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About modern MBT design philosophy, angled armor and modern ammunition


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Lert #1 Posted Apr 13 2015 - 12:48

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Three of the best MBT's currently in service everyone here would agree are the M1 Abrams, Challenger 2 and the Leopard 2. It's the design choices on these tanks that this thread wants to address.

 

First the Abrams:

 

 

If you note the front armor, both hull and turret, you'll see that they are flat slabs of armor under a minimal angle.

 

Now the Leopard 2:

 

This is the 2A5, but the 2A6 and 2A7+ have the same armor layout.

 

You will note that the both the front hull and turret armor of this tank are sharply sloped. What do the germans know that the americans don't? Or, vice versa, what do the americans know that the germans don't?

 

Then there is this, the Challenger 2, considered by many to be the best protected, most heavily armored of the three:

 

 

It has a flat, relatively unangled hull front with a relatively highly angled turret face.

 

So, what gives? We have:

 

- The american design with flat, slab everything

- The german design with sharp angled everything

- The british design with flat hull and angled turret

 

But wait, it gets even more interesting:

 

 

This picture of an older generation Leopard 2, from the 2A4 block in this case, shows a very flat, unangled, slab turret face. Yet the 2A5 and upwards have the sharp angles. What gives? Aren't those shot traps?

 

... Well, not really. The sharp angled wedge shape on the turret front of the Leopard 2A5 and upwards is actually a wedge-shape add-on piece of spaced armor. This picture of a Leopard 2A5 turret under construction shows the near side of the turret before the addition of the spaced add-on part, still showing the flat turret face of the 2A4. Here and here are two pictures of those wedges of shaped armor. My understanding is that they serve to deform penetrators before they reach the actual turret armor, which is still flat and unangled, like in Abrams.

 

Wiki backs me up in this:

 

"The A5 introduced a wedge-shaped, spaced add-on armour to the turret front and the frontal area of the sides. These spaced armour modules defeat a hollow charge prior to reaching the base armour, and causes kinetic-energy penetrators to change direction, eroding them in the process; it does not form a shot-trap since it doesn't deflect the penetrators outwards to hit the hull or turret ring."

 

The way this is phrased and from viewing the pictures of the armor addons, this leads me to believe that kinetic penetrators are meant to penetrate the wedge armor, being deflected inwards because of normalization and losing a lot of their penetrating potential before hitting the actual turret face armor, as per my crappy MSPaint drawing:

 

 

However, this is just wild guessing on my part; I claim no particular understanding or knowledge.

 

So, all this new information changes my earlier list to:

 

- The american design with flat, slab everything

- The german design with sharp angled hull and flat turret face

- The british design with flat hull and angled turret face

 

So, my questions are:

 

- Why the radical difference in design? What's the philosophy behind them?

- The german designers chose to add the wedge shaped spaced armor pieces to the Leopard 2 when the flat design of earlier Leo's as well as Abrams was 15+ years proven. So why the change in philosophy?

- What does sloping do to modern ammunition?

- Why is Leopard 2 so sexy? Mmmmmmmm ....

 

Note: Modern ammunitions interact with armor and slope differently from the ammunition of the time period that WoT encompasses. Don't bring your WoT theorems into this discussion, this is about modern composite armor, modern high density and chemical ammunition and modern design philosophies.

 

As a thank you for reading, have a video which celebrates two of these three amazing machines along with some classic rock:

 



Elevendy #2 Posted Apr 13 2015 - 12:57

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I think we put a little too much trust into our armor... Though, we aren't really fighting nations who use tanks anymore so what's the point in having sloped armor?

heavymetal1967 #3 Posted Apr 13 2015 - 12:59

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Getting basic their armor tries to deform and wear down the incoming rounds rather than bounce them. 

 

As for why they added angled pieces to the Leo I'm thinking it's more added protection for modules than trying to add angling.



Daigensui #4 Posted Apr 13 2015 - 13:05

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The thin penetrator hitting a sloped surface has a high possibility of snapping, or so I remember. It's 5:05 am over here, haven't slept, so might not be thinking correctly.

