Explosive Reactive Armor

[Collimatrix]

Explosive reactive armor is that brick-looking stuff that the Soviets loved covering their tanks in during the last days of the Cold War:

 

 

Kharkov Stronk!

 

I admit not knowing much about ERA, but a quick check around various sources has impressed the following things on me:

 

 

-ERA is, pound for pound, the most effective armor technology that exists.  Nothing else even comes remotely close.  First-generation Israeli Blazer ERA was estimated to have a mass efficiency (vs RHA) of 20-24 vs HEAT threats.  That's insane.  The very best modern steel laminates using ultra-high hardness alloys magically welded to high toughness alloys achieve a mass efficiency of 1.5.  MEs of 3 are spoken of in hushed whispers for exotic material composite arrays.  ERA must be mounted on something fairly stout, on account of the whole "explosive" thing, but even mounted to RHA, the ME of the entire array is on the order of 2.5-3.8, and better still for ERA mounted on top of something more sophisticated.

 

ERA is stupidly cheap and stupidly light for how effective it is.

 

-The most commonly available descriptions of how the Kontakt-5 "heavy" ERA works are probably wrong.  Surprise surprise; commonly available articles about a technical subject are completely wrong.  Robb Mcleod's article gives a more likely explanation on the basis of areal density vs. installation mass and coverage.  Instead of an extremely heavy one-piece flyer plate that snaps the APFSDS penetrators, Kontakt-5 works by having two flyer plates that move in different directions; one slightly up and one slightly down, guillotining off the front portion of long-rod APFSDS penetrators.

[Walter_Sobchak]

Hey Colli, if you really want to chew on some technical mumbo jumbo, be sure to check out Multifunctional Materials: Transparent Reactive Armor Utilizing Single-Walled Carbon Nanotube Frameworks.

[LoooSeR]

Kontakt-5 have one plate, it is Relikt that have 2 plates moving in opposite directions, which give to Relikt some anti-tandem HEAT capabilities.

[Collimatrix]

Kontakt-5 have one plate, it is Relikt that have 2 plates moving in opposite directions, which give to Relikt some anti-tandem HEAT capabilities.

 

 

Fofanov opines that Kontakt-5 has two flyer plates.

 

 

This is a cross section, supposedly of Kontakt-1 from the Steel Beasts forum:

 

 

It looks like even early Soviet ERA was multi-layer.

 

 

Diagram of Ukrainian "Nozh" ERA:

[LoooSeR]

That picture of Nozh was debunked after computer model showed that APFSDS projectile will not get any serious damage after crossing those HEAT jets. In fact, if my memory serves me right, HEAT jets would be like butter for APFSDS.

[Collimatrix]

Do you have a link to said debunking?  This it the first I've heard of it.

 

A lot of anti-APFSDS countermeasures seem to work by yawing the penetrator or chopping it into bits, which reduces its sectional density.

[LoooSeR]

IDK if he is right about first tile of explosives having its own plate to launch, but his post 26 in your link is what i said - in Relikt 2 plates do come into play, and because of how it use those 2 plates it achieve higher protection, including against tandem HEAT warheads and EFPs.

[LoooSeR]

Do you have a link to said debunking? This it the first I've heard of it.

A lot of anti-APFSDS countermeasures seem to work by yawing the penetrator or chopping it into bits, which reduces its sectional density.

Maybe tomorrow i will try to find a link and will translate some crucial parts.

[Collimatrix]

Cross section of Kontakt-5 from here:

 

 

 

It appears that you are right LoooSeR; there are two plates, but one of them is stationary; only the top plate flies.

[LoooSeR]

I just remembered that one of design features of Relikt, that was not presented in previous ERA designs was its ability to launch 2 plates in the same time by one explosive module.

[Collimatrix]

Image from a patent, showing how M829A3 (likely) deals with heavy ERA:

 

[LoooSeR]

http://www.i-mash.ru/materials/technology/57490-dinamicheskaja-zashhita-nozh-mify-i-realnost.html

 

 

 

Picture shows HEAT "knife" form:

 

 

Variant 1.

 

     AP projectile hitting Nozh ERA block, this model is trying to create situation when ERA block starts to "explode" in the moment of AP projectile is hitting external plate of ERA module.

 

 

 

 

 

 

     HEAT charges cut trough external ERA module plate after 49 microseconds. If ERA block explodes in the moment of AP round hitting external ERA plate, HEAT "knives" just cuts that plate creating many small 'plates' that are propelled against AP round by almost 2-2.5 kg of explosives detonation. Those cut out parts of external plate work in the same way as Kontakt-5 plate. HEAT jets themselves don't do serious damage to incoming projectile.

