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Making the tough tougher

Christopher F Foss looks at how new armoured fighting vehicles are being designed to survive the latest anti-armour systems

Since the first tanks appeared on the battlefield well over 80 years ago there has been a continual battle between armour and anti-armour teams, the advantage swinging between offence and defence. As one side improves protection, so the other increases the weapon size or develops new technology to defeat the latest armour.

Even simple weapons however, can prove devastating if used effectively. During fighting in Chechnya in 1995, the Russian Army lost over 250 vehicles, many to manportable RPG-7-type unguided anti-tank projectiles fired from very short range at the highly vulnerable sides and rear of their armoured fighting vehicles (AFV).

Armour, or armour systems play a key role in improving AFV survivability, but there are many other aspects to be taken into account. Four basic principles govern AFV survivability on the battlefield. In increasing magnitude, these are: remaining undetected in the first place; if detected - avoid being hit; if hit - stop the penetration and if penetrated - survive.

The most obvious way to prevent being hit is to minimise the possibility of detection by making the AFV small and compact and as difficult to detect by a variety of battlefield sensors including radar, acoustic and electro-optical systems as possible.

In practice many of today's AFVs, especially main battle tanks (MBTs), are very large and heavy but where possible AFV designers are striving to reduce the size of future armoured vehicles, with the twin incentives of not only enhancing their survivability but also making them easier to transport by air.

This especially applies to western countries that are now placing increased emphasis on the ability to transport equipment rapidly anywhere at very short notice. The key requirement is that equipment must fit into the widely-used C-130 Hercules transport aircraft.

Alongside the air transport question, users also require higher levels of battlefield protection following a design policy of 'fly light, fight heavy'. This foresees the vehicle transported with basic armour, which can subsequently be enhanced by an add-on package with a higher level of protection.

The United Defense M8 Armored Gun System (AGS) is a case in point, designed to take different levels of armour package to meet varying threat levels. Level I protects against small- arms fire and shell splinters, with a maximum vehicle weight of 19.052 tonnes. Level II has a higher level of protection, but pushes the weight up to 20.82 tonnes. Level III includes an explosive reactive armour (ERA) package that provides protection against hand-held anti-tank weapons with maximum vehicle weight a further 2.74 tonnes heavier than Level II.

Current MBTs often weigh over 60 tonnes, but the US Army's Future Combat System (FCS) project wants to reduce this to around 20 tonnes, while at the same time calling for a higher level of fire power and increased survivability of the platform.

The UK and USA have recently evaluated composite armoured vehicles that offer the potential user a higher level of protection for a lower weight. The UK vehicle is called the Advanced Composite Armoured Vehicle Platform (ACAVP) developed under the leadership of the Defence Evaluation and Research Agency (DERA - now QinetiQ) with final assembly and initial tests being carried out by Vickers Defence Systems.

To combat the proliferation of battlefield sensors and detection systems, many new AFV designs are incorporating stealth characteristics. This does not just cover expensive, stealthy materials but also simple, practical design measures. For example, the standard production Alvis Vehicles Warrior infantry fighting vehicle (IFV) exhaust outlet was on the right side of the hull, but on the more recent Warrior 2000 this has been moved to the rear to reduce the heat signature of the IFV. Also, the hull sides have been redesigned to lower the radar signature.

Rubber-band-type tracks can also help to reduce the noise profile of the vehicle with the secondary advantage of lowering the platform's overall weight. The possible future introduction of electric-drive systems into AFVs will reduce noise still further and allow more flexibility in vehicle design.

Once detected, AFVs are directly threatened by enemy armoured vehicles, aircraft, artillery, mines, anti-tank guided weapons (ATGWs) and a variety of infantry anti-armour weapons. These systems all attack in subtly different ways and provide individual challenges to AFV designers.

MBTs are traditionally the best protected of any AFV and the latest types have a very high level of protection over their frontal arc against both kinetic energy (KE) attack - for example, armour- piercing fin-stabilised discarding sabot - and chemical energy (CE) attack, such as, high explosive anti-tank (HEAT) projectiles and warheads.

