New armour solutions. (Ground Warfare).

Since the first tanks rolled into action in 1916, a constant duel has been underway between the designers of armoured vehicles and the manufacturers of anti-tank weapons. Every development seems to be quickly followed by measures designed to counter any advantage.

In the 1960s and early 1970s, the fielding of large numbers of guided missiles armed with High Explosive Anti-Tank (Heat) warheads seemed to pose a major threat to the world's tank fleets, which were then protected by steel-based armour. These cheap weapons included shoulder launched throw-away Soviet rocket-propelled grenades (known as RPGs) or American M72 Light Anti-tank Weapons as well as longer range wire guided weapons, like the Soviet-age 9K11 Malyutka (Nato: AT-3 `Sagger') and the American BGM-71 Tow.

The success of the new generations of anti-tank weapons during the 1973 Arab-Israeli war spurred many armies to look to ways to redress the balance and dramatically improve the protection of their tanks and other armoured vehicles.

The results of these efforts soon bore fruit and they were put to the test during the Israeli invasion of Lebanon in 1982. These add-on armour solutions have since been developed to a further degree and many of the technologies involved have been incorporated in almost all new-build armoured vehicles fielded over the past twenty years.

Heat Threat

Heat rounds were first used during World War Two with some success and as the first generation of guided antitank weapons were being developed in the late 1950s and early 1960s, the potential of Heat or chemical warhead technology was quickly recognised. Traditional kinetic energy rounds relied on their momentum combined with very hard metal to literally punch a hole through the steel armour of enemy vehicles. Heat rounds were based on a very different principal and used a shaped design to channel a high press jet of very high temperature molten metal from the explosive collapse of its internal cone to burn a hole in the enemy armour. The jet of molten metal would then burst into the crew compartment of the target vehicle, causing horrific injuries to the crew and damaging key equipment, as well igniting any exposed propellant. Crucially, Heat rounds did not need to impact their targets at anything like the velocity of kinetic rounds and so were ideal for use on relatively slow rocket-powered anti-tank weapons.

First ERA

Not surprisingly, the expertise required to produce explosive reactive armour is found with explosives companies, and they have since led the market for this technology. Chastened by their experiences and heavy losses to Soviet supplied anti-tank weapons in the Yom Kippur War, the Israeli Armoured Corps was keen to find counter measures to protect their existing M48, M60 and Centurion tank fleets. The Israelis turned to the Rafael Armament Development Authority to field what became known as Blazer reactive or explosive armour, the first explosive reactive armour to see operational service.

The appearance of Israeli tanks covered in explosive reactive armour blocks, as in the invasion of Lebanon, has since become a common sight on the world's battlefields.

The Israelis soon found the Blazer armour very effective against the RPG-7s used in abundance by Syrian, Palestinian and Lebanese troops defending Beirut. They also found that the use of the Blazer armour was not without some risks to friendly troops nearby when the explosive blocks were activated. Work was also needed to prevent the detonation of the explosive reactive armour blocks when hit by weapons that were unable to penetrate a vehicles armour, such as machine guns and artillery splinters. Since then, Rafael has refined the design of the original Blazer blocks and a second generation Blazer explosive reactive armour is in service with several armies around the world. The US Marine Corps purchased improved Rafael-designed blocks for use on its M60 tanks during the Gulf War. Rafael and Martin Marietta conducted trials on US Army Bradley infantry fighting vehicles but serial orders were not made.

The Slavin plant of Israel Military Industries also offers explosive reactive armour packages as part of tank upgrade programmes. These have been used on Israel Defence Forces M60 modernisation programmes and Slovenia used them to upgrade its T-55s. The company has recently unveiled a package for M113 troop carriers.

Russian Protection

The Soviets had been working on the explosive reactive armour during the 1970s but their efforts received a major boost when the Syrians donated them an Israeli M48 they had captured in Lebanon, complete with an undamaged set of Blazer armour.

The first Soviet explosive reactive armour was developed by the NIIBT research centre at Kubinka and named `dynamic reactive elements' or EDZ in Red Army jargon. A number of Soviet T-64BVs based in East Germany were first spotted protected with EDZ blocks in 1984.

The first T-72As appeared with explosive reactive armour from 1987 and the T-72B entered service in 1988 with it. This first generation EDZ was not normally fitted in peacetime because of the strain of the extra weight on the tank's automotive system. It covered 60 per cent of the front and side turret, 80 per cent of the front and 50 per cent of the side hull. It had a reputation for being very unreliable and tended to go off when hit by artillery shell fragments.

