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Of tanks and decapping plates

HansMustermann said:
20% of shell diameter seems to be a bit off, considering that the decapping plate on an Iowa was only 1.5" thick. If 20% were the number, then an Iowa can't even decap an 8" shell from a cruiser, which would just beg the question: why bother, then?

In fact, the thickest decapping plate I've ever heard of was the 70mm on Italian battleships. I don't think anyone ever made an 80mm one.
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I would think that in WW2 a battleship operating in the pacific would have been mostly worried about air attacks, and torpedo attacks.

a 1.5" plate would only be for sailor morale, make them feel safer.

The only time (Late in WW2) a US battleship would face any guns larger than 8" would have been at Battle of Surigao Strait, and they had the Japanese battleship outnumbered like 6 to 1.

Early on, at the 2nd Guadalcanal, Only one battleship was remaining for the Japanese. It had 14" guns, but it's secondary guns were only 6".

I'm thinking, in order to stop Main 14" guns, they needed 3" armor plate, but against a plunging shot, it wouldn't help anyway.

So build the skirt thick enough to stop the Japanese secondary guns, and focus on torpedo attacks and air attacks.
 
As in tanks, i'm sure there is some cost benefit analysis involved.

Heavier armor means slower vehicle.
Therefore, what level of armor provides the most protection with minimum loss of vehicle agility.
 
A little more digging into late 40's armour development reveals a truth.

Nobody really expected that thicker sloped frontal armor would be obsolete so quickly.

The panther, tiger II, Pershing, comet and even the maus (two unfinished prototypes) all shared a common line in development.

Lowest possible profile, heavy sloped frontal plate, bigger guns , power turret rotation and attempts at gun stabilizer tech to fire on the fly.

The tank crew was still expendable but effort was made to ensure it was the other guys crews.

Armour itself stayed heavy steel plate into post war gun tech making it inadequate. The sheer weight required would barely be mobile.
The composite and reactive tech came in. Less weight for better protection.
 
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And also what type of armor best solves the problems the designers are actually concerned about.

Probably the best way to think of these things is to view any piece of military equipment as essentially an interim design, rather than a final "perfect" form.
 
Drewbot said:
As in tanks, i'm sure there is some cost benefit analysis involved.

Heavier armor means slower vehicle.
Therefore, what level of armor provides the most protection with minimum loss of vehicle agility.
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And what gives the most useful volume in the tank.
Let's not forget that one. Tanks are not only weight limited, but also size limited (if you want to transport them via railways without having to divert other traffic on that rail, for instance).

That is one reason why sloped armor on the side of tanks also went away, (for those nations that had it) after WWII.
The added protection it gave wasn't worth the lack of internal volume it created.
 
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Sloped armor is making a bit of a comeback these days, as add-on modules. For example, the distinctive wedge on the front of the turret of Leopard IIs in German service. The turret of the Israeli Merkava is another example.

Sloped armor also shows up in other places. The v-shaped hulls of wheeled fighting vehicles, for example. Many MRAPs use this shape to better resist land mines. Most of the Stryker variants in US service are being retrofitted with v-hulls.
 
erwinl said:
And what gives the most useful volume in the tank.
Let's not forget that one. Tanks are not only weight limited, but also size limited (if you want to transport them via railways without having to divert other traffic on that rail, for instance).
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Hmm, true, empty space sandwiched between armour plates is still criticized as a problem about such tanks as the Crusader.
 
Drewbot said:
I would think that in WW2 a battleship operating in the pacific would have been mostly worried about air attacks, and torpedo attacks.

a 1.5" plate would only be for sailor morale, make them feel safer.

The only time (Late in WW2) a US battleship would face any guns larger than 8" would have been at Battle of Surigao Strait, and they had the Japanese battleship outnumbered like 6 to 1.

Early on, at the 2nd Guadalcanal, Only one battleship was remaining for the Japanese. It had 14" guns, but it's secondary guns were only 6".