While the basic structure of the MBT hull and turret is usually of cast or welded steel, this now incorporates more advanced composite or laminate-type armour. The final production General Dynamics Land Systems M1A2 MBT, for example, incorporates depleted uranium armour in its hull and turret.

Lighter AFVs, such as IFVs, usually have protection over their frontal arc from medium-calibre attack, typically 20mm to 30mm and protection against heavy machine gun fire in the rest of the vehicle. Protection levels for armoured personnel carriers (APC) are normally lower and can vary from 7.62mm to 20mm protection levels.

Their hulls and turrets are normally of all-welded steel or aluminium armour construction and some also have an additional applique armour package that can be fitted when required. 'Spall' liners provide extra protection and are often installed inside the hull to reduce the behind armour effect of HEAT type warheads, which can cause deadly shrapnel to ricochet around inside the vehicle.

In addition, crew survivability can benefit radically from a practical redesign. The original United Defense M113-series APC had fuel tanks inside the troop compartment but these are now mounted externally, on either side at the rear. As well as increasing survivability, this has created more room inside the vehicle.

The mobility required of reconnaissance vehicles means that they are more lightly armoured and therefore offer varying levels of protection, typically against 7.62mm ball attack through a full 360, although some have higher protection levels. Where it is not possible to provide protection for the complete vehicle, normal practice is to protect the crew only.

Many manufacturers offer greater levels of protection, but there are limits to which this can be taken without restricting the mobility of the vehicle or turning it into something the size of an APC or MBT. Too much additional weight can lower the maximum speed, reduce power-to-weight ratio, and affect the braking system, suspension and steering.

Armoured vehicles of all types are vulnerable to mines, an anti-tank mine exploding under a light vehicle will probably result in its total loss.

South Africa's combat experience has led it to pioneer the development and production of mine-protected vehicles. These vehicles, such as the Vickers OMC Casspir, normally have a V-shaped hull, which helps deflect the main blast of the anti-tank mine away from the crew compartment.

Following the loss of a number of AFVs in the Balkans, other countries are now increasing the protection of their vehicles against anti-tank mines. These include adding increased armour protection to the floor and the areas above the tracks. Driver safety is a particular concern as the driver is often the first casualty when the vehicle runs over an anti-tank mine. To remedy this some countries are providing additional armour protection for this position. Suspending the seat from the roof, as in some Russian vehicles, further enhances driver survivability instead of anchoring the seat to the floor as is standard practice.

One of the leading manufacturers of passive armour packages is German company IBD - Deisenroth Engineering - and supplies more than 7,000 armour packages for a wide range of tracked and wheeled AFVs. It has also supplied packages for trucks used in peacekeeping operations. The company markets three basic packages called MEXAS light, medium and heavy. The company also allows licensed production of its armour packages and has the capability to develop armour for specific applications.

AFV protection is not often given a high priority in peacetime, but once conflict is imminent or taking place there is usually a rush to improve survivability. During the 1990-91 Gulf War for example, the British Army had a crash programme to fit some of its key AFVs with additional protection.

The Challenger 1 MBT was fitted with more passive armour to its sides, while the front of the vehicle carried ERA developed by the now BAE Systems, RO Defence, which has also supplied ERA packages to Italy and Japan. More recently this up-armour package has been installed on the latest Challenger 2 MBTs deployed by the British Army to the Balkans. The Warrior IFV was also fitted with passive armour over the front and sides of its hull to improve protection. This has also been retained for operations in the Balkans.

Advanced armour systems such as Chobham normally have to be designed into the vehicle from the start but applique armour packages can be designed to be fitted once the vehicle has entered service.

Following combat experience in the 1967 war, the Israel Defence Force (IDF) sought ways to improve the combat survivability of its MBTs. This resulted in the development and installation of ERA on many of its M48, M60 and Centurions, among others.

This is typically fitted over the frontal arc of a MBT and is currently being marketed by the RAFAEL Armament Development Authority with backing from Israel Military Industries (IMI). The first system, Blazer, was retrofitted to many Israeli tanks. Further development has resulted in an improved version called Super Blazer, which provides increased performance against shaped charges and KE rounds.