Moscow's tank designers, however, saw the potential of using reactive armour as part of the integrated armour packages of new main battle tanks, and when early versions of the then T-80 began appearing in the early 1980s they had EDZ fitted as standard.

The Soviets continued to perfect their EDZ technology and second-generation versions, labelled Kondakt and designed by VNII Transmash, began appearing on production T-72BMs (T-90E for export) in the late 1980s. It featured the larger tiles that the Soviets claimed offered defence against both kinetic and Heat rounds.

In the 1990s Russian and Ukrainian tank manufacturers switched production over to versions of the T-72 and T-80/84, and with the new T-90 another version of the EDZ appeared. These tanks featured laminated, reactive and ceramic armour to counter the dual or tandem Heat warhead rounds that were then being deployed by Nato armies. This was a multi-layered approach to protection with large armoured skirts of explosive reactive armour arrayed around the hull and turret. By layering reactive armour on top of laminated ceramic material it was hoped the new armour would defeat both Heat rounds and sabots. The most advanced version of EDZ was dubbed Kondakt5 and appeared on T-90s and upgraded T-72s.

When the US Army acquired examples of the Kondakt5 in the mid-1990s they conducted test firings with the M829 120 mm Armour-Piercing Fin Stabilised Discarding Sabot (APFSDS) round. Some reports suggest the Russian armour successfully defeated the US `silver bullet' tungsten sabot round, with its explosive effects `blunting' the sabot and significantly reducing armour piecing characteristics.

NII Stali in Moscow produces the reactive armour used on many modern Russian main battle tanks. While Ukrainian modules, aptly named `Nozh' (knife), are produced by a joint project of the State Central Bureau of Critical Technologies Mikrotek, SD&TB IPS NAS of Ukraine, Scientific and Engineering Centre Materials Explosive Treatment of Paton Electric Welding Institute of Nas of Ukraine and Kharkov Morozov Machine Building Design Bureau. They claim that their explosive reactive armour improves protection from kinetic rounds by 145 per cent and by 200 per cent against Heat rounds.

ERA For All

ERA is now in widespread use around the world, with many countries exploiting Soviet and Israeli technology to establish domestic production capabilities. Although the principles of explosive reactive armour are well known and any country with a reasonably advanced explosive industry could be expected to field it. The following are a few examples from around the world.

In France, the state-owned Giat and SNPE enterprises have co-operated to field reactive armour products, including the Brenus blocks that can be easily fitted on all types of medium or heavy armoured vehicles. The French Army has retrofitted its AMX 30 B2 tank regiments with Brenus modules.

India's High Energy Materials Research Laboratory developed its own type, which is being adopted for upgrade of T-72 and possibly Arjun tanks.

China's North Industries Corporation (Norinco) has fielded ERA on a number of its tanks, including the Type 59 and Type 80/88. The state-owned outfit is also co-operating with Pakistan to produce the Al Khalid 2000 main battle tank, which boasts a comprehensive explosive reactive armour package. It is highly likely that the Chinese have transferred their technology to the Pakistanis. The Heavy Industries Taxila operation has used it to upgrade a number of tanks, which includes using it for the Al-Zarrar Type-59 modernisation programme.

Poland's Military Institute of Armament Technology has developed its own Erawa package for installation on T-72s. The Poles offer a number of versions, including double layers, combined with composite armour. In the Czech Republic, VOP 025 also offers explosive reactive armour packages for T-72 tanks.

Santa Barbara has produced explosive reactive armour blocks for use on Spain's AMX-30 tanks.

Britain's Royal Ordnance (now RO Defence) offered its own Romor-A module--which was then used to provide additional protection to Challenger 1s during the 1991 Gulf War. Italy bought the product to protect its Centauro wheeled heavy combat vehicles.

Passive Solutions

At the same time as moves were being made to field explosive reactive armour, Britain, the United States and a number of other countries were looking for other solutions to counter the Heat threat.

Britain's Fighting Vehicles Research and Development Establishment at Chobham, now part of QinetiQ, developed armour which provided remarkable protective characteristics. This Chobham armour was a composite sandwich of ceramics, aluminium, plastic and steel, that absorbed and defeated Heat rounds, squash head rounds and tungsten sabot kinetic rounds.

