Slat armor (also known as bar armor, cage armor and standoff armor) is a type of vehicle armor designed to protect against anti-tank rocket-propelled grenade (RPG) attacks. It functions by placing a rigid slatted grid around the vehicle, which disrupts the shaped charge of the warhead by either crushing it, preventing optimal detonation from occurring, or by damaging the fuzing mechanism, preventing detonation. It can, however, be defeated by tandem-charge designs such as the RPG-27 and RPG-29.
World War II
The German Wehrmacht was the first employer of cage armor during World War II, using Drahtgeflecht Schürzen (English: "wire mesh skirts") to fortify its tanks against shell fire. It was found to be just as effective as the steel plate schürzen also being utilized. In March 1943, Adolf Hitler ordered all new Sturmgeschütz, Panzer III, IV, and Panthers be outfitted with schürzen of either the wire mesh or steel plate type. However, the wire mesh was not as easy to mass-produce as steel plate schürzen. Red Army tanks, faced with the new and highly effective German Panzerfaust, were similarly outfitted with "bedspring" armor made from expanded metal mesh grating panels.
In the Vietnam War, slat armor was commonly used on the sides of American patrol barges and boats. The CCB-18 is a surviving example of the Mobile Riverine Force which used such armor. Wire fencing was also placed on vehicles such as the M113 to defeat Vietcong RPGs.
In modern times, slat armor has seen use on the Israel Defense Forces Caterpillar D9R armored bulldozer, the Force Protection Buffalo MPV MRAP Category III vehicle, the General Dynamics Stryker, the Warrior Infantry Fighting Vehicle, the M113, the Leopard 2A6 main battle tank, and Georgian T-62 tanks. Slat armor is favored over traditional plate armor not only due to its effectiveness against shaped-charge warheads, but also due to its much lighter weight, which improves maneuverability. BAE Systems has developed an extremely lightweight aluminum system called the LROD, already in use on the Buffalo MPV, which is claimed to weigh half the amount of comparable steel designs. BAE has equipped several US Army RG-31s with a variant of the LROD system, and is developing the system for its RG-33 vehicles, the Caiman and the JERRV. LROD is also the standard RPG solution for the Buffalo MPV in the field.
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