ERA has never been fitted to the locally designed Merkava MBT, however, as its passive armour package already provides a very high level of protection. The overall design of the Merkava with its front-mounted power pack and fighting compartment at the rear, greatly contributes to the overall survivability of the vehicle.

The Merkava also has elements of a defensive aids suite (DAS) including laser detectors and a specially designed IMI grenade launching system. Ammunition is kept in special containers and a Spectronix fire/explosion detection and suppression system is fitted as standard.

Since first introduced in 1979, the Merkava has been constantly updated and the latest Mk 3 version has significant improvements in armour, mobility and firepower.

RAFAEL has developed an ERA package for the M113-series APC that protects against attack from RPG-7-type anti-armour weapons.

These systems have had success in the export market and have led to the development of an ERA package for the Bradley IFV with co- operation of the now General Dynamics Armament Systems.

RAFAEL also provided the advanced armour package for the Slovenian upgraded T-55-series MBT, the M-55 S1, which incorporates many other Israeli subsystems. In addition, the company also won a US Marine Corps contract to provide additional passive armour for the LAV 8 x 8 vehicles. In an attempt to overcome the defensive effects of ERA packages, offensive weapons manufacturers developed tandem HEAT warheads. These systems involve an initial warhead that activates the ERA package prematurely, leaving a gap in the armour for the second warhead to penetrate.

Russian MBTs have incorporated advanced armour in their hulls and turrets for many years and from the 1980s, many were fitted with ERA packages over their frontal arc. Used in combination with the already advanced armour integrated into the hull and turrets of the T-72, T-80 and the more recent T-90, this provides a very high level of protection against KE and CE munitions, even if the latter are fitted with a tandem HEAT warhead.

The French Army has equipped several battalions of its AMX-30B2 MBTs with an ERA package developed by Giat Industries and the explosive element supplied by SNPE. This is being marketed as the BRENUS system and can also be fitted to other MBTs such as the M48, M60 and T-72. A similar kit has been developed for use on lighter armoured vehicles such as APCs.

The increased protection that these armour packages have provided for MBT frontal arcs has led anti-armour weapon designers to find new ways of defeating AFVs. A popular choice is to field top-attack weapons that exploit the more lightly armoured upper surfaces of the vehicles.

The increasing number of top-attack weapons include mortar rounds like the 120mm Stryx artillery projectiles containing bomblets, anti-tank guided weapons such as the Saab Bofors Dynamics Bill 2 and the Raytheon Systems TOW-2B that overfly the target and fire warheads from above and an increasing number of intelligent 155mm artillery-fired munitions such as the BONUS, SMArt and SADARM.

This has led to some of the more recent MBT designs, such as Krauss- Maffei Wegmann's Leopard 2 for the Swedish Army, having a significant increase in top-attack protection. This armour package was developed by the Swedish Akers Krutbruk Protection AB.

Most AFVs are fitted with electrically operated smoke grenade launchers, which can lay a smoke screen ahead of the vehicle to enable rapid redeployment under cover. These can also fire a variety of other screening or fragmentation grenades to discourage infantry attacks.

A good example is the French GALIX combat vehicle protection system that has been developed by Giat Industries and Etienne Lacroix. Ammunition for the 80mm launcher includes self-protection, infrared decoy, illumination, smoke, tear gas and warning combat types plus associated training grenades.

This is fitted on all production Giat Industries Leclerc-series MBTs and has also been purchased by a number of other countries including Sweden, Saudi Arabia and the United Arab Emirates.

Some countries are now adding laser detectors to their AFVs. These can rapidly inform the crew as to the direction of the laser and its type, either laser rangefinder or laser designator. This gives the option to get the turret quickly laid on to the threat and engage with the main armament or discharge grenades to cover a change of position.

Known users of laser warning devices include Iran, Israel (AMCORAM and Moked Engineering), Italy (Marconi), Japan, Pakistan (Al Technique Corporation), Poland (PCO), Romania, Russia and Slovenia (Fontana). Very often these laser systems utilise technology developed for the aerospace sector.

In the UK, Helio has developed the Cerberus joint grenade discharger and laser warning system. There are already almost 300 orders for the system.

