S 75 Dvina

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 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 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 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. 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-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 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 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.

Countermeasures and counter-countermeasures

Between 1965 and 1966, the US delivered countermeasures to the S-75 problem. The Navy soon had the AGM-45 Shrike 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 by developing smaller jamming pods for fighters (which 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 were able to adapt to some of these tactics. The USSR upgraded the radar several times to improve ECM (electronic counter measures) 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. 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 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 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 had 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 2% (15 losses for 729 flown sorties).

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 (200 to 330 ft) 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 (430 lb) fragmentation warhead, with proximity, contact, and command fusing. The warhead has a lethal radius of about 65 m (213 ft) at lower altitudes, but 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 (246 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 kiloton yield or a conventional warhead of similar weight.

Typical range for the missile is about 45 km (28 mi), with a maximum altitude around 20,000 m (66,000 ft). The radar and guidance system imposed a fairly long short-range cutoff of about 500 to 1,000 m (1,600 to 3,300 ft), 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 (171 mi). 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 mi), 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.

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.

DF-7

Current operators

Former operators

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