AP rounds fired by arty
 

I just finished to play 'Lybia again' and it makes me ask a question about the 'AP' shells fired by arty...
It is very efficient against infantry, very very efficient against low armored target, but seems to be unefficient against soft vehicles like trucks. http://forum.shrapnelgames.com/image...s/confused.gif
I remarked it because I was trying to kill some truck arty and it didn't work at all...
I made some check after that and it was a confirmation of the previous...
So, is it normal? And what are 'AP' ammo for?
I suppose it's a mix of bomblet and anti tank ammo...

Re: AP rounds fired by arty
 

AP ammo for indirect fire units is a cluster munition round. Cluster munitions are usually more effective against exposed and unarmored targets unless they are purpose built to defeat armor. The majority of artillery launched cluster munitions are not, though there are ones designed to be more effective against armor.

Re: AP rounds fired by arty
 

Oh.. I thought all Western cluster bomblets in artillery shells had a small shaped charge warhead to make them kinda dual purpose..?

Re: AP rounds fired by arty
 

Hmm I thought in-game cluster munition is not effective against infantry. Against tank, even heavily armored like Leclerc and Leopard it is very effective. I yhink I havn't seen it affect infantry ...

Re: AP rounds fired by arty
 

Maybe I've got it backwards, but I seem to remember artillery launched CMs being relatively effective against infantry.

As for artillery launched CM's intended targets, you're right too, that most of the modern ones are dual purpose in nature. Aircraft CMs follow more what I was talking about historically, though artillery launched CMs were initially what I said too...but that was 30 years ago. The development generally seems to have been toward dual purpose CMs over the last two decades or so.

Re: AP rounds fired by arty
 

If you look at the orbats, you'll see that the AP (cluster) rounds tend to have both kill and penetration in various ratios, meaning that most are effective against both infantry and armor.
AFAIK these cluster weapons (both artillery and air) are meant to be more effective against infantry on the move and/or on open terrain, while basic HE shells work better against entrenched infantry.

Re: AP rounds fired by arty
 

What seems to me very funny is the resistance of unarmored vehicles against this type of ammo.
Just try with two guns, one firing on APC and one on trucks...
The result is so odd...

Re: AP rounds fired by arty
 

It seems to me AP cluster kill soft vehicles perfectly well. One hit and vehicle killed. On the other hand on the armor it making not-penetrating ding sometimes.

Re: AP rounds fired by arty
 

Made some test (I love doing tests with SPMBT...):
the poor English were the target, firing unit was US paladin.
Target were grouped by 8 (vehicles or team), with two paladin firing at each target group. Target were immobile...
Here are the losses ratio[%], with (20)= roof anti-heat armor:
<font color="orange">Challenger 2 (20) [50%]</font>
<font color="red">Warrior II (5) [90%]
Spartan (1) [90%]</font>
<font color="blue">LandRover (0) [35%]
Medium Truck (0) [35%]</font>
<font color="green">Infantery (-) [15%]</font>

(I got these figures after 5 tests)
I may have the reason why there is a lowest ratio of destroyed unarmored vehicle: the ammo are AP and it seem that unarmored vehicle are easily destroyed by HE but not by
AP...
A test with MRL confirms it: for MRL cluster ammo are HE ammo and it's able to destroy easily unarmored vehicles...
Does anybody know more about how SP deals with unarmored vehicles hit by AP rounds?

Re: AP rounds fired by arty
 

I didn't do any test on that, but I'm beginning to wonder if it isn't smothing related to the way soft vehicles are dealt damage (any damage).

Try firing against trucks or such with a tank or any heavy direct-fire weapon, and you'll have chances of seeing the truck losing crew members, but still technically running between two shots.

Just my 2c, I don't know if there is any relation with what you saw. If there is, you may want to check non-lethal damage done to the trucks, maybe several of them are technically "ready" but have suffered several damage points.

P.S. just another idea popping up: how about unit size? Tanks tend to have a high size ratio, and seeing how cluster rounds work, I'd find totally logical that 'smaller' units get less hits.

Re: AP rounds fired by arty
 

Soft vehicles take crew casualties. If they are not located by the firer at the time that will not be reported to him in your testing. They will tend to debuss any passengers when hit, and the supression levels will go up as well - they may be in retreat status. Again - your test may not show this if the potential targets are over a hill say. Only total kills will be shown in such a test (to test arty it is best to have a spotter close to and overlooking the impact zone)

Cheers
Andy

Re: AP rounds fired by arty
 

In fact, I made my test with human control for both players, so I was able to know everything about casulties...
However, your answer gives a very clear explanation: theses ammo are not very effective against crew, and then it's slower to kill soft vehicles: if one wants to kill soft vehicles, I suppose one has to use the HE rounds.

