Modern Tank Armour.

t is often argued in some threads that such and such a tank as the equivalent of 1000mm of steel armor or 800mm. Or that a certain tank gun can penetrate how many mm of armor at a certain range. The fact is that it doesn’t work this way. Modern tank armor cannot be described as being equivalent to a certain thickness of rolled homogeneous steel, period. There is no equivalency to speak of.

Primarily there are two kinds of threats a tank’s armor has to defeat – Kinetic Energy and Chemical Energy.

In terms of kinetic energy threats, the only kind of projectile that even has a chance at penetrating a heavy tank’s frontal arc is a long rod projectile. You cannot describe the ability to protect against them as a thickness of steel. Depleted Uranium or Tungsten-Carbide rods will pierce ordinary steel like butter and any kind of sane thickness is quite irrelevant. If you shoot the LR penetrators into a 5m block of steel they’ll simply embed themselves in it. This is not how tank armor typically stop the APFSDS-T or DU rounds. There is no armor that is say 300mm thick, but equal 1200 mm of steel and hence cause a penetrator that will go through 1000mm of steel to be stopped after 250mm of this “miracle armor” and stick out like a dart on a dart board. It doesn’t work like that. The key to stopping long rod penetrators is fracturing it on impact. If you are successful, you will have an inch or two worth of a dent and there will be practically no penetration. If you fail, the rod will most likely go right through your armor no matter how thick or thin it physically is. Generally speaking, the system employed to achieve this is a very high tensile metal face plate that is relatively thin. And their effectiveness depends highly on the penetrator itself. The US uses Depleted Uranium for this. Most others use tungsten carbide or simply face hardened steel. Tungsten carbide is actually harder than DU, but DU is sufficiently hard and is less prone to shattering than TC. In the end, 80% of the tank’s ability to stop sabot KE rounds comes down to 10 to 20mm worth of armor.

When it comes to Chemical Energy warheads, there are primarily two types – HEAT and HESH. HEAT is the more common of the two today, and despite the name the way it works has nothing to do with heat. So, you can forget about any claims that ceramic armor is superior against HEAT rounds because they do not conduct heat. This is utter rubbish. HEAT – High Explosive Anti-Tank – rounds work by focusing explosive energy down a very narrow jet. They do so using a geometrically precise reverse cone hollow charge of high explosive which when detonated uses about 2/3 of its explosive energy to force the remain 1/3 or so into a concentrated jet. This jet penetrates armor by pressure, not by temperature. Stopping HEAT rounds really comes down to either dissipating this jet or giving it sufficient room to dissipate on its own. The simplest way is to have an armor skirt a good half a meter away from the tank’s armor. This is used in WWII on many German tanks when HEAT rounds started to become commonplace. The other way is to use a reactive armor. Both explosive and ceramic composite armor (such as Chobham) are in essence reactive armor. They work by reacting to the HEAT jet and disrupting it. ERA works by itself exploding. The resulting explosive force and the metal plate thrown out by it disrupts the focus of the HEAT jet rendering it a lot less effective that it otherwise will be. Chobham type armor typically crushes under the jet. This pulverizes the ceramic layers and turns the ceramic into a high modulus cloud of pulverized ceramic. This dense ceramic dust, under tremendous pressure, is almost like a fluid. As it gushes out in the face of the HEAT jet and neutralizes its energy. HESH – High Explosive Squash Head -- warheads work by flattening itself against the armored surface like a lump of clay. When detonated, the explosive force causes transfer through the metal – like a billard ball striking another, stopping and causing the other ball to get in motion. This force causes the inside surface of the armor to buckle and detach. The armor itself hence becomes the killing mechanism, showering the occupants inside the tank with shrapnel. Again spacing works against HESH. However, ERA and composite armor in their basic form do not. As long as you have continuous armor between the outer and inner surface, HESH will most likely kill you. Again, trying to measure resistance to chemical warhead as a “thickness of steel” worthless.

To sum it up, basically, to stop kinetic energy weapons, it really comes down to a few centimeters of very hard plating. To stop Chemical Energy weapons, it is all about spacing and reactive armor (not just ERA, but passive ones like Ceramic composites as well).

The common armor concepts used in modern tanks is as follows:-

(1) Steel armor. This is cheap and easy to make. It can be a casting or made from welded plates. Heat treating can be used to harden the faces of steel armor to improve performance against kinetic energy weapons at the expense of resilience against chemical warheads. Classic tanks like the M48 and T55 uses this.

