The Akash missile

The Akash (Sky) is a medium-range, theatre defence, surface-to-air missile. It operates in conjunction with the Rajendra surveillance & engagement radar. This system will replace the SA-6 / Straight Flush in Indian service and is also expected to be integrated with the S-300V (SA-10 Grumble) low-to-high altitude SAM in an integrated air defence system to counter SRBM / IRBM threats along the Pakistani and Chinese borders.

The missile is based heavily on the SA-6 and is claimed that Rajendra is similar to the 30N6 Flap-Lid B engagement radar, used by the S-300 ATBM system. The Akash’s first flight occurred in 1990, with development flights up to March 1997. Operational tests and evaluations are currently ongoing and the missile is expected to enter service with the army and air force only in 2003. Officials have said that the missile will also undergo user trials with the Army for integration with the S-300PMU-1 anti-tactical ballistic missile systems, of which the Army has purchased an unspecified number, as well as with AEW aircraft. Plans exist for a navalised version in VLS mode.

The Akash uses an integral ramjet rocket propulsion system to give a low-volume, low-weight (700 kg launch weight) missile configuration, and has a low reaction time - from detection to missile launch - of 15 seconds. This allows the missile to carry a heavier warhead (60 kg). The solid-propellant booster accelerates the missile in 4.5 seconds to Mach 1.5, which is then jettisoned and the ramjet motor is then ignited for 30 seconds to Mach 2.8 - 3.5 at 20g. Akash has a range of 27 km, with an effective ceiling of 15 km. It is capable of detecting & destroying aircraft flying at tree-top height. Development is on to increase speed, maximum altitude and range to 60 km. A dual mode radar/infra-red seeker is also being developed as is a longer range version of the Rajendra radar, to give earlier warning and tracking of ballistic missile targets.

In appearance, Akash is very similar to the ZRK-SD Kub (SA-6), with four long tube ramjet inlet ducts mounted mid-body between wings. Four clipped triangular moving wings, mid-body, for pitch/yaw control. Forward of tail, four inline clipped delta fins with ailerons for roll control. Flight control surfaces operated by pneumatic actuators. The warhead has a lethal radius of 20 metres, weighs 60 kg and has Doppler radar proximity/contact fusing. The missile is believed to have tail G/H-Band beacon to assist tracking by engagement radar. Guidance system is inertial with mid-course command updates from Rajendra and semi-active radar seeker for terminal phase (final 3-4 seconds).

Rajendra is a 3D phased-array surveillance/engagement radar developed by the Electronic Research & Development Establishment (ERDE). Also mounted on a modified BMP-1 chassis, like the Akash, the radar is capable of tracking 64 targets, engage 4 simultaneously and guide up to 12 missiles. The system is reportedly similar to the 30N6 (Flap-Lid B) engagement radar. Has air surveillance, multiple target tracking and multiple missile guidance functions via multi-channel monopulse. Features fully digital signal processing system with adaptive moving target indicator, coherent signal processing, FFTs, and variable pulse repetition frequency.

Mounted on a turntable at the front of a raised platform behind the driver’s station, the multi-element antenna arrangement folds flat when the vehicle is in motion. Radar comprises surveillance antenna array with 4000 elements operating in the G/H-Band (4-8 GHz), engagement antenna array with 1000 elements operating in the I/J-Band (8-20 GHz), a 16-element IFF array and steering units. The surveillance radar range is 60 km against aircraft targets. A longer range version is being developed. The Army intends to use the Rajendra radar in the artillery locating role as well. An Akash battery consists of three missile launch vehicles (triple launcher on a modified BMP-1 chassis), a Rajendra fire control radar vehicle, a long-range surveillance radar vehicle and an armoured command vehicle. Series production of ~25 missiles per year, was expected to commence in 2000 at Bharat Dynamics Ltd. No reliable information has been received so far, as to whether Akash missile production has begun.