Merkava with ears? It's ALWACS!

In the past months a number of photographs has been posted online, which shows some of the older, upgraded Merkava main battle tanks (MBTs) featuring so called "ears". In different forums people have speculated about the purpose of the oddly shaped turret add-ons, suggesting that these might be part of a 360° close proximity surveillance system or radars for detecting the launch of rocket propelled grenades or anti-tank missiles.

Operational Merkava tanks with "ears"

In fact the upgraded Merkava II and Merkava III tanks are fitted with the advanced laser warning and countermeasure system (ALWACS), which is made by the local manufacturer Elbit Systems. The ALWACS is a softkill active protection system (APS) capable of defeating anti-tank guided missiles (ATGMs) and other sorts of laser-guided ammunition, by distracting them or by hiding the tank using a multi-spectral smoke screen. ALWACS has also been proposed for adoption on the troubled Arjun Mk. 2 tank upgrade for the Indian Army; however it was not adopted into the upgrade package in favor of other components such as heavy explosive reactive armor (ERA).

The ALWACS softkill system has been proposed for adoption on the Arjun tank

Incoming threats are indirecly detected by the Elbit-made E-LAWS laser warning sensors. In case of the Merkava III tanks, these are usually mounted atop a mast on the turret; however there are also some cases where the E-LAWS modules are bolted to the turret sides. These laser warning sensors are also used on other vehicles inlcuding the TAM 2C upgrade for the Argentine Army and the British Ajax recon vehicle. If a laser source triggers the warning system, the direction of the source is calculated and the countermeasures are being engaged. The ALWACS softkill system includes two different types of defensive measures: the VIRCMs (vehicle infrared counter-measures) and multi-spectral smoke grenades.

Each VIRCM module consists of four smaller infrared (IR) jammers, which are set at different angles and cover more than 90° of azimuth; the coverage in elevation is probably limited to about 45°, maybe even less. The IR jammers can confuse missiles that are utilizing IR signales for semi-automatic guidance along the line of sight (SACLOS). The upgraded Merkava tanks feature two VIRCMs (one on the left and on of the right side of the turret rear bustle), covering a large portion of the sides and rear.  However the Merkava tanks fitted with the ALWACS softkill APS don't feature any additional smoke grenade launchers; it is not known if the smoke grenades used by the Merkava tanks are capable of blocking the most common IR and laser wavelengths.

The ports of the VIRCMs are open; also note the mast with E-LAWS on the center of the turret roof

The advanced laser warning and countermeasure system is essentially a more modern equivalent to the Soviet-made Shtora electro-optical countermeasure system and other simple softkill systems like the Ukranian Varta, which utilize laser warners to activate IR jammers and/or to launch smoke grenades. Similiar systems also include the LEDS-50 laser warning and the LEDS-100 softkill system from SAAB Electronics, the US AN/VLQ 6 missile countermeasure device (MCD), which is an infrared jammer not connected to a laser warning system, and Rheinmetall's ROSY_L. ROSY_L consists of multiple smoke grenade launchers in a 40 mm calibre, which are controlled by a manual control unit or by a computer control unit. The computer can be connected to sensor systems such as laser warners and accoustic sensors belonging to the company's SAS product suite in order to create a softkill system known as ROSY_L ISS (integrated sensor suite).

MUSS features optical sensors aswell as rotatable launchers and jammers.

The ALWACS is however not as advanced as the multifunctional self-protection system (MUSS) from German manufacturer Hensoldt, which has been fielded on the Puma infantry fighting vehicle (IFV) and is being tested by QinetiQ for a possible adoption on the British Challenger 2 main battle tank and other armored vehicles as part of the Medusa program. 

Aside of laser warners, the MUSS softkill system features optical UV sensors for threat detection and tracking, it therefore can detect and engage missiles that are not fired from a launcher with laser-rangefinder. Furthermore the IR jammer and multi-spectral smoke grenade launchers from MUSS are rotatable, allowing the system to protect a vehicle along the full 360° azimuth - systems like Shtora, Varta, the MCD and ALWACS are usually not capable to do so.

QinetiQ to test MUSS APS for British Army

The British Army has contracted QinetiQ to evaluate the options for active protection systems (APS) for use on British military vehicles. In the £7.6 million ($9.89 million) contract, QinetiQ is obligated to deliver a number of MUSS based systems for evaluation. These systems will be tested against different weapon systems and will also be tested as "applique integration" on the British Challenger 2 main battle tank (MBT) from BAE Systems.

The "multifunctional self-protection system", MUSS, is a protection system developed by the Franco-German company Airbus (formerly EADS) in cooperation with the companies KMW and Buck (a subsidiary of Rheinmetall) on behalf of the German Army. The development started in 1995, but the APS was first adopted on the Puma IFV in 2015. MUSS is a soft-kill active protection system, which uses a jammer and multi-sprectral countermeasures to prevent air-launched and ground-launched guided weapons of hitting the vehicle.

Leopard 2A5 testbed with the MUSS APS

The APS has been tested on the Boxer MRAV and on the Leopard 2A5, but was only adopted on the Puma. Presentations from EADS mention a number of further vehicles onto which MUSS was proposed, mounted or tested. These include LAV, Pandur and the Leclerc, although on the latter only the warning sensors were mounted, not the active countermeasures.

Combined missile and laser warners on the German Puma IFV

For detecting missiles, MUSS utilizes optical sensors and laser-warners. Originally the PMILDS missile warner, an improved version of the EADS-developed AN/AAR-60 missile warner used on many aircrafts including the F-16 "Fighting Faclon", the UH-60 "Black Hawk" and the Eurocopter Tiger, was used in combination with separate laser warners. EADS developed a system combining both missile and laser warner into a single package. Each of these sensors can cover about 95° in azimuth and elevation. The version tested on the Leopard 2A5 tank used only two sensor units, which were covering only the frontal arc. On the Puma IFV however MUSS is equipped with four sensor units, which together provide a 360° coverage in azimuth.

For deflecting the guided missiles, MUSS uses two components: a jammer and launched countermeasures. The rotatable jammer is aligned with the path of the missile by the computer system. It creates a modulated and focused IR beam to defeat SACLOS-type missiles. In 2002 it was estimated that more than 70% of all ATGMs could be jammed via such an IR beam.

Following the detection of an ATGM, the system can automatically launch the active countermeasures. These are located in smoke grenade dischargers, which can be rotated into the direction of the missiles. Unlike conventional smoke grenades, the MUSS countermeasures create a cloud of multi-spectral smoke, that blocks IR, UV and laser beams. This is believed to be an effective way of disabling fire-and-forget missiles. On the Puma IFV, there are eight countermeasure ready to fire.

The compact version of MUSS

A stand-alone version of the MUSS APS, called "MUSS 360° Compact System" by EADS, has been developed as drop-in solution for existing vehicles. This sounds a lot like the British press release speaking of the "applique integration" of the MUSS active protection system into the Challenger 2 MBT.

Old presentations on the MUSS APS suggested the integration of radar panels and hard-kill countermeasure launchers into the system. At the time, this was the AWiSS protection system developed by Diehl Defence for the German Army. It is not known if this suggestion has ever been realized, the current version on the Puma IFV at least lacks any hard-kill components.

The contract with QinetiQ is part of the MEDUSA Technical Assessment Programme of the British Defence Science and Technology Laboratory.  This program can lead to a major boost in the protection of British vehicles and soldiers in combat, but one has to keep in mind that a research program doesn't have to lead to the adoption of such systems in the near future, specifically given the economic havoc caused by Cameron's Brexit referendum.