How it Works: Armor | World of Warships

You already know, from the
previous episodes of How it Works, how armor-piercing
shells deal damage. But in order to deliver their harmful
payload to a ship’s vital compartments, they need to penetrate
the armor first. In today’s episode, we’re going
to talk about how the armor works, and how to penetrate
it the right way. How It Works The velocity of a shell, its mass, and the shell to armor incidence
angle affect armor penetration. However, a ship’s armor is a complex
multi-layered system of armor plates. The multi-layered armor structure is the primary feature
of the armor in World of Warships. Now let’s demonstrate
this with an example. New York fires an armor-
piercing 356-millimeter shell causing 10,000 damage to the side
of Fuso from a distance of 18 kilometers. The armor penetration of this shell
at such a distance is 204 millimeters. At the point of impact, the shell will
meet 19-mm antitorpedo protection, a 203-mm casemate armor belt,
and finally, a 99-mm citadel armor deck. In total, 321 millimeters. When a shell hits armor,
several checks are made. The first of them
is the 14.3 caliber rule. If the armor is thinner
at the impact point than a shell caliber divided by 14.3, then the shell won’t
ever bounce off the armor, regardless of the angle of incidence. Then, the penetration check starts. The antitorpedo protection,
of course, doesn’t stand a chance. But these 19 millimeters did their job and reduced the armor
penetration of the shell. 204-19=185. All the checks have to be done again
for each of the following armor layers. The 14.3 caliber rule
doesn’t work with 203 millimeters. Next, the second check
applies, the ricochet calculation. If the incidence angle is from 0 to
30 degrees, it’s 100% a ricochet. If the incidence angle
is from 31 to 45 degrees, the probability
of a ricochet is reduced. And, finally, if the incidence
angle is from 46 to 90 degrees, a ricochet is practically impossible,
and the armor penetration check starts. By the way, we should
note that British cruisers and American 203-millimeter cruiser
guns have sharper ricochet angles— ricochet is impossible
even at 30 degrees. New York’s shells have
two possible future outcomes: if there is no ricochet, then the remaining 185 millimeters
of the armor penetration, left after the shell goes through the
19 millimeters of antitorpedo protection, won’t penetrate the 203 millimeters
of Fuso’s casemate armor belt. The shell will detonate
and it won’t do any damage, because the explosion occurs
in the antitorpedo protection that is specifically designed
to prevent damage to a ship. The second outcome: the shell hits Fuso’s side at
a sufficiently sharp angle, bounces off, then, hits the 19 millimeters
of antitorpedo protection again, penetrates it according to the 14.3
caliber rule, and falls into the water. Now, let’s place New York closer
and fire a shell from 15 kilometers. The armor penetration
at such a distance is 224 millimeters. [224-19=205] That’s why New York has every chance
of penetrating the casemate armor belt and inflicting damage on Fuso following the rules we
discussed in our previous episodes. But this will happen only if the
shell to armor incidence angle is close to 90 degrees. The thing is, the shell penetration
is compared with not only the armor, but with the relative armor. Relative armor is the armor thickness calculated taking into account
the shell to armor incidence angle. The sharper the angle, the more
armor a shell needs to penetrate. A deviation of 5 to 10 degrees
will lead to the following: both the antitorpedo protection
and the casemate armor belt will become thicker
by a few millimeters, but it will be sufficient enough to prevent the 205 millimeters
of the shell penetration from piercing the 203-millimeter armor
and Fuso will remain undamaged. However, an AP shell has another
important parameter—normalization. It’s a small increase (but as we
saw, even a few degrees matter) of the angle of incidence towards the
perpendicular of the plate’s surface, and, therefore,
a decrease of the relative armor. Normalization of the
356-millimeter caliber is 6 degrees. That’s why our small deviation by
5-10 degrees will be compensated and the casemate
armor belt will be penetrated, but the citadel armor
deck will withstand the hit, so Fuso will lose only 3,300 HP. Now, let’s put New York
5 kilometers away and fire a shell. The shell penetration
is 337 millimeters, and the angle of incidence is close to
the perpendicular of the plate’s surface, so there is enough armor
penetration for three layers of the 321-millimeter armor
protecting Fuso’s citadel from damage. However, as you already know, a shell passes through all
the checks for each armor layer: starting with the 14.3 caliber rule
and ending with the normalization. The shell penetrates
the first two layers, hits the citadel armor deck at
a very sharp angle, and bounces off. Then, it explodes in the casemate
and deals 3,300 damage again. But if a shell hits Fuso’s side a little
close to the forward end and lower, it will have to penetrate 19 millimeters
of antitorpedo protection, 229 millimeters
of the casemate armor belt, and 76 millimeters of the citadel armor
deck slopes located at different angles. In total, there are 324 millimeters, which a shell
from New York will penetrate and inflict the full damage
on the prized citadel. And what will happen
if a shell hits Fuso’s fore end? The armor thickness in the most
protected spot is 102 millimeters. The armor penetration
of New York’s primary armament from 15 kilometers away
will be enough for a shell to over-penetrate through
Fuso and fall into the water. But engineers made
sure that the AP shells would deliver their harmful payload
to the hull, through the armor. The AP shells have
a special fuse installed inside; it activates after a shell penetrates
armor of a specific thickness. Activation of a fuse is delayed, so a shell has some time to reach
“deeper” into a ship after a hit. If the thickness
of the penetrated armor is greater or equals
1/6th of the shell caliber, the fuse activates,
and the shell detonates, inflicting damage to whichever
part the shell ended up in. In our example, New York’s
shells need to penetrate at least 59 millimeters
of armor to be activated. It doesn’t matter how many layers
of thinner armor it’s going to penetrate, the fuse won’t activate by any means. Therefore, after the shell penetrates
Fuso’s 102-mm fore end armor belt, the shell will
successfully detonate inside. However, if the shell hits the 25-mm
fore end casing above the armor belt, the fuse won’t activate, and
the shell will fly through the ship, inflicting only 10% of the
damage with the over-penetration. We can get the same result
when a shell hits a superstructure or when a shell activates
inside of the ship’s end and manages to over-penetrate
the ship before detonating. Another interesting showcase
is when a shell falls into the water. After that, it activates automatically. Then, the fate of the shell
depends on the angle of incidence— the velocity and, therefore, armor penetration of a shell
are significantly reduced in water, and the trajectory slightly changes. However, the shell has a chance
to reach the underwater parts of a ship, penetrate them,
and detonate inside of a ship. Such hits are extremely
dangerous for destroyers— it’s easy to penetrate
a destroyer’s side even underwater, plus, the fuse has been
activated by hitting the water. As you can see, multi-layered armor
is a unique feature of the ships’ armor that has its advantages
and disadvantages. But then, a question arises: what should I do if my shells
don’t penetrate an enemy ship? You’ll find the answer to that question
in our next episode of How it Works, which will be dedicated to HE shells. Subscribe to our channel,
so you won’t miss our next videos!

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