User:Jackehammond/sandboxes-Beyond-armour effect

Beyond-Armor Effect is a term that Försvarets Fabriksverk (FFV) the quasi-government Swedish defense firm that developed and manufactures the AT4 coined in 1980s in its' brochures, press releases, weapon instruction manuals, etc for the post-penetration effect of the AT4's HEAT antiarmour warhead against the interior and occupants of a hostile armoured vehicle. And today, it has become a standard phrase in military terminology.

History

It was World War Two that brought man-portable antitank weapons that used shape charge warheads more commonly known today as HEAT warheads in to wide spread use with almost all the armies involved in that conflict. HEAT warheads have the advantage of not being effected by the velocity the projectile. They penetrate armour plating by an explosive charge inverting a liner, which is usually copper, usually in the shape of a cone and turning it into highly focused particle stream moving at extreme speeds that penetrates the armour plating. The main kill mechanism of a HEAT warhead is also one of the two kill mechanisms of medium and high velocity solid shot armour piercing projectiles: spalling on the interior of the armour vehicles armored plating. But the problem with shape charge warheads is that if the cone shape liner is deep it will have more penetration, but makes a smaller hole and therefore less post-effect on penetrating the armour. Some photos of the effect of shape charge warheads have shown a hole the size of a large coin on the outside of a tanks turret, but the inside hole is the size pencil lead. But if the cone is shallow it will have less penetrate, but cause a larger hole in the armour which will result in a massive spalling on the inside of the armour vehicle. A rule of thumb on infantry antitank weapons is that if a HEAT warhead has to use more than two-thirds of its official penetration capability, it will less effect on the interior of the vehicle.

During the famous siege of Dien Bien Phu in 1954, the French had flown in a number of M24 Chaffee light tanks which thickest armor was only 25.4mm. The Communists Viet Minh main infantry antitank weapon was the old World War Two US 2.36 inch bazooka captured from Nationalists China and supplied by Communists China. During the siege The French launched counter attacks using the M24 Chaffees in support of the French infantry assaults. One French Army Chaffee took seven hits from 2.36 inch bazookas and still continued to fight!

Another example was the Second Indochina War. The North Vietnamese and their allied forces in South Vietnam were equipped with two types of light antiarmour weapons: the 1950s era B-40 which was a Chinese manufactured version of the Russian RPG-2 and the newer RPG-7. The RPG-2 had a shallow cone and the RPG-7 a deep cone. The RPG-2 had a maximum penetration against armour of approximately 150mm the RPG-7 penetration was more than double that of the RPG-2. But to the surprise of the North Vietnamese the RPG-2, while not effective against heavy tanks, was far more effective than the RPG-7 in killing or wounding the occupants of light armoured vehicles, and in igniting the ammunition storage or the vehicles fuel, this including the more modern M113 APC which US forces and South Vietnamese forces at that time operated in large numbers. In addition the B-40 proved more effective than the RPG-7, against non-armoured targets, like the bunkers at fire base camps than the newer RPG-7. There are many stores from US Vietnam vetrans of the enemy attacking or ambushing with the dread B-40. And also during the Vietnam War, the US Army discovered that in combat that with rare exception more than one hit by the M72 LAW rocket were required to disable or kill the North Vietnamese PT-76 light tank.

Development

All this past history light antiarmour weapons combat record was studied by the engineers at FFV working on a replacement for the Pansarskott m/68 in the late 1970s. The results was the AT4 with a HEAT warhead that had as the early AT4 brochures stated a special beyond-armour effect. The designers of the AT4s warhead intended that one hit would cause massive damage to the both the interior and occupants of the vehicle. FFV has said very little about the design of the AT4s warhead -- only its' effect. Many defense journalists and military experts have speculated. One, clue was a cutaway photo of the AT4s projectile which instead of the standard cone shape liner used by other HEAT warheads, has a unique liner which is trumpet in shape. Trumpet shape liners are believed to be more effective in resisting the effects of Reactive armour tiles, that explode and disrupt the HEAT warhead's particle stream. There has been speculation that the liner in the AT4s HEAT warhead is constructed of special aluminum alloy. Others have stated it is primer copper liner with a secondary liner of aluminum bonded to the back of the copper liner. But this has only been speculation. Educated speculation true. But still only speculation. But in tests of the AT4 by the US Army, they concluded that the claims by FFV that the AT4 had a devastating post-penetration effect to be as they claimed.

External images
Test Photos of AT4's Beyond-armour effect
AT4 launcher and HEAT projectile
Rear view of obsolete APC hit by AT4 HEAT projectile showing beyond-armour effect
Top view of obsolete APC hit by AT4 HEAT projectile showing beyond-armour effect

Description

As described by FFV in their early brochure of 1983 beyond-armour effect five distinctive items on penetration of a vehicles interior:

• A massive over pressure inside the vehicle of approximately 1 bar over normal.

• Secondary fragments from the warhead itself due to a larger entry hole, plus more extensive spalling than caused by HEAT warheads of similar diameter.

• An intense light that is 100 times than bright sunlight.

• A generation of dense smoke post-penetration.

• Extensive heat is generated inside the vehicle.

FFV claims that besides the effect of the massive spalling and fragmentation on the occupants of the armoured vehicle, the massive over pressure and intense heat will cause ammunition and more important diesel fuel</ref>diesel fuel has a very high flash point and is hard to ignite normally</ref> to catch fire. And that the intense light will blind any occupants for at least seven minutes if not longer, along with the dense smoke created by the AT4 unique HEAT projectile.