Active And Reactive Vehicle Protection Systems
As anti-armour weapons have become more powerful, armies have reacted by increasing the thickness and resilience of vehicle armour. Modern ammunition, however, destroys even the strongest armour, forcing armies to develop reactive and active protection systems.
The advent of potent shaped-charge warheads and kinetic-energy penetrators (KEPs) capable of defeating very thick armour forced armed forces to rethink their approach to vehicle protection, especially since thicker – and heavier – armour impedes mobility, increases fuel consumption and imposes significant strain on the power train and suspension.
Reactive Protection Systems
Reactive armour (RA) is designed to neutralise the impact of shaped-charge warheads and kinetic penetrators. It can be integrated into the vehicle’s primary armour or employed as modular or applique armour attached over the vehicle’s organic armour. Reactive armour was first patented in West Germany in 1970, but Israel was the first nation to introduce it operationally, deploying RA-equipped M-60 tanks during the Lebanon War of 1982.
There are various categories of reactive armour, including Explosive RA (ERA), Non-Explosive RA (NERA), and Electric/Electromagnetic RA.
ERA is composed of high-explosive sandwiched between two armour plates. When a shaped charge strikes the ERA, the warhead’s energy causes the sandwiched explosive to detonate, neutralising the warhead’s energy before it reaches the vehicle’s organic armour. Similarly, the ERA’s explosive force deflects KEPs such as sabot rounds, preventing their penetration of the main armour; heavy ERA can even break the kinetic rods.
Modern anti-tank missiles (ATM) often employ a tandem shaped charge warhead; this consists of a smaller explosive charge at the warhead’s tip, which has the sole purpose of tripping the ERA and exposing the underlying organic armour, and a larger main charge intended to attack the now exposed organic armour. In addition to this vulnerability, explosive armour has the disadvantage that it creates shrapnel, forcing dismounted infantry to remain at a safe distance from the vehicle rather than sheltering in its vicinity.
In place of the high-explosive, NERA employs an inert material such as rubber as liner between the armour plates. The basic principle behind its function – dissipating the warhead’s energy prematurely – is the same as that of ERAs, but non-explosive reactive armour is generally less effective than explosive plates. On the other hand, NERA is lighter and cannot be defeated by tandem warheads.
Electric or Electromagnetic RA is a comparatively recent concept. It consists of two metal plates separated by a nonconductive buffer. The plates are under a high-voltage charge, forming a capacitor. When a warhead or KEP strikes the outer plate, it penetrates the nonconductive buffer, bringing the two charged plates into contact. The capacitor releases its accumulated energy, repelling or weakening the projectile’s blast or kinetic energy.
Reactive armour is deployed worldwide, especially on heavier armoured vehicles capable of carrying extra weight. Because of the various negative factors – including the burden imposed by the additional weight – it is normally mounted only in high-threat scenarios, such as operations against forces deploying sophisticated anti-tank weapons or IEDs.
The US Army provides a prime example. The organic armour on the ABRAMS M1 MBT is considered among the best in the world, eliminating the need for add-on protection in many cases. However, reactive armour was mounted on ABRAMS tanks as extra protection against IEDs during stabilisation operations in Iraq. In 2017, ERA kits were also sent to armoured units in Germany in reaction to rising tensions with Russia.
The US Army maintains two different ERA systems for the M1; both are designated as ARAT (ABRAMS Reactive Armour Tile) and supplied by GDLS. The brick-like M19 ARAT 1 was introduced in 2006 and is mounted horizontally to defend against vehicle-mounted and man-portable weapons such as RPGs. The M32 ARAT 2 was introduced in 2008 and resembles ceramic roof tiles. The curved shape is better suited to deflecting high-energy ordnance. Unlike the M19, the M32 can be mounted at a downward or upward angle to optimise defence against IEDs or against altitude-launched weapons. The M19 can be mounted alone. Alternately, the M32 can be placed directly over the M19, creating a two-layer ERA system. Importantly, ARAT is designed to only react to high-energy explosive or kinetic weapons; small arms fire will not set off the tiles, so enemies cannot strip a tank of its RA through machine gun fire.
GDLS, in conjunction with Rafael, also supplies separate ERA systems for the M2 BRADLEY Fighting Vehicle System (BFVS Armour Tiles) and for the STRYKER family (STRYKER Reactive Armour Tiles – SRAT II). Introduced in 2014, these rectangular tiles use an insensitive high-energy explosive to counter shaped charge threats, and are lighter than previous ERA applique systems. The BFVS Armoured Tiles are rated against all shoulder-fired and most tube-launched AT-weapons, while SRAT II is optimised for urban settings.