Under contract to the French Delegation Generale pour l'Armement, Giat Industries has developed the Kit Basique de Countre Mesures (KBCM), which has been installed on a French Army AMX-10RC 6 x 6 armoured car for trials purposes. This technology demonstrator includes a man-machine interface and central processing system with infrared jammers, missile launch detectors, laser warning detectors and the previously mentioned GALIX system.

Germany is also active in DAS with a team consisting of LFK, Krauss- Maffei Wegmann and Buck integrating the MUSS (Multifunctional Self- Protection System) into a Leopard 2 MBT. MUSS consists of individual missile and laser warning systems, a central computer and dispensers for grenades (smoke, flares and chaff) as well as systems for active optronic and electronic countermeasures, including an infrared jammer and a laser repeater.

To combat ATGWs, a number of jammers have been developed and fielded, including the French EIREL and US AN/VLQ-6 and AN/VLQ-8A. These are typically mounted on the turret and scan the frontal arc to detect and decoy away many of the main types of ATGWs fielded today.

The Russian KBP Instrument Design Bureau developed the Drozd (Thrush) dynamic defence system, which was first installed on a T- 55AD MBT in the early 1980s. Drozd consists of a pair of millimetre- wave (MMW) sensors mounted on either side of the turret facing forwards and below each of these is a pair of quadruple 107mm rocket launchers covering the frontal arc.

The MMW sensors detect incoming ATGWs and when within range, two munitions are fired from each of the rocket launchers. The fuze activates the munition at a safe distance from the vehicle and projects a swathe of fragments into the path of the ATGW to prevent it impacting on the vehicle. More recently, KBP has developed the Drozd-2 system, similar in concept but with 18 launch tubes and associated MMW sensors mounted to give increased target coverage through 360.

The latest Russian active defence system Arena was developed by the KBM Design Bureau and has already been shown installed on a T-80 MBT and a BMP-3 IFV. Arena has also been marketed for western armoured vehicles.

Mounted on the roof of the vehicle, a multidirectional radar sensor system constantly scans for approaching ATGWs. If any approach the platform, the computer activates the defence system mounted around the turret, typically through about 260, which then fires an explosive projectile into the path of the incoming missile before its impacts.

The US Army does not have a complete DAS currently installed on any of its AFVs, although all have grenade launchers and some can also lay a smoke screen by injecting diesel fuel into the exhaust system. ATGW decoy systems have been fitted on some M1 and M2/M3 vehicles.

The army has also been developing a couple of other projects to increase AFV survivability. These are the Suite of Survivability System and Boeing's Small Low-cost Interceptor Device, designed to detect and defeat incoming targets at a range of 250m or more.

The complete system could be mounted on an AFV or a trailer to protect high-risk areas. If a warhead gets past these defensive systems and penetrates the armour - the greatest threat to AFV survival is explosion or fire. In the past most AFVs only had a fire/detection and suppression system for their engine compartments, operated automatically or manually.

Today virtually all newly built MBTs and many other AFVs have a fire/explosion detection and suppression system installed in their crew compartments as a matter of course. These have very quick reaction times and combat experience has proven that they save lives.

The world's largest producer is Kidde Graviner of the UK, which also owns the US company Santa Barbara Dual Spectrum (previously owned by Raytheon), supplier of well over 20,000 systems for vehicles such as the M1 MBT and M2/M3 Bradley vehicle.

The other leading company in this area is Israel's Spectronix, over 7,000 of its Automatic Fire and Explosion Detection and Suppression Systems, have been sold worldwide and it is standard equipment on all IDF MBTs and APCs.

There is a growing emphasis on AFV survivability and new vehicles such as the US Army FCS and the UK/USA TRACER (Tactical Reconnaissance Armoured Combat Equipment Requirement)/FSCS (Future Scout Cavalry System) have an inbuilt DAS.

All these recent developments in armour and defensive systems have swung the advantage back temporarily towards the defensive, or at least towards survivability of AFVs.

However, no AFV is totally resistant against all forms of attack and this is unlikely to happen in the near future. As long as defensive systems are developed, so too will be the systems designed to overcome them.