks in practice!

The armor plate thickness is 38 millimeters.

The shell's entry angle is 60 degrees.

In this case, the thickness of the relative armor

is 76 millimeters, which is one millimeter thicker

than the maximum allowed penetration capability of the shell.

However, we know that AP shells normalize by 5 degrees.

Due to this, the relative armor thickness decreases,

which gives us an opportunity to penetrate the vehicle's armor.

Not each time, but still.

But there's more than that!

Using a higher caliber will allow...

And now we will talk about one of the main axioms

of armor penetration mechanics: the Two Calibers Rule.

This rule says:

If the shell caliber is more than twice the nominal armor thickness,

the shell's shift angle to the normal vector

increases according to the formula:

So!

If you use a higher caliber,

the normalization factor will greatly increase!

The target, the angle,

and the armor penetration performance is the same.

But the shell has to pierce 50 millimeters of armor

instead of 66 millimeters.

Now, each shot results in damage!

But that's too simple!

Let's increase the angle.

It's still able to penetrate, but wait,

what do we have here?!

Ricochet!

By the way, talking of ricochets!

AP shells and APCR shells

ricochet at an angle of 70 degrees or more,

losing 25% of their penetration capability.

HEAT shells ricochet at an angle of more than 85 degrees

with no loss to their penetration capability.

HE shells don't ricochet at all.

And now it's high time for another important axiom

in World of Tanks: the Three Calibers Rule.

It only applies to AP shells

and APCR shells and says the following:

If the shell caliber

is more than thrice the nominal armor thickness,

there will be no ricochet.

Whatever the thickness of the relative armor,

the shell will attempt to penetrate it at any angle.

Woah-woah-woah!

Easy!

In summary, if the angle is more than 70 degrees,

there's no point in using

AP shells or APCR shells.

Unless you're trying to aim

at an enemy vehicle hiding behind a building!

Or you're firing from a really big gun!

If you use HEAT shells, you can fire at even greater angles.

However, note that this type of shell

doesn't normalize and it will have to pierce

the whole thickness of the relative armor.

So, don't be too surprised if you hear

“We didn't penetrate their armor.”

But we're not finished!

We haven't mentioned the screens!

When an Armor-Piercing or Armor-Piercing Composite Rigid shell

hits spaced armor, the following happens:

The entry angle

and the shell's precise penetration capacity are calculated.

At the same time, the ricochet

and the Three Calibers Rule are being verified.

If neither of the two is triggered,

normalization and relative

armor thickness are calculated.

Then, if the shell has enough piercing power,

it penetrates the screen.

But its penetration capability

is reduced by the value of relative armor thickness.

Then, if the projectile hits the main armor,

the abovementioned calculations are made again.

And it's only after this

that damage is or isn't inflicted on the enemy vehicle.

When a HEAT shell hits the screen,

the situation is somewhat different.

The Three Calibers Rule doesn't apply here,

the ricochet angle is different, and the shell doesn't normalize.

Hence, the cumulative jet attempts to pierce the screen

at the same angle as the shell's trajectory.

If the armor has been penetrated,

this jet will lose 5 percent of its armor-piercing power

for every 10 centimeters of travelled distance.

That's why HEAT shells rarely deliver damage

when hitting spaced armor or tracks.

The effect on the armor made by High-Explosive shells

is quite a long story, which we'll tell you next time!

And now, a few words about one painful issue:

“Critical hit.”

This doesn't happen very often,

but every time it does, players get frustrated.

This message should be familiar to every tanker.

It's played when a shell penetrates the screen

but doesn't hit the tank's main armor.

And if a shell penetrates the screen,

then hits the main armor, but fails to penetrate it,

the player hears “We didn't penetrate their armor.”

You can also hear this message when firing at any external module.

Each gun, track, and piece of optical equipment

has its own armor thickness.

When a shell hits these elements,

it doesn't rebound and has to pierce through their armor.

After this, if the projectile doesn't hit the main armor,

the player hears “Critical hit.”

And if it actually hits the main armor

without penetrating it, the firer hears