HotCreamyHunk #5 Posted Apr 13 2015 - 13:06

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I think the reason the spaced armor add-on is angled is because the Germans knew that angles are gorgeous.

Ogopogo #6 Posted Apr 13 2015 - 13:07

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Block Quote

 - Why the radical difference in design? What's the philosophy behind them?

 

I know on this point a part of it is the different material blends used in the armour in combination with the advances in ammunition. I can offer more when I get back from my exam.



DERP_IN_THE_FACE #7 Posted Apr 13 2015 - 13:14

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View PostDroplet, on Apr 13 2015 - 06:57, said:

I think we put a little too much trust into our armor... Though, we aren't really fighting nations who use tanks anymore so what's the point in having sloped armor?

 

about the first part of your statement, people of nations would rather have their soldiers have a fighting chance to survive hits, yes having no armor and being able to move around quickly and avoid shots that way would be nice but if said tank got hit then crew is screwed.

astroglide #8 Posted Apr 13 2015 - 13:15

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US tank philosophy has not changed much since WWII. The hull of the Abrams is considered to be the weak spot (if you want to call it that). All three tanks were designed to fight in Germany and stop a push through the Fulda Gap (learned this in my Military History class) so all three have remarkable depression. Using that depression on hilly terrain would add slope to the flat angles you see, especially on the Leopard and M1. The Germans added the spaced armor as ammunition improved (especially HEAT style ammo and ATGM'S) while the US felt their DU composite armor was enough and the British tank has very thick frontal armor and is well sloped to begin with. Just some thoughts as to why things may be the way they are is all, NOT claiming to know much but on sight, it makes some sense...

Chikungunya #9 Posted Apr 13 2015 - 13:26

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The ceramic layer of the composite armor is composed of multiple small tiles. The size is chosen to improve multiple hit survivability. The brittle ceramic shatters on impact. Using well sloped armor would expose more tiles to damage when hit.   

Lenzabi #10 Posted Apr 13 2015 - 13:32

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The slab sided look is due to their use on all three of Chobham armor. http://en.wikipedia..../Chobham_armour

 

Quote

Chobham armour is the name informally given to a composite armour developed in the 1960s at the British tank research centre on Chobham Common, Surrey, England. The name has since become the common generic term for ceramic vehicle armour. Other names informally given to Chobham Armour include "Burlington" and "Dorchester."

Although the construction details of the Chobham Common armour remain a secret, it has been described as being composed of ceramic tiles encased within a metal matrix and bonded to a backing plate and several elastic layers. Due to the extreme hardness of the ceramics used, they offer superior resistance against shaped charges such as high explosive anti-tank (HEAT) rounds and they shatter kinetic energy penetrators. Only the M1 Abrams, Challenger 1, and Challenger 2 tanks have been disclosed as being thus armoured. The armour was first tested in the context of the development of a British prototype vehicle, the FV4211.[1] Despite being a British invention, the armour type was first implemented on the American Abrams tank.

 

Although the part for the M1A2 also uses depleted uranium armor

Quote

M1A2: depleted uranium mesh-reinforced composite armor[7]
  from http://en.wikipedia.org/wiki/M1_Abrams

 

Leopard II;  http://en.wikipedia.org/wiki/Leopard_2

Using also a similar composite armor, which also explains the slab look, the extra armor modules used by the Leopard makes it safer I guess

Quote

2A6: 3rd generation composite; including high-hardness steel, tungsten and plastic filler with ceramic component.

 

 

I also know that while this thread is focusing on the BIG 3 of NATO we can also add in if OP likes the ideas as to the other big nation tanks as Israel seems to also use a similar mix up of armor like Germany the huge turret appearance on the Merkava IV is also modules added to the turret.

 

 

 

The Russian T-90 also uses similar armor design/techniques it seems http://en.wikipedia.org/wiki/T-90

 

I do recall the worries of masses of Soviet tanks and helicopters coming through the Gap. Got to watch A-10s practice runs on our Missile site in case Spetznats took us over.