Several European firms are refining their reactive protection systems, hoping to improve performance while minimising negative aspects.
Dynamit Nobel Defence GmbH has developed CLARA (Composite Lightweight Adaptable Reactive Armour), also known under the German designation HL-Schutz Rad/Kette (“shaped charge defence for wheeled and tracked vehicles”). By utilising composite fibre materials rather than metal or ceramic plates, CLARA reduces the threat posed by shrapnel from detonating ERA blocks. Several variants are produced, with aerial density – defined as the weight of the armoured panel (in grammes per square metre) divided by the protection area of the panel – varying between 70 and 270 kg per square metre. The lowest-density segments provide protection against RPGs, while the strongest variant can stop 30mm sabot rounds. CLARA has deployed on German Army PUMA IFVs and been tested on the MARDER IFV as well as the BOXER APC variant. In late 2017, the United Arab Emirates News Agency released images of UAE LECLERC MBTs equipped with the CLARA system.
Swiss company RUAG has also developed a composite-based ERA. The SidePRO-CE applique armour is applied to the flanks of armoured vehicles to defend against high-energy anti-tank systems (including those with tandem warheads) as well as against KEPs. According to RUAG, the ERA’s explosive reaction is confined to a minimal area, reducing the potential for collateral-inducing shrapnel. Customers include Jordan (M60 PHOENIX MBT).
Poland has improved its original ERAWA (Explosive Reactive Armour – Wiśniewski, Adam, named to honour its developer) by introducing the ERAWA 2. The ERAWA 2 contains two explosive charges and is specifically designed to neutralise tandem warheads. There is also a limited capability against KEPs. ERAWA and ERAWA 2 plates are smaller than most ERAs, with each block measuring 15×15 centimetres. This allows for a very tight fit, with minimal gaps between blocks. ERAWA is suitable for medium to lightweight armoured vehicles.
Russia’s third-generation RELIKT ERA introduced in 2006 is deployed on the T-72B, T-80B and T-90AM MBTs as well as the BMPT RAMKA/TERMINATOR fire support vehicle. It consists of a 2 kg explosive tile sandwiched between two metal plates; an inert buffer between the ERA and the organic armour provides additional protection for the tank body. Rectangular ERA boxes protect the flanks and back of the tank, while trapezoidal ERA kits are arrayed around the turret. The manufacturer NII Stali describes RELIKT as twice as effective against shaped charges as the Soviet-era, second-generation Kontakt-5 ERA. It also reduces sabot penetration by 50%.
With the advent of the ARMATA armoured vehicle series, Russia has introduced a fourth-generation ERA designated as MALACHIT. The precise composition of the ERA is not publicly known; Western experts speculate that the plates might be composed of a laminated ceramic composite matrix. The Russian news agency Tass has reported that the ARMATA T-14 MBT will be fully protected not only against Anti-Tank Guided Missiles (ATGM) but also against tank shells up to a calibre of 150mm.
Active Protection Systems – Hard Kill
Of course this claimed level of protection is not based solely on the performance of the MALACHIT reactive armour. The ARMATA family is also equipped with the AFGHANIT Active Protection System (APS). The AFGHANIT APS includes both electronic or “soft kill” subsystems and kinetic or “hard kill” countermeasures. The former includes an electronic warfare suite to disrupt warhead guidance systems including laser guidance systems. The latter includes interceptor rounds with explosively formed penetrators to physically destroy incoming missiles, grenades and shells. Russian claims that the interceptor rounds can even defeat incoming KEPs are put in question by many western experts.
Many nations are currently pursuing APS technology, which is defined as the capability to intercept enemy projectiles shortly before impact. An APS is mounted on each individual vehicle and protects only that vehicle. The concept offers numerous benefits: an APS weighs less than additional organic armour or applique armour, and can eliminate the need for bulky slat armour; by stopping incoming ordnance before impact, it minimises concussion of the vehicle and crew, and eliminates the risk of gaps being created in the applique armour through repeated enemy targeting of the same spot. Of course, there are also negative aspects to an APS. Since hard kill systems fire projectiles, there is the risk of collateral damage/victims through shrapnel or if the APS-fired projectile misses its target; since APS countermeasures are only activated immediately before impact, secondary protective measures (such as RA) may still be required in case of APS failure to intercept; APS requires an autonomous on-board battle management system to interface on-board sensors and the actual countermeasure weapons, differentiate threats from non-threats, calculate fire-solutions, choose the optimal weapon from the countermeasure suite, and engage at the optimal time – decisions to be made within fractions of a second. Finally, the APS must not interfere with other on-board systems, either through excessive demand for electricity or through its electromagnetic signals.
