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Grog question on 30 mm ammo to our Russian, Ukrainian and other mil/ex-mil types


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Over in the c3k vs DMS Free Game AAR, c3k lost a bunch of men to Russian 30 mm airburst fire from what turned out to be a BTR-82. I was confounded by this because, to my knowledge, no 30 mm Russian cannon currently extant can do that. When I raised the issue, he responded with this ammo fuze link, citing it as proof of the capability. A few posts later, I responded this way:

 

Fuze A-670M is PD, with just enough delay (0.002-0.004s) to get into the target and explode. The "distant arming" refers merely to the fact that the fuze arms a minimum of 20 meters away from the firing point and may not arm until as far away as 100 meters. This is in no way equivalent to or even imitative of things like Ainet. And 9-14 seconds after being fired, the fuze initiates and destroys the shell. Simply put, the BTR-82's 30 mm gun is operating the same way as the 25 mm Bushmaster on a Bradley. In fact, functionally speaking, it's exactly the same as what came out of a Sherman's barrel during WW II after the command, "HE, Delay" was issued as part of the fire order. Consequently, as things stand, every Russian or Ukrainian vehicle armed with the cannon 2A42, 2A-38 and 2A-72, whether firing HEI or HE-T, is affected. Further, this also applies to the Mi-28/HAVOC and the Ka-50/HOKUM. 

 

Would one or more of you who knows this fuze and its capabilities firsthand please wade in on this important matter? If I'm right, and I'm confident I am, it's going to put quite a dent in the in-game combat potential of every single 30 mm armed Russian and Ukrainian AFV and so armed attack helicopter. 

 

Regards,

 

John Kettler

 

 

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Ok, going to take a stab at this.

 

Re: A670 fuze in CMBS. Do you really believe that the developers have gotten so far down in the weeds and perfected their ballistics model to the point that they have been able to faithfully reproduce a specific type of fuze for a specific type of round? If they have, then I'll eat my slice of humble pie.

 

Re: Programmable timed fuzing on 30mm/25mm HE rounds. I don't buy it for a minute that anyone is taking a belt of several hundred or even a few thousand rounds of 30mm/25mm ammunition and setting time fuzes. First of all, when they load the belt into the ammo box of the vehicle at the resupply point, how do they know what to set the fuzes for? Second of all, for a weapon with max effective range of around 2500m you're talking milliseconds to try to get an airburst. I know for a fact on the M242 Bushmaster HEI round there is no "time fuzing" on that ammo. You load the belt into the ammo box and go. I've been on the range when the 30mm BTR rounds were fired and nobody there was setting time fuzes on anything. 20-100m arming is a safety feature to prevent rounds from arming in the weapon. The 9-14 sec self destruct you are talking about is most likely for when the ammunition is used in AA mode like with the Tunguska, so the rounds fired at high angle aren't coming back down to the ground and killing friendlies. At the typical ranges the 30mm is going to be used in ground mode, the round has long since detonated before 9-14 seconds transpires. And, .002-.004 seconds (that's 2-4 thousandths of a second) is going to look and act like an impact burst. Programmable distance input on a sighting unit is so you can manually enter range to target. Pretty much any sighting unit on an AFV is going to have that feature, or at least a sight reticle with a range scale on it. It doesn't set a time fuze on the ammo.

 

Time fuzing is for artillery type rounds where somebody puts the ballistics dope into a computer and it tells you how many seconds to set the fuze for the desired effect. Some modern time fuzing can be set to go off at a specific height from the ground or a specific depth of foliage penetration, thus eliminating the need for the time computation. Back in the day the old 105mm flechette or "beehive" tank round on the M48/M60 series tanks could be set to detonate at a certain distance.

 

Bottom line is in CMBS when we see "airbursts", we are probably seeing impact bursts in foliage or something. I don't think I've seen small caliber airbursts in open ground in my CMBS experience. If it does happen, it's a bug.

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Ok, going to take a stab at this.

 

Re: A670 fuze in CMBS. Do you really believe that the developers have gotten so far down in the weeds and perfected their ballistics model to the point that they have been able to faithfully reproduce a specific type of fuze for a specific type of round? If they have, then I'll eat my slice of humble pie.

 

They've done so for tanks, and it seems like they've done so for BTR-82A. I hope that humble pie is tasty  :lol: . 

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I'm more inclined to think the behavior of a type of round has been abstracted more than it has been modeled to true ballistic performance. Even for tank rounds. A real ballistic computer on a modern MBT takes into account many factors which I doubt are all being modeled in CMBS.

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Russia has new 30mm programmable airburst ammo and BTR-82A FCS can program it.

 

f0278443_54ad0e55862ec.jpeg

Do I believe you can select a specific type of ammunition from the sight, being fed from a different ammunition bin? Absolutely. That's how you do it on the Bradley, you switch between AP and HE by flipping a switch and it feeds from a different storage bin. Do I believe you can automatically change the setting on belted ammunition stowed in a box? Maybe, if the feed/firing mechanism has a way of grabbing the round as it is fed and turning a ring on the round or something to that effect. I'm betting it's the former - they load one bin with regular ammunition and another bin with this type of ammunition, and you flip a switch to change feed between the two different bins. You could probably add a third or a fourth if you have the room for it in the turret. I can even see a different reticle appearing in the sights depending on what type of ammo is being fired. If that's what you mean by "programming", then we are in fact talking about the same thing.