 

 

Variant 2.

 

      Nozh ERA block explodes when incoming projectile penetrated external plate, which means that HEAT warheads inside of ERA module affect projectile body directly.

 

 

  

   Computer model showed that in this case APFSDS round, after penetration of external plate and subsequent detonation of ERA, will not be damaged enough to be destroyed. ERA also will not significantly reduce its penetration ability, or change angle of impact. HEAT jet is "smeared" over the body of moving projectile. In statics, HEAT jets would damage this round more than in situation when it is moving at high velocity.

 

   Nozh offers slightly higher protection than Kontakt-5 against some warheads simply because K-5 module have 0.5 kg of explosives, while one block of Nozh is filled with ~2 kg of explosives. Relikt also have about same amount of explosive filler, but Nozh is mounted directly on tank armor, while Relkit is mounted at some distance, with second inner plate and damper mounted on armor plate to protect it from damage by ERA detonation.

 

Relikt:

 

[Collimatrix]

Nozh has four times as much explosive as Kontakt-5?  No wonder there were those pictures from Ukraine appearing to show it chain detonating.

 

So if the chief novelty of the Nozh design, the linear shaped charge jets don't work at all... how was this not caught in testing?

[Xlucine]

Just because a computer model says so, does not mean it's true. I have a module next year that's been summarised as "never trust a computer simulation"

[Tied]

Ukrainian corruption and general incompetence 

[LoooSeR]

That article was made by Tractornie Zavody concern based on results of Soviet -time tests of that type of ERA (NII Stali worked with it, NII Stali is part of that concern, BTW). In 1984 NII Stali made their ERA with HEAT warheads and even ERA that created EFPs. In my link there is a phito of one of their ERA and model of AP projectile hit by HEAT jet. They also did tests with real shells.

HEAT-based ERA were under dwvelopment by NII Stali for Kharkov new tank (Object 477?). Article also stated that Germany have designed similar type of ERA, but don't use it.

[LoooSeR]

Oplot-BM ERA layout. Note 3 layers of Nozh ERA bricks in a signle Duplet ERA side armor module.

 

 

 

 

 

 

Different versions of Nozh ERA

 

HEAT "knife"

 

[LoooSeR]

Oplot-BM turret frontal ERA layout. Duplet ERA fix some problems of Nozh, but creates other problems - size and power of detonation/chain reaction.

[LoooSeR]

[LoooSeR]

 

How good was this ERA?

[Collimatrix]

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.

[CrashbotUS]

I also am not particularly familiar with the details of ERA. 

 

Couple questions;

 

1. How effective would DPICM be in setting off ERA? One of the tactics we trained on as forward artillery observers was to shower tanks with DPICM to damage external components such as optics, antenna, gun tubes, and ERA. However, I never had the opportunity to do this and never actually had an real confirmation that it would work. 

 

2. What is the impact of the ERA detonation on the crew? 

[Collimatrix]

I also am not particularly familiar with the details of ERA. 

 

Couple questions;

 

1. How effective would DPICM be in setting off ERA? One of the tactics we trained on as forward artillery observers was to shower tanks with DPICM to damage external components such as optics, antenna, gun tubes, and ERA. However, I never had the opportunity to do this and never actually had an real confirmation that it would work. 

 

2. What is the impact of the ERA detonation on the crew? 

 

 

1)  Probably quite good.  The submunitions appear to be little shaped charges.

 

2)  Not sure.

Abrams' TUSK side ERA:

[CrashbotUS]

The M483A1 DPICM round has a top down firing shaped charge that is supposed to be able to penetrate ~7cm of RHA and there are 88 (64 M42 grenades and 24 M46 grenades) sub munitions in each projectile. They both have aout 1.1 oz composition A5 explosively shaped charges but one has a scored surface for greater fragmentation.  When doing fire for effect, we'd typically receive a battery 3 (6 guns, 3 rounds each) giving us around 1500 bomblets in a specific area (open or closed sheaf). 

 

 

I guess this charge is enough to set off ERA? 

[Collimatrix]

I would guess that such a shaped charge is enough to set off ERA.  They're quite a bit bigger than the precursor charges on a lot of tandem-charge warheads, and those are specifically designed to set off ERA.

 

That said, some of the later-model Russian ERA is supposed to be harder to set off.