(2) Aluminum armor. This is very light. Every pound of aluminum armor is also more effective against chemical warheads as an equivalent pound of steel since aluminum is bulkier but less dense and stronger than steel by weight. The M113 uses aluminum armor – too little of it really to be of much value. The protection of the M113 was bad to the point where assault rifle rounds with steel cores will penetrate it at close range.

(3) Perforated steel armor. This involved steel armor that is in effect drilled full of holes perpendicular to the face of the armor. The holes are no bigger than half the expected diameter of the expected penetrator. This allows the armor to be 40-50% the weight of a solid block of steel, but 70% as effective against kinetic threats. It also makes the armor bulkier and full of empty space, which enhances survivability against HEAT and HESH type warheads. Usually the perforated blocks will form the core of the armor, with harden steel strike faces and/or unperforated panels capping off both ends. Advanced versions of perforated armor use hard cylinder liners for the holes to increase kinetic protection and/or ceramic fillers within for protection against HEAT rounds. Despite popular believe, the original Leopard II does not use Chobham type ceramic laminate armor, rather it uses perforated armor. Because the orientation of the holes are very important to effective protection, perforated armor does not lend itself to curved surfaces very well.

(4) Ceramic Laminates (Chobham type). This is usually a laminate of multiple layers of metal and ceramic plates. The ceramic used is usually a guarded secret, but it is speculated that Alumina (Aluminium Oxide or Sapphire), Boron Carbide (the hardest simple ceramic), and similar materials are probably used. Sometimes synthetic fibers are used to enhance the effectiveness of the metal backing plates and metal mesh is integrated into the ceramic plates to localize shattering when struck. Sometimes the term Ceramic Matrix Composite is coined to discribed laminated armor employing these advanced techniques. Because the ceramics are both very hard and crushes into a HEAT jet disrupting retro-fluid action, it is very effective against HEAT warheads. Because it is numerously layered, it is more effective against modern HEAT warheads which frequently has tandem charges to defeat ERA. When it is hit by a tandem charge, the precursor charge will not expend the entire reactive package just the top layer or two. Ceramic laminates also resist kinetic energy penetrators better than steel armor of a comparable weight though not as drastically better as they resist shaped charges from chemical warheads. Pound for pound, this is currently the most effective single armor concept though it is frequently used in conjunction with other armor concepts. Because ceramics cannot be bent into curved surfaces, tank designs using ceramic laminates also tend to be squarish.

(5) High tensile alloy faced armor. This is an arrangement common amongst state of the art tanks. Basically, it is a thin sheet of tungsten alloy or in the case of late model M1 tanks Depleted Uranium acting as the strike face of whatever the armor type is underneath. The mission of this is to fracture long rod penetrators and render them practically useless. Tungsten-carbide is actually harder than DU, but DU is also very hard and is less prone to shattering making it a superior material for penetrators and strike faces. The problem is DU dust is toxic and is very unhealthy if breathed in.

(6) ERA – Explosive Reactive Armor. This is a cheap and relative light way of protecting against HEAT projectiles. Basically it is high explosive sandwiched between steel plates which explodes when it is hit by a HEAT warhead. It is practically useless against kinetic rounds and there is no repeated strike capability making it very venerable to tandem charge warheads. But it is light, modular and easy to apply over existing vehicles. You will see this on Soviet tanks and Chinese tanks a lot. Generally it is a quick fix for tanks which does not use advanced ceramic laminate type “passive” reactive armor.

(7) Spaced armor. This is one of the oldest tricks in the book and really the only one that does not involve heavy materials and the only thing that is truly effective against HESH rounds. This can be simple slats or skirts mounted some distance off the sides of the hull or turret. It is also a feature inside the advanced construct of some tanks. An empty space is just about as good as steel in countering shaped charges and empty space is weightless. Modern internal spacings also tend to have angled baffles to channel the jet off the centerline to further increase effectiveness against chemical energy attacks.

(8) Advanced Combinations. Most of the best tanks in the world use a combination of two or more of the above.

Oh, BTW, because they offer more protection for the same weight compared to steel but takes up more space, perforated armor and ceramic laminate armor is sometimes called "Bulky Armor".

The current armor package for the M1A2 for example uses Depleted Uranium strike faces, an advanced Chobham type ceramic laminate, baffled spacing and Kevlar type supplementary backing for critical spaces. The exact thickness and construct of the laminated armor blocks are of course highly classified. I believe the core armor for the up armored Leopard 2s remain the same as the original Leopard 2’s perforated type. However, the big chunks of additional armor probably has high tensile strike faces and are probably mostly hollow – if they were not largely hollow, the Leopard 2A6 would be a lot more than 70 tons. Only the Chinese military officials will know the exact composition of the armor on the Type 98 and 99 tanks. However, if I have to take a guess I say they are using perforated armor with hardened strike faces and ERA. This will be consistent with the need for squared profiles and the modest weight of the packge.



