DPICM in direct fire mode for self defence

[ChrisWerb]

Hi. I just did a mini test scenario where I used YPR765s as substitute Spz. 63/73 and attacked a battery of Soviet 2S3. The 2S3s shot back with DPICM in direct fire mode. I had never considered that possibility. Is direct fire with DPICM something that artillery units train to do (including in the past in the case of ban treaty signatories)? I imagine it would be quite devastating in the right circumstances, but never heard of it mentioned anywhere as a capability.

[Ssnake]

Probably more of an AI brainfart. Okay, you shoot what you have but still it sounds, well, not very convincing at first glance. Of course, much depends on the circumstances. But IRL I'd suspect the dispersion pattern to be rather unfavorable unless they shot everything in (extremely) high trajectory (with the resulting long flight times).

 

Generally, I find many DPICM rounds to be not very convincing. MLRS M26 is, I think, the most convincing case. From there it's all downhill, and occasionally rapidly so (I'm looking at you, Egyptian M-42D) where you just have too few bomblets dispersed over too wide of an area. We should however keep in mind that SB Pro can only do an approximation of the battlefield effects as 644 bomblets producing 200 fragments each would mean almost 130,000 fragments that would need to be raytraced; that'd still be 43,000 fragments per second, possibly just 15,000 if you'd cull all those that go straight down and straight up. That's a bit much for current hardware. So we're working with fragment density maps rather than tracking every fragment. Which inevitably incurs an underprediction of fragmentary effects on non-soldier entities. We try to compensate that a bit with a few other tricks, but even then I wouldn't claim that our simulated results are always spot on.

Much of that is classified information anyway, you can only get so far with first order principle-based approximations.

[Grenny]

57 minutes ago, ChrisWerb said:

Hi. I just did a mini test scenario where I used YPR765s as substitute Spz. 63/73 and attacked a battery of Soviet 2S3. The 2S3s shot back with DPICM in direct fire mode. I had never considered that possibility. Is direct fire with DPICM something that artillery units train to do (including in the past in the case of ban treaty signatories)? I imagine it would be quite devastating in the right circumstances, but never heard of it mentioned anywhere as a capability.

If you do shoot it, then only because its a real emergency an the ICM round happens to be in the barrel...and then still the fuse would be set to a time of flight way beyond the intendet target distance.. It'd be like shooting a KE round...

[Gibsonm]

1 hour ago, Grenny said:

If you do shoot it, then only because its a real emergency an the ICM round happens to be in the barrel...and then still the fuse would be set to a time of flight way beyond the intendet target distance.. It'd be like shooting a KE round...

And then the KE effect would be negligible as the carrier shell is just that, a flimsy (relatively speaking) metal container.

 

In addition pretty sure the bomblets would be totally inert since they only arm after they leave the carrier shell and start their intended downward travel. None of which happens if the carrier shell - still carrying the bomblets (because as you say they aren't distributed until they travel for the time required for the fuse to spread them) - slams into the target.

 

Edited November 25, 2020 by Gibsonm

[Breakthrough7]

5 hours ago, ChrisWerb said:

The 2S3s shot back with DPICM in direct fire mode. I had never considered that possibility.

Was the enemy fire support configured to; (1) allow all units and (2) allow ai to call for fire?  Sounds to me like the AI battery just generated a DPICM fire mission on the units it could personally see, rather than a direct fire engagement, or each howitzer firing DPICM at individual vehicles within it's LOS.

I conducted a test where a lone 2s3 battery equipped only with DPICM waits to fire as a few red platoons advance into visual range.  When the AI fire support options are (1) allow all, and (2) allow ai to call for fire, the 2s3 battery will generate and fulfill a DPICM fire mission on the vehicles it sees, even if the enemy is super close.  When those options are unchecked the batteries will allow the enemy to advance without firing on them.

As for reality-- I'm not familiar with anyone that trains or plans to shoot direct fire DPICM, so I don't have anything to say about that.  But-- Theoretically, if you can hit the target with direct fire, and the time of flight from tube to target is greater than 2 seconds then at least with the M483A1 DPICMs M577(A1), the fuse should be able to function (minimum MT fuse on M577 is 2 secs), for what it's worth.  

 

Furthermore replacing the expulsion charge with a spotting charge causes the round to function like a unitary (HE) warhead.  

Edited November 26, 2020 by Breakthrough7
emboldened "generates and fulfills"

[ChrisWerb]

I would guess the KE effect of a 40x kg carrier shell with a forged steel body and an Mv of >600 m/sec, would be significant on a vehicle like a YPR-765 at distances less than 1000 metres. 

 

In the scenario, the effects were what I would expect from one projectile's worth of grenades and its timing coincided with the muzzle flash from the vehicle shooting, so I really don't think it was a fire mission called in from off map artillery. Thinking on, I only gave the Blue side off map arty, so that surely excludes the possibility altogether.

[Breakthrough7]

1 hour ago, ChrisWerb said:

so I really don't think it was a fire mission called in from off map artillery. Thinking on, I only gave the Blue side off map arty, so that surely excludes the possibility altogether.

Did I say anything about off-map artillery? That's a rhetorical question, no I did not.

 

The mentioned Fire Support settings affect on-map fire support asset behavior. 

Edited November 25, 2020 by Breakthrough7

[Mirzayev]

@ChrisWerb Do you have an AAR file saved for the event? I tried reproducing this in a test scenario with both the 2S3 and the 2S1. I couldn't get either artillery piece to shoot in direct fire mode at two Platoons of YPR765s sitting at 1000 meters. I had two Platoons of artillery, one loaded with the standard loadout for the vehicle, and the second loaded with only DPICM. The only time they would fire is with an AI-called artillery strike. 

[ChrisWerb]

17 hours ago, Breakthrough7 said:

Did I say anything about off-map artillery? That's a rhetorical question, no I did not.

 

The mentioned Fire Support settings affect on-map fire support asset behavior. 

Sorry Breakthrough. When I first read your post, it didn't have the bold bits in it and it just said "generate" which I took to mean called for. I didn't realise you meant generate organically.  Again, looking back at your edited post, I see you had the same result I had and your explanation is extremely logical. Thank you!

[Breakthrough7]

@ChrisWerb No worries dude.  Sorry for the curt reply.