Tank Layout

[Collimatrix]

 

       First, frontal engine and frontal transmission screw up weight distribution. In Object 416 it was "balanced" by removing driver from his usual position, increasing turret size, and moving this big turret to the rear part of hull. Still, frontal armor was not better than T-54's, even if 416's UFP had smaller overal sizes and area than T-54's UFP. 

 

 

416 doesn't have better armor than a T-55 because it is much lighter.  Object 416 is about 1 tonne heavier than an M41 light tank, but with the same armament as T-55!  It's an insanely efficient design.

 

 

       Second, such layout makes engine and transmission more vulnerable to incoming fire. Instead of using... actual god damn armor to act as "armor", engine and transmission partially plays that role. Thanks to weight of engine/trany module, designers had problems placing enough armor on UFP (and we don't speak about pretty big LFP), which leave engine as substitute for lacking armor. And question of crew survivabilty "being better because engine will catch all cr@p" is not so obvious, if you look at complex problem of tank not able to move and fires in engine compartment after even non-penetrating hits.

 

I don't think the actual designers believe that the engine doubles as armor in the merkava; it clearly doesn't.  For one thing, it doesn't protect the driver at all because the engine is only in the right side of the hull while the driver is to the side of the engine in the left.

 

I don't think that the mass of the engine makes that much difference to the weight distribution because the turret ends up being further back.  The turret is much, much heavier than the engine, so even a small shift rearward of the turret should allow a considerable increase in frontal armor.

 

The reason the merkava has such poor frontal armor is that the hull is enormous; there's simply too much area to cover with thick armor.  But if you use an engine with less frontal area, this problem goes away.

 

It's true that frontal transmissions are more vulnerable to mines, but I don't think that incoming fire is that much of a problem.  Tanks almost never get hit that low on the vehicle (notwithstanding that one record of a panther catching on fire from a frontal transmission hit).

[LoooSeR]

     Object 416 efficient design comes from a fact that commies put a whole crew just in one compartment, instead of spreading them around vehicle hull and turret. This decrease area that needs to be armored (insert story about total area of many spheres with total volume of X and total area of one sphere with same volume as all small spheres). Somebody said Armata here?

 

     I also think that actual designers did not thought about engine working as armor, more like additional bonus protection for 3 boys/girls in fighting compartment. But Merk's weaker UFP will fail more frequently than other tanks of same age, if we assume that APFSDS used against Merks are no worse than APFSDS used against Soviet T-80Us or T-72s.

 

     I am interested in area of UFP of the Merkava 2, 3 and 4 compared to UFPs of the T-72B and T-80U. I have a reason to think that difference is not so critical.

 

     Engine compartment of the Merkava tanks are more vulnerable to any frontal fire, simply because that compartment is almost totaly covers frontal projection of Merk's hull. To put it simply - trajectory of any projectile, coming to UFP, have very high chance to cross the engine compartment as well. Add here generally weaker UFP (Merk 4 is seems to me is exception) and story is not so bright. IIRC Merks 4 had pretty high rate of engine and transmissions failers during 2006 Lebanon war, some say that it happenes because of high stress on frontal part of vehicle. I will try to find numbers (later, i am sort of busy today).

[LoooSeR]

Found this, Merkava 4 (not all compenets are showed).

 

 

Ignore red arrows, look at "open" plate. Not much different from T-80's UFP thickness. Although note that this plate have 2 section - second one is smaller and partially covered by external part of plate.

 

Another angle on that UFP plate. lol, naked Merkava 4.

[Walter_Sobchak]

 

     Object 416 efficient design comes from a fact that commies put a whole crew just in one compartment, instead of spreading them around vehicle hull and turret. This decrease area that needs to be armored (insert story about total area of many spheres with total volume of X and total area of one sphere with same volume as all small spheres). Somebody said Armata here?

 

     I also think that actual designers did not thought about engine working as armor, more like additional bonus protection for 3 boys/girls in fighting compartment. But Merk's weaker UFP will fail more frequently than other tanks of same age, if we assume that APFSDS used against Merks are no worse than APFSDS used against Soviet T-80Us or T-72s.

 

     I am interested in area of UFP of the Merkava 2, 3 and 4 compared to UFPs of the T-72B and T-80U. I have a reason to think that difference is not so critical.

