UK IFV Warrior, new infomation.

[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.

[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.

[PlasmaKrab]

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.

I guess the most efficient spaced armour types use that kind of filler materials, eventually boiling down to some knid of thicker and lighter composite armour...

However, I know for a thing that at least one version of the improved M-113 fielded by Tsahal uses perforated steel plates on a standoff mount against RPG-7 (both sides having deduced from experience that the RPG-7 was a deadly enough weapon against the basic M-113).
Look closely at the pictures on this page for confirmation.

Then again, I don't know exactly how such systems are supposed to work. Istill assume that thermic energy plays its part in the penetration of armour by a shaped charge penetrator (that is, thermic energy gained by the penetrator from the charge explosion). In this regard I think that air spacing will tend to let the penetrator energy decay slightly.
I may be totally wrong here, and I fell more and more like I am
Apparently the main point is jet focusing indeed, and however modern and powerful your charge may be, the shaped charge is meant to have optimal efficiency at a specific standoff, basically that one between the fuze tip and the bottom and the shaped charge, minus what the front cover will be compressed between fuze hit and penetrator buildup.
Any modification of this distance by detonating the rocket away from the main armour will make the penetrator hit the armour out of focus.
I agree fully that the more standoff is the better. But I guess no one was willing to fit a one meter wide wire cage on any vehicle...

So I guess that 33 or 40 could be a correct modelling value for SLAT armor. Probably there is not enough hard data around yet for us to know what it will stop exactly in which conditions.

[JaM]

Yes, 40 will be ok, as there are some AT weapons like LAW that will be affected too (pen 35) or PG-9 round (pen 40)

[PlasmaKrab]

Problem: some tank guns have a HEAT penetrationvalue well under 30. These are old late-WW2 guns or such, but high velocity nonetheless. Do we assume these rounds will be stopped by the SLAT anyway? Maybe low-tech enough to be totally spent by 25cm standoff.

For reference, 35 is the lowest HEAT value for 105mm tank guns I have found (haven't checked everything though). 90mm guns, even the most modern, are generally slightly under 30.

Since the basic Stryker has no HEAT armour, what will be added will be the only protection between HEAT rounds and destruction.

[JaM]

I think that game engine will use different ammunition, if target is imune against HEAT,so those tanks will automatically use AP against SLAT equiped APC

[Listy]

Points.
Slat armour is around 8-10 extra points on Anti-heat armour. Look at the Stryker's in the US OOB.

You start assigning 33 points of armour for slat and you've got to wonnder where it will end! a Warrior is easily able to stop RPG's on it's chobham armour, this has been proved in Iraq So it would have an AV of around 40 for anti-heat. +your proposed 33, and you start getting itno MBT Class armour...

[PlasmaKrab]

So what? That won't be the first APC with MBT armor: look at the Russian BTR-T, the Jordanian Temsah and several Israeli derivates: that is their very purpose!

Besides, Warrior+Chobham+slat will only have a huge HEAT armor. One sabot round or KE missile and over with it!

And, correct me if I'm wrong, but I think the Stryker+ featured in the US OOB has only the standard Piranha III applique armor pack on. I don't know when the US oob was made, but probably before slat packs were fielded. Not too long ago though since there are numerous armored Humvees.

[Backis]

Listy said:
Points.
Slat armour is around 8-10 extra points on Anti-heat armour. Look at the Stryker's in the US OOB.

Which doesn't simulate its expected effects very well at all IMHO. the "best" simulation would be if you could "flag" the a protected area as covered by slats or not, and induce a failure rate (0-25% pen value) of, oh, lets say 75% on HEAT rounds flagged as "old".

Of course the factual basis of these assumed values are zero and none, just me talking out of my arse.

Listy said:
You start assigning 33 points of armour for slat and you've got to wonnder where it will end! a Warrior is easily able to stop RPG's on it's chobham armour, this has been proved in Iraq So it would have an AV of around 40 for anti-heat. +your proposed 33, and you start getting itno MBT Class armour...

I'm not really reading the suggestion as plain adding 33 points to the armour value regardless of what it was before, rather I read it as pushing it up towards the 35-40 level where most of the target warheads are (33+ vs PG-7 at ~280mm RHA and PG-7V at ~320mm RHA).

Short of coding a new type of "reactive armour" as I suggested above I feel this is the best simulation of slat type armours.

I sincerely doubt that Warriors "Chobham" (lets call it what it is, composite armour) addon plates cover the profile 100%, and that even if they do they probably won't truly "easily" stop PG-7 class threats all over. After all, if they did, why the need to add the slats to begin with?

If the use is to prevent damage to the armour and lower operational costs (wich it probably won't in many or even most cases) then the game mechanical effects of the addon would be pretty negligent.

My take (simplified). Units carrying slat addon armour should have an armour value against HEAT of around 33-40 (preferably closer to the lower value IMHO), most of the projected threat rounds hang around in that neighbourhood.