How does tank, reactive armour, work?

Answer 1

This gets a little complicated but I'll try to simplify it down.

First we have to talk about an anti-tank round.

When you look at a shaped charge anti tank round, what happens is the shaped charge explodes right at impact. However, the high explosive has a large indentation shaped like an inverted cone inside the explosive. This is lined with a metal such as copper and other alloys which are secret.

When it explodes it shoots a jet of liquid metal that travels at about 7 - 14 km/s or 15,659 - 31 317 mph. Now THAT is FAST! This is also extremely highly pressured.

Now the way it works is the actual explosive in the shell doesn't do much damage. It's all in this metal stream. What the metal jet does is it hits the armor and just digs straight in. When it breaks through the armor, it will spray around the cabin pretty much destroying everything inside. This is so much energy that things basically just explode. One of the examples my professor brought in was a 6" piece of hardened steel with a 1/4" hole straight through!

The stream can do two things
1. allow the hot molten metal to break through into the cabin at
2. cause shock waves throughout the armor and cause "spalling". Basically, pieces of metal break off from within the cabin and bounce around, like bullets inside destroying everything.

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OK now we know what we are trying to fight against. Basically, we want to find a way to prevent this jet of metal from damaging the tank.

Let's talk about the main "weakness" of a HEAT, or anti tank shaped charge round. That is, for the jet to form, the explosion must occur at a precise distance from the target.

If it is too close, the jet cannot really form into a nice stream and it will just splatter the lining with simple explosive damage which won't be too bad.

If it is too far, the stream will start breaking apart. Imagine a water hose, the stream is constant right at the nozzle, but breaks apart into droplets of water. This is basically what happens. The droplets of liquid metal themselves won't do enough damage to penetrate the tank armor because individually they don't have enough momentum to drive into it. Now this distance is in the range of inches so it is very important to get a detonation at the right distance.

This is where the reactive armor comes in. You see, reactive armor, when detonated, sends a plate of material outwards. In reactive armor, there are explosives underneath these plates of material. This is layered on top of the real under-armor. What happens when an anti-tank round hits is it triggers the explosive under the skin. This sends a sheet of hard material towards the round. This, in turn, causes the round to prematurely explode, and the jet of metal cannot properly form.

Answer 2

That was close, except for the last part. An explosively formed warhead usually has its detonator probe well in front of the main warhead. That't to get it time to explosively form the warhead. Note that the warhead does not actually liquidfy, it's a plastic deformation. This has been demonstrated by showing that the warhead still retains certain features that would disappear if it had liquidified. The pointy end breaks off when the remainder of the warhead can't make it through the armor. The pointy end goes ricocheting inside the tank, slicing and dicing throughout.

A reactive armor cannot do anything until it actually gets impacted by the detonator probe. When the RA gets hit, the RA is ejected toward the warhead, while the forming is also occuring, but the RA hitting the warhead prematurely is supposed to disrupt the formation of the warhead.:
http://en.wikipedia.org/wiki/Shaped_charge
http://en.wikipedia.org/wiki/Reactive_armor

RA is already passe, since the countermeasure is the so-called tandem warhead., wherein the detonator probe causes the first of two warheads to explode, which disrupts RA from disruptnig the second warhead, which is the explosively formed one.

Answer 3

Reactive Armor

Answer 4

Yep, what Polloloco (above me) said.

Also note however, that there is another way Explosive Reactive Armor can work, and that is to set of explosions at an angle to the incoming explosion. An explosion creates a tremendous pressure wave (this is the blast front that does all the damage from a normal bomb or plastic explosive) and this wavefront can be used to "knock aside" and break apart the shaped charge warhead's metal jet.

Here is a website with more information about various types of reactive armor -- though the Explosive Reactive Armor (or ERA for short) which Polloloco describes is the most common type:
http://en.wikipedia.org/wiki/Reactive_armour

You can learn more about the shaped-charge warheads he was describing by clicking on the links to it in that article:
http://en.wikipedia.org/wiki/Shaped_charge

Answer 5

This Site Might Help You.

RE:
How does tank, reactive armour, work?

Answer 6

Reactive armor was a retrofit for tanks like the m-60. It works incredibly well for most threats, and it doesn't really trouble the crew at all. Remember marines are known as bullet sponges not because they are smart, but because they will charge a machine gun nest.