 

As my legs were number 2 profile, tanks were barred, :( Otherwise, in 1983, I would have been training in older model M1's , eyes also not good enough for then new Apaches, got stuck in Missile Arty, job was to hope the 400kiloton warheads never got launched.

 

   

Edited by Lenzabi, Apr 13 2015 - 13:50.


Lert #11 Posted Apr 13 2015 - 13:54

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View PostLenzabi, on Apr 13 2015 - 12:32, said:

 job was to hope the 400kiloton warheads never got launched.

   

 

It must be a very interesting feeling that part of your job is hoping you never get to do your job.



alternaive #12 Posted Apr 13 2015 - 14:05

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View PostLert, on Apr 13 2015 - 11:48, said:

 

Wiki backs me up in this:

 

"The A5 introduced a wedge-shaped, spaced add-on armour to the turret front and the frontal area of the sides. These spaced armour modules defeat a hollow charge prior to reaching the base armour, and causes kinetic-energy penetrators to change direction, eroding them in the process; it does not form a shot-trap since it doesn't deflect the penetrators outwards to hit the hull or turret ring."

 

The way this is phrased and from viewing the pictures of the armor addons, this leads me to believe that kinetic penetrators are meant to penetrate the wedge armor, being deflected inwards because of normalization and losing a lot of their penetrating potential before hitting the actual turret face armor, as per my crappy MSPaint drawing:

 

 

However, this is just wild guessing on my part; I claim no particular understanding or knowledge.

 

The wedges consist of sandwich plates (depending on location two or three). The sandwich plates work as NERA (non-explosive reactive armor) and have - just like ERA - to be sloped to make use of their full potential. Simple NERA consists of rubber sandwiched between two metal layers, also more specialized types of material have been developed by the armor industry (like IBD of Germany).

 

How it works: The plate is hit, which causes the rubber (or alternatively another type of elastic material) to compress to it's point of maximum depression. When the steel layer however is penetrated, the rubber will decompress and force additional material into the path of the penetrator, while redirecting some of the impact energy of the penetrator back to it.

 

Such armor is also known as 'bulging plates armor' (literal translation of the German term) or 'reflecting sheet armor' (literal translation of the Russian term).

 

These are two full scale APFSDS-penetrators after penetrating a NERA plate made of two 8mm steel plates of higher hardness between which a 2mm rubber sheet was sandwiched. The penetrators do not change their path of flight, but break and the parts become disarranged. These actual tests were done in a cooperation between Switzerland and the Netherlands, both which are/were user countries of the Leopard 2.

 

Two NERA plates against a shaped charges, this time the tests was done in Germany with different materials (including special high performance material from the armor industry). In the best case the penetration of a shaped charge with a diameter of 136mm was reduced from 950mm to 22mm, but the distance between the fusing point and the steel target was changed, i.e. I think it should be less.

 

The big advantage of NERA over ERA is that one can utilize multiple layers on top of each other.

 

View PostLert, on Apr 13 2015 - 11:48, said:

- Why the radical difference in design? What's the philosophy behind them?

 

Different construction of the turret. The Leopard 2 and the M1 Abrams use a monocoque construction - i.e. the structure of the tank is made with forming empty 'boxes' in which the armor is inserted. The Leopard 2 simply has further armor added ontop of the base armor to reach a higher level of protection.

The Challenger 1 and 2 are constructed in a different way - the turret is cast and includes sloped armor, with the composite armor boxes being attached via rails to the outside of the tank:

Why the British tank designers did this? No idea. Might have something to do with the industrial capacities or they just wanted to be special (who the hell drives on the left side of the road...).

 

 

View PostLert, on Apr 13 2015 - 11:48, said:

- The german designers chose to add the wedge shaped spaced armor pieces to the Leopard 2 when the flat design of earlier Leo's as well as Abrams was 15+ years proven. So why the change in philosophy?

