Explosive Reactive Armor

[Walter_Sobchak]

Per the Robb McLeod article, Blazer was rather crude.  However, even crude ERA is very effective.

 

Ogorkiewicz's An Extensive Treatise on the History and Construction of Them Grate Steel Beasts gives a ME of 20, and he would surely only have figures available for the Israeli stuff.

Ogorkiewicz is pretty rad, but he really loves those German MTU engines.  Seriously, in his last book he disses on the Continental AVCR-1360 four times.  Most engines don't even get mentioned that many times in his book so its a bit odd that an engine that never even went into production gets that much criticism.  Seriously, how does he poop on that engine more than he does on the British Leyland L60?  Still, I gave the book all the stars on amazon.  

[LoooSeR]

BMPT with additional ERA on sides in special fabric "pockets".

 

 

Something rather similar on Abrams with TUSK.

[CrashbotUS]

Engaging tanks with artillery was really our secondary mission. We typically wanted to hit infantry, C2, strong points, and softer skinned vehicles. If the opportunity arose, we would attempt to break up tank formations by peppering them with HE-PD, HE-VT and DPICM with the intent of causing mobility kills,  damaging external systems, and then allowing direct fire weapons systems to engage.  Back then we only had one round that was specifically for killing armor. The 155mm M712 cannon launched laser guided projectile. It packed 6.5 kg of comp b in a shaped charge. It is incredibly accurate, but typically not used for picking off the onsie twosie tanks but was reserved for high value targets.  

I know this will set off ERA and pretty much ruin most tanks day. I've seen this one in action. 

 

[Toxn]

Crosspost time!

 

Is it valid to point to the development of non-explosive reactive armour as the beginning of a new ERA?

[Mike E]

NERA won't be nearly as effective versus KE than ERA for at least a few decades... It doesn't use enough energy, and honestly can't defeat rods kn the same matter as ERA.

Armata's "ballistic relative armor" might be more competitive, as Nii Stali's president has suggested they have NxRA more powerful than Relikt.

[Mike E]

~7 mm of penetration isn't enough to penetrate the outer layer of Kontakt-5 (as an example), so the DPICM could possible set off ERA, depending on what model it is.

What are curved plates on top of TUSK ERA for?

[Collimatrix]

They might be to ensure that the hit is oblique to the armor, like the lays wavy potato chip ERA in LoooSeR's picture of the BMPT.  ERA only works if the threat hits obliquely.

 

I did also see some computer models of semi-circular ERA that was supposed to have novel defeat mechanisms.  Didn't understand it, and don't know if the TUSK ERA is curved enough to be doing the same thing.

[Mike E]

I made a very, very crude diagram of how I think Relikt ERA works. It goes off of the idea that a plate is shot outwards, an inner plate is shot down into another explosive charge, which then shoots it upwards again. I'm not sure if this has ever been proven, but it seems to be the general consensus of how 4S23 Relikt operates. 

 

(Missing a "3"   )

 

1 - General design; "thrown" plate -> charge -> "thrown" plate -> spacing -> charge -> static rear plate. 

 

2 - Initiation; Outer plate is thrown, inner plate is shot downwards into next charge. 

 

3 - Result; Inner plate detonates charge, and shoots outwards. 

 

I am confused by the all-too-popular Narod diagram, that conflicts with the above layout and operation. 

 

This seems to show something completely different, to my eye.

 

Any thoughts? 

[LoooSeR]

   As i posted earlier, Relikt consist of single explosive tile, sandwiched between 2 plates. At event of hit, explosive detonates and "push" plates in opposite directions. And thats all, there is no second explosive charge. IIRC NII Stali noted that there is a sort of damper layer on armor itself (between ERA main part and armor plate of a tank), to soften up a force from second ("inner") plate hit.

 

 

[Collimatrix]

Interesting, and consistent with Rob McLeod's analysis.

 

Who was the first to start calling K5 and related designs "heavy ERA?"  I almost wonder if it was deliberate misinformation about how it worked.  The design needs more space than older ERA, but it's not much heavier.

[LoooSeR]

Maybe "heavy" was an indication that this ERA is a 'real deal'. I never saw "heavy ERA" name used by russians.

Relikt also has different from K-5 explosive, AFAIK, that is harder to set of by small caliber weapons, including autocannons.

[Marsh]

Interesting, and consistent with Rob McLeod's analysis.

