Chaffs and flares: Passive countermeasures to thwart missile attacks

March 24, 2020 2:17 PM

Since its development a decade back, Kavach system has undergone upgrades and latest version Kavach MOD II is in service.

Representational Image: Reuters
  • By Milind Kulshreshtha

A passive countermeasure system against incoming anti-aircraft missiles forms an important and effective part in an aircraft’s arsenal. Similarly, warships to carry these last-minute support self-defence systems onboard as a standard fit. These systems are also categorized in Electronic Warfare terms as expendable ECM (Electronic Counter Measure) to protect the platform. When Chaff and Flares are launched from the onboard Counter Measure Dispensing System (CMDS), these degrade the performance characteristics of adversaries weapon system and help safeguard own platform.

Indigenization Effort of CMDS

Defence Research and Development Organisation (DRDO) has taken up the task of indigenous development of chaff cartridges to bridge the technology gap in this field and evolve an import substitute for Defence. This becomes a critical requirement since Chaff is one of the most widely used expendable electronic countermeasure devices.

A need for more than hundred thousand Chaffs and flares exists in next five years, making indigenization an important factor. DRDO has reported that the checks and trials of indigenously developed Chaff cartridge system have been undertaken onboard a fighter jet by Indian Air Force’s Aircraft and Systems Testing Establishment (ASTE) in 2018.

These checks include safe ejection of chaff from indigenous Chaff cartridge, envelope clearance trials in sub-sonic, super-sonic range and manoeuvrability test. Further checks are in progress in various configuration like Nose-on, sideways (beamforming) and tail-on configurations. For the airborne CMDS Bharat Dynamics Ltd., Hyderabad is the manufacturing unit. Ordnance Factory Board (OFB) had undertaken the effort to indigenize the CMDS section comprising of the Chaff rockets and launchers.

OFB developed Kavach system is a standard fit on all frontline warships.

What are CMDS?

Counter Measure Dispensing System (CMDS) mainly comprises of two units viz. a Chaff system and Flares.

Chaff System

A Chaff system onboard an aircraft is used to protect the host aircraft or a helicopter from the radar-guided missile. This is carried out by firing the chaff cartridge into the air, where chaff cloud is formed rapidly. Chaff forms a volumetric radar reflecting material and is composed of distributed metalized radar reflector material. This protects the host aircraft from a radar-guided missile by luring it to a better radar cross-section substitute, thus achieving a distraction towards the Chaff cloud. This decoy is considered effective when it is able to lead the anti-aircraft missile away from the host aircraft such that it passes target aircraft safely.

The chaff are designed to operate in a frequency band of 2 to 18 GHz and can create an average Radar Cross Section (RCS) of about few square meter within a fraction of a second. These systems are designed for extreme environmental conditions like minus 45 to plus 70 degrees Celsius etc.

Similarly, Indian Navy uses shipborne chaff naval decoy system to distract radar-guided anti-ship missiles in a self-defence role of the ship. The indigenized version is christened Kavach decoy system which releases Chaff made up of silver coated glass fibre. The Chaff forms a radar clutter using these fibres, while they remain suspended in the air. This clutter is aimed to confuse the incoming missile to lock-on it instead of the warship.

Chaff system basically comprises of a multiple barrel launchers (Port and Starboard configuration), with each launcher possessing a built-in stabilization system against roll, pitch and yaw motions. The Chaff launcher comes in various ranges viz. Short Range, Medium Range and Long Range. Chaff rockets are pre-loaded into the barrels and are fired using squibs, the firing initiation controlled electrically by an FCS system located in the Operation Centre of the ship. The FCS computer calculates the best solution for chaff launch sequence based on various factors like target motion parameters, wind speed, wind direction etc. The computer can prioritise the threat also and suggests to the Commanding Officer the Course to Steer to obtain best decoy capability.

Since its development a decade back, Kavach system has undergone upgrades and latest version Kavach MOD II is in service. Kavach MOD II brain is the Bharat Electronics Ltd (BEL) developed Kavach MOD II Fire Control Solution (FCS) computer. On a naval warship, Chaff system forms an important part of modern C4I functionality and this capability is achieved by integrating the Kavach system with the onboard Combat Management System. With this now Chaff system forms a part of Warfare tactics to engage any anti-ship missile threat.

Flares

Onboard an aircraft, Flares are part of CMDS configuration and protect the platform from the Infrared (IR) seeking missiles. Flares on being fired provide an alternate strong IR source to heat-seeking anti-air missiles so that they are lured away from the aircraft. The dispensation of the flares is a well-measured solution so as to create a new energy centroid in the field of view of the chasing missile. Thus, the IR radiation signature created by flare is larger than that of the aircraft and attracts the missile towards it.

( The author is C4I expert. Views expressed are personal.)

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