General Main Battle Tank Technology Thread:

What exactly is Chobham armour ? It is a series of layers of steel, ceramic and air gaps.

Chobham armour does provide some protection against HEAT and HESH rounds . However , against APFSDS rounds it provides no protection at all . And as we all know that against tanks placement of shots is more important than what is shot. It's not a coincidence that IED's ( mostly artillery shells ) blew up Abraham tanks in Iraq.


APFSDS rounds are solid projectiles which by its nature would be far less affected by all the layers than the plasma jet of HEAT or the concussion of HESH. The projectile is a long thin pencil of some extremely hard and dense metal, with little fins on the back and a sharpened point.  Where older tank rounds relied primarily on the power of the explosives they carried, a sabot round is entirely dependent on the muzzle velocity of the gun which fires it. The faster it's traveling, the harder it hits and the more it can penetrate. Chobham pales into insignificance.


The reason why tank guns are almost by definition smoothbore these days is the development of the APFSDS rounds. The Soviets realized it long ago that smoothbore guns were better for sabot rounds and therefore placed such a gun on the T 72 . At that time Chobham armour did not even exist . But then, there is something on earth called foresight.

That is not strictly true.

Layers of different materials can be very effective against APFSDS rounds, and in practical terms at the velocities we are talking about, both the penetrator and the armour can be considered as liquids because of the temperatures and forces involved, the main difference is that the APFSDS tends to be rigid but where it contacts the material it is penetrating it acts like a liquid on contact because of the heat and pressure involved.

The Soviets introduced the first smoothbore tank gun on the T-62, it was a 115mm calibre weapon and it was primarily because their favourite ammo... the HEAT round, is more effective if it is not spinning. Their HEAT rounds tended to be the most accurate right up into the 1980s and were the preferred round to use as they were multipurpose rounds effective against vehicles and structures etc.

Chobham armour was very effective against HEAT rounds as was developed as part of the program to produce the Shah-1... a tank for the CIA puppet Shah of Iran, but obviously that fell through and the British got the Challenger I tank largely paid for by Iran.

Right now Chobham armour would actually be inferior to the armour on the T-90 model tanks and would not be an improvement as it would increase the weight of the tank and require dramatic changes in shape for no improvement in protection.

You would end up with a 60 ton tank that had better side protection but less front protection.


The idea behind the layers of protection is to break up and fracture the penetrator so that its penetration performance is greatly reduced. In many ways the purpose of ERA is generally to guillotine the front 10cm or more off the tip of the penetrator so that it reduces its weight and length and creates a large flat penetrator tip which is very inefficient for penetrating, though the force behind the penetrator means that as it penetrates it will use a lot more energy and the penetration will shape the tip into a rough point again, though penetration will be greatly reduced... assuming the penetrator doesn't snap or shatter.

*** Below calculations/formulas as per Armour Penetration table ***

[These formulas are not necessarily very accurate but nonetheless they give a ballpark estimate] .

To find out the penetration capability of any round you need to know 2 of the three factors :

a)weight,
b)velocity, or
c) penetration

and you can workout the missing variable.

Armour Penetration Calculator

To find out the probable penetration of a HEAT round you take the warhead diameter times its generation modifier DxM=P

1st generation modifier 3.5
2nd generation modifier 7.5
3rd generation modifier 10

To figure out 120/125mm tank cannon APFSDS penetration you use the Ke (Ke=1/2MxV^2) formula and divide the result by 11,000 the number you end up with is penetration vs RHAe in milimeters .

Formula of tank kinetic rounds (long rod):

T * (1/cos@)^0.75 = (M/D^3) * (D/L)^0.3 *(v^2/U^2)

T = plate thickness (cm)
* = multiplication
^= to the power of
@ = angle
u = constant
L = penetrator length (cm)
M = penetrator mass (g)
D = penetrator diameter (cm)
v = penetrator velocity (m/s)

The 3BM48M developed for the T80UM2 Black eagle can penetrate 900mm RHAe and APFSDS fired from the 2A46M4 travels at1750m/s

http://webcache.googleusercontent.com/search?q=cache:http://russianarmor.info/Tanks/ARM/apfsds/ammo.html

Therefore , the 3BM48 "Свинец-2" can penetrate Cobham armour.

You are ignoring your own terms...

RHAe is rolled steel armour all the way through and Chobham is anything but homogenious rolled hardened armour.

That is what they mean by an armour array that has the equivalent thickness of say 800mm of RHAe against APDSFS rounds while its performance might be 1,200mm against HEAT rounds. Very simply it is the same armour, but the layers of the armour interact in a very specific way to impede HEAT more than APFSDS rounds.

Another important thing is that previously ERA had little to no effect on APFSDS rounds and was largely effective against HEAT rounds only.

A change in the design has allowed new ERA armour to degrade the performance of APFSDS rounds too.

