Surface-to-air missile
A surface-to-air missile, also known as a ground-to-air missile or surface-to-air guided weapon, is a missile designed to be launched from the ground or the sea to destroy aircraft or other missiles. It is one type of anti-aircraft system; in modern armed forces, missiles have replaced most other forms of dedicated anti-aircraft weapons, with anti-aircraft guns pushed into specialized roles.
World War II saw the initial development of SAMs, yet no system became operational. Further development in the 1940s and 1950s led to operational systems being introduced by most major forces during the second half of the 1950s. Smaller systems, suitable for close-range work, evolved through the 1960s and 1970s, to modern systems that are man-portable. Shipborne systems followed the evolution of land-based models, starting with long-range weapons and steadily evolving toward smaller designs to provide a layered defence. This evolution of design increasingly pushed gun-based systems into the shortest-range roles.
The American Nike Ajax was the first operational SAM system, and the Soviet Union's S-75 Dvina was the most-produced SAM system. Widely used modern examples include the Patriot and S-300 wide-area systems, SM-6 and
MBDA Aster Missile naval missiles, and short-range man-portable systems like the Stinger and 9K38 Igla.
History
The first known idea for a guided surface-to-air missile was in 1925, when a beam riding system was proposed whereby a rocket would follow a searchlight beam onto a target. A selenium cell was mounted on the tip of each of the rocket's four tail fins, with the cells facing backwards. When one selenium cell was no longer in the light beam, it would be steered in the opposite direction back into the beam. The first historical mention of a concept and design of a surface-to-air missile in which a drawing was presented, was by inventor Gustav Rasmus in 1931, who proposed a design that would home in on the sound of an aircraft's engines.World War II
During World War II, efforts were started to develop surface-to-air missiles as it was generally considered that flak was of little use against bombers of ever-increasing performance. The lethal radius of a flak shell is fairly small, and the chance of delivering a "hit" is essentially a fixed percentage per round. In order to attack a target, guns fire continually while the aircraft are in range in order to launch as many shells as possible, increasing the chance that one of these will end up within the lethal range. Against the Boeing B-17, which operated just within the range of the numerous German eighty-eights, an average of 2,805 rounds had to be fired per bomber destroyed.Bombers flying at higher altitudes require larger guns and shells to reach them. This greatly increases the cost of the system, and slows the rate of fire. Faster aircraft fly out of range more quickly, reducing the number of rounds fired against them. Against late-war designs like the Boeing B-29 Superfortress or jet-powered designs like the Arado Ar 234, flak would be essentially useless. This potential was already obvious by 1942, when Walther von Axthelm outlined the growing problems with flak defences that he predicted would soon be dealing with "aircraft speeds and flight altitudes will gradually reach and between." This was seen generally; in November 1943 the Director of Gunnery Division of the Royal Navy concluded that guns would be useless against jets, stating "No projectile of which control is lost when it leaves the ship can be of any use to us in this matter."
Axis efforts
The first serious consideration of a SAM development project was a series of conversations that took place in Germany during 1941. In February, Friederich Halder proposed a "flak rocket" concept, which led Walter Dornberger to ask Wernher von Braun to prepare a study on a guided missile able to reach between altitude. Von Braun became convinced a better solution was a crewed rocket interceptor, and said as much to the director of the T-Amt, Roluf Lucht, in July. The directors of the Luftwaffe flak arm were not interested in crewed aircraft, and the resulting disagreements between the teams delayed serious consideration of a SAM for two years.Von Axthelm published his concerns in 1942, and the subject saw serious consideration for the first time; initial development programs for liquid- and solid-fuel rockets became part of the Flak Development Program of 1942. By this point serious studies by the Peenemünde team had been prepared, and several rocket designs had been proposed, including 1940's Feuerlilie, and 1941's Wasserfall and Henschel Hs 117 Schmetterling. None of these projects saw any real development until 1943, when the first large-scale raids by the Allied air forces started. As the urgency of the problem grew, new designs were added, including Enzian and Rheintochter, as well as the unguided Taifun which was designed to be launched in waves.