 

     Engine compartment of the Merkava tanks are more vulnerable to any frontal fire, simply because that compartment is almost totaly covers frontal projection of Merk's hull. To put it simply - trajectory of any projectile, coming to UFP, have very high chance to cross the engine compartment as well. Add here generally weaker UFP (Merk 4 is seems to me is exception) and story is not so bright. IIRC Merks 4 had pretty high rate of engine and transmissions failers during 2006 Lebanon war, some say that it happenes because of high stress on frontal part of vehicle. I will try to find numbers (later, i am sort of busy today).

 

If you can remember where you read that the Merkava 4 had a high rate of engine failures in lebanon, I would be very curious to know.  I know that General Dynamics had quite a few issues with the first batch of MT883 engines they put together for Israel in the late 90's (the engine parts were made by MTU then shipped to the US for assembly.) 

[Collimatrix]

 

 

     Object 416 efficient design comes from a fact that commies put a whole crew just in one compartment, instead of spreading them around vehicle hull and turret. This decrease area that needs to be armored (insert story about total area of many spheres with total volume of X and total area of one sphere with same volume as all small spheres). Somebody said Armata here?

 

 

Placing the crew together would reduce the total surface area that needs to be armored for a given volume, but this is misleading.  Tanks aren't equally armored everywhere; most of their armor is on the front.  What you want to do is to reduce frontal area.

 

The turret in object 416 cannot be made any lower than the turret for any other tank of the era, because the two biggest considerations in turret ceiling height (the need for space for the gun breech to depress and the need for space for the loader to be while servicing the gun) are the same as other tanks.  However, the hull can be much lower because the driver doesn't live in it anymore and because they have that special low-profile engine.  The turret only looks big on 416 because the hull is so tiny.  Considering how low the ceiling is from The_Chieftain's video of the inside, and considering that it only has 3 degrees of gun depression, they've clearly cut back on those things to the bare minimum!

 

As long as you had the special low-profile engine, the hull wouldn't be that much taller if the driver were in it.

 

I am not convinced that the merkava has comparable UFP thickness to T-72/T-80.  The normal thickness might well be close, but LOS thickness is largely a function of slope in this case, and the human eye is bad at estimating inverse cosines.

[LoooSeR]

You want to reduce all dimensions to make overall area as low as possible, for example with long enough tank you can have a side armor plate that weight as much as frotnal part! So decreasing any area (side armor, roof, rear plate area, etc.) will help to cut weight back.

 

Again, i am interested in total area of Merkava frontal part and UFP in particular, i have a feeling that in case of Merk's UFP vs T-72/80 UFPs difference is not too big. I don't have numbers for Merk's frontal armor thickness.

[Collimatrix]

Saying for sure would require exact dimensions and slope.

 

Let's say for sake of argument that the merkava and some variant of T-72 have exactly the same thickness of glacis armor and comparable construction (this is probably actually true because there are so many variants of T-72!).  But let's say T-72 glacis is 70 degrees while merkava's glacis is at a 60 degree slope.

 

The inverse of the cosine of 60 degrees is 2, while the inverse of the cosine of 70 degrees is nearly 3, so the T-72 would have 50% thicker armor thanks to a 10 degree increase in slope, which would be quite hard to tell exactly from pictures.

 

In any case, from pictures it is clear that the frontal area of the merkava is greater, so if its protection is similar to a T-72/T-80/T-90, its armor is much heavier, or it has much, much better materials available.

 

Where did you hear that textolite fill acts as NERA?

 

 

Side area isn't nearly as much a mass driver in modern MBTs because there is simply too much side area to armor to a reasonable standard.  Given how bulky high-efficiency armor is, it is clear that most MBTs don't even have composite armor on the hull sides.  They're lucky if they even have ERA there!

[LoooSeR]

IIRC Abrams have side multi-layer armor (only confirmed for turret).

 

 

I also heard that T-14 have multi-layered armor in some parts of hull sides. 

[Collimatrix]

Yes; composites are common on the turret sides, but harder to put on the hull sides because the tank must be narrow enough to fit on trains.

 

Heavy side-skirts added on in the field are one way around this, like on chally 2:

 

[Walter_Sobchak]

My favorite new name for an old timey AFV is a "skirmish machine."

