SA-2 Guideline / S-75 Dvina

The Lavochkin OKB S-75 Russian: С-75, NATO reporting name SA-2 Guideline is a Soviet designed high-altitude, command guided, surface-to-air missile (SAM) system. Since its first deployment in 1957, it has become the most widely deployed and used air defense missile in history.

This system first gained notoriety when an S-75 battery shot down a U.S. Air Force U-2 overflying the Soviet Union in 1960. Later, North Vietnamese forces used the S-75 extensively during the Vietnam War to defend Hanoi and Haiphong. It has also been locally-produced in the People's Republic of China using the names HQ-1 and HQ-2. Other nations have produced so many local variants combining portions of the S-75 system with both indigenously developed components or third party systems, that it has become virtually impossible to find a pure S-75 system today.

The SA-2/V-75 is a two-stage missile, consisting of a solid-fuel booster and a storable liquid-fuel upper stage burning red fuming nitric acid as the oxidizer, and kerosene as the fuel. The booster fires for about 4-5 seconds, and the main engine for about 22 seconds, by which time the missile is traveling at about Mach 3. The booster mounts four large cropped-delta wing fins with small control surfaces in their trailing edges, used to control roll. The upper stage has smaller cropped-deltas near the middle of the airframe, with a smaller set of control surfaces are at the extreme rear and (in most models) much smaller fins on the nose.The missiles are guided using radio control signals from the guidance computers at the site, sent on one of three channels. The earlier S-75 models received their commands via two sets of four small antennas in front of the forward fins, while the D models and on used four much larger strip antennas running between the forward and middle fins. The guidance system at an S-75 site can handle only one target at a time, but can direct three missiles against it. Additional missiles could be fired against the same target after one or more missiles of the first salvo had completed their run and the radio channel was freed.

The missile typically mounts a 195 kg (430 lb) fragmentation warhead, with proximity, contact and command fusing. The warhead has a lethal radius of about 65 m (215 ft) at lower altitudes, while at higher altitudes the thinner atmosphere allows for a wider radius of up to 250 m (820 ft). The missile itself is accurate to about 75 m (250 ft), which explains why two were typically fired in a salvo. One version, the SA-2E, mounted a 295 kg (650 lb) nuclear warhead of an estimated 15 kt yield, or a conventional warhead of similar weight.

Specification

Minimum Range 500-1,000 m (3,000 ft), making them fairly safe to attack at low level.
Maximum Range 45 km (30 miles)
Maximum altitude around 20,000 m (60,000 ft).

Radar

The S-75 typically uses the Spoon Rest early warning radar which has a range of about 275 km (170 miles). The Spoon Rest provides early detection of incoming aircraft which are then handed off to the acquisition Fan Song radar. These radars, having a range of about 65 km (40 miles), are used to refine the location, altitude, and speed of the hostile aircraft. The Fan Song system consists of two antennas operating on different frequencies, one providing elevation (altitude) information and the other azimuth (bearing) information. Regimental headquarters also include a Spoon Rest, as well as a Flat Face long-range C-band radar and Side Net height-finder. Information from these radars is sent from the regiment down to the battalion Spoon Rest operators to allow them to coordinate their searches. Earlier S-75 versions used a targeting radar known as Knife Rest, which was replaced in Soviet use, but can still be found in older installations.

Major variants

V-750 missile in transitUpgrades to anti-aircraft missile systems typically combine improved missiles, radars and operator consoles. Usually missile upgrades drive changes to other components to take advantage of the missile's improved performance. Therefore, when the Soviets introduced a new S-75, it was paired with an improved radar to match the missile's greater range and altitude.

