Vehicle armour

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For body armour see armour, for armoured forces see armoured.

Military vehicles are commonly armoured to withstand the impact of shrapnel, bullets, missiles, or shells, protecting the personnel inside from enemy fire. Such vehicles include tanks, aircraft, and ships.

Civilian vehicles may also be armoured. These vehicles include cars used by reporters, officials and others in conflict zones or where violent crime is common, and presidential limousines. Armoured cars are also routinely used by security firms to carry money or valuables to reduce the risk of highway robbery or the hijacking of the cargo.

Armour may also be used in vehicles from threats other than deliberate attack. Some spacecraft are equipped with specialised armour to protect them against impacts from tiny meteors or fragments of space junk. Even normal civilian aircraft may carry armour in the form of debris containment walls built into the casing of their gas turbines to prevent injuries or airframe damage should the compressor/turbine wheel disintegrate.<ref>http://www.pinnaclearmor.com/transport-armor/containment-device.php</ref>

The design and purpose of the vehicle determines the amount of armour plating carried, as the plating is often very heavy and excessive amounts of armour restrict mobility.

Vehicle armour is sometimes improvised in the midst of an armed conflict. In World War II, U.S. tank crews welded spare strips of tank track to the hulls of their Sherman, Grant, and Stuart tanks.<ref name="Moran">Moran, Michael. "Frantically, the Army tries to armor Humvees: Soft-skinned workhorses turning into death traps," MSNBC, April 15, 2004.</ref> In the Vietnam War, U.S. "gun trucks" were armored with sandbags and locally fabricated steel armour plate.<ref name="Gardiner">Gardiner, Paul S. "Gun Trucks: Genuine Examples of American Ingenuity," Army Logistician, PB 700-03-4, Vol. 35, No. 4, July-August 2003, Army Combined Arms Support Command, Fort Lee, Virginia. ISSN 0004-2528</ref> More recently, U.S. troops in Iraq armoured Humvees and various military transport vehicles with scrap materials: this came to be known as "haji" armour by Iraqis<ref name="Moran" /> and "hillbilly" armour by the Americans.<ref name="Hirsh">Hirsh, Michael; Barry, John and Dehghanpisheh, Babak. "'Hillbilly Armor': Defense sees it's fallen short in securing the troops. The grunts already knew," Newsweek, December 20, 2004.</ref>

1 Armoured Fighting Vehicles
2 See also
3 References
4 External links

[edit] Armoured Fighting Vehicles

The most heavily armoured vehicles today are the main battle tanks, which are the spearhead of the ground forces, and are designed to withstand anti-tank missiles, kinetic energy penetrators, NBC threats and in some tanks even steep-trajectory shells. The Israeli Merkava tanks were designed in a way that each tank component functions as additional back-up armour to protect the crew. Outer armour is modular and enables quick replacement of damaged armour.

[edit] Technologies

For efficiency, the heaviest armour on an AFV is placed on its front: on the gun mantlet and glacis plate. Tank tactics require the vehicle to always face the likely direction of enemy fire as much as possible, even in defence or withdrawal operations.

Sloping and curving armour both increase its protection. Given a fixed thickness of armour plate, a projectile striking at an angle must penetrate more armour than one impacting perpendicularly. An angled surface also increases the chance of deflecting a projectile.

Appliqué armour screens have sometimes been bolted or welded onto armoured vehicles to increase protection.

Beginning during the Cold War, many AFVs have spall liners inside of the armour, designed to protect crew and equipment inside from fragmentation (spalling) released from the impact of enemy shells, especially high explosive squash head warheads. Spall liners are made of Kevlar, Dyneema or similar materials.

[edit] Spaced armour

Spaced armour can cause bullets and solid shot to tumble, deflect, and disintegrate, reducing their penetrating ability—for which effect spaced armour was used as early as the First World War, on the Schneider CA1 and St Chamond tanks. Many early-WWII German tanks also had armoured skirts installed, to help protect their thinner side armour from anti-tank rifles and anti-tank guns.

