Explained: How Explosive Reactive Armour Works?

Hello defence lovers! Ever wondered what those large square panels on the side skirts of T 72s and T 90s are? Ever noticed those small boxes all over the turret of the T-72 Ajeya? Those are explosive reactive armour or commonly known as ERA. Yeah, you heard it right, those are explosives. Now you must be wondering why would someone mount explosives on the body of tanks unless one has the intension to blow it up. How can some explosives act as armour? We will answer all these questions in this article.

What is Explosive reactive Armour

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Explosive reactive armour (ERA) is a type of armour that is used in modern tanks and other armoured vehicles to protect them from projectiles that employ shaped charged warheads. An ERA is extremely effective on HEAT and HESH rounds. It also protects the vehicle from APFSDS rounds up to some extent. However, some APFSDS rounds with tungsten or depleted Uranium cores are able to penetrate most of the modern ERAs.

How ERA Work?

Explosive Reactive Armour is a peculiar type of armour that uses explosive charges to defend from other explosives which are fired at it. So let us understand how it works.

To understand how explosive reactive armour works we have to first understand how the shaped charge explosive works. The HEAT rounds usually use the shaped charge principle. The most common threat to armoured vehicles is the RPG. These RPGs work on the shaped charge principle. The shaped charge warhead consists of a conical cavity with a metal disk. When the warhead explodes, a jet of molten metal (usually copper) at very high temperatures is generated which penetrates the armour. The jet melts the armour and pierces it just as a knife cuts through butter. This jet of extremely hot metal often kills the crew. If the crew is lucky enough to survive, the jet can also hit ammunition and fuel to blow up the entire turret.

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So how do the modern tanks defend themselves from these warheads? Most of the well-protected tanks like the British Challenger, American Abrams, German Leopard and Indian Arjun use composite armours made of high strength materials like depleted uranium. Often these armours are covered by explosive reactive armours to complement the armour’s protection.

So now let us understand how the Explosive armour works. A typical explosive reactive armour consists of plastic explosives like C4 sandwiched between two metal plates. These are mounted on the top of the regular tank armour. When the warhead hits the upper plate, it ignites the explosive. The shockwave created by the explosion scatters the molten metal jet away. the upper plate flies in the outward direction and thus helps in scattering the molten metal jet.

The ERAs are often mounted on the areas which are most likely to hit like the front part of the hull, the entire turret, side skirts covering the tracks etc. ERAs are extremely useful in urban warfare where the RPGs and other anti-tank missiles carried by the infantry soldiers pose a maximum threat to the tanks.

Why Doesn’t The Explosion Damages The Tank?

So the explosive reactive armour is explosive mounted on the tank’s body. But why doesn’t it damages the Tank? Its because the energy is directed outwards and the shockwave is not that huge to kill the crew or damage the tank. The entire energy of the blast is dispersed radially outward.

But still, to use explosive reactive armour the tank must have adequately thick armour to protects its crew from the blast. However ERAs pose significant threat to other infantrymen near the tank as when an ERA explodes, its upper plate breaks into fragments which are lethal enough to give fatal injuries to nearby infantrymen.

Explosive Reactive Armour On Indian Army Tanks

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The ERA panels can be easily observed on the T-72 Ajeya. The box-type structures mounted all over the turret and hull are ERA pannels. These ERAs were developed indigenously by DRDO’s HEMRL lab. These reduce the penetration chances of heat and other shaped charge missiles by 70 per cent. These are also immune to detonation by small arms fire. The MK I version is used on over 1400 T 72s. DRDO has also developed MK II which acts as a substitute for imported Kontakt 5 ERA.

The Large square panels on the side skirts of T 90 and the tapered structures on the turret are also ERA pannels. T 90 uses advance Kontakt 5 ERA. The technology of Kontakt 5 was transferred to DRDO under the transfer of technology. Arjun’s ERA is a reversed engineered version of Kontakt 5.

So this was all about explosive reactive armour. We hope you enjoyed the article and learned something new. Follow our website DefenceXP to read more articles like this.