In general, these designs could be split into two groups. One set of designs would be boosted to altitude in front of the bombers and then flown towards them on a head-on approach at low speeds comparable to crewed aircraft. These designs included the Feuerlilie, Schmetterling and Enzian. The second group were high-speed missiles, typically supersonic, that flew directly towards their targets from below. These included Wasserfall and Rheintochter. Both types used radio control for guidance, either by eye, or by comparing the returns of the missile and target on a single radar screen. Development of all these systems was carried out at the same time, and the war ended before any of them was ready for combat use. The infighting between various groups in the military also delayed development. Some extreme fighter designs, like the Komet and Natter, also overlapped with SAMs in their intended uses.
Albert Speer was especially supportive of missile development. In his opinion, had they been consistently developed from the start, the large scale bomber raids of 1944 would have been impossible.
Allied efforts
The British developed unguided antiaircraft rockets close to the start of World War II, but the air superiority usually held by the Allies meant that the demand for similar weapons was not as acute.When several Allied ships were sunk in 1943 by Henschel Hs 293 and Fritz X glide bombs, Allied interest changed. These weapons were released from stand-off distances, with the bomber remaining outside the range of the ship's antiaircraft guns, and the missiles themselves were too small and fast to be attacked effectively.
To combat this threat, the U.S. Navy launched Operation Bumblebee to develop a ramjet-powered missile to destroy the launching aircraft at long range. The initial performance goal was to target an intercept at a horizontal range of and altitude, with a warhead for a 30 to 60 percent kill probability. This weapon did not emerge for 16 years, when it entered operation as the RIM-8 Talos.
Heavy shipping losses to kamikaze attacks during the Liberation of the Philippines and the Battle of Okinawa provided additional incentive for guided missile development. This led to the British Fairey Stooge and Brakemine efforts, and the U.S. Navy's SAM-N-2 Lark. The Lark ran into considerable difficulty and it never entered operational use. The end of the war led to the British efforts being used strictly for research and development throughout their lifetime.
Post-war deployments
In the immediate post-war era, SAM developments were under way around the world, with several of these entering service in the early- and mid-1950s.Coming to the same conclusions as the Germans regarding flak, the U.S. Army started its Project Nike developments in 1944. Led by Bell Labs, the Nike Ajax was tested in production form in 1952, becoming the first operational SAM system when it was activated in March 1954. Concerns about Ajax's ability to deal with formations of aircraft led to greatly updated version of the same basic design entering service in 1958 as the Nike Hercules, the first nuclear-armed SAM. The U.S. Army Air Forces had also considered collision-course weapons and launched Project Thumper in 1946. This was merged with another project, Wizard, and emerged as the CIM-10 Bomarc in 1959. The Bomarc had a range of over 500 km, but it was quite expensive and somewhat unreliable.
Development of Oerlikon's RSD 58 started in 1947, and was a closely held secret until 1955. Early versions of the missile were available for purchase as early as 1952, but never entered operational service. The RSD 58 used beam riding guidance, which has limited performance against high-speed aircraft, as the missile is unable to "lead" the target to a collision point. Examples were purchased by several nations for testing and training purposes, but no operational sales were made.
The Soviet Union began development of a SAM system in earnest with the opening of the Cold War. Joseph Stalin was worried that Moscow would be subjected to American and British air raids, like those against Berlin, and, in 1951, he demanded that a missile system to counter a 900 bomber raid be built as quickly as possible. This led to the S-25 Berkut system, which was designed, developed and deployed in a rush program. Early units entered operational service on 7 May 1955, and the entire system ringing Moscow was completely activated by June 1956. The system failed, however, to detect, track, and intercept the only overflight of the Soviet capital Moscow by a U-2 reconnaissance plane on July 5, 1956. The S-25 was a static system, but efforts were also put into a smaller design that would be much more mobile. This emerged in 1957 as the famous S-75 Dvina, a portable system, with very high performance, that remained in operation into the 2000s. The Soviet Union remained at the forefront of SAM development throughout its history; and Russia has followed suit.
The early British developments with Stooge and Brakemine were successful, but further development was curtailed in the post-war era. These efforts picked up again with the opening of the Cold War, following the "Stage Plan" of improving UK air defences with new radars, fighters and missiles. Two competing designs were proposed for "Stage 1", based on common radar and control units, and these emerged as the RAF's Bristol Bloodhound in 1958, and the Army's English Electric Thunderbird in 1959. A third design followed the American Bumblebee efforts in terms of role and timeline, and entered service in 1961 as the Sea Slug.