Israel has been a pioneer in APS development. Two systems stand out. The TROPHY APS developed by Rafael was declared operational by the Israeli Army in 2009 and first tested in combat in 2011. The original TROPHY, now designated TROPHY-HV (Heavy Vehicle) is designed for medium to heavy combat vehicles; it is currently in use on the MERKAVA MBT and the NAMER Armoured Fighting Vehicle, and it has been successfully integrated on the GDLS LAV III. In June 2018, the US Army awarded Rafael the initial contract to supply the TROPHY APS for the M1 ABRAMS MBT. The German Army has selected TROPHY to protect one LEOPARD 2 tank company to be deployed with the NATO Very High Readiness Joint Task Force as of 2023.
The TROPHY-LV was introduced in 2014 for light and medium vehicles, ranging from 4×4 jeeps to armoured personnel carriers and IFVs. Both variants utilise a 360° Elta EL/M-2133 fire-control radar system for detection and targeting. Two rotating containers atop the vehicle fire 35 metal balls against each incoming missile, rocket or RPG, targeting the warhead. The balls are miniaturised explosively formed projectiles (EFP) which can either disable the incoming weapon – the preferred solution – or cause it to explode prematurely. Both variants offer a hostile fire detection capability to identify the source of incoming fire. Each container has three countermeasure warheads, so that a TROPHY-equipped vehicle can only defeat six incoming projectiles before reloading.
The HV variant is effective against ATGMs, RPGs, recoilless rifles and tank-fired HEAT rounds, but not KEPs. It can react to simultaneous threats from different directions, including projectiles approaching from a high angle. The LV is designed primarily for urban operations and is optimised against RPGs, including those with dual/tandem warheads. The system is easily mounted atop wheeled and tracked vehicles using an integrated roof-rack assembly. In addition to the radar, the LV incorporates electro-optical sensors which trigger the countermeasures when the enemy projectile enters the system’s field of vision.
The IRON FIST APS produced by IMI also comes in different variants optimised for heavy and for medium to light vehicle classes, respectively. It utilises both infrared and radio-frequency sensors for surveillance and targeting. Each Iron Fist has two launchers, with each launcher mounting two tubes. The tubes fire high-energy blast grenades armed with proximity fuses which detonate within 80 centimetres of the incoming projectile; target destruction or deflection is achieved solely through the grenade’s blast wave, without any fragmentation effect. The system is effective against ATGMs, RPGs, recoilless rifles and KEPs. The heavy configuration includes a soft-kill electro-optical and laser jammer as a primary option before deploying the hard-kill projectile. This enables the heavy-vehicle IRON FIST to theoretically engage an unlimited number of incoming threats, in contrast to the purely hard-kill, light-vehicle variant or the TROPHY ASP. The IRON FIST has garnered several export contracts. The Royal Netherlands Army has contracted BAE Systems to integrate the IRON FIST Light Compact (IF-LC) system on its CV9035NL.
IRON FIST Light has entered phase 2 evaluation for the US Army’s BRADLEY IFV, while the Australian Defence Force has asked Rheinmetall to evaluate IRON FIST for use on the BOXER Combat Reconnaissance Vehicle. Other weapon systems being hypothetically paired with the IRON FIST include the GDLS AJAX armoured fighting vehicle and the
In 2014, IMI and Rafael agreed to collaborate on development of a next-generation APS integrating the best features of the TROPHY and IRON FIST concepts. Rafael is to act as prime contractor, with IMI and Israel Aerospace Industries as partners.
Several European firms are also pursuing or upgrading APS solutions. Rheinmetall Defence offers the Advanced Modular Armour Protection – Active Defence System (AMAP-ADS). This flexible system can be customised to meet client needs. It provides a dual layer of sensors. According to the manufacturer, the first ring of sensors consists of a multi-frequency radar with planar antenna. This early warning system detects and classifies threats, and enables initial trajectory calculation. It demands only a low level of radiated power, thereby avoiding interference with other radars. The second or inner sensor ring consists of a high-resolution electro-optical system which confirms the radar findings and calculates a more precise estimate of the incoming projectile’s point and time of impact, enabling a fire solution. According to Rheinmetall, initial radar detection takes place 50-200 milliseconds (10-35 metres) before impact, while the optical system acquires incoming ordnance 10 milliseconds or two metres before impact. Hard kill countermeasures deploy only four milliseconds before the hostile warhead’s impact, destroying it at a distance of one metre from the protected vehicle.