 

The wedge shaped armor was added after a higher level of protection was required - I'd say they did it because the German engineers came to the conclusion that this is the best possible way to increase the protection level. The Abrams does still have flat armor because of different armor design (maybe because the Americans do use DU), different requirements of protection (maybe the Abrams requirements were lower so that adding external armor was not required) or due to space constraints (the M1 Abrams frontal turret armor is closer to the front, i.e. it 'hangs' above the driver).

 

View PostLert, on Apr 13 2015 - 11:48, said:

- What does sloping do to modern ammunition?


Sloping requires thickness to work. At extremely high slopes armor can still bounce modern ammo, but in a different way - too high stress will break the penetrator and a part will be deflected, which is how the glacis (1.5 inch thick steel) of the Abrams and Leopard 2 work.

Against armor that is sloped at less extreme angles, modern APFSDS ammunition will actually penetrate more armor than against unsloped armor, due to failure by plug generation/tearing up of armor.

 

View PostChikungunya, on Apr 13 2015 - 12:26, said:

The ceramic layer of the composite armor is composed of multiple small tiles. The size is chosen to improve multiple hit survivability. The brittle ceramic shatters on impact. Using well sloped armor would expose more tiles to damage when hit.   

 

If there are any ceramic layers in modern composite armor...

Edited by alternaive, Apr 13 2015 - 14:09.


Lert #13 Posted Apr 13 2015 - 14:18

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View Postalternaive, on Apr 13 2015 - 13:05, said:

 

<Bunch of great stuff>

 

Very interesting. Much thanks and a +1 to you good sir.

 

 

View Postalternaive, on Apr 13 2015 - 13:05, said:

 

The wedges consist of sandwich plates (depending on location two or three). The sandwich plates work as NERA (non-explosive reactive armor) and have - just like ERA - to be sloped to make use of their full potential. Simple NERA consists of rubber sandwiched between two metal layers, also more specialized types of material have been developed by the armor industry (like IBD of Germany).

 

How it works: The plate is hit, which causes the rubber (or alternatively another type of elastic material) to compress to it's point of maximum depression. When the steel layer however is penetrated, the rubber will decompress and force additional material into the path of the penetrator, while redirecting some of the impact energy of the penetrator back to it.

 

That explains the bolted look of the NERA wedge on Leopard 2A5 and upwards; those are simply the bolts that hold the layer of rubber compressed between the layers of steel. Bolts so the pressure can be adjusted, and the plates easily replaced.

 
Spoiler

 

 

View PostThe_DireWolf, on Apr 13 2015 - 13:11, said:

I'm pretty ignorant when it comes to modern military stuff, but I have a question- are tanks still actually needed? I don't mean that they are obsolete, but I can't imagine tank v tank warfare im the current age. 

 

The dutch sold them because they were 'too expensive' and 'we don't really need them anymore' but we dutch know ourselves surrounded by powerful allies who still have them.

 

The problem I think with tanks is that "We need them because they have them".

 

Other than that, there is still the fact that nothing really projects power as well in the eyes of the opponents as parking a current gen MBT on top of the thing you are wanting to keep secure.

 

Finally, you need only look at Iraq to see what armor can do in a modern a-symmetric conflict environment. It was armor supported by air superiority and infantry that broke Saddam's military. Air superiority is good and all, but airplanes can't hold a strategic objective. Infantry can, but unless you put your infantry in tin cans or send a few of those tin cans along with them, they are very vulnerable. Tanks are simply things that is can hold a strategic objectives, and be difficult to shift off of them.

 



Wuluck #14 Posted Apr 13 2015 - 14:26

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you have way too much free time on your hands

Lert #15 Posted Apr 13 2015 - 14:28

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View PostWuluck, on Apr 13 2015 - 13:26, said:

you have way too much free time on your hands

 

I would say I have 'just enough' and you have too little. :)

Lenzabi #16 Posted Apr 13 2015 - 14:51

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View PostLert, on Apr 13 2015 - 07:54, said:

 

It must be a very interesting feeling that part of your job is hoping you never get to do your job.

