Modern Tank Armour.

damn grunt2 bet me to it

Chobham is much more than ceramic.

And how much of the T80U is chobham?

Chobham is a type of compostie armour given a fancy name?

the T-80 has multi-layer armour on the glacis plate and front turnet. this is the areas i know it has it in. but not to sure where else

The Brits went from Stillbrew to Chobham, the Yanks went from DU to Chobham.

The exact recipe of Chobham is still classified, a bit like saying the USS Ronald Raegan is capable of "somewhere over 30 knots..."

But the last steel tank the Brits made was the Chieftan. And they invented Stillbrew as an aftermarket add-on. Challenger 1 was the natural progression of that.

The Yanks were still working in steel when M1 was on its way, and they only put a 105 in it, Cheiftan already had a 120mm. But the Yanks chose DU for its incredible density, the problem is the associated after effects of battle using depleted uranium armour and armour-penetrators. Gulf-War Syndrome, anyone?

Leo 1 has nearly the perfect turret shape. Why was Leo 2 given vertical mantlet surfaces and the update made to look like a Merkava?

Leo 1 has nearly the perfect turret shape. Why was Leo 2 given vertical mantlet surfaces and the update made to look like a Merkava?

ahhh, the original shape of thr Leo2 was a mistake, they fix that with the new versions of leo2a5-6, take again a look, the leo 1 was a conventional 70s turret

again your chobham is a good material, but again the same kind of materials are used with out problems in other hull shapes, please dont start with that classified speculation, i already have had enought of that

Grunt2,

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

This applies only based on two conditions:

1. The wall thickness remains the same in all dimensions of the curve. Such cannot be true in a 30-40 ton tank.

2. The curve is complete to transfer force around both sides of the impact sheer angle.

One of the reasons why it is so easy to pop a T-55/72 turret off (other than the idiotic policy of cased round stowage inside) is that the curvilinear turret top meets a squared off ring race and _even if_ the round does not penetrate, the impact force translates straight down across rim of the turret wall into the hull mount.

Now, look at a nominally 'straight' (slab sided) armor panel as being the best way to generate -space- behind the front face. And realize that the level of protection provided is a function of BOTH the hardness of the strike panel AND the rigidity of it's mount to the rest of the armor system (floor, roof, rear anchor point).

If the area behind this front panel looks like a right or isosceles triangle with the hypotenuse acting as a stiffener based on focusing impact force through a lateral 'tripod' effect. Then the amount that the strike plate can yield in the plane of the impact as a function of total MJ force (creating the initial moment transfer of penetration energy) is a function of how much that focussing of energy to a point is SECURED from shifting by the horizontal frame also coming back and likely EBW'd to a secondary turret floor well ahead of the crew compartment.

Now, whether you fill the rest of the void beside/between the frames with more tilted panels to further absorb/deflect or frange a long rod or chemical stream. Or go to some kind of exotic ceramic laminate to provide a gas:fluid diffusion that sheers it, the fact remains that if the tank turret looks like this-
___________________
CREW AREA |_L or S_/_\

The VOLUME described by the Laminate or Spaced armor section ahead of the crew compartment is going to be _vastly_ denser, stiffer and _better protected_ than an armor array that looks like a simple frying pan upside down ala-


/`````````````\

so.

>>
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-
>>

It appears you understand the basics of shaping geometry on energy transfer (though I'll be danged if I'm going to potentially deflect even a partial penetrator rod down through the front hull roof over the driver) but what you fail to 'get' is that an M-1 or similar vehicle has, not one but likely Two Or More compartmentalized armor vessels. Albeit these only cover the frontal arc; they still provide an effectively MASSIVELY thicker protection to direct fire than any rounded protection system.

The likely irony being that, while it is fully possible to mold ceramics to the inside of a curved surface (like thermos glass around the inside of an aluminum tube), securing them there against impact and interior spalling is (let alone repairing them after) is probably just short of impossible. So that, where the brittle ceramic material derives NO benefit from shaping (one way or the other) it is BETTER for the impact energy to be transfered as directly as possible to multiple 'baffles' if you will of layered or spaced armor laminates set up as simple sequential strike plates behind the DU or Steel front.

i.e. the notion that a rounded form offers better kinetic 'deflection' may be exactly the opposite of the theory the tank designer is working for.

In any case, the argument must remain that to get effective (deep) armor, you have to have the spall and/or fluid compression buildup void space inside a _regular_ shape to provide adequate energy depletion before a final interior wall and spall liners is hit.

The question then being whether you first want to try to stop the penetration from happening at all by mounting the hardest tensile material you can to the most rigid floor-to-roof stiffening frame before you exercise any secondary internal material/layering/spaced defense strategy.

And here too, it just doesn't make sense to reinforce the egg with angle iron since you not only haven't got the volume. But you are also localizing stress at two points on the INTERIOR (weak) wall to do so.

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

I disagree.

>>
simply physics, guys, simply physics
>>

Simple Physics are why Iraq and Kuwait were littered with dead Russian Tanks in 1991.

I don't /care/ if these were 'export models' or 'badly crewed and commanded'. The simple fact is that the _basic configurations_ are largely the same between home use and foreign military sale versions and thus 'no matter what materials' (as in dolly'd armor addon packages welded to the OUTER front face of a space limited turret) are used, it was the thru-and-thru capabilities of the long rods that could and did kill tanks behind berms or even behind other tanks that highlighted a major deficiency in the design inherent to an inability to shatter the round at the front face or SLOW IT prior to penetrating the crew compartment.

