S-75 Dvina

The S-75 Dvina (Russian: С-75; NATO reporting name SA-2 Guideline) is a Soviet-designed, high-altitude air defense system, built around a command guided surface-to-air missile. Since its first deployment in 1957 it has become the most widely deployed air defense system in history. It scored the first destruction of an enemy aircraft by a surface-to-air missile, shooting down a Taiwanese Martin RB-57D Canberra over China, on October 7, 1959, hitting it with three V-750 (1D) missiles at an altitude of 20 km (65,600 ft). The success was attributed to Chinese fighters at the time in order to keep the S-75 program secret.

This system first gained international fame when an S-75 battery, using the newer, longer-range and higher-altitude V-750VN (13D) missile shot down the U-2 of Francis Gary Powers overflying the Soviet Union on May 1, 1960. The system was also deployed in Cuba during the Cuban Missile Crisis, where on October 27, 1962, it shot down a U-2 overflying Cuba flown by Rudolf Anderson, almost precipitating nuclear war. 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.

Development


In the early 1950s, the United States Air Force rapidly accelerated its development of long-range jet bombers carrying nuclear weapons. The USAF program led to the deployment of Boeing B-47 Stratojet supported by aerial refueling aircraft to extend its range deep into the Soviet Union. The USAF quickly followed the B-47 with the development of the Boeing B-52 Stratofortress, which had greater range and payload than the B-47. The range, speed, and payload of these U.S. bombers posed a significant threat to the Soviet Union in the event of a war between the two countries.



Consequently, the Soviets initiated the development of improved air defense systems. Although the Soviet Air Defence Forces had large numbers of anti-aircraft artillery (AAA), including radar-directed batteries, the limitations of guns versus high-altitude jet bombers were obvious. Therefore, the Soviet Air Defense Forces began the development of missile systems to replace the World War II-vintage gun defenses.

In 1953, KB-2 began the development of what became the S-75 under the direction of Pyotr Grushin. This program focused on producing a missile which could bring down a large, non-maneuvering, high-altitude aircraft. As such it did not need to be highly maneuverable, merely fast and able to resist aircraft counter-measures. For such a pioneering system, development proceeded rapidly, and testing began a few years later. In 1957, the wider public first became aware of the S-75 when the missile was shown at that year's May Day parade in Moscow.

Initial deployment
Wide-scale deployment started in 1957, with various upgrades following over the next few years. The S-75 was never meant to replace the S-25 Berkut surface-to-air missile sites around Moscow, but it did replace high-altitude anti-aircraft guns, such as the 130 mm KS-30 and 100 mm KS-19. Between mid-1958 and 1964, U.S. intelligence assets located more than 600 S-75 sites in the USSR. These sites tended to cluster around population centers, industrial complexes, and government control centers. A ring of sites was also located around likely bomber routes into the Soviet heartland. By the mid-1960s, the Soviet Union had ended the deployment of the S-75 with perhaps 1,000 operational sites.

In addition to the Soviet Union, several S-75 batteries were deployed during the 1960s in East Germany to protect Soviet forces stationed in that country. Later the system was sold to most Warsaw Pact countries and was provided to China, North Korea, and eventually, North Vietnam.

Employment


While the shooting down of Francis Gary Powers' U-2 in 1960 is the first publicized success for the S-75, the first aircraft actually shot down by the S-75 was a Taiwanese Martin RB-57D Canberra high-altitude reconnaissance aircraft. In this case, the aircraft was hit by a Chinese-operated S-75 site near Beijing on October 7, 1959. Over the next few years, the Taiwanese ROCAF would lose a number of aircraft to the S-75: both RB-57s and various drones. On May 1, 1960, Gary Powers's U-2 was shot down while flying over the testing site near Sverdlovsk, although it is thought to have taken 14 missiles to hit his high-flying plane. That action led to the U-2 Crisis of 1960. Additionally, Chinese S-75s downed five ROCAF-piloted U-2s based in Taiwan.

During the Cuban Missile Crisis, a U-2 piloted by USAF Major Rudolf Anderson was shot down over Cuba by an S-75 in October 1962.

In 1965, North Vietnam asked for some assistance against American airpower, for their own air-defense system lacked the ability to shoot down aircraft flying at high altitude. After some discussion it was agreed to supply the PAVN with the S-75. The decision was not made lightly, because it greatly increased the chances that one would fall into US hands for study. Site preparation started early in the year, and the US detected the program almost immediately on April 5, 1965.



On July 24, 1965, a USAF F-4C aircraft was shot down by an SA-2. Three days later, the US responded with Operation Iron Hand to attack the other sites before they could become operational. Most of the S-75 were deployed around the Hanoi-Haiphong area and were off-limits to attack (as were local airfields) for political reasons.

