From a chapter on explosives this image and surrounding discussion will probably be withdrawn from my book. On the modern battlefield, MBT’s (Main Battle Tanks) are still very much the dangerous deathtraps they were back in WWII.
In the documentary type TV shows shown in some Discovery channel and History channel episodes the American M1 Abrams tank is lauded as being the newest, toughest and best tank of all. The M1 is a good tank but any perceived superiority over many other modern competitors is only marginal. The Abrams uses a copy of the German Leopard’s fully-stabilized Rheinmetall RH-M-120 120-mm smoothbore gun. The M1’s composite armor was originally influenced by and adapted from the British Challenger’s ‘Burlington’ and then ‘Chobham’ armors. The Challenger II tanks progressed to a 3rd generation composite “Dorchester armor” while all active M1’s (approximately 6,000) have been improved or retrofitted with an additional layer of depleted uranium mesh.
While the British and American tanks have state of the art protection they are far from impervious to battle damage from the plethora of anti-tank weaponry available nowadays. Made in smaller numbers, the Italian ‘Ariete’, Israeli ‘Merkava’, German ‘Leopard’ and French ‘Leclerc’ tanks also have modern sophisticated armor. These tanks use the same NATO standardized ammunition, use the same or similar 120mm smoothbore cannon (except for the Challenger 2), use comparable computerized fire control systems, have infrared night vision and so on. Any capable modern tank designed by Russia, Japan and South Korea would likewise pose a serious threat to the M1 Abrams in a one on one showdown. In comparing the Abrams with these other examples, perhaps its only shortcoming is in the choice of engine. While the rest use diesel piston engines, the Abrams uses a fuel glutinous turbine. The engine causes a logistical challenge to keep it fueled and infantrymen cannot walk behind it for protection because of its hot exhaust blast. The engine is fickle and demands complicated maintenance, although replacement engines can be swapped out quickly due to modular design.
* The smoothbore cannons prevalent in most modern tanks are a result of the desire to create as much velocity as possible for (specifically) a kinetic round. Rifling in the bore would restrict the maximum velocity. With projectile velocities upward of 4,000 fps the rifling could actually be stripped out of the barrel.
Briefly, tank armor consists of just a few main types: RHS, composite armor and ERA (or a combination of these). Cast steel and then RHS (Rolled Homogenous Steel) is what a WWII tank would have used. Later it was realized that sloping the armor improved the protection of RHS. Composite armor is made of layers of different materials. Metals, ceramics, plastics, Kevlar and other materials are built up in layers that create armor that is normally more voluminous than traditional cast or rolled homogenous steel would be. Oftentimes the sloping of composite armor offers no penetration protection advantage. ERA or Explosive Reactive Armor actually uses its own explosive to blow back or disrupt penetration rounds. Reactive armor is hung on the exterior of regular armor in vital areas, in the form of removable plates or modules. It usually consists of a plastic explosive sandwiched between two metal plates. If struck, reactive armor endangers infantry or anyone else in the vicinity – with flying shrapnel. Reactive armor is said to be very effective against kinetic energy penetrators. Another type of reactive armor is called NERA (Non Explosive Reactive Armor) and might resemble ERA but the explosive is replaced with a flexible barrier like rubber. This type of secondary armor is said to be very effective against tandem warhead shaped charges. * When a HEAT (High Explosive Anti Tank) round is fired an elongated molten jet of metal plasma penetrates the armor and squirts through a small hole; ideally. When such a round hits a ceramic within composite armor however, the ceramic is expected to shatter and then the fragments act to breakup, divide and deflect the metallic jet, reducing the penetration. A “tandem charged HEAT round” attempts to breakup and clear away the ceramic barrier first, milliseconds before a second shaped charge follows through to penetrate the armor beneath.
During the 1991 war Operation Desert Storm, the Iraqis possessed a miss-mash of about 4,280 cast off and obsolete Russian and Chinese tanks. Most of the Iraqi tanks were based on 40-50 year old technology and these proved to be hopelessly outclassed by new and improved Coalition armor and munitions. In one instance an immobilized M1 Abrams stuck in the mud was caught off guard by three Republican Guard Iraqi T-72 tanks. The Russian built T-72 is cold war, 1980-ish, 2nd generation hardware. The M1’s armor withstood direct and even close range hits from both shaped-charge and sabot rounds, but ably dispatched all three T-72s. In that engagement the M1 used combustible cartridge cased, M829A1 120mm, depleted uranium sabots. Used for the first time, depleted uranium projectiles gave the U.S. tanks a pronounced advantage over the enemy. Since depleted uranium is twice as dense as lead, these projectiles also had twice to three times the effective range as Iraqi tank munitions.
Four M1’s were lost or disabled during the Gulf War due to ‘friendly fire’ from Hellfire missiles fired from AH-64 attack helicopters. In another instance and due to the ‘fog of war’ the side armor of the hull and the rear armor of the turret of M1s were penetrated by friendly DU ammunition during the Battle of Norfolk (final battle of the Gulf War). During this same confusing engagement however, the front armor and fore side turret armor of M1s survived direct kinetic energy penetrator hits from other M1A1s. Further proving that composite armor is not impenetrable, a British tank driver lost his foot when the thickest part of his Challenger II’s ‘Dorchester’ frontal armor was penetrated, by something. It is assumed that an infantry carried RGP-29 (the Russian’s best at the time) was responsible for making that hole. Fortunately for the coalition forces, the Iraqis had very, very few RGP-29s.
During the Gulf War most Iraqi tanks took the apparently sensible precaution of burying their hulls under the sand and leaving only their turrets exposed. This tactic lead to an Iraqi demise however because the modern anti-tank munitions used by the Coalition forces were quite capable of penetrating the thick turret armor. It was a “turkey shoot”. The Iraqis lost something like 3,700 tanks – mostly to munitions delivered by aircraft. The most effective aircraft of that war, the A-10 Warthog is credited with destroying more than 900 Iraqi tanks, 2,000 other military vehicles and 1,200 artillery pieces. The Warthog (or Fairchild Republic A-10 Thunderbolt II) undoubtedly made those tank kills with missiles; not its famous DU ammo firing GAU-8 Avenger rotary cannon. The GAU-8’s armor piercing incendiary and high explosive incendiary ammunition is devastating to most targets but lacks sufficient energy to defeat modern MTB armor. At best an A-10 pilot firing the gun would only hope to disable a tank by peppering its engine compartment and setting it on fire. Specifically designed with the role of close air support for infantry in mind the A-10 has proven to be reliable, efficient, resilient and effective. Since its introduction in the 1970’s however, the Air Force brass has never liked the A-10 because it is too cheap, too slow and too un-sexy. Despite its effectiveness the Air Force either intends to or already has whittled down the number of A-10 squadrons.
Shaped charged munitions
A discussion of tank armor should be accompanied with some information of the munitions necessary to defeat it. That discussion may be added later.
Added March, 24, 2017