 

Who was the first to start calling K5 and related designs "heavy ERA?"  I almost wonder if it was deliberate misinformation about how it worked.  The design needs more space than older ERA, but it's not much heavier.

Rob McLeod's article is riddled with mistakes when he discusses the origins of Blazer. (Some of them are down to me, my knowledge of Blazer was incomplete. When I put out unintentionally skewed information on the web, it became accepted as factual). Because of this, no fault of Rob, I do wonder how accurate the information on K5 is.

[Collimatrix]

Maybe "heavy" was an indication that this ERA is a 'real deal'. I never saw "heavy ERA" name used by russians.

Relikt also has different from K-5 explosive, AFAIK, that is harder to set of by small caliber weapons, including autocannons.

 

Aha, so most likely "heavy ERA" is an English-language mistake?  Does K-5 have any special name or description in Russian sources?

 

Rob McLeod's article is riddled with mistakes when he discusses the origins of Blazer. (Some of them are down to me, my knowledge of Blazer was incomplete. When I put out unintentionally skewed information on the web, it became accepted as factual). Because of this, no fault of Rob, I do wonder how accurate the information on K5 is.

 

Are you at liberty to elaborate more on this?  I am very curious about the origins of Blazer; it seems to have been developed very rapidly.

 

Rob McLeod may be mistaken about K5 "guillotining" off the front of LRPs.  I have seen high-speed x-ray photography that seems to indicate that LRPs actually bend when they get twisted in the K5.  That is why M829A3 has that sacrificial section at the front that gets broken off; it keeps the entire rod from being distorted.

[LoooSeR]

Russian term for K-5-type of ERA is VDZ / "Vstroennaya dinamicheskaya zashita" / "Build-in dynamic protection". Every ERA is called "DZ" (dynamic protection) almost all latest ERAs are usually refered as VDZ or simply DZ.

[Mike E]

It's odd to think how it can be so much more effective without additional explosives. A little design change goes a long way.

Thanks LoooSeR.

[Marsh]

 

 

"Are you at liberty to elaborate more on this?  I am very curious about the origins of Blazer; it seems to have been developed very rapidly."

 

Hi Collimatrix,

 

I first met Manfred Held, the progenitor of ERA, at least in its initial fielded form, Blazer, at an AFV symposium run by SMi held in London in January 2004. He is not of course a Norwegian who once worked for Rafael,  but a German academic specialising in ballistics.

 

If I remember a conversation around a dinner table correctly, He came up for the idea for ERA when given permission to examine some of the hundreds of T-54s and T-55s the IDF had captured in 1967. He paid particular emphasis to those vehicles that had been damaged. To his surprise, he noted that in certain cases, where propellant for individual isolated shells had cooked off and hadn't caused a general catastrophic explosion, the force of the propellant had disrupted the efficacy of a penetrating shaped charge jet. Held then worked on methodologies for harnessing this phenomena and came up with the idea of ERA sandwiches and drive plates within steel boxes.

 

Although Held patented his ideas in 1970, he could not generate interest in his ideas in Western Europe. however, he returned to Israel in 1974, again to examine the hulls of knocked out or damaged T-55s and T-62s. He explained his ideas to the IDF who arranged an experiment using primitive ERA boxes. A very convincing and successful demonstration of the efficacy of ERA was held, I know the exact date for this, it was on the 16th May 1974, where the prototype ERA boxes defeated both Sagger and RPG warheads.  After that demonstration, Rafael was given the task of rapidly developing applique ERA boxes which could be fitted to the IDF's increasingly obsolescent Centurion and M48 tanks. The rest you know. 

 

cheers

Marsh

 

 

[Collimatrix]

Interesting.  I'd heard that story about seeing ammo explosions disrupting HEAT jets before, but didn't think it could be true.

[LoooSeR]

   One thing i remember about Armata ERA rumors is that some of the "western" medias reported that ERA was able to pre-detonate, before being hit via special sensors in each module. Apperently, NII Stali worked on such project, as one of photos shows (photos of T-14 active sfot-kill protection system placard).

 

   I don't understand the benefits of pre-detonation of ERA modules, especially now, in times of tandem HEAT warheads.

[Collimatrix]

David Luster opines that the applique armor on chally 2s is not ERA:

http://overlord-wot.blogspot.com/2015/12/explosive-challenger.html

[Collimatrix]

One thing i remember about Armata ERA rumors is that some of the "western" medias reported that ERA was able to pre-detonate, before being hit via special sensors in each module. Apperently, NII Stali worked on such project, as one of photos shows (photos of T-14 active sfot-kill protection system placard).

