Using cloth to protect military vehicles from RPGs

A ground-breaking armor system and a fleet of new armored vehicles that will provide better protection to British troops in Afghanistan were unveiled at the Defense Vehicle Dynamics (DVD) event yesterday, Wednesday 24 June 2009. Equipment and Logistics reports that the revolutionary, textile-based TARIAN vehicle armor system will give lightweight protection against rocket-propelled grenades, in place of the current bar armor that is fitted to vehicles such as Mastiff and Ridgback.

More than twenty sets of TARIAN armor have been ordered and are already being used on operations in Afghanistan, with half of them fitted to the Heavy Equipment Transporters. The new system, developed with Dorset-based AmSafe in Bridport, will mean that weight saved on armor can be applied elsewhere on the vehicle.

How can a piece of cloth protect a vehicle from shoulder-fired missiles or an RPG? An RPG warhead, after all, can blast a hole through thick armor plate. Lewis Page writes that the TARIAN does it because it is a replacement not for armor plate, but for so-called “bar” or “slat” RPG protection. An RPG warhead pierces heavy armor using the shaped-charge effect, in which a hollow cone of explosive — usually lined with copper — is detonated. The effect is to form the copper into a pencil-thin slug of incredibly hot, high-velocity molten metal which can burn its way through armor which would have shrugged off an ordinary explosive charge.

A shaped charge only works if it is detonated at the correct stand-off distance from the surface of the armor. This is done by having the detonator mounted ahead of the cone — in the case of an RPG, at the tip of the streamlined nose put on the end of the warhead in order to make it fly straight.

Bar armor is basically a heavy wire fence mounted a few inches out from a vehicle’s normal plating. Page writes that it is just strong enough that hitting it makes an RPG warhead go off early. The copper jet blasts through the flimsy cage with ease, but by the time it reaches the real armor it has spread, cooled, and slowed and it can not penetrate.

Bar protection is light compared to the main plates of a fighting vehicle, but it is still noticeably cumbersome and reduces the load a vehicle can carry. This is where TARIAN comes in, replacing metal bars or slats with super-strong, tough textile. The TARIAN cloth is stretched taut enough so that it can trigger an RPG just as well as a bar kit.