Until and unless you can get your industry to fabricate _just one_ testbed gun that generates the same bore pressures and MJ muzzle energy as the M256 with a DU round (currently better than even the Leo2A6 for total energy at 2,000m). FIRE THAT TUBE at a frying pan tank with 'equivalent RHA' to a similar design that uses vertical laminate/spaced armor with a hard tungsten or DU face plate, and _show_ that the former turret design survives better at equvalent weight; you will never convince anybody that you know how to do anything but produce mass quantities of tracked coffins.

And THAT sir is a lesson in 'simple economics'. Them's as sell crap, no matter how cheap, don't do so for very long once higher grade alternatives are avavailable.


KPl.

The latest american APFSDS [the M-829A3] is on par with the penetration performance of the German DM-53 with the 120L55 and the latest Russian and Chinese 125mm APFSDS....they all have similar performance.

first, there are ballistic reports that show the difference between the iraqi model and the east german model, both thaks were very diffrent, so dont start with the clasic gulf war claim

the tank was designed under the force propagation concept, thats actually why isnt a welded turred and it use mono-hull, actually for a flat-welded structure is very hard to do that

other myth is the sabots location, tell me what is the best secure location in the tank???? the turret???????, how cant you see that blow effect in a war with such numerical-technologic-moral etc.. advantages???, the western designs moved the sabots to the turret to increase the living conditions in the tank -a live in the t72 is a hell-

an homogeneus thickness have nothing to do here, if you have a tangential orientation in the impact point the forces -or part of the forces- are tranfered to other areas, so thickness is lower in other areas, then just the deformation is higher in other areas, nothing more-but in these areas there is a compression, not cut deformation-

where you see flat surfaces in the t72???? you dont need a perfect 10/10 circle,yes you need a circular shape, the right inclination, and avoid angles or big tangential differences

your "tripod" effect is in the Leo1A5-6 or Merkava, not in the M1, it dont have a good angle or shape to transfer the energy into tangential deformation and the effect in under only a face of your triangle

also the russian tanks arent so light armoured unless you compare 80s with last 90s western tanks

and again materials have nothing to do with the shape of the tank

but rounded sahpe isnt perfect, again, othere designs are muuuuch better like the Leo2a6


[edit on 18-8-2005 by grunt2]

Gulf war examples of the T-72 are complete nonsense, using highly inferior tanks with underrated engines, baseline armor, nothing but low quality, anti infantry shells, and manned by crews that had no idea what they were doing, against the Americans who had complete training to be effecient and quick, and have massive situational and long range detection awareness advantages.

The long rods, you must remember, if hitting the turret, are very likely to hit at a off angle of 30 degrees or more, and although some T-72s simply use harden steel, which does poorly against them, a harder substance, with such a high deflection angle, does give a better chance of cracking the rod or having it careen off the side, rather than giving it a broad target that may have a harden face, but also requires enough depth and internal structure to defeat it.

Does anyone have any good references for Leopard armor, since I have heard much, but the only good photo or text of the Leopard shows a flat turret front, which is pretty strange. Any links would be excellent, as for the Abrams armor or Black eagle. I'll be looking myself.

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Long rod penetrators can't be deflected from their target, regardless of angle of incidence, because the physics of the interaction don't allow it. At velocities obove 1700m/s the impact becomes a hydrostratic interaction, which is to say, one liquid squirting into another. The impact pressures are so high that they completely exceed the yield strength of materials.... all materials. So when the long rod penetrator strikes a surface, it splashes away as a liquid, blowing away target substrate. Penetration is equal to length of penetrator, times ratio of relative mass. Interestingly, above that critical velocity, a faster penetrator doesn't make a deeper hole, just a wider one. For this reason, weapons designers have been putting their efforts into longer penetrators for some time now. Trying things like telescoping or sliding section penetrators.

The reason for using DU or Tungsten penetrators then is nothing to do with shatter resistance or the like, it is simply because these materials are very dense. Well, DU is also a pyrophoric material, so it gives sparks when struck. That is a handy attribute for internal effect.

Also the initial post about shaped charges is a common misunderstanding. Common, but not wrong for all of that. The explosive component is machined to tolerances as fine as those of eyeglass lenses. The resulting pressure wave squeezes the (typically copper, but gold would be better - see density effect above) to a fraction of its initial volume (as an aside this is how sub-critical plutonium pits in the smallest atomic weapons can be induced to fission - critical mass is a function of surface area and neutron emission rate. If the surface area can be reduced dramatically without losing emission rate, a sub-critical mass becomes super-critical on demand. The change of volume can be as high as a factor of 4!... amazing stuff)
But I digress. The copper liner is squeezed inwards, compressed to a fraction of it's starting volume. The only direction not under pressure is forwards, so a needle (often misnamed a jet, but x-rays of the forming extrusion have proved that the material is still, remarkably enough, a solid) squirts out the front. This needle is in fact extremely long and thing, and strikes the target with sufficient velocity that, once again, the pressure is many times the yield strength of any known material, so the target blows away like a liquid. Angle of incidence just doesn't matter here either, except trigonometrically, where a shallow angle gives more material to penetrate. Internal material and density transitions do disrupt the needle, as does the outflowing material plume. The diameter of the hole is not reflective of the formed penetrator diameter, but rather a manifestation of the excessive energy making the hole wider.

Interestingly, the formed penetrator from a shaped charge is moving fastest at its tip, and slower as later length is formed, so it eventually stretches and brakes up into a stream of particles. Reactive armor only works when the launched outer plate moves across this stream, disrupting a length of it. when a shaped charge functions at a right angle to reactive armor, the effectiveness is minimal.

Yours

Dog Cavalry