UK IFV Warrior, new infomation.

[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.

[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.

[Backis]

PlasmaKrab said:
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.

In truth, gun launched HEAT rounds should usually not be affected by lightweight slat armour like that carried by the Stryker. The rounds are constructed a lot tougher mainly because they are supposed to be fired out of a gun, and won't be "dashed to bits" so easily as a PG-7. Older types can be even tougher since they are supposed to be fired out of a rifled gun...

BUT, these types are old rounds, how often will slat type armour come up against these old type gunlaunched rounds?

Perhaps this would be a smaller problem than not representing the slat protection against early RPG ammunition?