The missile system was used widely throughout the world, especially in the Middle East, where Egypt and Syria used them to defend against the Israeli Air Force, with the air defense net accounting for the majority of the downed Israeli aircraft. The last apparent success seems to have occurred during the War in Abkhazia (1992–1993), when Georgian missiles shot down a Russian Sukhoi Su-27 fighter near Gudauta on March 19, 1993.

Countermeasures and counter-countermeasures
Between 1965 and 1966, the US delivered a number of solutions to the S-75 problem. The Navy soon had the Shrike missile in service and mounted their first offensive strike on a site in October 1965. The Air Force responded by fitting B-66 bombers with powerful jammers (that blinded the early warning radars) and by developing smaller jamming pods for fighters (that denied range information to the radars). Later developments included the Wild Weasel aircraft, which were fitted with anti-radiation air-to-surface missile systems made to home in on the radar from the threat. This freed them to shoot the sites with Shrikes of their own.

The Soviets and Vietnamese, however, were able to adapt to some of these tactics. The USSR upgraded the radar several times to improve ECM (electronic counter measure) resistance. They also introduced a passive guidance mode, whereby the tracking radar could lock on the jamming signal itself and guide missiles directly towards the jamming source. This also meant the SAM site's tracking radar could be turned off, which prevented Shrikes from homing in on it. Moreover, some new tactics were developed to combat the Shrike. One of them was to point the radar to the side and then turn it off briefly. Since the Shrike was a relatively primitive anti-radiation missile, it would follow the beam away from the radar and then simply crash when it lost the signal (after the radar was turned off). SAM crews could briefly illuminate a hostile aircraft to see if the target was equipped with a Shrike. If the aircraft fired one, the Shrike could be neutralized with the side-pointing technique without sacrificing any S-75s. Another tactic was a "false launch" in which missile guidance signals were transmitted without a missile actually being launched. This could distract enemy pilots, or even occasionally cause them to drop ordnance prematurely to lighten their aircraft enough to dodge the nonexistent missile.

Despite these advances, the US was able to come up with effective ECM packages for the B-52E models. These planes were able to fly raids against Hanoi with relatively few losses (though still significant enough to cause some concern; see Operation Linebacker II).

Replacement systems
Soviet Air Defence Forces started to replace the S-75 with the vastly superior S-300 system in the 1980s. The S-75 remains in widespread service throughout the world, with some level of operational ability in 35 countries. Vietnam and Egypt are tied for the largest deployments at 280 missiles each, while North Korea has 270, and Poland has 240. The Chinese also deploy the HQ-2, an upgrade of the S-75, in relatively large numbers.

Soviet doctrinal organization
The Soviet Union used a fairly standard organizational structure for S-75 units. Other countries that have employed the S-75 may have modified this structure. Typically, the S-75 is organized into a regimental structure with three subordinate battalions. The regimental headquarters will control the early-warning radars and coordinate battalion actions. The battalions will contain several batteries with their associated acquisition and targeting radars.



Site layout
Each battalion will typically have six, semi-fixed, single-rail launchers for their V-750 missiles positioned approximately 60 to 100 m apart from each other in a hexagonal "flower" pattern, with radars and guidance systems placed in the center. It was this unique "flower" shape that led to the sites being easily recognizable in reconnaissance photos. Typically another six missiles are stored on tractor-trailers near the center of the site.

Missile
The V-750 is a two-stage missile consisting of a solid-fuel booster and a storable liquid-fuel upper stage, which burns 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 that have small control surfaces in their trailing edges to control roll. The upper stage has smaller cropped-deltas near the middle of the airframe, with a smaller set of control surfaces at the extreme rear and (in most models) much smaller fins on the nose.

The missiles are guided using radio control signals (sent on one of three channels) from the guidance computers at the site. The earlier S-75 models received their commands via two sets of four small antennas in front of the forward fins, while the D model and later models 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 it 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, freeing the radio channel.

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

Typical range for the missile is about 45 km, with a maximum altitude around 20000 m. The radar and guidance system imposed a fairly long short-range cutoff of about 500 to 1000 m, making them fairly safe for engagements at low level.

Radar


The S-75 typically uses the Spoon Rest early warning radar which has a range of about 275 km. 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, 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
Upgrades 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; SA-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 long, with a booster having a diameter of 0.65 m, and the missile a diameter of 0.5 m. Launch weight is 2,287 kg. The missile has a maximum effective range of 30 km, a minimum range of 8 km, and an intercept altitude envelope of between 450 and 25000 m.
 * 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. This second deployment version entered service in 1959. The missiles were slightly longer than the A versions, at 10.8 m, due to a more powerful booster. The SA-2B could engage targets at altitudes between 500 and 30000 m and ranges up to 34 km.