The very latest ERA uses a lot less explosives and actually use deforming plates that move on impact and greatly increase the amount of actual material the incoming round has to penetrate.

The point is that this new technology doesn't just apply to external armour... when there is no explosives involved then there is no maintainence required and such NERA designs can be applied to internal armour structures. This is not to say that NERA can be replaced by internal structural NERA, in fact it can be applied to both external and internal armours... the new armata will likely have modular armour, so making that modular armour with NERA performance maximises its protection level, allows NERA panels to be externally attached that increase protection even further and with the external and modular internal design allow fairly straight forward replacement of both in the field to offer excellent protection and easy of repair and maintainence in the field. Damaged blocks and modules could be fairly easily replaced... assuming it gets through the APS in the first place.

In many ways APFSDS rounds are like arrows... angled plate is never effective in deflecting them because their energy is concentrated over a narrow radius, but a side thrust can completely destabilise the round, which risks total failure in the same way that hitting a nail in with one sharp very heavy hammer blow will lead to lack of penetration and a very bent nail if the nail is on any angle at all.

It an APFSDS round it wont bend... it will simply shatter and the fragments will simply not have the mass or shape to penetrate even very light armour.

The formula you posted is interesting, but doesn't include hardness... either of the target or the penetrator.

I would suggest there is a significant range in penetration performance for different materials... Tungsten, DU, steel... and of course all the related alloys and combinations.

DU would offer the best performance having the highest density, good hardness with certain alloys, and of course its natural pyrophoric reaction to steel armours.

The obvious problem is its toxic nature and ongoing radiation hazard on the training grounds and war zones...

Don't you know that DU is 100% safe, with absolutely zero negative health effects.

Any Russian round can penetrate Chobham, just depends on thickness of the array.

Don't you know that DU is 100% safe, with absolutely zero negative health effects.

There is no such thing as a 100% safe heavy metal.

Lead is perfectly safe in solid form... if you wash your hands after handling it.

The problem with DU is that it is mildly radioactive... which all experts agree on. What they don't agree on is how safe that level of radiation is.

Most of the supporters of DU ammo will say that DU is actually less radioactive than things you will find in your garden in many northern hemisphere countries and therefore it is not dangerous.

Those who oppose DU as an ammo option talk about how, when it is used, the pyrophoric nature of DU (ie it burns) and of course the velocity and energy of impacts both create a very very fine dust of DU that spreads over a very wide area around the impact point.

In other words they are not saying the material is dangerous to handle, they are saying that when you use it it suddenly becomes very ingestible... and that is the problem. Outside you body it could be two or three times more radioactive than it is and still not do you any harm. Once it is inside your body however the problems suddenly become fairly drastic. Your body does not recognise is for what it is and mistakes it for different materials... just like caesium is mistaken and used in bone structure, the DU gets built into the body structure and while its low level of radiation can't penetrate skin it is genotoxic. It damages human body cells at the genetic level.
Victims will suffer the effects of radiation poisoning... though the very low doses will delay the onset of symptoms, the half life of DU is billions of years... which means if you have a 7kg penetrator that completely burns out with the vehicle it destroys then in a billion years the radioactive decay means there will be 3.5kgs of DU and 3.5kgs of lead left. After another billion years there will be 1.75 kilos of DU etc etc.

The effect on the soldiers will be serious and unexplained sicknesses that will be quite debilitating, but the worst thing is that their children will suffer a much higher rate of mutation because of the genotoxic nature of the DU.

BTW if you don't believe me that is fine... there is a powerful lobby in the US that wants to pretend that DU is perfectly safe... it is certainly effective in the role.

The problem is the clean up afterwards, but then the US military doesn't care about that... look at how much agent orange and a range of other chemicals they poured over Vietnam in the 70s.

Very simply DU is depleted uranium and is basically made of spent nuclear fuel rods. It is radioactive waste.

While tricky to handle (it reacts with steel) it is very cheap and a "good use for waste".

The alternative is very expensive alloys of tungsten, which together with a longer barrel like the L55 gun on the new Leopards gives it comparable performance to a DU round from the shorter barrel of the US Abrams.

If DU really was 100% safe then why bother with expensive tungsten alternatives?

Why do the US keep their DU rounds for war and not use them at their own training grounds?

Clean up at home is expensive, while clean up in Iraq and Afghanistan and Serbia... is total free because it isn't done, because they deny there is a problem.

It is the head in the sand attitude... we don't know that it is dangerous so we will continue to use it till proved otherwise.

Of course they don't use it at home and as my nephew said... he can get me the empty 25mm shell cases from a LAV III, but he can't get the live AP rounds because they are radioactive... (and to be honest... I don't want the radioactive bits anyway.)

BTW if you don't believe me that is fine... there is a powerful lobby in the US that wants to pretend that DU is perfectly safe... it is certainly effective in the role.