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Spaced armour also takes advantage of the principle that a high explosive anti-tank (HEAT) warhead creates a focussed jet of plasticised metal, which dissipates with distance. The innovation of the Bazooka, Panzerfaust, and other HEAT weapons in the Second World War prompted the employment of factory-made and improvised stand-off armour. Relatively thin armour plates or even metal mesh were attached as side skirts or turret skirts on tanks and other armoured vehicles. Even today, light armoured vehicles mount panels of metal mesh, known as "slat armour", and some main battle tanks carry rubber skirts to protect their relatively fragile suspension and front belly armour. The mesh approach is sufficient to detonate the warhead while remaining relatively light compared to solid sheet panels.

In response to very heavy HEAT warheads, integral spaced armour was reintroduced in the 1960s on the German Leopard 1. There are hollow spaces inside this type of armour, increasing the length of travel from the exterior of the vehicle to the interior, in hopes of reducing the shaped charge's penetrating power; in some cases the interior surfaces of these hollow cavities are sloped, presenting angles to the anticipated path of the shaped charge's jet in order to further dissipate its power. Thus instead of having a single 30 cm (12 in) layer of steel armour, it is possible to have two 15 cm (6 in) layers half a metre or more apart, giving far greater protection against shaped charges with no penalty in additional weight.

The Whipple shield uses the principle of spaced armour to protect spacecraft from the impacts of very fast micrometeoroids. The impact with the first wall melts or breaks up the incoming particle, causing fragments to be spread over a wider area when striking the subsequent walls.

[edit] Composite armour

Main article: Composite armour

Composite armour (including Chobham armour) was developed in the 1960s by the British and first used on the American M1 Abrams but not, as is often presumed, on the German Leopard 2. It consists of layers of steel, ceramic, and plastic honeycomb, sometimes with layers of depleted uranium added. Composite is effective against both kinetic and shaped charge munitions. Against kinetic penetrators, the brittle ceramic blunts the projectile while the softer steel layers absorb its kinetic energy. Still, it is significantly less effective against a kinetic energy penetrator, so sometimes depleted uranium layers are added to provide extra protection against these warheads.

An alternate description of Chobham armour is that it combines spaced armour with composites. Supposedly the deeper interior heavy metal layer is a cast aluminium slab with rods of tungsten (encased in titanium) or depleted uranium running perpendicularly through it, intended to cause the points of high-velocity long-rod penetrator armour-piercing projectiles to deform, which sometimes causes the projectile to tip and strike the armour at an angle, presenting far greater surface area to the armour and therefore greatly increasing the resistance.

Another type is perforated-steel armour with hollow perpendicular spaces serving the same function that they do in spaced armour, often filled with ceramic foam and backed by layers of Kevlar®, Dyneema® or similar material to trap and reduce fragmentation. This is the type used in the original version of the Leopard 2.

[edit] Reactive armour

Main article: Reactive armour

Explosive reactive armour, initially developed by German researcher, Manfred Held, working in Israel, uses layers of high explosive sandwiched between steel plates. When a shaped-charge warhead hits, the explosive detonates and pushes the steel plates into the warhead, disrupting the flow of the charge's liquid metal penetrator (usually copper at around 500 degrees; it can be made to flow like water by sufficiently immense pressure). It is less effective against kinetic penetrators. Reactive armour poses a threat to friendly troops in the area of the vehicle.

Non-explosive reactive armour is an advanced sort of spaced armour, using the changing geometry of materials under stress to increase its protection.

Active protection systems use a sensor to detect an incoming projectile and explosively launch a counter-projectile into its path.

[edit] Electrically charged armour

Electrically charged armour is a recent development in the UK by the Defence Science and Technology Laboratory. A vehicle is fitted with two thin shells, separated by insulating material. The outer shell holds an enormous electrical charge, while the inner shell is a ground. If an incoming HEAT jet penetrates the outer shell and forms a bridge between the shells, the electrical energy discharges through the jet, disrupting it. Trials have so far been extremely promising, and it is hoped that improved systems could protect against KE penetrators. Developers of the Future Rapid Effect System (FRES) series of armoured vehicles are considering this technology.