Russian “Cope Cages” and how Bar/Slat/Mesh Protections Broadly Work

March 23, 2022

Anyone following the military confrontation between Ukraine and Russia will likely have noticed that most Russian tanks have entered the war zone with a form of applique armour added as a roof fixture to them.

 

This is widely recognized as a form of standoff armour, generally known as bar or slat armour, which is normally intended to provide the tank with additional protection from munitions that utilise a shaped charge warhead.

However, the use of these cages has caused much speculation and comment. Amongst the military aid given to the Ukrainians are large quantities of NLAW rockets and Javelin missiles that can employ a top attack method, which allows them to directly target the thinner roof armour rather than the much thicker and more robust frontal and side protection.

The initial widespread opinion was that the cages were being fitted to attempt to counteract these weapons, probably because they first began to be seen regularly after the shipment of advanced western anti-armour weapons to Ukraine was announced. The general idea is that the armour detonates the warhead before contacting the tanks thin top armour, therefore helping to negate the penetration possible and perhaps saving the tank.

 

Unfortunately for the Russian tank crews, this theory, which is extremely widespread, is nonsense. This has led to the set up being nicknamed as “cope armour”, as it appears to be more for the crews peace of mind than any actual effectiveness.

But given how widespread this perception is – that standoff armours add protection by causing the warhead to detonate before they hit the main armour protection – I thought it might be of interest to give a very basic explanation of the principles and physics involved.

Depending on their makeup, these standoff armours have different names; Slat, Bar, Mesh, Chain and Net.

In fact, they can all be lumped under one group term; statistical armour, which I am pinching from John Hawkes of the Tankology website.

All these afore-mentioned armours are designed to basically defeat one specific type of warhead; shaped charge munitions that utilize a double-skinned construction that conducts an electric current from a piezoelectric-based fuzing system in the nose; basically, the system used on smaller, earlier and lighter infantry anti-tank weapons and, to be quite frank, that used on the ubiquitous RPG-7.

 

The armour works not by causing the warhead to detonate away from the main armour, it works by allowing the projectile to pass through the gaps, where the edge of the projectile then takes damage from striking the armour BEFORE the fuze strikes.

This damage to the projectile either disrupts the electric ignition system when the fuze does make contact, making the weapon a dud, or else disrupts the focused explosion from the detonation that is how the penetration of the armour is achieved.

 

Very broadly speaking, shaped charges work by focusing the force of their detonation into creating a super plastic jet that literally punches a stream of material through armour. This jet is created from material that forms a cone inside the warhead and must be perfectly shaped to achieve optimum penetration.

Damaging the projectile casing and the cone inside disrupts the formation of the jet and reduces or negates its ability to penetrate.

However, should the projectile actually hit something solid, like one of the bars itself, and detonate cleanly then you have a good chance that in fact it would work effectively and form its proper focused explosion, which would be extremely unfortunate for the targeted vehicle.

In fact, many shaped charges perform far better if detonated away from their target, an effect recognized in the design of larger or more recent anti-armour weapons to utilize the benefits that these “stand-off” effects have on improved penetration.

But by carefully designing your armour you are statistically reducing the chance of that happening, and instead having the projectile pass through the gap and being damaged – the intended result.

So, for statistical armour to be effective you really need it to be designed to deal with a specific size of projectile – and that generally means the PG-7 rocket used in the RPG-7, simply because that is the most likely threat that is expected to be encountered pretty much anywhere.

But against more modern weapons, such as a Javelin or an NLAW, this is highly unlikely to be effective. These generally use electronic sensors to detonate the warhead at the optimum point, punching clean through the targets armour. This has been graphically demonstrated by pre-war testing conducted by the Ukrainians, and in the huge toll that the Russian invasion force is experiencing in the ongoing conflict.

So, if it doesn’t work, why are the Russians employing this type of armour? After all. they are perfectly aware of how shaped charges work, and that these cages are highly unlikely to be effective against modern top-attack munitions.

It could be that the add on kits have been provided serve as a psychological measure to reassure the tank crews that they are in fact protected from these top attack munitions that were so publicly dispatched to Ukraine before the start of the invasion.

 

This is certainly the origin of the derogatory “cope cage” name – that the Russian army retrofitted this protection to reassure their soldiers prior to the launch of the invasion.

The psychological value of armour, even if actually ineffective, has long been recognized. Having said that, it is also recognized that the negative price to soldiers psyches tends to outweigh the original benefits once it is realized that in fact the protection that they are relying on is false.

Certainly, that may be a contributing factor to the apparent widespread desertion that the Russian force in Ukraine is experiencing, though the generally poor preparation in planning is probably a much bigger factor in this.

I have, however, other suspicions behind the reasoning for the “cope cages”.

It is obvious that the Russians expected to simply roll in and occupy Ukraine without any significant difficulties, something they have been thoroughly disabused of by now. But if their planning had proven correct, then they may have expected to have faced only a limited and low-grade insurgency from a few disgruntled hardliners.

And such a force would have had very limited access to high end anti-tank weapons like Javelins, likely having to rely largely on light weight weapons like RPGs.

If there is one lesson that the Russian military learnt in the disastrous first Battle of Grozny, which went on from December 1994 to March 1995, it was how dangerous RPGs are to their tanks in built up areas.

 

Chechen forces inflicted carnage on Russian armoured units in the battle with little more than RPGs fired from rooftops into the tops of tanks and IFVs. I haven’t been able to measure a “cope cage” properly, but I wonder if that is what they have been designed for – countering RPG rockets coming down from slant angles above.

Plus they may also serve other intended design purposes.

Another common threat in an urban occupation situation would be something as simple as a grenade – or even a rock – thrown from above from a window as a tank passed by. The sloped screening would be useful in protecting crews against such danger, with the weapon rolling off. Indeed, grenade screens have been a common feature in armoured vehicles engaged in urban warfare for decades.

And there is one recent development that is seeing use all around the world in the hands of ill-equipped insurgents, one that has proven surprisingly useful; the use of civilian drones to drop small explosive charges.

This is something that the Russians, with their years of fighting in Syria, have seen in use against both their Assadist allies and their own forces on many occasions. Indeed, footage from Ukraine indicates that some of the resistance forces are using exactly these sorts of weapons against the Russian invasion force, including converting old anti-tank grenades into air droppable munitions for use from small commercial drones. And against those, the “cope cages” would be effective.

This is speculation on my part, but it’s possible, despite the scorn heaped upon them, that the “cope cages” may actually start to prove their worth.

According to the Ukrainians, they are burning through their stocks of anti-armour weapons, understandable given the intensity of the conflict. In fact, the expenditure levels are so great that some of the Western nations that have supplied them are warning that they are running out of munitions for their own forces, let alone having capacity spare to send to Ukraine as aid.

With the Russians apparently committed to their attempt to achieve at least something in Ukraine, throwing more and more reserves in, and should the Ukrainians not be able to replace their weapon stocks, then methods like firing RPGs from rooftops or civilian drones dropping explosive charges may have to become the norm.

 

And at that point, the “cope cage” may well prove its value after all.

Sources/Related:

https://www.tanknology.co.uk/post/statistical-armour

https://www.oryxspioenkop.com/2022/02/attack-on-europe-documenting-equipment.html

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Interview with Prof. Alaric Searle on the Russian Invasion of Ukraine

How You Can Help Ukraine

 

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