MOSCOW, August 21 (RIA Novosti) - On August 21, 1957, the USSR successfully launched the R-7/SS-6 Sapwood intercontinental ballistic missile, which was developed by experts from Special Design Bureau (OKB) No. 1, under the supervision of Chief Designer Sergei Korolev.
The two-stage R-7 ICBM could deliver one thermonuclear warhead to just about any region of a theoretical enemy’s territory. This new formidable weapons system also became a prototype launch vehicle for various space satellites and manned spacecraft.
The R-7 was also known as the Semyorka and Item No. 8K71 in technical documents.
Soviet experts began developing the R-7 in the late 1940s and early 1950s, long before its first launch. At that time, Korolev was overseeing the development of single-stage R-1, R-2, R-3 and R-5 ballistic missiles. After assessing the results of these research and development projects, experts realized that a much more powerful composite (multi-stage) missile was needed to reach a theoretical enemy’s territory on another continent. The concept of this missile was suggested by Konstantin Tsiolkovsky, the father of space travel.
In 1947, Mikhail Tikhonravov established a group for conducting systematic research projects at the Research Institute of Artillery Sciences. Members of this group were instructed to study the possibility of developing composite (multi-stage) ballistic missiles. After analyzing the group’s findings, Korolev decided to create a rough sketch of a powerful composite missile. On May 20, 1954, the Soviet Government issued a resolution instructing the above-mentioned OKB-1 to develop an intercontinental and thermonuclear-capable missile. Special Design Bureau No. 456 headed by Valentin Glushko developed powerful new engines for the R-7 missile. The R-7’s guidance system was designed by Nikolai Pilyugin and Boris Petrov, and Vladimir Barmin designed the launch facility. Several other organizations were also involved in this project.
At the same time, the decision was made to establish a new ICBM testing site. In February 1955, the Council of Ministers of the USSR (Soviet Government) adopted a resolution on starting the construction of a testing site called the Fifth Research and Testing Site of the Soviet Defense Ministry (NIIP-5). The decision was made to build the testing site near the village of Baikonur and the Tyura-Tam double-track railway section in Kazakhstan. This space center was considered a top-secret facility, and the R-7 launch facility was completed in April 1957.
The design of the R-7 missile was completed in July 1954, and the Soviet Government approved its creation on November 20, 1954. The missile was ready for testing in early 1957. Starting mid-May 1957, the first tests of the missile were conducted, revealing major drawbacks in its design.
The first missile lifted off on May 15, 1957. Visual observations showed the flight pattern to be normal, but changes in the composition of missile engine gases were subsequently detected in its tail section. An assessment of telemetry data showed that the missile had become unstable, after one of side sections fell off. The accident was caused by a ruptured fuel pipeline.
The next launch was scheduled for June 11, 1957, but it never took place due to defective engines in the missile’s central section. The missile lifted off once again on July 12, 1957, but lost its in-flight stability in the 33rd second of flight and started deviating from its preset trajectory. This particular malfunction was caused by a short-circuited integrator responsible for the missile’s revolution.
The fourth R-7 launch (August 21, 1957) finally proved successful, and the missile hit a preset target area for the first time. This missile, also known as Item No. 8K718, with an M1-9 warhead, lifted off from the Baikonur space center (Tyura-Tam testing site), completed its active trajectory leg and released its warhead, which then hit a preset area of the Kamchatka Peninsula. But this launch had one major drawback: the warhead disintegrated during reentry.
On August 27, 1957, Soviet newspapers reported the successful test of a multi-stage missile with an enhanced range in the USSR.
Positive results of R-7 flights along the active trajectory leg made it possible to use the missile for launching the first two man-made satellites, on October 4 and November 3, 1957. Conceived as an ICBM, the R-7 possessed a sufficient thrust-to-weight ratio for sending a rather heavy payload into orbit, and this factor was used to full advantage during the launching of these two satellites.
After assessing the results of six R-7 launches, experts upgraded the missile warhead (they installed a new one). They also upgraded the warhead-separation systems and installed slot-type antennas (also called slot arrays) of the telemetry system. The first fully successful R-7 launch took place on March 29, 1958, and its warhead reached the target area intact.
Subsequent flight tests were conducted in 1958-1959, making it possible to upgrade the R-7 design still further.
