S-75 Dvina

The first widely deployed Soviet surface-to-air missile was the S-75 Dvina, designated the SA-2 by NATO with the reporting name GUIDELINE.

Originally deployed to protect Soviet areas other than Moscow, which had a special system (NATO designation SA-1), the S-75 is a transportable rather than mobile system: it could not operate on the move, but could be delivered to an area and set up in a reasonable period of time (days).

The V-75 (SA-2) surface-to-air missile system was designed for the defense of both fixed targets and field forces. The V-75 was designed to cope with the threat posed by small groups of aircraft rather than massed raids. Flexibility and mobility are its chief advantages over the SA-1.

In contrast to the massive SA-1 sites, each of which is capable of defending only a limited sector around the target area, each SA-2 site is capable of 360° coverage. This flexibility is obtained at the expense of target handling capacity and rate of fire relative to the SA-1. It is intended for defeat of manned and pilotless air attack weapons at the heights from 100 m to 30 km, which fly with speeds of up to 3000 km/h, at the distances to 58 km.

Unit organization

Air defense units armed with the Dvina were formed as regiments, usually of three battalions each, with several batteries of six launchers and the associated radars.

Although there are a variety of arrangement patterns, all sites consist of six launching positions -- usually revetted - deployed around a guidance radar and linked by service roads to facilitate loading. While the sites were permanent installations, all operating components of the system are mounted on wheeled vehicles and are capable of movement by road or raiL

The 295 kg nuclear warhead used only on the SA-2E variant is believed to have a yield of 15 kT. The other V-75 variants have an internally grooved fragmentation warhead weighs 195 kg (130 kg of which is high explosive) with proximity, contact and command fusing available. This conventional warhead is fitted forward of the main fins and behind the nose-mounted guidance assembly. At medium and low altitudes the kill radius is about 65 meters and the blast radius for severe damage is 100-120 meters. The maximum blast radius against a high altitude target is approximately 250 meters, due to the rarefied atmosphere. The weapon has a accuracy of 75 meters with the large blast radius compensating for system inaccuracies.

The V-75 system is designed to be simple and easy to operate with the minimum of specialized training. The standard deployment pattern of a battalion site consists of six semi-fixed trainable single rail launchers are deployed in the familiar hexagon arrangement about 60-100 meters apart. The launchers may be dug into pits, left at ground level or hardened in concrete revetments. The battery command post fire control team and its computer, the Fan Song missile control radar, the P-12 Spoon Rest early warning radar, and typically six reload rounds on their articulated trailers are all located in the center of the launchers array.

Missiles

The V-75 SA-2 GUIDELINE is a medium to high altitude surface-to-air missile system. This two-stage missile has a large solid propellant booster stage fitted with four very large delta fins. The core stage consists of a storable liquid propellant sustainer rocket motor using inhibited red fuming nitric acid oxidizer and kerosene fuel. A set of four cropped delta-shaped wings are located near the mid-section, with a second in-line set of smaller fixed fins at the nose, and a third in-line set of slightly larger powered control fins at the tail.

The S-75 surface-to-air missile would consist of a 1D (V-750) cruise stage, with an Isayev S2.711 engine, and a solid propellant booster by Kartukov's KB-2 Factory 81 GKAT. Isayev had begun development of the engine in accordance with the decree of 1 October 1954. It was the first Isayev engine using a gas generator-powered turbopump for propellant feed. The gas generator was powered by OT-155 monopropellant to ensure a quick start and build-up to full thrust. D D Sevruk at OKB-3 was tasked with building a competing motor design, and both motors reached the stage of flight trials. Isayev's was judged the more successful, and in 1955 Factory 82 began series production of the S2.711 engine.

In November 1957 the V-750 missile and S-75 Dvina surface-to-air missile system were accepted into service. During production a modernised S2-711V1 engine with 3100 to 3452 kgf was introduced to power the improved V-750V rocket.

Warhead

The 295 kg nuclear warhead used only on the SA-2E variant is believed to have a yield of 15 kT. The other V-75 variants have an internally grooved fragmentation warhead weighs 195 kg (130 kg of which is high explosive) with proximity, contact and command fusing available. This conventional warhead is fitted forward of the main fins and behind the nose-mounted guidance assembly. At medium and low altitudes the kill radius is about 65 meters and the blast radius for severe damage is 100-120 meters. The maximum blast radius against a high altitude target is approximately 250 meters, due to the rarefied atmosphere. The weapon has a accuracy of 75 meters with the large blast radius compensating for system inaccuracies.