[Collimatrix]

There are several good reasons to think that tanks will continue to have the best protection restricted to the frontal arc:

 

 

-The front of a tank has a lot less surface area than the sides, so improving armor protection to a given standard weighs less and costs less if it is restricted to the front only.

 

-Top of the line armor provides far better protection pound for pound than does steel, but it is much bulkier.  Width constraints mean that tanks cannot have the same protection on the sides as they do on the front and still have adequate accommodations inside for the crew.

 

-Post-combat studies show that more than 50% of hits occur from the frontal sixty degree arc on tanks.

 

 

The idea that urban combat will force better side protection is rather dubious in the long run.  Thermal sights, which are standard for new tank designs and becoming common as retrofits for T-72s and the like, make it much harder for infantry to hide in ambush positions.

 

 

 

Edit:

This equation could change somewhat if active protection systems become very good, since an APS that protects the front is basically the same weight as one that protects the sides.

 

 

 

The long-term trend, IMO, will be towards having good protection against all threats on the front, but having the sides protected only against HEAT threats.  With current technology, armor is more efficient at defending against shaped charges than it is at defending against long-rod penetrators.  Until someone invents some sort of uber-APS that's actually fast enough to swat long-rod penetrators out of they sky (which would be hard, considering they move at mach 5 or so), APS will just add to this.

 

Top-attack is a bit of a wildcard.

[Sturgeon]

We all well know that the future MBT paradigm is to have huge nuclear-powered antigravity vehicles with iridium and heterodiamond armor, gravity shielding, and armed with 90cm ion cannons and multiple weapon emplacements:

[Walter_Sobchak]

I found this in a 1989 issue of ARMOR magazine.  What caught my eye was the "model" in the picture.  It seemed rather familiar to me, as it might to others who liked army themed toys as kids in the early 1980's.  A gold star to whoever can identify it.  

 

[Belesarius]

GI Joe tank, IIRC.

 

I can't remember the name of it.

 

Edit: Nope... I thought it was the MOBAT, but I'm wrong.  But damn, I recognize it...

[Donward]

I think it is the Mauler M.B.T. driven by Heavy Metal.

[Belesarius]

Nope.

 

http://www.yojoe.com/vehicles/85/mauler/

[Donward]

Well hell then. I really am getting old. If it was made after 1987 it doesn't matter cause GI Joe went into the crapper after that.

[Sturgeon]

That looks like an RDF (LT).

 

[Walter_Sobchak]

No, it is indeed the MOBAT.  

 

GI Joe tank, IIRC.

 

I can't remember the name of it.

 

Edit: Nope... I thought it was the MOBAT, but I'm wrong.  But damn, I recognize it...

You were right the first time, it's a MOBAT with some crap glued to it.  I had a MOBAT tank when I was a kid, I played with it quite.  

[EnsignExpendable]

Nope.

 

http://www.yojoe.com/vehicles/85/mauler/

 

 

Sure are a lot of red stars on this so called "American hero".

[Brick Fight]

That looks like an RDF (LT).

 

Reminds me of that experiment they had where they mounted the 75mm Ares on a Sheridan.

[Walter_Sobchak]

 

Sure are a lot of red stars on this so called "American hero".

Nah, the GI Joe team were true American capitalists.  We know this because they occasionally fought their Soviet equivalent, the Oktober Guard.  Typically, they start out fighting each other but then have to team up to defeat Cobra.  Kinda like WW2 I guess.  

 

 

When I was a kid I always wanted more Oktober Guard appearances in the GI Joe comic.  Unfortunately, they didn't make Oktober guard figures until I was too old to play with toys anymore.  

[LoooSeR]

Proposed new (2000-2010s) turret designs for Russian tanks. Upper turret is "Proriv-2" (you can see it on T-90M), second one is "Burlak", those two projects were competitors.

 

 

Second turret have bustle autoloader + classical Soviet autoloader. Sides of Proriv-2 are covered with ERA, while Burlak use some sort of active protection system. I can say that Burlak looks very unusually.

 

Proriv-2 

 

 

Burlak...

 

 

 

 

[Walter_Sobchak]

The Burlak turret is really weird looking.  It's nice that they took environmental sustainability into account with the design and put those rain water collectors on the front of the turret. 

[Belesarius]

That proriv-2 turret looks pretty cool.