January 1981:the Sandal program

When the first Cosmos satellite was launched on 16 March 1962 a new small launch vehicle was introduced which was based on the Soviet SS-4/Sandal vehicle. Previously all the Soviet orbital launches had used the SS-6/Sapwood derivative launch vehicle, flown from Tyuratam, while the Sandal vehicle introduced the small launch site of Kapustin Yar to orbital flights. While it was flown operationally the Sandal made a total of 144 orbital launches until it was retired in 1977 after the launch of Cosmos 919. The missions flown by the Sandal vehicle now use the more versatile SS-5/Skean vehicle.

The Launch Vehicle

After the successful flights with the SS-16/Sapwood launch vehicle in the early days of the Space Age the Soviets wished to launch small satellites for scientific and military missions,but the use of the large Sapwood for these missions would have been a case of overkill. The Soviets looked to other elements of their missile arsenal for the basis of a smaller satellite launcher. They chose to develop the SS-4 missile with the NATO code name “Sandal” for the small satellite launch vehicle, and added a second orbital stage to the missile. The complete assembly, when revealed in 1967, was named the “Cosmos Rocket”, and is the "B-1” in Dr. C. S. Sheldon’s classification of launch vehicles.

The first stage has a length of 19.7 m and a principal diameter of 1.65 m. At the base the engine mount, with a length of 1.8 m, expands to a diameter of 2.26 m. The engine extends into a section some 2.3 m long, above which is the main 15.2 m fuel tank area. Atop the first stage is an open truss framework, reminiscent of the Sapwood rocket, which extends for 1.2 m. The second stage has a length of 6.74 m with the single engine nozzle protruding 0.8 m below the base of the rocket body. The second stage has a constant diameter of 1.65 m. The payload shroud consists of a cylinder, 1.0 m long and 1.65 m in diameter,topped by a cone with a length of 1.75 m.

The first stage of the launch vehicle is powered by a single RD-214 engine, which seems to be a close relative of the RD-107 and RD-108 engines which power the first stage of the Sapwood rocket. There are four nozzles with integrated verniers. The engine burns kerosene and nitric acid: it has a base diameter of about 1.8 m and a height of 3.5 m. Although the Sandal missile has four base fins when trundled through Moscow on display, the modified version used for orbital launches seems to be without fins.

The second stage of the Sandal uses a single RD-119 engine with a single main nozzle and four smaller vernier nozzles. The RD-119 burns UDMH and liquid oxygen. The main chamber of the engine has a base diameter of 0.8 m and a height of 1.9 m.

Payload Capacity

Until recently, there seemed to be no official masses available of the Sandal-launched payloads. Sheldon estimated that the general capacity was within the range 260-425 kg, while reporting that Woods had obtained a range of 280-600 kg from Soviet officials. More recently the writer’s attention has been drawn to figures quoted in a Polish publication for the Sandal-launched Intercosmos flights, and these are given below:

Intercosmos 1 315 kg? Intercosmos 2 ~320kg

Intercosmos 3 340 kg Intercosmos 4 ~320kg

Intercosmos 5 340 kg? Intercosmos 7 375 kg

Intercosmos 8 340 kg? Intercosmos 9 340 kg?

The use of “?” and above follows their use in the Polish original. Of the exact masses quoted, Intercosmos 3 had the largest launch delta-V and therefore this was used to scale the payload capacity of the Sandal to its other orbital “slots”. This suggests that the general payload range is about 150-350 kg.

Satellite Missions

When one compares the number of scientific missions flown from Kapustin Yar and Plesetsk using the Sandal it is clear that the Kapustin Yar site is used for more “civilian” flights. Of the 60 flights from Kapustin Yar, 40 have been tagged as being scientific, while only 4 of the 84 Plesetsk flights have been identified as having a primarily scientific purpose (plus Cosmos 321 and 481 which had supplementary scientific experiments). A review of Cosmos 71° missions indicated that those flights were for some ill-defined military purpose, and it would seem that all we can do with the other military Sandal missions is leave the detailed clandestine mission with a question mark. Certainly, the Soviets are not likely to indicate the actual missions of the craft in the open press.

Kapustin Yar Flights

The initial flights of the Sandal vehicles were made at an orbital inclination of 49.0°, but in 1965 the first sign of a slight change in inclination came when Cosmos 53 was launched into a 48.8° orbit. After a few years overlap all the flights have been made into an inclination of 48.4°, which implies a virtual due east launch for the vehicle, giving the greatest launch assistance due to the Earth’s rotation. The Kapustin Yar launch rate settled down to a virtually constant annual total of about 7 flights, with 1968 hitting a peak of 8 flights. The final orbital flight from Kapustin Yar of the Sandal was Intercosmos 9 (also called Copernicus-500) in 1973, the same year that the first orbital flight of the Skean was made from the site. Orbital plane spacings were calculated for the flights in the same groups which were in orbit at the same time, and only two significant ones were noted. Cosmos 53/Cosmos 70 were about 90° apart, and Cosmos 211/Cosmos 233 were 45° apart. Of course, since the satellite orbits were in differing stages of decay the plane spacings were not maintained for long.

In concluding the Kapustin Yar section, two other launches should be noted. Cosmos 42/Cosmos 43 was the only dual payload carried by a Sandal, and the satellites might have been connected with the developing Skean programme. Cosmos 119 remained attached to the final stage of the launch vehicle, and therefore might have been a scientific payload which failed,since the other flights in the small group have had scientific missions announced.

Plesetsk Flights

The vast majority of the Plesetsk Sandal flights have been to 71° orbits, and are therefore covered elsewhere. The orbits for some Plesetsk missions have counterparts with a few earlier Kapustin Yar flights, so one is led to wonder whether some initial proving missions were flown from Kapustin Yar before operational flights began from Plesetsk. Certainly, it would seem reasonable to assume that the Cosmos 148 trio was in preparation for the operational flights from Plesetsk in the 71 ° Group B beginning with Cosmos 152.

While the Sandal was phased out from Kapustin Yar in 1973, flights from Plesetsk continued until June 1977 when Cosmos 919 ended the programme. Presumably the Soviets simply ran out of Sandal rockets, since there was no significant payload mass increase - at least for the Intercosmos flights - when missions were switched to the larger Skean vehicle.