I did not write this.

i cut and paste this from sinodefence.com. posted by member jatt2ooo

haha I know Jatt from WAFF forum some1 posted this same article.

thanks,
drfunk

oh... this was posted in WAFF.

heres a link
www.network54.com...

Have you guys ever wondered that we might be looking at the wrong direction of Tank protection?

We focus too much on the amour itself. Kinda forgotten, we need better Track design, I mean how good is a tank without its tracks or stuck in mud.

The best way to defend a tank IMO, is to prevent the projectile from hitting the amour in the first place. Maybe a mini phalanx system?

Originally posted by Humster
Have you guys ever wondered that we might be looking at the wrong direction of Tank protection?

We focus too much on the amour itself. Kinda forgotten, we need better Track design, I mean how good is a tank without its tracks or stuck in mud.

the U.S. military has been improving the tank tracks. look at the M1a1 Abrams from the 90s and look at the new Abrams with different track pads.

The best way to defend a tank IMO, is to prevent the projectile from hitting the amour in the first place. Maybe a mini phalanx system?

no phalanx can stop a tank projectile, maybe an RPG or some other anti-tank weapon.

Good point Humster.

This was basically the problem with the German medium/heavy and heavy tanks during WWII. The Tiger I, II and JagdPanther / JagdTiger were chronically underpowered for the weight of the vehicles and the tracks were standard at the time.

The onslaught of the T-34s and the way they powered through the thick Siberian mud, ice and snow came as a complete shock to the Germans.

I also think that the Christie suspension (return rollers) also inhibit the way the track behaves whilst the 'slack-track' system most WWII Russian era tanks employed, gave them [track] greater flexibility.

I still say that, even with the best armor materials in the world, if your armor is a flat, upright surface, it will be many times easier to defeat than say, sloped and rounded armor. Certainly, the dome of the old FSU tanks dont look as impressive as the Abrams, and they do not have the resistance to HEAT rounds, but they do have very good reflection dynamics in terms of rods. That dome, and very low profileed and highly sloped glacis plates makes for an poor target to land a rod against a flat surface, where as, the Leopard has nearly flat forward turret armor, which I never quite understood.

Even their new tanks, mostly the "Black Eagle" with the large, western looking turret, have that traditional rounded, low, frypan looking front to bounce off kinetics.

I really think its all in the tank design, rather than the materials used.

This idea of thick armour plate is history. The FCS and its ilk will be airmobile light vehicles (under 20 tons) with deeply layered active protection. You won't be able to detect them, and if you can you won't target them, and if you do guidance will be jammed or spoofed. Projectiles will be intercepted by active armour elements including directed energy beams.

Originally posted by Wembley

This idea of thick armour plate is history. The FCS and its ilk will be airmobile light vehicles (under 20 tons) with deeply layered active protection. You won't be able to detect them, and if you can you won't target them, and if you do guidance will be jammed or spoofed. Projectiles will be intercepted by active armour elements including directed energy beams.

Gona need one hell of a power source to power all that gear...

rounded hull works better than sloped, but also depends of the sloping angle, for example the design of the LeoA4 is muuuuch better than the M1 and i think that better in a face impact than a rounded hull

Its simply physics, (dont get me wrong with this simple analogy) Whats harder to poke a hole in, a sphere or a box with sides? Unless you hit directly in the center of the sphere, the box is a better target.
Same goes with armor in tanks, though it would be hell giving the glacis plate and sides that kind of angled protection.

ups.... i just confuse the leo2a4 with the leo2a5, sorry by the mistake

The article has a lot of misconceptions and is out right wrong in some cases.

Modern research papers [many available on line] used two distinct methods for measuring the penetrative power of a projectile or the relative resistance of modern armors tested. These are mass effectiveness and space or thickness effectiveness. Both armors compare a projectiles penetration into a reference material [usually RHA or some steel but sometimes Aluminum is used] and then compares the same projectile penetration into a different material or layering of different materials , including sloped armors and monolithic blocks of armor.

Mass effectiveness compares these depth of penetration [DOP] results based on the relative difference in the mass of the target, while space effectiveness compares the DOP into the reference material and target material.

