Early on in the postwar period both the United States and the Soviet Union realized the potential deterrent value of basing nuclear missiles on submarines. Both nations looked at derivatives of the German V-2 missile but in the United States development first focused on the use of cruise missiles on submarines but as a deterrent, the system was slow. Cruise missiles of the day flew no faster than the jet bombers and were thus prone to interception and the need to launch from the surface made the sub platform vulnerable to detection and attack.

In the Soviet Union, however, the nuclear-tipped missile in its various forms was seen by Premier Nikita Khrushchev as a way of leveling the playing field against the US military without the great expenditure of cost needed by large fleets of ships, aircraft and tanks. While sub-launched cruise missiles were developed, they came afterwards and as an insurance on the missile development. Several days ago I talked about a secret precision-guided version of the Russian Scud missile. What's little known about the Scud is that it was also the Russian's first sub-launched ballistic missile (SLBM). In fact, the operational deployment of the SLBM version of the Scud, designated the R-11FM, was the first operational deployment in the world of an SLBM when it went to sea in 1956, five years before the American Polaris A-1 SLBM went to sea aboard the USS George Washington.

As the Russians were quite aware of the start of the development of the Polaris in the mid-1950s, time was of the essence in fielding an operational SLBM and the Scud was selected for adaptation rather than use an all-new design. As the American George Washington-class ballistic missile submarine was based on a stretching of the Skipjack attack submarine, the Russians similarly stretched the Project 611 attack submarine (NATO code name Zulu) into the 611AV. As the missile was too long to enclose in the hull, the sail of the submarine was stretched to hold two launch tubes that held the missiles which extended from the hull and into the sail.

Word began in 1954 and the first technical hurdle was how to launch the missile from underwater. As the R-11FM system was intended to be an interim option, this hurdle was deferred to the next series of missiles under development. So for the time being, the R-11FM would be launched from a surfaced submarine. The missile would be elevated out of its launch tube and then fired.

The second hurdle was how to launch the missile when the submarine was moving due to sea motion. As the land-based Scud had to be aligned a certain direction for launch, the sub-based version was mounted on a launch table that was gyroscopically stabilized in three axes similar to what was done for battleship turrets (in fact, the stabilization system was designed by a naval artillery design bureau in Leningrad). Once launch was commanded, the system would only fire the missile if the stabilized table was in the proper position.

In the fall of 1954 a series of test launches were made from ground-based test platforms and on 16 September 1955 the world's first submarine-launched ballistic missile launch took place in the White Sea. After further testing, the R-11FM and the Project 611AV submarines became operational with the Northern Fleet in 1956 and the Pacific Fleet in 1959.

The system was abysmal, to say the least. Poor quality control and the need to carry the hypergolic fuels for the R-11FM led to numerous accidents and launch failures. The CEP of the missile was an atrocious 7 kilometers (meaning that 50% of the time the missile would hit inside a 7km circle) compared to 1-2 kilometers for the land-based version. The 611AV submarine had to maintain a steady course, depth and speed for 2-4 hours before launch for the launch system to properly align and once surfaced, it took five minutes to launch the first missile and another five minutes for the second missile to be fired.

The Soviet Navy was very reluctant to take the missile into service, but pressure from Premier Khrushchev and the defense minister, Dmitri Ustinov, resulted in six 611AV submarines going into service with the R-11FM. The rationale was that while impractical and cumbersome, it was the first step in getting practical experience of launching missiles at sea.

Source: Scud Ballistic Missile and Launch Systems 1955-2005, New Vanguard #120 by Steven J. Zaloga. Osprey Publishing, 2006, p8-11.

The legendary Russian rocket designer Sergei Korolev and his special design bureau (designated OKB-1) were given responsibility in the early 1950s to develop a practical tactical ballistic missile designated the R-11 that would better be known by its NATO code name, SS-1 "Scud". The first Scud-A/R-11 missiles were accepted for operational use by the Soviet Army in July 1955 but the early versions were cumbersome to set up and fire, requiring multiple vehicles for support and despite advances in technology was little more practical than the German V-2 rocket. As a result, few operational batteries of the early versions of the Scud-A/R-11 missiles were fielded in the 1950s.