Electronics

The guidance system at an SA-2 site can handle only one target at a time, but can direct three missiles against a target simultaneously. Additional missiles could be fired against the same target after one or more missiles of the first salvo had completed their run. The Soviets apparently believed they must program three or four missiles against each target in order to achieve acceptable kill probabilities.

Firing battery level

The first surface-to-air missile (SAM) system deployed by the Soviet Union, the S-75 Dvina (NATO identifier SA-2, designation name GUIDELINE) had, in its original versions, two primary radars at the firing battery level, SPOON REST long-range search (range 170mi/275km) and FAN SONG (range 40 mi/65 KM) acquisition/fire control. Later versions increased both the radar's range and resistance to jamming.

FAN SONG has two antennas operating on different frequencies, one to track the target's compass bearing and the other to track its altitude.

Regimental command and control level radars

SA-2 regimental headquarters have an additional FLAT FACE long-range radar as well a SIDE NET height-finder; the regimental headquarters coordinates the multiple batteries. At regimental HQ there is a fourth Spoon Rest, a van-mounted P-15 Flat Face 250 km range C-band search and tracking radar with two elliptical parabolic reflectors and a PRV-11 Side Net 180 km range E-band nodding height-finder radar mounted on a box-bodied trailer. There is also a radar control truck and a Mercury Grass truck-mounted command communications system for linking the HQ to the three battalions

Combat record

The S-75 first came to the world's attention when it downed an American U-2 spy aircraft at 20.4 km over the Soviet Union on May Day 1960. The Americans had thought the aircraft out of the reach of any Soviet missiles until then. It again downed a U-2 during the Cuban Missile Crisis on October 27, 1962.

In American bombing of North Vietnam in 1965-1966 and 1972-1973, it downed from 68 to 105 American fighters and 15 B-52 bombers. Intense American countermeasures, including avoiding protected areas, jamming aircraft, chaff, and anti-radar missiles kept the loss rate low for the American fighters (less than 0.03% per fighter sortie over North Vietnam), but this statistic disguises the manner in which the S-75 dictated the air battle. The American fighters could fly under the S-75's envelope, but there they could be picked off by anti-aircraft guns, ground fire, and shoulder-launched missiles. Over 1000 American aircraft met this fate. When the B-52's flew directly over areas defended by S-75's during the Linebacker campaign of 1972-1973, they suffered losses of 3% per sortie. It was said that this was only achieved due to the Strategic Air Command's insistence on flying the same course night after night. Even in the face of jamming, the North Vietnamese could fire the S-75's, fused for altitude, into B-52 bomber formations with some success. It was also claimed that 2,000 S-75's were expended to achieve these 15 kills. But from the Soviet point of view, the S-75 was a success. From the point of view of US pilots, the 'flying telephone pole' was greatly feared.

The S-75 continued to play a role in the Arab-Israeli wars of 1967 and 1973, the various wars in the Persian Gulf, and the Balkan conflicts. It was no longer the primary threat, but it could not be ignored and continued to set the context for the air battle into the 1990's

Derivatives

China

The People's Republic of China developed its own modified version of the V-750 under the designation HQ-2 (Hong Qian = Red Leader), with the Western designation CSA-1.

According to a China sales brochure, the FT-2000A SAM will use a highly-modified HQ-2/ CSA-1 missile that has been equipped with a passive radio frequency homing seeker operating in the 2- to 6-GHz band. The FT-2000A also will contain a new millimeter-wave band fuze, a new guidance-and-control section, and a new 60 kg fragmentation warhead. The missile has a cutoff valve for thrust adjustment while in flight, probably to extend its range. The missile seeker is loaded with the target aircraft’s radio frequency (RF) signature before launch and relies on this information for tracking and intercept. The missile has an estimated maximum range of 60 km, with a maximum altitude of 18,000 meters.

A stand-alone FT-2000A battery consists of a central control station and twelve launchers, each holding one missile. The central control station has one master passive sensor and three auxiliary passive sensors. The auxiliary passive sensors coordinate with the master passive sensor through triangulation to determine angle and range of targets emitting in the 2- to 6-GHz band. This configuration is totally passive, relying on the RF emissions of the target.

A composite fire unit consists of FT-2000A launchers and missiles, integrated with standard SAM components like those of the HQ-2, SA-2, or SA-3. Although a special fire control unit and launcher are required, this configuration allows anti-jamming missiles to replace several of the command guided missiles normally associated with these SAMs.