So if you have two targets on made of RHA [7.8g/cc] and another made of aluminum [density 2.8g/cc]. IF the projectile [14.5mm API] penetrates say 2 inches into the RHA target and 6 inches into the Aluminum target, then the aluminum target is said to have a space effectiveness of 0.33 and a mass effectiveness of 0.87. So this means that the aluminum armor would resist about 1/3 the thickeness of RHA but it would be almost as mass efficent as the RHA interms of mass. So given the fact that aluminum would be twice as costly as Steel its not a better armor choice unless other factors creep in....like since armor weigth counts for 1/2 of the vehilce weight , an aluminum AFV may offer weight savings in that other half allowing for more over all weight going towards the armor.

If the same aluminum was struck by an APFSDS or Shaped charge its resistance might be 4" into RHA or 8" into Aluminum. So the aluminum armor would have a space effectiveness of 0.5 and a mass effectiveness of 1.44. So you would need twice as much aluminum but this would be still less overall mass than the same protection offered by RHA . So against modern threats aluminum would be a better choice than RHA, especially if the overall vehicle weight savings creep in to boost overall armor mass.

So if you scale these results up to a tank with 300mm RHA mass, then the same target made with aluminum armor, should offer the equivilent of 430mm RHA against modern APFSDS & HEAT warheads. Its just a usefull yardstick to measure relative benifits of one armor arrangement over another.

In the article it claims the Leopard 2 has no chobham armor. How do they source this claim? I have spoken with Germans who have crewed that tank and they claim it does have chobham armor. I wonder if the article is written by an american?

Maybe this will be of interest to this discussion as it progresses?
Tank Protection Levels and Ammunition






seekerof

>>
Its simply physics, (dont get me wrong with this simple analogy) Whats harder to poke a hole in, a sphere or a box with sides?
>>

I see it the other way.

Like knights laying poles or treeboles at an angle behind a gate to help increase the stiffness of the gate to a battering attack.

The 'strength' defined by RHA equivalency is in fact the DISTANCE defined by the hypotenuse described that is the length of the pole to the ground and back again to the 'armor face' of the gate panel.

While 'egg theory' applied to a castle gate might prove interesting, on a tank, an ovoid or curved shape is _innefficient_ because you cannot stack the same material/void/'framing' (I swear the description in the above definition is like unto lightening holes in a conventional rib) angles as you can with a simple planar set of geometric integers (non fractional separations of the curve into definable geometric planes).

The real 'description of volume vs. space' ideal going on here is of course inherent to a 2 dimensional fixation with LOS fires across a shared horizon.

I would be much more interested in seeing the relative penetrating value of an 'archer takes the wall and fires into the back of the men leaning on those poles' type scenario by which a relatively slow round is lobbed high on a soft launch (1,800-2,500fps) and then uses blip motor squibs around a core package to keep the round 'bunting' along while some kind of characterizing seeker looks down.

When a target is detected, the round stoops off the perch and THEN goes hypersonic on a central core motor while it dives /behind/ the layered/spaced/face hardened armor.

I think that this is what will ultimately return turret shapes to, not merely a less bulky overlay on the hull (with all it's attendant shottraps and massive structural load stress variables on the ring with rotation), but a completely _unmanned_ pedestal mount rather like that on the AMX-13.

Indeed, you need only look at the following-

'MGV = Wheeled Maus Breeds With South African 155 SPH'
www.globalsecurity.org...
www.globalsecurity.org...

vs.

NLOS/Mortar Vehicles
www.globalsecurity.org...
www.globalsecurity.org...

And then compare them with the 'low profile' vehicles shown in the video and pictures here-

www.globalsecurity.org...
www.globalsecurity.org...

And it becomes obvious, ESPECIALLY IF YOU WANT AIR MECH DELIVERY that a system designed to accomodate a longbarrel, high pressure, tube, it's mantlet and the men standing or even sitting behind it, is just never going to meet required protection levels, load weight or most likely, both.

If you instead ditch the turret, put your sensors on a mast to depress the horizon and spread your remaining armor ('spaced', re/active or otherwise) evenly across the majority of at least the crew compartment to protect against the vertical attack while maintaining at least /some/ (IFV light cannon and ATGW) defense in the frontal arc.

i.e. better no turret than one which attempts to armor-enclose is a man heighted volume to the extent that it increases the vehicles weight, height and vulnerability to FIBUA (all round) threats.

The irony of especially the last then being that, so long as the U.S. maintains dominance in the highest-rung of the airborne-sensor graze on targeting that NO MBT which clusters vulnerability in a pimple or boxlike cavity in the overall shell of the armored enclosure is going to be safe to even relatively small/slow approaching rounds (indeed, the need for fast terminals is strictly related to beating the Arena/Drozhd APS).