Subsequent developments of the early Scud-A/R-11 missile led to the development of the Scud-B/R-17 which featured a whole host of improvements in design and use. A new tracked TEL (transporter-erector-launcher) vehicle simplified operational deployment and advances in construction and propulsion extended the Scud-B/R-17's range over the Scud-A/R-11 missile. In addition, the Scud-B/R-17 was nuclear-tipped along with the options for conventional or chemical warheads. Soviet Army formations that fielded the nuclear-tipped versions of the Scud-B/R-17 usually had one chemical warhead for every 25 nuclear warheads. To simplify the ballistics and guidance, each of the possible warhead options for the missile was standardized at 1 metric ton. The first Scud-B/R-17 missiles become operational in 1962.

Despite the improvements from the Scud-A/R-11 to the Scud-B/R-17, the missile remained relatively inaccurate which was more problematic when using a conventional or chemical warhead which required more precise targeting than a nuclear warhead. The Scud-A/R-11 had a CEP (circular error probable- a circle in which the warhead was expected to land 50% of the time) of 4 kilometers. The first Scud-B/R-17s cut the CEP down to 2 kilometers, eventually attaining a 1 kilometer CEP. But with a conventional warhead, a 1-km CEP was nearly unacceptable. With a move in the 1960s by both the United States and the Soviet Union towards a more "flexible" response in a nuclear crisis, the Soviet military leadership saw that there would be times that a non-nuclear/non-chemical Scud missile warhead would be more desirable to use.

In 1967 the Central Scientific Research Institute for Automation and Hydraulics in Moscow was tasked to develop a top-secret precision-guided version of the Scud-B/R-17. It was originally designated R-17VTO Aerofon and the Institute decided upon a very prescient form of guidance, optical comparison in which the missile would hit its target by comparing an image of the target with an image stored in its memory. In the late-1960s the development of the guidance proved impractical and the Aerofon project was reorganized in 1974 to take advantage of advances in digital computing. The new system relied on digital images and a computer library could be kept of possible targets. The first Aerofon optical guidance prototype was completed in 1975 and successfully tested pod-mounted under a Sukhoi Su-17 strike fighter.

In the United States we had a similar guidance system under development called "digital scene matching area correlation" (DSMAC). The idea in the US system was that DSMAC would be used on cruise missiles on the final run-in on the target after using TERCOM (terrain contour-matching) on the flight into the target vicinity. It's likely that the first Aerofon guidance package was similar to the first analog version of DSMAC tested here in the United States- a stored photographic negative of the target was compared with a photograph taken of the target area. It was a cumbersome system as tested with DSMAC and the first tests were performed with a Tomahawk cruise missile in 1978.

The Aerofon optical guidance system was air-tested in 1975 and flight tested on an actual Scud-B/R-17 missile in late 1979, the Aerofon hitting only a few meters from the designated target. This represented a massive leap in improvement over the 1-km CEP of the Scud-B/R-17 standard missile. The planned operational Aerofon would have had a CEP on the order of 20 meters.

Unlike the other variants of the Scud missile family where the whole missile impacted the target, the Aerofon variant had a warhead section that separated from the main body of the missile (the first Aerofon missiles, though, did not have a detachable warhead section). At the base of this warhead section were lattice-section steering vanes that folded out into the air stream, providing maneuvering capability to the Aerofon warhead. In the base of the warhead section was the batteries for the power supply and its associated electronics. The nose section was tipped with an optical seeker that updated the inertial guidance and accessed the onboard computer for optical comparison of the target. In between the guidance section at the nose and the power/steering section at the base was the warhead which took up the majority of the space.

The production version of the Aerofon was ready for deployment by 1989 but it never went into large scale production as it was superseded by two more advanced battlefield ballistic missiles- the OTR-21 Tochka (NATO code name SS-21 "Scarab") and the OTR-23 Oka (NATO code name SS-23 "Spider"). However, in the 1990s, the Aerofon was offered for export to existing customers of the Scud missile.

Source: Scud Ballistic Missile and Launch Systems 1955-2005, New Vanguard #120 by Steven J. Zaloga. Osprey Publishing, 2006, p1-19.