This is significantly closer than most APS systems, which tend (on average) to engage at a range of circa ten metres. The difference is that Rheinmetall’s ADS relies fully on directed energy to destroy or divert the incoming warhead; it does not fire any projectile or shrapnel of its own. This eliminates the threat of collateral (except, of course, from the remnants of the incoming weapon). Sensors and countermeasure pods are distributed all around the protected vehicle. Depending on configuration, the entire system adds between 140 and 500 kg of weight, making it suitable for light wheeled vehicles as well as medium to heavy IFVs and MBTs. Since larger projectiles may only be fragmented but not completely stopped by the ADS, some form of organic or applique armour is recommended to ensure full vehicle protection.
At the IDEX 2019 Exposition in Abu Dhabi, Rheinmetall introduced its new Hybrid Protection Module. It combines the ADS with two layers of passive armour components as an integrated module. The ADS sensors are sandwiched between the outer and inner passive armour layers, which protects them against shell fragments and small arms fire. The ADS countermeasure component is embedded within the external armour plate. The individual modules measure 18×15 centimetres and are intended to replace other passive modular armour on the flanks of tracked and wheeled vehicles.
China’s NORINCO demonstrated its more traditional GL5 APS hard kill system to foreign observers in 2017 and presented it to the general public at the China Air Show in November 2018. As presented, the GL5 consists of four multipurpose millimetre-wave radars distributed for 360° coverage, four countermeasure launcher sets, and a control computer. Each of the four launchers mounts three pods containing high-explosive fragmentation grenades capable of intercepting ATGMs, RPGs and tank-fired HEAT rounds. Intercept range is circa ten metres from the protected vehicle. According to NORINCO, a second grenade can be fired if the first fails to destroy or deflect the incoming projectile. The GL5 is suitable for the full range of vehicles, from light tactical vehicles to MBTs.
Electronic Protection Systems – Soft Kill
While most APS concepts are built around hard kill options to destroy or physically deflect incoming ordnance, some include soft kill options as part of the package. The term “soft kill” is actually misleading, as these systems are not intended to bring down the incoming projectile, but simply to misdirect it so that it flies past the intended target. The Land Electronic Defence System (LEDS) marketed by Saab, for instance, begins with a laser-detection and soft kill suite, adding a hard kill option as an upgrade. Soft kill elements of LEDS include smoke grenades to counter laser guidance systems and dispensing flame retardant foam to alter the vehicle’s infrared and radar signature. MONGOOSE rockets can be added as a hard kill option.
Other soft kill systems are based on electronic warfare or laser technology, and they can include so-called dazzlers to blind optical targeting systems. Such systems have the advantage of a virtually unlimited magazine, while a hard kill APS can engage only a limited number of targets – in some cases as few as four – before reloading. Vehicles mounting both soft and hard kill systems engage first with the former, holding the hard kill weapons as a reserve.
The US Army is planning to include both hard and soft kill capabilities in its Modular APS architecture (MAPS). Still being defined, MAPS will provide a framework for future APS solutions across the vehicle fleet. It is intended to integrate various technologies and systems offered by different manufacturers. In late 2018, the US Army conducted a so-called “Soft Kill Rodeo” to evaluate three contenders for the soft kill component. All three contenders – BAE Systems’ RAVEN Multi-Function Counter-Measure (MFCM), Northrop Grumman’s Multifunction Electro-Optical System (MEOS), and Ariel Photonics’ Colour Light Operational Unit for Deflection (CLOUD) – utilise electronic countermeasures to defeat incoming ATGMs. The MAPS base kit was used to control all three systems during the test.
While all three systems reportedly performed well, the US Army selected the BAE Systems RAVEN MFCM – a derivative of an airborne electronic warfare jamming system – for further evaluation. It will be mounted – together with the MAPS base kit control unit and the hard kill IRON FIST APS – on a BRADLEY IFV for a more challenging layered demonstrator scheduled for July through September of this year. This trial will further evaluate the individual ASPs, but more importantly, it will evaluate the capability of the MAPS controller to integrate and coordinate the hard and soft kill systems effectively.
Sidney E. Dean is President of Transatlantic Euro-American Multimedia LLC. and a regular contributor to ESD.
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