SA-2

The S-75 (Russian: С-75; NATO reporting name SA-2 Guideline) is a Soviet-designed, high-altitude air defence system. It is built around a surface-to-air missile with command guidance. Following its first deployment in 1957 it became one of the most widely deployed air defence systems in history. It scored the first destruction of an enemy aircraft by a surface-to-air missile, with the shooting down of a Taiwanese Martin RB-57D Canberra over China on 7 October 1959 that was hit by a salvo of three V-750 (1D) missiles at an altitude of . This success was credited to Chinese fighter aircraft at the time to keep the S-75 program secret.: "On October 7, 1959, one of the Taiwanese RB-57Ds was struck at an altitude of 65,600ft (20km) by a salvo of three V-750 missiles"

This system first gained international fame when an S-75 battery, using the newer, longer-range, higher-altitude V-750VN (13D) missile was deployed in the 1960 U-2 incident, when it 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, when it shot down another U-2 (piloted by Rudolf Anderson) overflying Cuba on October 27, 1962, almost precipitating a nuclear war. North Vietnamese forces used the S-75 extensively during the Vietnam War to successfully defend Hanoi and Haiphong against US bombing. It was produced in the People's Republic of China under the names HQ-1 (under licence) and HQ-2 (modified, named FT-2000A). Egyptian engineers produced a reverse-engineered S-75 with the name ''Tayir-as-Sabah''.

History

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 US 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 defence 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 Defence Forces began the development of missile systems to replace the World War II-vintage gun defences.

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 KS-30 and KS-19. Between mid-1958 and 1964, US 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 shot down by the S-75 was a Taiwanese Martin RB-57D Canberra high-altitude reconnaissance aircraft. 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 several aircraft to the S-75, both RB-57s and various drones. On May 1, 1960, Gary Powers' U-2 was shot down while flying over the testing site near Sverdlovsk. The first missile destroyed the U-2, and a further 13 were also fired, hitting a pursuing high-altitude MiG-19. The downing of the U-2 led to the U-2 Crisis of 1960. Additionally, Chinese S-75s downed five ROCAF-piloted U-2s.

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 assistance against American airpower, since their own air-defence 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 5 April 1965.

On 24 July 1965, a USAF F-4C aircraft was shot down by an S-75. 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.

On 8 September 1965, during the 1965 Indo-Pakistani war, an Indian S-75 Dvina was fired at an unidentified target believed to have been on a night mission above Ghaziabad near Delhi during the height of a paratrooper scare. Subsequent news reports would claim the destruction of a Pakistani C-130 west of Delhi, showing a photograph of the wreckage of the self-destructed missile as evidence of airplane wreckage. According to Indian sources, no Pakistani aircraft penetrated so deeply into Indian territory.

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 defence net accounting for the majority of the downed Israeli aircraft. The last 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.

During the siege of Bihac, in the Bosnian War (1992-1995), Serb forces from Krajina fired at least three S-75 in the ground-to-ground mode at the Bosnian city of Cazin. In the Yemeni Civil War (2015-present), Houthis modified some of their S-75 into surface-to-surface ballistic missiles to attack Saudi bases with them.

War in Vietnam: Countermeasures and counter-countermeasures

Between 1964 and early 1965 the Vietnamese had nothing to threaten American pilots in the air. U.S aircraft flew at an altitude of , and the Vietnamese anti-aircraft guns were unable to reach them. However, after an S-75 shot down a US F-4 Phantom aircraft, the US bombers began to descend below , below the minimum operational height of the Dvina. This brought them within the reach of Vietnamese anti-aircraft guns.

On July 24, 1965, four US Air Force McDonnell F-4C Phantoms took part in an airstrike against the Điện Biên Phủ munitions storage depot and the Lang Chi munitions factory west of Hanoi. One was shot down and three damaged by S-75s. This was the first time US aircraft were attacked by SAMs.

Two days later President Johnson gave the order to attack known S-75 positions outside the exclusion zone. On the morning of July 27, 48 F-105s participated in the strike, Operation Spring High. The Vietnamese knew US aircraft were coming, and set up many and anti-aircraft guns at the two SAM sites. These anti-aircraft guns were lethal at close range. The Vietnamese shot down six aircraft and more than half of the remaining US aircraft suffered damage from ground fire. However, the Vietnamese had replaced the SAMs with white-painted bundles of bamboo. Operation Spring High had destroyed two decoy targets for the loss of six aircraft and five pilots.

Between 1965 and 1966 the US developed countermeasures to the S-75 threat. The Navy soon had the AGM-45 Shrike anti-radiation air-to-surface missile in service and mounted their first offensive strike on a site in October 1965. The Air Force fitted B-66 bombers with powerful jammers (which blinded the early warning radars) and developed smaller jamming pods for fighters (which denied range information to enemy radars). Later developments included the Wild Weasel aircraft, which were fitted with AGM-45 Shrike missile systems made to home in on the radar from the threat.