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That BTR-82 is a really good deal in quick battles.  I think its only about 130 points, carries a lot of guys, has supplies. Big firepower. I like to take one even if I'm going pretty much only infantry. 

 

Edit to add:

 

Blasting: remote/ command [co]ntact type

Blasting command Input Channel:  Optical

 

 

 

Does that mean that the FCS optically inputs the timed airburst while it gets ready to shoot, or does it mean that it remotely signals the inflight rounds to detonate via a laser or something?  The later seems harder but somehow I got the impression, I guess from the word remote, that it might do it that way anyway.  How would that work?  fire a burst, wait for it to get there, then shine a signal all over the burst to blow 'em all up in the air?  They wouldn't be all blowing up over the same place if that were the case so I assume I'm just reading into the wording too much.  I guess all the BTR to ammo communication is done before the round is shot but it would be interesting to hear otherwise.  

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Most airburst rounds are set electromagnetically, as fast as they are loaded. It's part of the fire control system.

The nosecone spring-wound timer is no longer used. Electronic timers count the rotations. Knowing the rpm, muzzle velocity, and range to target, yields the number of spins needed for accurate airbursting. That number is imparted to the fuse as it is loaded.

Ken

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Counting rotations is exactly what I thought it probably actually did.  I think it was just a translation thing, they wrote optical and remote which to me implies lasers or little fiber optic ports, when they just meant electromagnetic. Thanks a lot for the clarification!

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This thread is most informative and thought provoking. It would appear that at least the BTR-82 and, likely, other AFVs with equally capable advanced FCS can, in fact, fire an airburst projectile. Had no idea such a round existed. Those lacking such an advanced FCS are evidently stuck with PD. This has some interesting implications regarding AFV costs, since there's a whopping performance delta on infantry lethality between the way past XM25 capability 30 mm equipped AFVs with the new round and those which have to smite infantry via ground impact, treebursts or impacts on things such as walls right behind the soldiers being shot at. 

 

The round description above is quite confusing. Fuze type specifically lists Time, whereas the blasting (projectile detonation) is described as "remote" and what appears to read "command contact" (FCS "talks" to shell at a distance?). If the blasting command channel is, in fact, optical, then my understanding of the principle would be that no programming of the fuze occurs in the weapon. Instead of inputting time into the fuze either right before the breech or in it US style, the projectile gets sent a detonation command optically (by laser?) when it's at the desired range, as determined by the FCS. The FCS could easily come up with the requisite timing information to do this. This interpretation is consistent with the round characteristics provided. Next question. Is the round pure Incendiary or is it really HE-I? Never heard of an exploding Incendiary round. Not sure how to categorize Raufoss.

 

Regards,

 

John Kettler

 

Since we're talking about advanced auto cannon ammo, I wanted to make sure my fellow grogs saw the truly amazing work Rheinmetall has been doing in this same area.

 

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A few of those systems that shoot down mortar rounds would be pretty cool.  Like an APS system for a whole OP.

 

While going through the training campaign I once noticed a Tunguska firing a missile at a mortar round. The intercept failed and the mortar round landed as it was aimed, but the Tunguska did try. It kind of surprised me as in a heated battle I'd reckon it to run through its supply of missiles pretty quickly.

 

Michael

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Most airburst rounds are set electromagnetically, as fast as they are loaded. It's part of the fire control system.

The nosecone spring-wound timer is no longer used. Electronic timers count the rotations. Knowing the rpm, muzzle velocity, and range to target, yields the number of spins needed for accurate airbursting. That number is imparted to the fuse as it is loaded.

Ken

Now that one I will agree sounds easy enough because it takes the human factor out of it. That way it could be done automatically by the ballistic computer according to what range the gunner has dialed in. I'll admit I'm surprised to see that as an ability on such a small round, especially a belted round. 

 

In the picture below is a Hungarian BTR-80A in Afghanistan circa 2009. If you can zoom in on the ammo it appears they have the two belts mixed HE/AP with AP being every 3rd or 4th round. The HE rounds look very similar to the ones in the photo further above, but I have no idea if the Hungarians might or might not have this type ammo. I've seen these on the range before and they must have had them set to impact or they were in fact just plain old HE rounds.

 

16522326718_949ca85ce3_o.jpgIMG_2723 by apd1004, on Flickr

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While going through the training campaign I once noticed a Tunguska firing a missile at a mortar round. The intercept failed and the mortar round landed as it was aimed, but the Tunguska did try. It kind of surprised me as in a heated battle I'd reckon it to run through its supply of missiles pretty quickly.

 

Michael

Really?

 

Are you implying that Tunguskas will try to engage also incoming air munitions like guided missiles and bombs? Totally didn't know it was modeled in-game, but if it is, hats-off to the devs.

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