SA-2A - S-75 Dvina (Двина - Dvina River) with Fan Song-A guidance radar and V-750 or V-750V missiles. Initial deployment began in 1957. The combined missile and booster was 10.6 m (34.8 ft) long, with a booster having a diameter of 0.65 m (25.5 in), and the missile a diameter of 0.5 m (19.7 in). Launch weight is 2287 kg (5,041 lb). The missile has a maximum effective range of 30 km (19 miles), a minimum range of 8 km (5 miles) and an intercept altitude envelope of between 450 and 25,000 m (1,500-82,000 ft).
SA-N-2A - S-75M-2 Volkhov-M (Russian Волхов - Volkhov River): Naval version of the A model fitted to the Sverdlov Class cruiser Dzerzhinski. Generally considered unsuccessful and not fitted to any other ships.
SA-2B - S-75 Desna (Russian Десна - Desna River). This version featured upgraded Fan Song-B radars with V-750VK and V-750VN missiles. The second deployment version, the B model entered service in 1959. The missiles were slightly longer than the A versions, at 10.8 m (35.4 ft), due to a more powerful booster. The SA-2B could engage targets at altitudes between 500 m and 30 km (1,640-98,450 ft) and ranges up to 34 km (21 miles).
SA-2C - S-75M Volkhov. Once again, the new model featured an upgraded radar, the Fan Song-C, mated to an improved V-750M missile. Improved -2B deployed in 1961. The V-750M was externally identical to the V-750VK/V-750VN, but with improved performance for range up to 43 km (27 miles) and reduced lower altitude limits of 400 m (1,312 ft).
SA-2D - Fan Song-E radar and V-750SM missiles. The V-750SM differed significantly from the A/B/C versions in having new antennas and a longer barometric nose probe. Several other differences were associated with the sustainer motor casing. The missile is 10.8 m (35.4 ft) long, has the same body diameters and warhead as the SA-2C, but the weight is increased to 2450 kg (5,400 lb). The effective maximum range is 43 km (27 miles), the minimum range is 6 km (4 miles) and the intercept altitude envelope is between 250 and 25000 m (820-82,000 ft). Improved aircraft counter measures led to the development of the Fan Song-E with its better antennas which could cut through heavy jamming.
SA-2E - Fan Song-E radar and V-750AK missiles. Similar rocket to the D model, but with a bulbous warhead section lacking the older missile's forward fins. The SA-2E is 11.2 m (36.7 ft) long, has a body diameter of 0.5 m (19.7 in) and weighs 2450 kg (5,400 lb) at launch. The missile can be fitted with either a command detonated 15 kt nuclear warhead or a 295 kg (650 lb) conventional HE warhead.
SA-2F - Fan Song-F radar and V-750SM missiles. After watching jamming in Vietnam and the Six-Day War render the SA-2 completely ineffective, the existing systems were quickly upgraded with a new radar system designed to help ignore wide-band scintillation jamming. The command system also included a home-on-jam mode to attack aircraft carrying strobe jammers, as well as a completely optical system (of limited use) when these failed. F's were developed starting in 1968 and deployed in the USSR later that year, while shipments to Vietnam started in late 1970.
S-75M Volga (Russian С-75М Волга - Volga River). Version from 1995. As previously mentioned, most nations with S-75s have matched parts from different versions, from third party missile systems or have added locally produced components. This has created a wide variety of S-75 systems which meet local needs.

As previously mentioned, most nations with S-75s have matched parts from different versions, from third party missile systems or have added locally produced components. This has created a wide variety of S-75 systems which meet local needs.

HQ-1 - (Hong Qi, Red Flag): Chinese version of SA-2 with additional ECCM electronics to counter the System-12 ECM aboard U-2s flown by the Republic of China Air Force Black Cat Squadron.
HQ-2 - Upgraded HQ-1 with additional ECCM capability to counter the System-13 ECM aboard U-2s flown by Republic of China Air Force Black Cat Squadron. Upgraded HQ-2s remain in service today, and the latest version utilizes passive phased array radar designated SJ-202, which is able to simultaneously track and engage multiple targets at 115 km and 80 km, respectively. The adoption of multifunction SJ-202 radar has eliminated the need to have multiple radars each with single function, and thus greatly improved the overall effectiveness of the HQ-2 air defense system. A target drone version is designated BA-6.