9A4172 Vikhr (Russian: Вихрь, English: Whirlwind) (NATO reporting name: AT-16 Scallion) is a Russian laser guided anti-tank missile. "9K121" is the GRAU designation for the missile system. The missile is launched from ships, Ka-50, Ka-52 helicopters and Su-25T aircraft. It was first shown publicly at the 1992 Farnborough Airshow.
The missile is designed to engage vital ground targets, including armoured targets fitted out with built-in and add-on explosive reactive armor, at a range of up to 8 km when fired from a helicopter and 10 km when fired from a fixed-wing aircraft in daytime and up to 5 km at night, as well as air targets in conditions of air defense assets activity.
The automatic sight is provided with TV and IR channels for target sighting, a laser beam channel for missile control, a laser rangefinder, an automatic target tracking unit, a digital computer and a system for stabilization and aiming the sighting and beam channels. The automatic sight provides for target detection and identification both by day and night, automatic target tracking and missile guidance, and generates exact information for gun and rocket firing. The guided missile consists of a HEAT fragmentation warhead fitted with a contact and a proximity fuze, an air-dynamic control actuator, control electronics, a motor and laser detector. It is kept in a sealed launching transporting container.
The multi-purpose warhead (two-stage HEAT and an additional fragmentation sleeve) allows the missile to be used against armoured, airborne and area targets alike. This is an advantage compared to the three different missiles required in the 9M120 Ataka-V complex. The use of the proximity fuze allows a near miss of up to 5 m and makes it possible to engage an air target at speeds of 500 m/s.
The Vikhr missile laser beam control system provides for its precise guidance owing to data transmission to the missile in the course of its launch, which is excluded in homing systems. The Vikhr missile control system has high jamming immunity because its receiver faces the carrier, thereby protecting it from jamming signals.
The high pinpoint target hit probability (reported 0.95 against stationary targets) is provided by the automatic target tracking system and highly accurate missile control system that makes allowance for changes in the parameters of the carrier and the target in the course of firing.
The missiles can be fired singly or in pairs (at the same target to increase lethality). The high flight speed allows it to engage targets rapidly. The system is capable of launching Vikhr missiles against two to four targets during a 30-second period and starting at a range of 10 km, which increases its lethality to three to four times that of earlier systems.
Confusion with the 9M120 Ataka-V
There was much confusion toward the end of the 1980s regarding the latest Soviet anti-tank systems. The end of the Cold War cleared much of this up, but also led to a general failure to properly publicise new information. This has resulted in a large portion of Western literature including incorrect information.
The most common error is simply confusing the 9M120 Ataka-V complex with the 9A4172 Vikhr system. These are completely different systems that have been competing for the Russian market. Mil Moscow Helicopter Plant favours the former, while Sukhoi and Kamov favour the latter. As some foreign Mi-24 derivatives have actually been fitted with the 9A4172 the most reliable way to tell them apart is to look for the number of barrels: Eight per launcher for the helicopter borne 9M120 and the fixed wing version of the 9A4172 and six per launcher for the helicopter version of the 9A4172. A four barrel launcher is typical of the Igla short range anti-aircraft missile. Russia does not use currently four barrel launchers for airborne anti-tank systems although this will possibly change with the next generation of missile (which will probably weigh considerably more).
The next most common error is in understanding the guidance systems:
- The 9M120 is a radio command SACLOS (Semi-Automatic Command to Line-Of-Sight) missile and an improved version of the popular 9K114 Shturm system carried on the Mi-24V and by some ground units. This system gradually loses accuracy at longer ranges (as each as radii as viewed from the launch platform encompasses more space) but can be fired in any condition where a target can be spotted.
- On the other hand, the 9A4172 is a "laser beam riding missile". When this first became known, it caused much confusion in the West. Analysts simply assumed that the Soviet designers (KPB Instrument Design) had produced a weapon similar to the AGM-114 Hellfire, which uses semi-active laser homing (similar to laser-guided bombs). Early artist impressions even went so far as to show what appears to be a miniature copy of the Kh-29L (or "AS-14 Kedge", a large semi-active laser-guided missile that borrows its aerodynamic design from the R-73).
When the first good photographs appeared they led to still more confusion: There was no visible seeker (causing some analysts to believe it to be an unguided rocket system).
All of this was a long way from the mark: Russia had developed a very different approach. A series of non-imaging detectors face backwards from the missile toward the launch platform and guide the missile toward the centre of the laser beam (unlike semi-active laser seekers, which aim for a laser reflected off the target). This is much cheaper and also more resistant to countermeasures.
To capitalise on the advantage given by using a lower cost seeker the Soviet designers also produced a new flight control system: Fixed fins cause the missile to spin in flight and a single moving control surface adjusts its course during this rotation. The result is that for the cost of one equivalent Western model, the Soviets could build five. Any loss of effectiveness being partially counteracted by pilots being encouraged to fire their missiles in pairs.
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- Russia's Arms Catalog 2004
- Jane's Air Launched Weapons, Issue thirty six.