 

Yes it was. Alert klaxon goes off, you worry it may be the prez pressing that red button of the Nuclear Football, relief washes over you as you see the inspectors and find out it is a drill, only a drill, and the missiles stay laying down, the retention pins on the truck they rest on still to be left in their sockets. Go through doing a practice launch, and then cover the missiles up and go back to sleep, or grab a hot shower if a cold German Rain hits.

 

Trust me, no one in their right mind wished to be going home as part of a nuclear dust cloud on the trade winds, and also being part of why all we knew were also cinders and ashes. Cold War was a weird war



Chikungunya #17 Posted Apr 13 2015 - 15:15

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View PostLenzabi, on Apr 13 2015 - 08:51, said:

 

Yes it was. Alert klaxon goes off, you worry it may be the prez pressing that red button of the Nuclear Football, relief washes over you as you see the inspectors and find out it is a drill, only a drill, and the missiles stay laying down, the retention pins on the truck they rest on still to be left in their sockets. Go through doing a practice launch, and then cover the missiles up and go back to sleep, or grab a hot shower if a cold German Rain hits.

 

Trust me, no one in their right mind wished to be going home as part of a nuclear dust cloud on the trade winds, and also being part of why all we knew were also cinders and ashes. Cold War was a weird war

 

My brother in law was a Pershing 2 missile crewman in Germany right up until they were decommissioned.

 



Lenzabi #18 Posted Apr 13 2015 - 15:25

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View PostChikungunya, on Apr 13 2015 - 09:15, said:

 

My brother in law was a Pershing 2 missile crewman in Germany right up until they were decommissioned.

 

 

Ah, I got out in 1985 actually, Germany was nice, Neu Ulm was my billeting. C-Battery 1/81FA, Where was he stationed? Last I checked, with the decommissioning of the missiles, the old unit went back to cannons.

 


Edited by Lenzabi, Apr 13 2015 - 15:29.


GAJohnnie #19 Posted Apr 13 2015 - 16:18

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View PostThe_DireWolf, on Apr 13 2015 - 08:11, said:

I'm pretty ignorant when it comes to modern military stuff, but I have a question- are tanks still actually needed? I don't mean that they are obsolete, but I can't imagine tank v tank warfare im the current age.

 

http://www.globalfirepower.com/armor-tanks-total.asp

 

You might be surprised how many nations have tank forces. See link above for  a 2014 list by nation of Main Battle Tank strengths. Even if you fight one of the small countries on this list, you are going to want to have some tanks in your force.



kmanweiss #20 Posted Apr 13 2015 - 16:19

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View PostThe_DireWolf, on Apr 13 2015 - 07:11, said:

I'm pretty ignorant when it comes to modern military stuff, but I have a question- are tanks still actually needed? I don't mean that they are obsolete, but I can't imagine tank v tank warfare im the current age.

 

It all depends on who you are fighting.

If you are facing a major power with lots of tanks, then you need some tanks to be able to compete.  Trying to take on tanks with air units isn't all bad, but trying to hold a strategic location against a tank advance can be difficult if you don't have some armor yourself.

If you are facing a mobile guerrilla force, the tank becomes kind of worthless.  It's big, slow, and not exactly excellent at fighting infantry.  $ for $, your money would be spent better elsewhere.

In city environments, tanks are really troublesome.

We don't have many Abrams in Afghanistan.  I doubt we deployed more than 2 dozen if that.  The terrain and style of combat just doesn't favor a vehicle that large.


They are expensive to build, expensive to maintain, and limited in their overall effectiveness against our most common enemy right now.


The Russian T-90 is actually a more appropriate tank for today's conflicts.  Smaller, faster, less of a logistical strain to keep operating (4-5x the range on a single tank of fuel).  All that at half the initial cost.  Sure, 1 on 1 it would likely lose to an Abrams, but that's not a condition it needs to meet.

 

 






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