In 1956, a decision was made to improve the S-75 Dvina system. This marked the beginning of work on the next variant of this complex, designated S-75 Desna. In 1957, a prototype was ready for testing at the proving ground. In the new system, mobility was improved by placing its components on trailers towed by trucks.
New solutions in the field of radar were also introduced. The system was adopted for service in May 1959. And in this case too, when the Desna system was being introduced, work on the next missile complex, the S-75M Volkhov, began in 1958. It featured a more precise missile guidance system. After completing proving ground tests, the Volkhov was adopted for service in April 1961. Following this decision, serial production began and from 1962 it started to be introduced into missile units.
There is a thesis, not unambiguously confirmed in Russian sources, according to which the Volkhov was the ultimate target system that had been under development throughout the 1950s. However, the Russians had quite serious difficulties developing a sufficiently precise missile guidance method, and therefore, in order not to delay the programme, less advanced solutions were introduced along the way, resulting in the Dvina and Desna systems. It was not until the early 1960s that they achieved a system that met all the requirements set before it.
The improvements introduced in successive versions of the S-75 allowed engagement of aerial targets flying at ever higher speeds. New solutions in the electronic part of the Volkhov system allowed firing under conditions of intensive active and passive jamming conducted by the enemy. A special equipment cabin was introduced into the complex, enabling operation within the Vektor automated command system. A number of modifications were also introduced in the design and equipment of the missile. These changes allowed for an increased flight range and new types and methods of warhead operation (including a nuclear warhead with a yield of 15 kt TNT).
The S-75 system was based on a two-stage missile, whose first stage (booster, operating for approx. 4.5 seconds) was powered by a solid-fuel engine, while the second stage (sustainer) operated for approx. 50 seconds and used liquid propellants. The horizontal range of the missile reached 43 km, the vertical range up to 30 km (35 km when engaging balloons), and the missile achieved a maximum speed of Mach 3.5 (approximate data for the Volkhov system missile).
The guidance method, in all versions of the S-75, was based on radio commands calculated from data determined by the radar guidance station, which tracked both the target and the missile flying towards it. The detonation of the warhead, weighing approx. 190-197 kg, was initiated by a radio proximity fuse or by command from the system’s command post. Self-destruction occurred after exceeding the specified flight time necessary to engage the target. A little-known fact was the ability to use the missile against naval and ground targets. The system worked in conjunction with the P-12 early warning radar.
Throughout the entire period of production and use of S-75-based systems, they were subject to continuous changes and modernisations resulting from combat and operational experience. They were adapted to various climatic conditions. Changes in the detection and guidance systems enabled the engagement of low-flying targets, allowing the minimum engagement altitude to be reduced from 500 to 100 metres. To harden the system against active and passive jamming and anti-radar missile attacks, various countermeasures were introduced (initially aided by a special cabin with observers mounted on the radar guidance station, later replaced by a television camera).
The SA-75 Dvina system was introduced into the air defence of Poland in 1963. In subsequent years it was supplemented by the S-75M Volkhov system. Both systems were withdrawn from service in the 1990s, first the Dvina and then the Volkhov. In 1995, the Russians proposed a modernisation programme for users of the S-75 system to adapt the complex to modern requirements.
