UK IFV Warrior, new infomation.

[Backis]

PlasmaKrab said:
the whole concept derived from the RPG fences used in Vietnam.

Its older than that. Russians used to tie bed-springs to the outside of their tanks to interfere with HEAT warheads.

Back then the penetrator stream lost coherence pretty fast so the standoff distance affected the effectiveness of the penetrator. Everything from sandbags to logs were used like this in WW2 by most sides, so I would not attribute this to the Vietnam era.

[PlasmaKrab]

Alright, I didn't know about these, WW2 is not quite my forte. Was that meant to fence off German hand-held rockets like the Panzerfaust? I thought there weren't that any tank HEAT rounds at the time.

Vietnam RPG fences were just the older example I knew of, and I wanted to point out that spaced grill armor wasn't a new idea.

Anyway any old material was fitted onto armor in conflicts all over the world, since WW2 propulsed HEAT warheads and steel armor have been employed on many occasions.

So sandbags, planks, tyres, etc. can be used to some extent. What would be useful to know is the precise efficiency of these things in terms of armouring.

[Backis]

PlasmaKrab said:
Alright, I didn't know about these, WW2 is not quite my forte. Was that meant to fence off German hand-held rockets like the Panzerfaust? I thought there weren't that any tank HEAT rounds at the time.

Vietnam RPG fences were just the older example I knew of, and I wanted to point out that spaced grill armor wasn't a new idea.

Anyway any old material was fitted onto armor in conflicts all over the world, since WW2 propulsed HEAT warheads and steel armor have been employed on many occasions.

So sandbags, planks, tyres, etc. can be used to some extent. What would be useful to know is the precise efficiency of these things in terms of armouring.

I believe the main intention of the bedsprings were as a stopgap measure to protect against Panzerfaust and Panzershreck. The effect may have been mainly psychological though. But as early HEAT rounds had poor focus they lost coherence and efficiency very fast, so a decimeter of extra standoff could give the equivalent of welding on several centimeters of steel for a fraction of weight and cost.

[kevin]

JaM...

Why do you say SLAT armor would stop 70% of RPG's? I'm just wondering what your source is, or is it a judgement call on your part?

I'm not real knowledgable on this subject, but I wonder what we can learn from the fact that SLAT is not applied to tanks or soft vehicles? (HMMVWs and trucks) I think it 'trips' a HEAT warhead, so that the blast disapates enough not to penetrate an IFV, but it not enough to protect a truck. But, it must not provide enough additional protection to tanks to be cost effective. Given those 2 assumptions, it should be easy to look at SP armor values, and then determine what additional protection SLAT offers.

I am also interested by the fact that the SLAT armor is not sloped. I'd think that even a 30% slope in the grills would provide much more protection benefit, than the benefit one would loose from decreased vision. Anyone want to speculate?

[PlasmaKrab]

Apparently one of the main advantages of a SLAT-type armor is that many low-level HEAT rockets have a thin enough fuze-tip for it to slip between two bars without hitting something that would cause the rocket to detonate. Then the sheer inertia and speed of the projectile will have it somehow crushed on the cage, the shaped-charge warhead warped so that it is inoperable.

Look at the early PG-7 rockets, and you'll see the point about rocket shape.

If you slope the bars, you will have nearly no space between them, in the incoming rocket direction, so the fuze is bound to hit something and ignite the charge. Of course you will have a sloped steel sheet and some air standoff to hinder the penetration, but no more of these numerous 'dud' cases, which are one of the best ways to prevent a round from penetrating your armour!

One more efficient measure in that style could be to fix together a SLAT-type armor with good standoff AND a sloped up-armouring similar to the EAAK you see on the AAV7,, or on Danish or NZ M-113s. Such a kit would work both ways, but also be twice as heavy.

I think you're right about light vehicles, Kevin, there is just no way of armouring a soft-skinned truck against HEAD rounds, since there is bound to at least some spray from the penetrator going through the SLAT armour, easily wreaking havoc on the unarmoured truck body. Armoured trucks are mainly meant to be protected against small-arms fire.
Besides, any type of RPG-fencing armor kit would be nearly as heavy as the truck it would be mounted on.

About tanks now, I guess the first thing is volume. A Stryker or a BRDM-2 are somewhat smaller AFVs, ut don't have the same mobility requiremnents as a truck forasmuch. As a stop-gap measure, SLAT armor on these is fine enough, but on a 3,5m (11+ ft) wide tank, one additionnal foot of armour on each side would be hell for the drivers in urban areas.
Still there is already some kind of SLAT armour on the turrets of most tanks, in the form of loadout baskets. They provide a primitive standoff protection over the weakest parts of the armor.
Anyway most tanks can stand RPG blows from nearly all angles without too much damage (at least Abrams can), so there is no point is uparmoring anything that much, particularly in the horizontal plane. They would gain more from an ERA pack fitted on the turret roof to shield against attacks from buildings.

