R-7 Semyorka
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The R-7 Semyorka (Russian: Р-7 "Семёрка") was the world's first intercontinental ballistic missile and was deployed by the Soviet Union during the Cold War from 1959 to 1968. To the West it was known by the NATO reporting name SS-6 Sapwood and within the Soviet Union by the GRAU index 8K71. The rocket was also the basis for the Soyuz space launcher and the Molniya, Vostok and Voskhod variants.
The widely used nickname for the R-7 launcher, "semyorka", simply means "the digit 7" in Russian.
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[edit] Description
The R-7 was 34 m long, 3 m in diameter and weighed 280 metric tons, it was two-stage, powered by rocket motors using liquid oxygen (lox) and kerosene and was capable of delivering its payload around 8,800 km, with an accuracy (CEP) of around 5,000 m. A single nuclear warhead was carried with a nominal yield of 3 megatons of TNT (Mt of TNT). The initial launch was boosted by four strap-on rockets making up the first stage with a central 'sustainer' motor powering through both the first and the second stage. The guidance system was inertial with radio control vernier rockets.
[edit] Development
Design work began at OKB-1, Kaliningrad (later S.P. Korolev Rocket and Space Corporation Energia) and other divisions in 1953 with the requirement for a two-stage missile of 170 metric tons with a range of 8,000 km carrying a 300 kg warhead. Following first ground tests in late 1953 the initial design was heavily reworked and the final design was not approved until May 1954. The first testing of the new missile, codenamed 8K71, was on May 15, 1957 from Baikonur Cosmodrome. A fire in a strap-on rocket led to an unintended crash 400 km from the site. Following another unsuccessful test the first successful long flight, of 6,000 km, was made on August 21. It was announced by TASS on August 26. A modified version of the missile placed Sputnik 1 in orbit from Baikonur on October 4 and Sputnik 2 on November 3.
Following these first tests certain modifications were found to be needed and test flights were not completed until December 1959. The additional development resulted in the 8K74 which compared to the 8K71 was lighter, had better navigation systems, more powerful engines and more fuel extending its range to 12,000 km and payload to 5,370 kg. The warhead was tested on Novaya Zemlya in October 1957 and again in 1958, yielding an estimated 2.9 Mt of TNT.
The 8K71 and the 8K74 variants were manufactured as the R-7 and R-7A. The missiles were fully deployed by 1962 and were phased-out by 1968. But it was still used for space research, where it was further developed into the reliable Vostok, Voskhod and later the Soyuz launchers.
[edit] Operational history
The first strategic-missile unit became operational on 9 February 1959 at Plesetsk in north-west Russia. On 15 December, 1959 it tested its R-7 missile for the first time. However, the R-7 missiles were considered to be a failure as a weapons system. Only six launch sites in total became operational, four at Plesetsk and two at Baikonur in Kazakhstan. The costs of the system were huge, mostly due to the difficulty of constructing in remote areas the large launch sites required. At one point, each launch site was projected to cost 5% of the Soviet defence budget. However, these huge costs were not unique for a first generation missile and the US experienced similar problems.
Besides the cost, the missile had other debilitating operational problems. With the U-2 overflights, the huge R-7 launch complexes could not be hidden and could expect to be destroyed quickly in any nuclear war. Also, the R-7 took almost twenty hours to prepare for launching, and it could not be left on alert for more than a day due to its cryogenic fuel system. Therefore, the Soviet force could not be kept on permanent alert, and could be destroyed before launching even by American bombers while they stood no chance against American ICBMs. The failure of the R-7 pushed the Soviet Union into rapidly developing second-generation missiles which would be viable weapons systems.
Total service was limited to no more than ten nuclear armed missiles active at any time. A single launch pad was operational at Baikonur and from six to eight were in operation at Plesetsk.
| Sapwood SS-6 8K71PS | ||
|---|---|---|
 |
||
| Stages | 1 1/2 | |
| 0 - Strap-on boosters | Engines | 4 x RD-107 |
| Thrust | 4 x 99,000 kgf = 396 Mgf (3.89 MN) | |
| Burn time | 118 seconds | |
| Fuels | LOX/kerosene | |
| 1 - Core Stage | Engines | 1 x RD-108 |
| Thrust | 912 kN | |
| Burn time | 301 seconds | |
| Fuels | LOX/kerosene | |
| Launch vehicle | 1st Launch October 4, 1957 | |
| Payload LEO 65-degree | 500 kg | |
[edit] 8K71PS
8K71PS was an ICBM used as a launch vehicle by the Soviet Union to launch all 5 Sputnik satellites. No other rocket stages were added to the ICBM to launch the satellites. The 8K71PS is essentially a modified R-7 ICBM. It was also known under the name "Semyorka".
[edit] 8K71PS specifications
- Stage number: 0 - Strap-on boosters; 4 x 8K71K-0
- Gross mass: 43,300 kg
- Empty mass: 3,710 kg
- Thrust (vac): 4 × 99,000 kgf = 396 Mgf (3.89 MN)
- Isp: 313 s (3.07 kN·s/kg)
- Burn time: 118 s
- Isp(sl): 256 s (2.51 kN·s/kg)
- Diameter: 2.68 m
- Span: 9.76 m
- Length: 19.00 m
- Propellants: Lox/kerosene
- Engines: 1 x RD-107-8D74-1959 per booster = 4
- Stage number: 1 - Core stage; 1 x 8K71K-1
- Gross mass: 100,400 kg
- