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Slat Armor
Also known as bar armor, cage armor and standoff armor, slat armor is specifically designed to protect armored vehicles against anti-tank rocket-propelled grenade attacks. Slat armor takes the form of a rigid slatted metal grid fitted around key sections of the vehicle, such as its engine and transmission. The grid disrupts the shaped charge of the warhead by either crushing it, preventing optimal detonation from occurring, or by damaging the fusing mechanism, preventing detonation outright. Slat armor's efficiency is lower than that of dynamic protection, but slat armor is much easier to produce and cheaper. These metal grids help protect military equipment from cumulative grenades, something that especially matters during an urban combat when a vehicle can be fired upon from any direction. It is worth noting that although slat armor is effective against incoming missiles, it doesn't offer complete protection, given that about 50 percent of missile impacts remain unimpeded by the slat design.
Armor is often used inter alia for neutralizing the triggering mechanism of weapons, such as for example a rocket propelled grenade (RPG), known to be a shoulder-fired, anti-tank weapon commonly used against vehicles, which typically fires rockets equipped with an explosive warhead. When the warhead hits the target, the trigger actuates an electric signal, which is transmitted through conductive cone to conductor, which in return sets off the explosives. The explosive is then urged through an aperture in the conical liner toward the target.
During the times of terrorism and war, various guided and unguided missiles have been used resulting in casualties. A system that protects structures, ground/air/sea vehicles, and the people inside them against missile attack could save the lives of military troops as well as civilians. A common unguided missile currently used is the rocket-propelled-grenade (RPG). RPGs can come in both a single and tandem warhead form. The tandem warhead has two or more stages of detonation, namely a first stage detonation designed to trigger a reactive defense and a second stage detonation designed to attack the same location as the first stage detonation location. Tandem warheads generally are much larger and more lethal than single warheads, making predetonation alone a less attractive defense strategy. Also due to different fuzing methods at the different stages, short circuiting via impact of tandem warheads may not be achievable.
Heavily armored, lightly armored, and unarmored vehicles have been proven vulnerable to the RPG shaped charge. Pick-up trucks, HMMWV's, 21/2 ton trucks, 5 ton trucks, light armor vehicles, and M118 armored personnel carriers are frequently defeated by a single RPG shot. Even heavily armored vehicles such as the M1 Abrams Tank have been felled by a single RPG shot. The PG-7 and PG-7M are the most prolific class of warheads, accounting for a reported 90% of the engagements. RPG-18s, RPG-69s, and RPG-7Ls have been reported as well, accounting for a significant remainder of the threat encounters. Close engagements 30 meters away occur in less than 0.25 seconds and an impact speed ranging from 120-180 m/s. Engagements at 100 meters will reach a target in approximately 1.0 second and at impact speeds approaching 300 m/s.
The RPG-7 is in general use in Africa, Asia, and the Middle East and weapon caches are found in random locations making them available to the inexperienced insurgent. The RPG threat in Iraq was present at every turn and caches had been found under bridges, in pickup trucks, buried by the road sides, and even in churches.
Existing technologies for RPG or missile defeat systems include application of slat armor to the military vehicles. The principle of slat armor is to stop the missile before it strikes the body of the target, to crush the missile and short circuit its electric fuze, or to cause shaped charge detonation at a standoff distance, rather than directly on the body of the vehicle. Steel grille armor is said to destroy and interrupt the electrical energy produced by the piezoelectric crystal in the firing head of the RPG. Bar/slat armor is also designed to dud an RPG. But, bar/slat armor is also very heavy. Often, a vehicle designed to be carried by a specific class of aircraft cannot be carried when outfitted with bar/slat armor. Also, if the bar/slat armor is hit with a strike, the RPG still detonates. Bar/slat armor, if damaged, can block doors, windows, and access hatches of a vehicle.
Slat armor is known to typically include a rigid grid deployed around the vehicle, which can naturalize the warhead, either by deforming the conical liner, or by short-circuiting the fuzing mechanism of the warhead. The slat armor is in the form of a rigid grid disposed in a predetermined distance from the vehicle, so as to allow the armor to come in contact with the cover of the RPG in order to neutralize it before the trigger hits the vehicle's body. The distance between the grid and the body of the vehicle is known as the standoff. The slat armor can include a flexible mesh having rigid elements spaced from one another in such a way as not to allow an RPG warhead to hit the mesh without contacting at least one rigid element. Thus, the rigid element neutralizes the devastating effect of the warhead by deforming the conical liner and/or by short-circuiting the fuzing mechanism.
Disadvantages to slat armor are that it adds significant weight to the vehicle, and sacrifices maneuverability. The standoff distance it provides in case of predetonation is too short to be of significant benefit. Other RPG or missile defeat systems launch a single or small number of projectiles toward the incoming missile. These systems require accurate sensing of the missile trajectory, accurate aim of the projectiles in order to intercept the missile, and fast reaction time to slew and fire the projectile.