[Backis]

Regarding the slat armour, this is how I have understood the matter.

The main intention with the armour is probably not just to increase standoff distance as the methods I mentioned in my earlier post. Most modern HEAT rounds retain coherence of their penetrator stream long enough to penetrate most AFV through both sides from a flanking shot, thereby pretty evidently proving that a few decimeters more standoff will make no difference for initial penetration.

My take on the slats as used today are that they are mainly intended to "disrupt" the warhead before they detonate. This is mainly effective against the older type or HEAT rounds such as those used by Iraq (main HEAT threat being the PG-7 and perhaps some PG-7V). This type of protection is effective since the piezoelectric fuze only covers the tip of the forward cone of the round. If this misses the slat the remainder of the warhead will strike them and break up, severely degrading its effectiveness. If the fuze strikes the slat the round will work and probably retain almost full effect regardless of the standoff distance.

However, modern HEAT rounds are usually fuzed over their entire front(f e the AT-4 is) and will detonate when striking the slat, negating any advantage other than the increased standoff (which I hold as rather insignificant).

Add to this that the rounds used in Iraq are mostly really old and crappy examples, having been stored a decade and half longer than they were ever intended to. Some AAR's report a quarter to a third failing to detonate at all, how well those that DO detonate actually work one can only speculate.

[PlasmaKrab]

This is broadly what we have discussed above in this thread.

Many older warheads, plus probably some tandem HEATs, will have a fine enough fuze well that can slip between two bars, which will lead the warhead to be crushed against the bars without detonating.

About standoff, the question is: from what weapon up can the penetrator be considered untouched by one foot thick of cold air? That is, neglecting the incidence angle. Air won't spend and slow the penetrator jet down as steel would, but the metal will cool down anywauy. If the amount of energy spent is significant or not I must still calculate...

Additionally the bars in these systems seem to be thick enough, in the penetration direction, to deflect and maybe disrupt a penetrator coming at an angle.

Standoff plus a thin steel of hardened sheet seem effective enough against RPGs, since Tsahal has fielded a different kind of plated perforated spaced armor on their M113 "Zelda".

[JaM]

So you think that +33 heat armor will be not enough? Even if this type of armor was such perfect against missiles, tank HEAT rounds will crush it,so we need some value wich will represent SLAT.

[Backis]

JaM said:
So you think that +33 heat armor will be not enough? Even if this type of armor was such perfect against missiles, tank HEAT rounds will crush it,so we need some value wich will represent SLAT.

This is directed to Plasma, but I will state my opinion anyway.

IMHO a HEAT armour of 33 is what simulates this system best within the game engine. Most systems more modern than the PG-7 and 7V will have have higher pen. Some smaller of the modern systems like SARPAC will get fragged by this though...

My opinion of the slat armour is that its a stopgap measure performing its intended purpose, defending against older RPG warheads. If the Stryker brigade would be used against a better equipped foe I think they'd ditch the birdcages, it wouldn't be worth the mobility loss.

[Backis]

PlasmaKrab said:

About standoff, the question is: from what weapon up can the penetrator be considered untouched by one foot thick of cold air? That is, neglecting the incidence angle. Air won't spend and slow the penetrator jet down as steel would, but the metal will cool down anywauy. If the amount of energy spent is significant or not I must still calculate...

I said nothing about it being "untouched, I said it the standoff distance practically possible on vehicles of reasonable size will be pretty insignificant.

Why are you talking about projectile temperature btw? Projectile temperature has nothing to do with its effectiveness.

The HEAT penetrator uses velocity and mass to penetrate. Due to its nature (being a liquid hyper-velocity penetrator formed by an explosion) makes it interact differently with armour, but it still works through kinetic energy.

The standoff gives the liquid stream time to disperse (f e turn into smaller droplets through friction) and loose coherence" and effectiveness. Modern warheads loose coherence slower than early types decreasing the effect of stand off armour.

Most "spaced" armour today has "something" in the space, f e small aluminum balls suspended in foam, that interacts with the penetrator stream rather more agressivley than atmosphere.

I think that the APC mods you refer to use spaced armour matixes more advanced than mere standoff plates. The chain skirt on the Merk is probably intended to prevent people lodging a bomb between the hull and turret overhang, but perhaps also to induce yaw on kinetic penetrators.