Now exploited by numerous manufacturers the sandwich effect is designed to bring together materials with different properties to provide protection against a number of types of rounds. A layer of heat absorbing chemicals, more often of a rubber or plastic base, combined with a high melting point ceramic composite is used to vanquish Heat rounds. The heat-absorbing chemicals take a portion of the energy from the jet and the ceramic layer prevents it from melting, thus stopping the weakened jet.

A layer of deformable plastic is then backed up by mild steel to provide shock absorbing capacity for protection from squash head rounds that are designed to force chunks of metal to break off inside the tank, creating a shower of hot fragments. A kevlar or ballistic nylon liner fixed to the inner side of armour, known as an anti-spall liner, and internal compartmentalisation of the tank help reduce damage and prevents the crew from receiving serious injuries from these rounds.

Standard steel armour, embedded with heavy hard metal, either tungsten or depleted uranium rods, blocks or mesh provides a last line of defence against kinetic sabot rounds. Any projectiles entering the steel will strike these elements and shear because of the violent course deflection, resulting in the sabot loosing much of its mass and therefore momentum.

The British retrofitted the armour to create the Stillbrew Chieftain, and made it available under licence to the Americans and Germans for use on their new tanks. They in turn further developed the armour and the Americans began to refer to Burlington armour.

Advances in metallurgy during the 1980s led to the development of new types of rounds and armour based on the waste products of the nuclear industry. Like tungsten, depleted uranium (DU) is one of the hardest metals known to man but crucially it is less brittle than tungsten. So far the United States is the only country that is known to have deployed depleted uranium armour for its tanks. During the 1980s, a DU armour package was developed for the General Dynamics M1 Abrams tank that is supposed to be the equivalent of 1300 mm thickness armour against shaped warheads and 600 mm armour against APFSDS rounds. It raised the total weight of the Abrams tank by more than five tons to around 65 tons. The depleted uranium armour kits were retrofitted to US Army M1A1 creating M1A1(HA)s and they were used to great effect during the Gulf War providing 100 per cent protection against tank main armament hits.

Evolutions of Chobham armour were used in the German Army's Leopard 2 tanks in the 1980s and the Bundeswehr has since fielded applique armour packages for its improved Leopard tanks. These improvements have also been made available to European Leopard operators, including Sweden, Netherlands and Switzerland. IBD-Deisenroth is playing a leading role in the development of the Modular EXpandable Armor Systems (Mexas) that the German Army hopes to field on the next generation of tanks and armoured vehicles.

The Israelis were so keen to adopted Chobham-style solutions that they soon started to field what was known as `hybrid' armour packages that combined add-on Blazer explosive reactive armour and composite armour, to create a sandwich of ERA/composite/ ERA. Israel Military Industries has played a key role in these efforts including fielding the armour on the M60 Megach/Sabra series upgrades and Merkava Mk 2 and Mk 3 production tanks.

Interest in composite armour is now widespread, with a number of countries keen to acquire the protection it offers. Iraq, for example, found its T-55s, T-62s and early model T-72s very vulnerable to hostile fire during its war with Iran and began to experiment with its own versions of Chobham armour. These included laminated armour packs of ceramics, rubber, aluminium and steel. One version included layers of sand inside armoured boxes placed around tank hulls and turrets.

South Africa's MOH-9 Armour Ceramics produced the composite armour for the Oliphant 1B upgrade of Centurion tanks. B+V of Germany offers composite up-armouring kits for Leopard 1s, M48s and AMX-30s.

Spaced

While explosive reactive armour and composite add-on armour has entered widespread use on main battle tanks, their heavy weight and bulk make them far from ideal for use on lighter armoured vehicles. One solution for this class of vehicle has been to employ spaced armour. The Germans developed this during World War Two to defeat Heat rounds. They bolted armour plates around the turrets and hulls of tanks to detonate Heat rounds and prematurely release the round's hot jet before it contacts the vehicle's main armour.

Israel has experimented with fitting mesh screens on their M113 tracked armoured personnel carriers after they faced heavy RPG fire in Lebanon. Several Nato armies, like Denmark's, adopted spaced armour solutions to improve the protection of their M1113s on United nations and Nato peacekeeping missions during the 1990s.

Ruag Land Systems in Switzerland is one of many companies offering spaced solutions for M113 class vehicles.

