The Nudelman 9K31 "Strela-1" (Russian 9К31 "Стрела-1" - arrow, NATO reporting name SA-9 "Gaskin") is a highly mobile, short-range, low altitude infra-red guided surface-to-air missile system. Each TEL consists of two pairs of ready-to-fire 9M31 missiles mounted in boxes on either side of a turret on a BRDM-2 amphibious vehicle. The missiles used in this system were developed alongside the prolific Russian MANPADS 9K32M "Strela-2" (NATO designation SA-7 "Grail") in the 1960s and first became operational in 1968. For more information on the related development see the SA-7 article.

Missiles and Guidance

Each missile weighs 30 kg (66 lb), is 1.8 m (6 ft) long, flies at an average of around Mach 1.5 with a top speed of Mach 1.8 and carries a 2.6 kg (5.7 lb) warhead with proximity and contact fuzes. Propulsion is by a single-stage solid fuel rocket motor. Effective range for the initial version with the 9M31 missile (US DoD designation SA-9A "Gaskin-Mod0") is 800-6500 m (0.5-4 miles) at altitudes between 15-5200 m (50-17,000 ft). The 9M31M "Strela-1M" (US DoD designation SA-9B "Gaskin-Mod0") improves the range to 560-8000 m (0.33-5 miles) and range to 10-6100 m (35-20000 ft). Targets can be travelling at up to Mach 1.

Due to the low frequency, first generation lead sulfide uncooled (PbS) infra-red seeker on the missiles, engagement range is actually greater when the missile is used in a tail-chase engagement, i.e. fired at an aircraft flying away from the launcher. In this case effective range might be as long as 11 km (6.8 miles). Similarly, when engaging an aircraft head-on, effective range is below the maximum specified above. The 9M31M/SA-9B missile's seeker is improved, including a cooling system, which partially accounts for the better range figures. The new seeker is able to detect radiation in the 1-5 μm range, an improvement over the old seeker with its 1-3 μm range. Steering is performed by canards and tail-fins with proportional guidance based on the information from the seeker. The rocket motor is a solid fuel, dual-thrust type which only fires after the missile has been ejected from the launcher.

Each TEL does not typically carry missiles for reloading. Reloading is performed manually and usually takes around 5 minutes. The missile boxes are lowered for transport to lower the total height of the vehicle. The driver and commander have periscopes for viewing outside the vehicle when the hatches are closed.

Vehicle

Apart from the new turret, the other major change to the BRDM-2 chassis is the removal of the belly wheels (which are presumably to improve off-road performance). The driver and commander both have infra-red vision systems. The vehicle has standard NBC (Nuclear, Biological and Chemical) protection including overpressure. The missiles fold down to the sides of the turret which greatly reduces the height of the vehicle whilst travelling. Each vehicle weighs around 7 tonnes (7.7 tons) and has a 104 kW (140 HP) engine and a central tire pressure control system.

History and Deployment

The 9K31 system was introduced in 1968 and the 9K31M system in 1970. Each battery contains, in addition to a command vehicle, one TEL fitted with a passive radar detection system and several more (usually three) without any radar system. The radar detection system is the 9S16 "Flat Box" and consists of four sensors mounted around the BRDM vehicle giving it 360 degree coverage. This system emits no radar energy but can detect radio waves emitted from aircraft, giving the vehicle warning about incoming aircraft and aiding in the acquisition of the target aircraft with the optical system. Typical tactics call for the launch of two missiles against each target to improve the chance of destroying it.

The 9K31 system was superseded by the 9K35 Strela-10 (SA-13 "Gopher") and has replaced the SA-9 units in use in Russia.

Other operators include:

• Algeria, Angola, Benin, Bulgaria, Cuba, Croatia, Czech Republic, Egypt, Ethiopia, Hungary, India, Iraq, Libya, Mauritania, Mozambique, Nicaragua, Poland, Romania, Slovakia, Syria, Uganda, Ukraine, Uzbekistan, Vietnam, Yemen and former Yugoslavia

The 9K31 first saw combat in May 1981 over Lebanon when Syrian batteries fired at Israeli aircraft during one of the Arab-Israeli Wars. 9K31s were also blooded during the Iran-Iraq war, the Gulf War, fighting in Angola and Operation Allied Force over the former Yugoslavia.

In December 1983 a Syrian SA-9 battery shot down a US Navy A-6 Intruder bomber.

Some SA-9s were used by Iraq during Operation Iraqi Freedom.

References

• Federation of American Scientists page
• Astronautix.com