I'm thinking, in order to stop Main 14" guns, they needed 3" armor plate, but against a plunging shot, it wouldn't help anyway.

So build the skirt thick enough to stop the Japanese secondary guns, and focus on torpedo attacks and air attacks.
Click to expand...

When they were laid down they were expecting to have to defend against the main batteries of other Battleships. Once they were built then the armour was fixed short of totally rebuilding them.

Plunging shells wouldn't need the same armour for 'de-capping' as the angle of incidence means a thinner belt will do the job.
 
I've seen the insides of a Russian T-34 tank. The amount of space the Christie suspension takes up on the inside is rather large.
It would at least interfere in things like the size of the turret basket. And if no basket fitted, then interfering in the space the crew has left for working.
 
theprestige said:
Sloped armor is making a bit of a comeback these days, as add-on modules. For example, the distinctive wedge on the front of the turret of Leopard IIs in German service. The turret of the Israeli Merkava is another example.

Sloped armor also shows up in other places. The v-shaped hulls of wheeled fighting vehicles, for example. Many MRAPs use this shape to better resist land mines. Most of the Stryker variants in US service are being retrofitted with v-hulls.
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Yes. But that sloped armor has a radical different way of working than traditional sloped armor. It actually is a bit equivalent to the decapping plates HansMustermann talked about. The main task being absorbing the incoming projectile and sending it through various sloped layers of rubber and steel plates, thereby breaking up the incoming round, so that the thicker backing armor can handle the rest of the projectile.

The v-shaped bottoms of MRAPS are more based on deflecting the blastwave of mines coming upwards.
 
Drewbot said:
Sloped armor isn't going to be important for much longer.

The Javelin missle seems to be dropping straight down onto the armored vehicles.

https://www.youtube.com/watch?v=fX7e6FLaksE
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The Javelin has been in service for over 20 years. It's one of a long list of anti-tank guided munitions that uses a top attack profile to bypass the heavy front armor. The BGM-71F TOW variant with top-attack capability predates it by almost ten years. The Soviet 2K25 Krasnopol anti-tank artillery round uses top-attack, and is a contemporary of the BGM-71F. Top attack is not a novel solution that is about revolutionize tank armor.

Top attack calls for a new approach to protecting the tops of tanks, but doesn't actually make front and side armor geometries irrelevant. A main battle tank still has to deal with RPGs and heavy autocannons, and it still has to be able to engage enemy armor head-on when the situation calls for it. I think it's clear that sloped armor (in its modern configurations and compositions) is going to continue to be important for the forseeable future.
 
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Mmm, modern warfare is bifurcating into two distinctive scenarios:

1) All out superpower war. Here nothing matters, because tanks and indeed any kind of armor is outdated.

2) Interfering in local wars. Here, you are typically up against non-sophisticated adversaries, with fairly light weapons. However, even light losses are hard to accept (because the home country is in peace condition). Here moderate armor is useful, and hi-tech weapons make the day.

Stuff like heavy tanks are museum exhibits.

Hans
 
MRC_Hans said:
Mmm, modern warfare is bifurcating into two distinctive scenarios:

1) All out superpower war. Here nothing matters, because tanks and indeed any kind of armor is outdated.

2) Interfering in local wars. Here, you are typically up against non-sophisticated adversaries, with fairly light weapons. However, even light losses are hard to accept (because the home country is in peace condition). Here moderate armor is useful, and hi-tech weapons make the day.

Stuff like heavy tanks are museum exhibits.

Hans
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I think Ukraine might beg to differ.
 
jimbob said:
I think Ukraine might beg to differ.
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Israel, too. They have some of the heaviest main battle tanks in current service, and their doctrine seems to be based on the assumption that they're surrounded by regimes that would happily roll tank treads from the Jordan to the sea, if there weren't heavy tanks in the force arrayed against them.
 
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