 

   I don't understand the benefits of pre-detonation of ERA modules, especially now, in times of tandem HEAT warheads.

Just my guess, it may have to do with timing. HEAT rounds get very screwed up if there is material in or near the warhead when it goes off. That is how that roof spike armor you see on some SPGs works. DPICM-type submunitions have open-faced shaped charges. If one of the spikes is inside it, the liner won't collapse optimally and the jet's penetration will be much less.

So with conventional ERA, the explosive goes off once the jet has already formed, since it is set off by the tip of the jet. If you could pre-detonate the ERA, the flyer plate would hit the shaped charge before it fused and possibly screw up the symmetry of the implosion, which would greatly reduce the penetration of the jet.

Ogorkiewicz mentions a similar effect happening when a shaped charge hits very sloped armor just wrong and some of the armor is sticking into the area where the liner collapse occurs.

My other guess is that it gets rid of problems where the threat hits between the edges of two tiles.

[Collimatrix]

This is interesting.  I will have to re-think how I believe tandem-charge warheads and ERA to interact.

 

I could believe, for instance, that a panzerfaust 3's forward charge acts as an initiator:

 

 

Since an RPG-type weapon moves fairly slowly, and there's a good amount of space between the precursor charge and the main charge.

 

But on a 3BK31 round where the charges are much closer together and the round moves five times faster?

 

 

There would be barely any time or room for the flyer plate to get out of the way of the main charge.

[LoooSeR]

   I am sure that ERA/tandem HEAT warheads interaction is much more complex than "first warhead destroy ERA, second is penetrating armor". Especially taking into account plenty of ERA models and differences in HEAT warheads/missiles/rockets, etc. But there is not much info on that subject.  

[Bronezhilet]

The jet itself moves at hypersonic speeds, you'd need a bit more room if you want things to get out of the way. Jets laugh at thing like that anyway. I've seen footage of a forward charge/initiator penetrate an APC hull from side to side, after which it kept going*. Unless the flyer plate interferes with the proper detonation of the shaped charge, it will not have a noticable effect on the jet.

 

Also, it looks like the forward mirror of the Panzerfaust 3T is aluminium, unlike the main mirror.

 

 

* Cant tell what hit what, because OPSEC.

[Collimatrix]

The jet itself moves at hypersonic speeds, you'd need a bit more room if you want things to get out of the way. Jets laugh at thing like that anyway. I've seen footage of a forward charge/initiator penetrate an APC hull from side to side, after which it kept going*. Unless the flyer plate interferes with the proper detonation of the shaped charge, it will not have a noticable effect on the jet.

 

Also, it looks like the forward mirror of the Panzerfaust 3T is aluminium, unlike the main mirror.

 

 

* Cant tell what hit what, because OPSEC.

 

The issue isn't the speed of the jet, it's the speed of the flyer plate.

 

I don't think the flyer plate interferes with jet formation in most cases.  The timing doesn't make sense.  The only reason the flyer plate flies in the first place is that the explosive underneath it got set off, and the explosive underneath it got set off by the jet.  Ipso facto the jet has already mostly formed (obviously the tip is somewhat faster than the rest of the jet, but you get the idea).

 

ERA doesn't work very well unless it's oblique to the threat, is my understanding.  If the ERA gets hit straight on, a hole gets punched through it and that's that.  But if it's at an angle it is constantly feeding material into the path of the jet, which uses up a lot more of the jet's energy.

[Bronezhilet]

Apart from me thinking the flyer plate was something completely different, the post still stands (yay).

 

But it's the forward charge that sets off the flyer plate, not the main charge. To see how the flyer plate would interact with the main charge, I'd have to time a bunch of stuff. Basically you'd want to know if the main jet is following the (intended) path of the forward charge. Seeing the material and shape of the forward charge (in the Panzerfaust 3T), it is intended to make a wider hole than the main charge. Same with the 3BK31, all mirrors have a different size and shape.

As I see it, the forward charge clears a wide enough path for the main charge, allowing the main charge a clear path/corridor to the main armour, before the expansion of the ERA. But that completely depends on the timing of, well, everything. It would be nice to find out though.

 

Does somebody have a better picture of a 3BK31 round? I can't find anything.