 * 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. The improved -2B was deployed in 1961. The V-750M was externally identical to the V-750VK/V-750VN, but it had improved performance for range up to 43 km and reduced lower altitude limits of 400 m.
 * 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 long and has the same body diameters and warhead as the SA-2C, but the weight is increased to 2,450 kg. The effective maximum range is 43 km, the minimum range is 6 km, and the intercept altitude envelope is between 250 and 25000 m. 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 long, has a body diameter of 0.5 m, and weighs 2450 kg at launch. The missile can be fitted with either a command-detonated 15 kt nuclear warhead or a 295 kg 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. Fs were developed starting in 1968 and deployed in the USSR later that year, while shipments to Vietnam started in late 1970.
 * SA-2 FC: Latest Chinese version. It can track six targets simultaneously and is able to control 3 missiles simultaneously.
 * 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 or third-party missile systems, or they 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, single-function radars, and thus greatly improved the overall effectiveness of the HQ-2 air defense system. A target drone version is designated BA-6.
 * HQ-3: Development of HQ-2 with maximum ceiling increased to 30 km, specifically targeted for high altitude and high speed spy planes like SR-71. Maximum range is 42 km and launching weight is around 1 ton, and maximum speed in 3.5 Mach. A total of 150 built before the program ended and the subsequent withdraw of HQ-3 from active service, and the knowledge gained from HQ-3 was used to develop later version of HQ-2.
 * HQ-4: Further development of HQ-2 from HQ-3, with solid rocket engines, resulting in two third reduction of logistic vehicles needed for a typical SAM battalion with six launchers: from the original more than 60 vehicles for HQ-1/2/3 to just slightly over 20 vehicles for HQ-4. After 33 missiles were built (5 from batch 01, 16 from batch 02, and 12 from batch 03), the program was cancelled, but most of the technologies were continued as separate independent research programs, and these technologies were later used on later Chinese SAMs upgrades and developments such as HQ-2 and HQ-9.
 * M-7: Chinese surface-to-surface ballistic missile converted from HQ-1/2/3/4. M-7 missile is the only Chinese ballistic missile that can be launched at a slant angle. The rear section of the HQ SAMs are retained, but the forward half is greatly enlarged into a shuttle shape to house bigger warhead and more fuel, while the control surfaces on the forward section are deleted. Armed with a 500 kg warhead (two and half a time of that of the original SAM version) the maximum range of M-7 is 200 km (more than four times of that of the original SAM version).

Operators

 * Current


 * 🇦🇿 - 250
 * 🇧🇬 - 18
 * 🇪🇬 - 240, Tayer el-Sabah variant
 * 🇮🇷 - 300+ Launchers, HQ-2J and indigenous Sayyad-1/1A & 2.
 * 🇰🇬 - few
 * 🇱🇾 Free Libyan Air Force
 * - 48 next 250 in 2008
 * 🇰🇵 - up to 270
 * 🇵🇰 - HQ-2B in service with the Pakistan Air Force.
 * - 700
 * 🇸🇾 - 275
 * 🇹🇯 - few
 * - 280
 * - 700
 * 🇸🇾 - 275
 * 🇹🇯 - few
 * - 280
 * - 280


 * Former operators
 * 🇦🇱 - 84 launchers
 * - 23
 * Most retired in 1991-1996. Missiles used as targets for training. RM-75V/MV Armavir, Sinitsa-1/6(SAM S-75M, missile 20DSU), Sinitsa-23/Korshun (Launcher S-75M3, missile 5YA23), (all in service as of 2011)
 * - passed on to successor states
 * - passed on to successor states, but retired shortly afterwards
 * 🇸🇴 - not operational
 * Most retired in 1991-1996. Missiles used as targets for training. RM-75V/MV Armavir, Sinitsa-1/6(SAM S-75M, missile 20DSU), Sinitsa-23/Korshun (Launcher S-75M3, missile 5YA23), (all in service as of 2011)
 * - passed on to successor states
 * - passed on to successor states, but retired shortly afterwards
 * 🇸🇴 - not operational
 * Most retired in 1991-1996. Missiles used as targets for training. RM-75V/MV Armavir, Sinitsa-1/6(SAM S-75M, missile 20DSU), Sinitsa-23/Korshun (Launcher S-75M3, missile 5YA23), (all in service as of 2011)
 * - passed on to successor states
 * - passed on to successor states, but retired shortly afterwards
 * 🇸🇴 - not operational
 * - passed on to successor states, but retired shortly afterwards
 * 🇸🇴 - not operational

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