Future Options

Explosive reactive armour and composite armour come at a very heavy price in bulk and weight--something that will continue to increase as the efficiency of warheads also increases. Many armies are looking to field new families of lightweight armoured vehicles that offer the same protection as current heavy vehicles, while at the same time being air transportable in a C-130--which means 17 tonnes maximum.

The American project to develop the Future Combat System (FCS) and the British Future Rapid Effects System (Fres) are both in the early stages of development. Unconventional armour is being studied closely in both projects. Lightweight but strong materials such as titanium are increasingly being seen as replacements for aluminium or steel. In Britain, QinetiQ built an experimental Advanced Composite Armoured Vehicle Platform (Acavp) that is the world's first plastic composite monocoque armoured fighting vehicle. Instrumental in the concept was the use of add-on armour packages to protect key parts of the vehicle, possibly using explosive reactive armour or composites.

Armour a la Carte

It now appears that unless radically new technologies, materials and techniques are developed, the amount of armour required to protect a vehicle will never cease to increase. The Swedish Leopard 2 is a good example, being several tonnes heavier than others (amazingly, manufacturer performance and range data remain unchanged). So the idea of modular protection has begun to cut in, not only with heavy tanks, but also for lighter vehicles. Giat, for example is looking into such solutions for its Leclercs on which armour could be placed where needed depending on the missions (incidentally, the Leclerc already has a modular armour). The French manufacturer has adopted a similar approach in the development of the VBCI ordered by the French Army--the vehicle hull being made of aluminium. The side advantage of this is that vehicles dangerously close to the Hercules yardstick in terms of weight could be sped out where needed in separate aircraft--one for hull and the other for armour.

Lighter Vehicles

When it comes to smaller vehicles like the Hummer, the armouring process calls for a heavy redesign of the bodywork. In such cases merely adding armoured plate and glass is not a practical solution. Both O'Gara-Hess & Eisenhardt in the United States and Mowag in Switzerland have had to extensively redesign panels and glasswork for their respective Hummer-based M1114 and Eagle II. In the case of the Swiss Army scout vehicle, the redesign is even more drastic to the extent that the vehicle is visually quite different. There is a weight penalty however: the M1114 tips the scales at nearly 4.5 tonnes against 2.85 tonnes for the standard model. The American vehicle had real-life testing in Kosovo when it ran on a heavy mine, and yet its occupants were just left with a noisy experience to talk about when they returned home.

Active

Another solution envisaged to protect vehicles--and other assets for that matter--is an active system. Again, the Russians appear to have been avant-guardists with the Arena. Developed by KBM, the system detects incoming threats and automatically dispatches an explosive munition in their path. The system's operation is extremely impressive to watch on video, but immediately suggests that anyone not under armour cover around that vehicle will have difficulties in telling the story.

A few years ago, probably as a response to the Arena, the US Army showed some of its active protection projects, notably an electromagnetically-powered system that would toss disrupting hard material plates at high speed in the way of the incoming charge or dart. Somehow, this seems to have been given a lower priority.

How ERA Works

Early in the 1970's Dr. Manfred Held, a German working for the Nobel Company, invented a device called a drive-plate explosive sandwich. This device was composed of two metal plates separated by a layer of explosive.

Dr. Held's concept formed the basis of what is known as 'Explosive Reactive Armour' or ERA. It works on the following principal: as a Heat round impacts the ERA, the molten jet perforates the outermost steel plate of the sandwich and ignites the explosive layer; as the explosive layer detonates, the pressure forces the metal sheets apart. Because the metal sheets are set at an angle oblique to the axis of the shaped charge jet, the flying plate continuously feeds new armour material into the path of the penetrator jet, deflecting it (called perturbation) and consuming its energy. The destabilised jet then reaches the rear plate, which is moving in the opposite direction to the original plate. The force exerted by the rear plate is essentially a torque when taken with that of the front plate, and this causes the already destabilised jet to break up into smaller pieces.

Essentially, the tip or head of a Heat jet is its most efficient part and it allows the rest of the jet to efficiently pile into the hole it generates and forces the armour material out of its path. Removing the jet head reduces the penetration of the jet by 30 per cent or more, even though it is a relatively small part of the jet's mass. Explosive reactive armour is mounted above the main hull of the vehicle it is protecting, which further decreases the penetration capability of the shaped charge jet. The net result is that the shaped charge weapon cannot achieve a significant penetration of the armour.