Sarcasm, DU is horrible stuff. I hate it and it's sad to see my country using it, when even the supposedly evil Russians wont unless it's a doomsday WWIII scenario. I don't think many other European countries use it either.

Really, there's some serious denial in the US military regarding DU munitions.

Question guys. Whats the difference between the "cassette" loader and the "basket" loader, as in the difference between the ones used on the T-64/80 and the T-72/90?

Chobham armor is good, but it isn't invincible. The M1 has incurred causalities from the humble rpg-7, same with the T-72. There's also instances were both tanks have absorbed multiple RPG hits and have made it out with the crew intact.

The east and the west have just taken far different approaches to MBT design and protection.

The T-72's autoloader stores both the projectiles and propellant charges horizontally, underneath a firewall. Both the projectile and the propellant are raised into position by an elevator simultaneously then rammed separately into the breech.

Like this.



The T-80 stores the projectiles horizontally, and the propellant charges vertically.

Here's a hard to find image of the T-80's magazine. It's actually a T-84, but it's the same setup.



However, unlike the T-72, the T-80 loads in one smooth motion. This is why the T-80 has a slightly faster rate of fire.

Nice vids Zivo.

Basically cassette and basket generally refer to both or either system... which are basically automated ammo handling systems.

The T-80 system evolved from the system from the T-64, and the T-72 system was developed separately.

The T-80 system is faster but is fatally flawed.

The whole reason the Black Eagle had a rear turret bustle autoloader and removed all the under floor ammo is because in the T-80 autoloader the ammo stubs are positioned vertically and are exposed... and are made of propellent impregnated cardboard. They are supposed to combust completely in the chamber during firing so all that is left is a small stub steel shell case.

The problem is that any penetration in the crew compartment will send a shower of sparks and hot fragments and any contact with the propellent stubs on the floor will start a fierce fire and explosion of propellent with all the stubs igniting each other together.

In the T-72 they are horizontal and separated from the crew compartment by steel armour plate, which means any fragments or hot sparks that enter the crew compartment can't contact the propellent stubs and will fairly rapidly burn out.

Experience in Chechnia is that a penetration with a T-80... boom. Penetration of the T-72 with the loose ammo in the crew compartment removed and no boom.

Only solution for T-80 was to move the autoloader to the turret bustle.

For the T-72/90 move the extra ammo to an armoured box between the turret and engine and the rear turret bustle in a separated protected position.

Absolutely

Another issue with the vertical propellant storage is that it produces a significantly larger target vs the T-72/90's magazine. By being cylindrical in form, any hit on the T-80's lower hull could result it a catastrophic detonation of the ammunition.

Thanks a for the explanations Zivo and Garry.

Anyways, what is the current status of Russian Tank Optics? I have read that improved Catherine Thermals are under licensed production in Russia which is good news. Still, considering the importance of such equipment in staying relevant in today's battlefield why has there been no attempts as of late(dunno much , please correct me if I am wrong, I just google translate potential "tags" and try to understand as much ) to establish the domestic capability to independently produce and develop the tech.

They just concluded a new licence to produce the newer Catherine XP thermals, which are third gen QWIP based thermal imagers, and if you pay careful attention quite a few new Russian systems actually use Russian developed thermal sights including their current thermal weapon sights.

The experience and production facilities used for the production of the older Catherine Thermals and now the new models is being used to further advance Russian capabilities in this field.

In fact in image intensification technology the last time I looked they were working on sights that could distinguish between natural colours (ie plants) and artifical colours (ie camouflage coloured fabric or paint).

They seem to be moving forward just fine.

AFAIK modern MBTs offroad speeds don't really have any practical difference, If there is
then it would be a liability since you need to stay in straight path to do so and you
would be going to encounter all sorts of nasty bumps along the way that you would rather
slowly cross. Also, I highly doubt Leopard 2s and Leclerc could withstand flying and falling
2m in the air in T-90 speeds let alone their top speeds.

Haha. There is nothing practical with jumping and shooting in same time. Stupid pakazukha(maybe not only Soviet as i've seen germans doing it too). Can You imagine the stress T-90 suspension and equipment gets? There is a reason why T-90MS don't jump.
Judging by that kangaroos are best MBT in the world.
And TOP SPEED is not IMPORTANT in battle. Acceleration in forward and in reverse is.
T-90 is not really flagship of advanced technology and mechanics. There is a reason it was called T-34 by Russian general. It does cost cheap, but Russian army never had big interest in this tank, they even stopped buying them for a year. It's clearly stopgap tank and if Soviet union wouldn't collapsed, T-90 would never happen. It's evolutionary dead end.

Regular wrote:Haha. There is nothing practical with jumping and shooting in same time. Stupid pakazukha(maybe not only Soviet as i've seen germans doing it too). Can You imagine the stress T-90 suspension and equipment gets? There is a reason why T-90MS don't jump.
Judging by that kangaroos are best MBT in the world.

