Tank Layout

[Collimatrix]

The rear of the bustle does not appear to have any armor (protection against artillery fragments and small-bore autocannons at most), and its is unclear how far the turret "cheek" armor extends rearward.  But you can't hit the bustle from the front, or even from a fairly generous off-angle from the front, because the area that actually has ammo in it is narrower than the front and sides of the turret.


I have made a helpful MS paint diagram:

[LoooSeR]

Your excellent diagram is not accurate - turret bustle is bigger and NERA coverage of turret side is lower. Let's move this discussion to Tank layout thread. 

[LoooSeR]

For example, Leo 2. One small note - side armor is nowhere near as good as frontal armor, how much Abrams tanks have is question that i would like to know answer for.

 

 

Abrams turret, turned at ~20 degrees shows a lot of side armor.

[Collimatrix]

Your excellent diagram is not accurate - turret bustle is bigger and NERA coverage of turret side is lower. Let's move this discussion to Tank layout thread. 

Good suggestion.

This picture of a damaged Abrams seems to show that the NERA goes all the way back to the end of the turret side:

 

 

It looks nowhere near as thick as the frontal turret armor, but it doesn't need to be.  From a hit thirty degrees from the front, the shot will have to go through at least double that LOS thickness of armor (a little more than that, actually, since the turret sides aren't perfectly straight).

[LoooSeR]

As i said in the Yemen thread, old ATGMs is not as much of a problem as APFSDS rounds. Turret layout create a problem, when hull down position of Abrams against tanks is undermined by turret design itself. Modern ATGMs will also go through it. Later version of M1 should do something with that.

[Collimatrix]

Depends on the thickness of the side armor and how effective it is vs. KE threats.  NERA does work better when angled, and the LOS thickness of the side armor will be better than doubled when the turret is thirty degrees from the front.  The bustle would be vulnerable if the turret were fired at directly from the side, but the same is true of almost every tank.

 

Satisfactory ammunition stowage is problematic with current ammunition technology.  It would be difficult to store the ammunition under the turret ring the way a T-72 does because NATO 120mm ammunition is unitary and it is also much wider than Russian 125mm ammunition.

 

 

125mm ammunition is straight-walled, 120mm ammunition has a large bottleneck.

 

Also, carousel autoloaders are quite wasteful of space; there's a lot of unused volume in-between the rounds.  This means that you can't really store that many rounds in the autoloader, which means you start storing ammo elsewhere in the tank, which means this:

 

The Swiss NKPz had an autoloader where the ammo was entirely stored in the hull, and brought to the gun:



This was, as you might imagine, rather complicated.

[LoooSeR]

Wasted space is a design problem of Soviet "horizontal" autoloaders.

 

Also:

[Collimatrix]

The M1128 MGS autoloader is similar.  It seems like a good way to do things if you're confident enough in your situational awareness aids to go to an unmanned turret.

 

Speaking of which, were there any stills in that Armata presentation of the ammo?

[LoooSeR]

No, ammunition was not shown to film yet. There are rumors about Vacuum rounds not being main ammunition, but a stopgap measure.

[Collimatrix]

 

US proposal for a future MBT.


OK, so estimates from the Steel Beasts forum are 350-400mm thick for the Abrams' side armor.  So, a hit from thirty degrees off would have to dig through better than 700-800mm NERA.

 

Depending on what the RHAE of that stuff is, I guess that might work against earlier ATGMs.  Might want to put some ERA on there if expecting real opposition...

[LoooSeR]

That thing looks similar to Object 490A coupled with TTB.

Steel Beast armor values are inaccurate, sometimes very.

[Mohamed A]

Steel Beast values are also outdated.

[Tied]

Depends on the thickness of the side armor and how effective it is vs. KE threats. NERA does work better when angled, and the LOS thickness of the side armor will be better than doubled when the turret is thirty degrees from the front. The bustle would be vulnerable if the turret were fired at directly from the side, but the same is true of almost every tank.

Satisfactory ammunition stowage is problematic with current ammunition technology. It would be difficult to store the ammunition under the turret ring the way a T-72 does because NATO 120mm ammunition is unitary and it is also much wider than Russian 125mm ammunition.

125mm ammunition is straight-walled, 120mm ammunition has a large bottleneck.

Also, carousel autoloaders are quite wasteful of space; there's a lot of unused volume in-between the rounds. This means that you can't really store that many rounds in the autoloader, which means you start storing ammo elsewhere in the tank, which means this:

The Swiss NKPz had an autoloader where the ammo was entirely stored in the hull, and brought to the gun:

This was, as you might imagine, rather complicated.

Most of thr time extra rounds would be stored on the outside rear turrent storages. Anyway, if a round gets deep enough in a Soviet tank to cook off its autoloader the crew is done for nonetheless

[Collimatrix]

Estimates from the SB forums, not the in-game files.  The in-game files show the turret side armor ending before the bustle area, which the picture above shows is incorrect.

 

How much protection that would actually provide would require me to know how NERA responds to oblique hits.  Is it an inverse cosine function?  More?  Less?

I would lean towards more, since the stuff only works in the first place when it's oblique.

[Xlucine]

I'm fairly sure the armour on the side of the ammo store is thicker than the bit over the crew

just after 2:30 is the best view of the side of the ammo rack I can find, and the rack is a lot thinner than the armoured door

[LoooSeR]

Are you saying that turret bustle sides are better protected than sides over manned part of turret, or i misunderstood something?

[LoooSeR]

 

[Walter_Sobchak]

 

US proposal for a future MBT.

OK, so estimates from the Steel Beasts forum are 350-400mm thick for the Abrams' side armor.  So, a hit from thirty degrees off would have to dig through better than 700-800mm NERA.

 

Depending on what the RHAE of that stuff is, I guess that might work against earlier ATGMs.  Might want to put some ERA on there if expecting real opposition...

I just noticed that this thing is powered by the AIPS engine.  Another US idea that went nowhere.  

[LoooSeR]

Speaking about engines in sponsons, here is M59:

 

[LoooSeR]

Diploma project of one of military-oriented universities.

[LoooSeR]

One more dimploma work, and again with sponson-mounted engines.

[Meplat]

Speaking about engines in sponsons, here is M59:

 

A bit of trivia, many M59's you encounter do not have their original mills, as the 302's were very popular as slim and affordable race/rod engines.

I've met more than a few old MV'ers who mentioned buying (then selling) M59's and other 302 milled MV's JUST for the engines.

[LoooSeR]

http://www.liveleak.com/view?i=91b_1444431849

 

One more export Abrams was penetrated through turret side armor.

[LoooSeR]

So, one thing that bothers me - why ammunition storage between cre compartment and engine is almost never used in tanks designs? Maybe because it is harder to provide reliable work for blow-out panels?

[Tied]

What purpose would this serve outside of sending more Jap tankers to the grave early?

 

Its not like the Nano-yon-shiki series is known for its armor