The R-7 differed completely from all previously developed missiles in terms of its layout, frame configuration, dimensions, weight, rated engine power, the number of systems and their designation, and more.
The R-7 missile’s layout featured two stages with parallel separation and was, in fact, a multiple booster assembly. Its first stage comprised four strap-on boosters measuring 19 meters (62 feet) long each and with a maximum diameter of three meters (10 feet). They were attached symmetrically to the missile’s central section (second stage).
Strap-on boosters and the central section were similar to single-stage missiles with front-mounted oxidizer tanks. The fuel tanks of all sections served as load-bearing structures. During launch, the propulsion units of all five sections were activated simultaneously.
This layout made it possible to activate all engines on the ground, rather than during flight (in the vacuum of space). Each section was equipped with a four-chamber and open-layout liquid-propellant sustainer engine firing liquid oxygen and kerosene.
Hydrogen peroxide and liquid nitrogen were used to operate turbo-pump units of rocket engines and for supercharging fuel tanks, respectively.
The R-7 missile was 31.4 meters (103 feet) long and had a diameter of 11.2 meters (36.7 feet). It had a liftoff weight of 283 metric tons, including 250 metric tons of fuel, a range of 8,000 kilometers (4,971 miles) and a payload of 5.4 metric tons. It could carry a nuclear warhead with a yield of three to five megatons.
The nuclear warhead was attached to the instrument compartment of the central section using three ejection explosive charges. Using it, it was possible to destroy a large area through an air or ground burst.
The R-7 missile was equipped with a combined guidance system, the autonomous subsystem of which ensured angular stabilization and stabilization of the center of mass during the active trajectory leg. A radio-technical subsystem adjusted the sideways movement of the center of mass at the end of the active trajectory leg and shut off the engines for greater targeting accuracy. Reversible steering-engine chambers and rudders executed various commands of the guidance system.
The first R-7 missiles were manufactured at Plant No. 88, a pilot production facility of the OKB-1, in Kaliningrad, now Korolyov, near Moscow. Due to the pilot plant’s limited capacity, Dmitry Kozlov, the leading designer of the R-7 missile, was sent on a business trip to Kuibyshev, now Samara, in February 1958, with instructions to launch commercial production of these missiles at Aviation Plant No. 1, now the Progress State Research and Production Rocket Space Center, which manufactured bombers in the past. The first production missiles came off the assembly line already in December 1958.
Joint R-7 flight tests were conducted from December 1958 until November 1959. A total of 16 missiles were launched during these tests, including eight production versions. The tests made it possible to decide whether the Soviet Armed Forces could adopt the R-7 missile.
The R-7 ICBM was adopted for service on January 20, 1960.
In 1958, the decision was made to build a combat launch station, called the Angara facility, near the town of Plesetsk in Russia’s Arkhangelsk Region. This facility was completed on January 1, 1960, and it successfully launched two test missiles on July 16, 1960, for the first time in the history of the Soviet Armed Forces. Prior to launch, the missile was delivered from a technical position aboard a railway train with a transporter/erector, and placed on a massive launch facility. Pre-launch operations lasted over two hours.
Apart from the R-7, Soviet experts continued to develop the R-7A missile system with an even longer range of 12,000 kilometers (7,450 miles), an upgraded guidance system, more reliable engines and a lighter warhead. The R-7A missile featured more powerful engines and a somewhat larger fuel load, made possible by reducing the free volume of its fuel tanks. The R-7A ICBM was officially adopted for service on September 12, 1960.
The entire missile system proved to be cumbersome, vulnerable, expensive and hard to operate. A refueled missile could remain on the launch pad for no more than 30 days. An entire factory was needed to generate and replenish the required oxygen reserves for refueling deployed missiles. The targeting accuracy of these missiles was not very impressive either. It became obvious that only a few R-7 missiles and their modified versions could be placed on combat duty. A total of four launch pads were built, and both missile versions were discarded from service by late 1968.
The reliable design of the R-7 and R-7A missiles made it possible to develop an entire family of Vostok, Voskhod, Molniya and Soyuz launch vehicles, as well as modified versions of them, for launching the first man-made satellites, and lunar and interplanetary probes. These rockets also launched numerous manned missions, and they continue to be used to this day.