Re: AP rounds fired by arty
 

The only thing I can think of is a story an Abrams gunner told me. At long range a dark smudge on the horizon can be a tank, a truck, or a camel, so they have engaged some questionable targets more than once. Once they were engaging a target that turned out to be a land rover. After 4 hits which tore away the canvas, the windshield, and various fenders, the land rover still drove. Maybe the shock of a hit isn't absorbed by the whole vehicle, unlike an AFV. Following this reasoning, softer targets would have less critical hits than an AFV.
Would this apply to the arty rounds? Not my area of expertise, but it seems logical.
Will

Re: AP rounds fired by arty
 

Yeah, 5kg sabot dart traveling at 1500 m/s isn´t going to expend any enrgy going through a canvas or a windshield or some regular car bonnet. The HEAT ammo may not even detonate going through thin objects, and will appear to detonate, but only behind the vehicle hitting ground. But a HEAT or a SABOT through the engine, that´s another story.

Hail for the real comeback of 120mm HE rounds!

Re: AP rounds fired by arty
 

Pretty much.Most of the mechanisms that an APFSDS uses to inflict damage on a tank, from spalling to thermal effects, don't work well against thin skinned vehicles (bar hits on the engine and similar of course).Artillery cluster munitions should be a different matter however, as these use explosive bomblets.
Against tank fired HEAT rounds it should boil down to how much the fuze is sensitive and if it impacts something hard enough to trigger it.If that happens then you have a very dead Land Rover.

Re: AP rounds fired by arty
 

Regarding the sensitivity of HEAT fuzes, I'm not sure that the material hit is very relevant at the impact velocities considered.
Think about the "necklace" of the Merkava Mk3/4: there are simple weighted chains dangling from the turret basket, and they are supposed to (and I guess reliably tested to do so) detonate RPG rounds at a standoff from the turret.

I'm out on a limb with my physics here, but I'd say that the inertia of the chains (in this example) prevents them from being significantly displaced before the fuze fires.
The same thing can probably be said of any unarmored vehicle bonnet, given the material is hard enough.
Admittedly, a canvas top has a chance of folding around the fuze probe, or ripping open, letting the fuze tip through, and stop only the thin and conductive warhead cover,making the round a dud. As far as I know that was how RPG fences worked back in Vietnam.

Just my 2c, don't ask me to back that up with calculation! http://forum.shrapnelgames.com/images/smilies/wink.gif

Re: AP rounds fired by arty
 

Note the ball on the end of the chains on the "necklace" - these are needed to provide enough resistance to trip the fuse, I think?. Modern HEAT fuses are designed to not trigger on twigs and other foliage - the ball on the chain end will likely make the thing think the impact is more substantial than some piece of incidental shrubbery.

As to chicken-wire RPG fences, these stopped the rounds by trapping them in the gaps (there was not that much forward velocity) without triggering the fuse, and also by shorting the fuse if it touched the wires as well (early RPG used a crush pezio-electric fuse). Or it could also trigger the fuse - hence the need for the chicken wire to be some distance from the protected vehicle. All if I remember correctly - the details were in the old 1976 Jane's Infantry weapons section on the RPG, but I foolishly sold that off at a second-hand book shop back in 95 or so. Exellent reference work - but nowadays fiendishly expensive http://forum.shrapnelgames.com/images/smilies/happy.gif.

Anyway - the early RPG's simple pezio electrical fuse was a weakness and there was a proposed "electrical" defence which generated a field to set these things off at a certain distance from a field generator. It was just a bit big to cart around (so would only have been good for static observation posts etc), and a simple change in fuse design would have made the thing obsolete. Later RPG fuses tend to be more sophisticated.

Oh - and another way to defend against RPGs was to fight on a windy day - the thing tended to "weathercock" at longer ranges as the wind acted on the extended stabilising vanes at the rear end of the round, and so it would end up flying more sideways than end-on..

Cheers
Andy

Re: AP rounds fired by arty
 

Thanks for the update, Andy, I didn't know the fuse technology had changed so much over time.
Considering this, most old HEAT warheads (say, up to and including the PG7VM) should go off at a whim, even (case considered here) when hitting the canvas top of a soft-skin vehicle. And I guess this should also be the case for most first-generation ATGMs (AT-3, SS-11, Cobra, Vigilant...) which have equivalent technology and similar velocities (not above 1000 ft/s).

Now we agree about the way RPG fences used to work, by trapping the fuse tip between the wire and in some cases crushing the conductive warhead cover. My point was that with a high enough velocity and an insensitive enough fuse, a vehicle canvas (or even bonnet) could act the same way if the fuse tip managed to rip through without detonating.

If you want some more RPG references of the olden days, I've found this TRADOC manual from 1976, building on Vietnam and Israeli experience, with info on RPG fences, weathercocking and riding the wind, and of course those damn aiming procedures.
Probably not worth the Jane's data, but worth a look for everyone.