While the difference between a rocket based soft launch (in which the barrel is simply present to contain firing signature and channel back blast) and a propellant generated recoil and erosive gas capable hot-tube is only that of the _miniaturization_ needed to make (say) a 72-85mm diameter seeker enclosure (the equivalent of a typical LAW) perform while maintaining adequate reserves for warhead or kinetic boost terminals.

Since a 30-45mm kinetic round (the same as that on many upgun IFVs) is more than adequate to engage point targets behind walls in builtup zones (A-10 strafes Iraqi hotel for instance) in support of infantry and indeed even 'MBT', given surprise from a vulnerable sidestreet or alley type rollout ambush aspect.

Go small. Go remote firing station. Define your caliber/engagement zone by how far out you can see a threat which can kill you. Send in the equivalent to robotic Wiesels as hunter killer flush groups to set the battelfield in motion or trip any hidden ambush position. Kill hard targets from beyond LOS. Cleanup with packbots and infantry using you MCS/MGV in 'gun mode' (same or coaxial barrel) in direct support while protected ONLY against LAW/ATGW and similar (light auto cannon) threats.

It should work even when high energy DEWs start to go weaponized. Simply because things like the 32rd SUAV launcher vehicle can always squirt out more sacrificial drones and HAEUAV can (probably) still outslant the threat floor for lookin.


KPl.

Originally posted by Raideur
Its simply physics, (dont get me wrong with this simple analogy) Whats harder to poke a hole in, a sphere or a box with sides? Unless you hit directly in the center of the sphere, the box is a better target.
Same goes with armor in tanks, though it would be hell giving the glacis plate and sides that kind of angled protection.

Put the box on an angle and the resulting cross-section just "doubled" the width of the box wall and made your finger bounce off. That's the theory behind tank protection. And Chobham can't be shaped, that's why the turrets on modern tanks are flat surfaces instead of spheres. The Soviet/Russian turrets prior to Chiormy Oriol all had steel turrets, they could be cast in shape. Steel ain't so strong, so you have to cover it in ERA blocks to boost it's protection.

CH pretty much nailed the problem all future tanks face. It's like the first "steam-powered" crossing of the Atlantic. It was nothing of the kind. The coal is so heavy, you need a bigger engine. But the engine is so inefficinet that you need to feed it more coal to haul that weight around. Now you're burning so much coal that you need to carry larger reserves...
Your tank requires protection from all threats, so it's armour needs to be greater. Now it's so heavy it needs a bigger engine. Now it's engine is so large we need to make the tank bigger, now it's such a big target that we need to give it better protection...now it looks like an A7V!

The only argument that remains in favour of MBT's given the plethora of man-portable anti-tank weapons, from RPG7 to Carl Gustav to Milan, is that the range and accuracy on a 120mm gun is so many times greater (especially if rifled) than a man-portable system that only in ambush can you kill an MBT, while said MBT can kill you at any time.

The German's goliath may have been so slow and poorly armoured that you could pick it off with a .303 and detonate it, but R/C systems and armour have come a long way since then...Hell, look at the picture in the Metalstorm thread.

The Swedes were looking in other directions with the Bofors S-tank, but that couldn't fire on the move. Not a big problem when your warfare will be purely defensive and really you're after an SPG tank-killer anyway, but not much good if your raison d'etre is mobile warfare. Still, the turretless concept deserved a lot more examination.

Just look at what the Israelis are doing.

ch1466, ha!!, crap said in complicated words!!!, i never saw that

the deformation rate is relationated in how the forces are distibuted on the frame, the rounded shape distribute better the force arround a larger area in the hull, so the deformation is lower

but again also depends with the angle -in the case of the sloped armour-, like the comparation between the leoA5-6 and the M1, the sharped armour of the leo have an effective angle to turn part of the vector force into tangential compression -i mean tangential over the armour-

the materials have nothing to do with the shape, you see a huge quantify of angles and compossed angles in tanks

simply physics, guys, simply physics


[edit on 17-8-2005 by grunt2]

Originally posted by grunt2

the materials have nothing to do with the shape, you see a huge quantify of angles and compossed angles in tanks

simply physics, guys, simply physics

Ever see a Chobham turret that is rounded? Ever wonder why? Tank designers have known for seventy years that sloped armour is better and round turrets perfect. As useless as the Sherman was, it's turret was pretty good. Why are modern turret side-walls and bustles vertical if they know that's wrong?

Chobham can only be worked in flat/straight sections.

the chobham is a ceramic, also russian rounded hulls have ceramic armour, yes i know that some guys think that the chobham is the something like a brick of the gods, but also is only ceramic

does't the T-80U use a multi-layered type of armour? its shape is rounded