No one said shooting in midair was practical, if anything I was merely pointing out that for whatever reason these 3 tanks were to go top speed offroad and were to jump off dirt ramps, the slightly higher top speed would work against the western tanks. Anyway, marketing stunt or not, the point is they were confident enough that such stress would be handled by the suspension, something I don't see in the 2 other tanks. As for T-90MS, well there is a substantial 1.5 ton weight increase so we'll see.

Regular wrote: And TOP SPEED is not IMPORTANT in battle. Acceleration in forward and in reverse is.

Well, of course it is. The ability to move from cover to cover as quickly as possible would be the best armor of all.

Regular wrote:Haha. There is nothing practical with jumping and shooting in same time. Stupid pakazukha(maybe not only Soviet as i've seen germans doing it too). Can You imagine the stress T-90 suspension and equipment gets? There is a reason why T-90MS don't jump.
Judging by that kangaroos are best MBT in the world.
And TOP SPEED is not IMPORTANT in battle. Acceleration in forward and in reverse is.
T-90 is not really flagship of advanced technology and mechanics. There is a reason it was called T-34 by Russian general. It does cost cheap, but Russian army never had big interest in this tank, they even stopped buying them for a year. It's clearly stopgap tank and if Soviet union wouldn't collapsed, T-90 would never happen. It's evolutionary dead end.

That has nothing to do with the T-90, and everything to do with Makarov being an idiot.

And it is not cheap either.

collegeboy16 wrote:

Sorry, but off road speed of T-90 is adequate to batter it's crew into pulp by simply jumping from every "ramp". Same goes to western tanks too. Jumping does massive stress to suspension and equipment inside.
Ever seen live fire exercises? Tanks move relatively slowly while maintaining precise fire for about 1km distance. To hit something precisely over 1 km You have to be stationary. That's Russian tactics. There would be serious consequences for driver-mechanic if his cowboyish actions would cause any mechanical problem.

The ability to move from cover to cover as quickly as possible would be the best armor of all.

You are right here, but You make it sound like tank is running on two legs and can dodge bullets like Neo.
When we have big distances and tanks get in the duel there is certain time till projectiles reach their target. And here comes acceleration. Shoot, move ,shoot, move. TC is orchestrating those moves.
You can't run from cover to cover while closing as You have upper hand in long distance engagements because of ATGM. One thing is certain, top speed and jumping is good for shows, military exercises that portray real battle look different.

As for T-90MS, well there is a substantial 1.5 ton weight increase so we'll see.

I think T-90MS can jump like it's preprocessors, 1.5t doesn't mean much.
Hell, even Merkava jumps.

Why we should be impressed by it? Would like to see drivers toothless grin after doing those jumps with battle-loaded tank.

TR1 wrote:
That has nothing to do with the T-90, and everything to do with Makarov being an idiot.

And it is not cheap either.

It wasn't just Makarov that stated that. Maybe You are right, he has some retarded statements. T-90 is a product of collapsed industry.
And what about it's price? How the hell it's not cheap? It's fully domestic product. One general said that it would be cheaper to buy leopard-2 tanks, but sure they cost about 6 mil per unit not to mention logistics needed. So Armata will be what, over 8 mil per unit ?

T-90 is a fine product for the time. Was USSR working on replacement? Yes, but as T-90MS shows, T-90 is about as evolutionary dead as its late COld War contemporaries.

If we compare export prices, T-90A is not a cheap product at all by world standards. And why should it be, it is a good MBT. I can't imagine T-90MS being much cheaper than Leopard 2s either.

It's clearly stopgap tank and if Soviet union wouldn't collapsed, T-90 would never happen. It's evolutionary dead end.

You are being unfair... the T-90 is a tank developed from a cheap mass production tank that turned out to be even better than the top line expensive tank it was produced in parallel with... ie the T-80.

The T-90 is the top of its evolutionary chart the same way the M1 Abrams in its current in service model is too. Just because the next gen vehicles will likely have unmanned turrets and perhaps even be completely unmanned does not mean they are bad tanks.

The ability of a tank to leave the ground and not require to be immediately sent for repair is not a practical thing that would be useful in combat... much like a tail slide for a fighter, but it shows acceleration and a certain level of mobility... just as a tailslide shows robust engines that are not bothered even by reverse air flows... which is very significant in combat... no point fitting your plane with TVC systems if your engines stall when the airflow changes direction.

To hit something precisely over 1 km You have to be stationary.

Except with Refleks...

You are right here, but You make it sound like tank is running on two legs and can dodge bullets like Neo.

Claims of marketing departments are often exaggerated... but even the tail slide manouver showed a level of design and performance with symetrical air flow that suggested these aircraft were not like the generation before them.