The Soviets and Vietnamese were able to adapt to some of these tactics. The USSR upgraded the radar several times to improve electronic countermeasure (ECM) resistance. They also introduced a passive guidance mode, whereby the tracking radar could lock onto 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. 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 a missile, 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 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.

At the same time, evasive maneuvers were used, and intensive bombardments of identified SAM firing positions were organized. Under these conditions, camouflage and radio silence became especially important. After combat launches, an anti-aircraft missile division was to leave the area immediately, otherwise it would be destroyed by a bombing attack. Until December 1965, according to American data, eight S-75M systems were destroyed, although sometimes American aircraft bombed dummy positions equipped with decoy missiles made of bamboo. Soviet and Vietnamese calculations claimed the destruction of 31 aircraft; the Americans acknowledged the loss of 13 aircraft. According to the memoirs of Soviet advisers, on average an anti-aircraft missile unit destroyed 5-6 American aircraft before being put out of action.

Despite these advances, the US was able to come up with effective ECM packages for the B-52E and later models. When the B-52s flew large-scale raids against Hanoi and Haiphong over an eleven-day period in December 1972, 266 S-75 missiles were fired, resulting in the loss of 15 of the bombers and damage to numerous others. The ECM proved to be generally effective, but repetitive USAF flight tactics early in the bombing campaign increased the vulnerability of the bombers and the North Vietnamese missile crews adopted a practice of firing large S-75 salvos to overwhelm the planes' defensive countermeasures (see Operation Linebacker II). By the conclusion of the Linebacker II campaign, the shootdown rate of the S-75 against the B-52s was 7.52% (15 B-52s were shot down, 5 B-52s were heavily damaged for 266 missiles).

However, some of the U.S aircraft which "crashed in flight accidents" in fact were lost due to S-75 missiles. When landing at an airfield in Thailand, one B-52 that had been heavily damaged by a SAM rolled off the runway and exploded on mines installed around the airfield to protect from the guerrillas; only one crewman survived. Subsequently, this B-52 was counted as "crashed in flight accidents". According to Dana Drenkowski and Lester W. Grau, the number of US aircraft confirmed by themselves as lost is uncorroborated since the US figures are also suspect. If a plane was badly damaged but managed to land, the USAF did not count as a loss even if it was too damaged to fly again.

During the Vietnam war, the Soviet Union delivered 95 S-75 systems and 7,658 missiles to the Vietnamese. 6,806 missiles were launched or removed by outdating. According to the Vietnamese, the S-75 shot down 1,046 aircraft, or 31% of all downed US aircraft. By comparison, air-defense guns brought down 60% and 9% were shot down by MiG fighters. The higher rate of anti-aircraft artillery is partially caused by the fact that gun units received data from the S-75 radar stations that significantly improved their effectiveness.

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. In the 2000s, Vietnam and Egypt are tied for the largest deployments at 280 missiles each, while North Korea has 270. The Chinese also deploy the HQ-2, an upgrade of the S-75, in relatively large numbers.

Description

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 apart from each other in a hexagonal "flower" pattern, with radars and guidance systems placed in the center. This unique "flower" shape 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 AK-20 (based on red fuming nitric acid) as the oxidizer and TG-02 (toxic mixture of 50-52% triethylamine and 48-50% isomeric xylidine) 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 . 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 fragmentation warhead, with proximity, contact, and command fusing. The warhead has a lethal radius of about at lower altitudes, but at higher altitudes the thinner atmosphere allows for a wider radius of up to . The missile itself is accurate to about , which explains why two were typically fired in a salvo. One version, the S-75AK, mounted a nuclear warhead of an estimated 15 kiloton yield or a conventional warhead of similar weight.

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

Table of SA-2 / S-75 missiles

Radar

The S-75 typically uses the P-12 early warning radar (also known by its NATO codename, "Spoon Rest"), which has a range of about . The P-12 provides early detection of incoming aircraft, which are then handed off to the acquisition Fan Song radar. These radars, having a range of about , 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.
* S-75 Dvina () (NATO codename SA-2) with Fan Song-A guidance radar and V-750 or V-750V missiles. Initial deployment began in 1957. The combined missile and booster was long, with a booster having a diameter of , and the missile a diameter of . Launch weight is . The missile has a maximum effective range of , a minimum range of , and an intercept altitude envelope of between .
* S-75M-2 Volkhov-M (Russian - Volkhov River) (NATO codename SA-N-2A): Naval version of the A model fitted to the Sverdlov Class cruiser ''Dzerzhinski''. Generally considered unsuccessful and not fitted to any other ships.
* S-75 Desna (Russian - Desna River

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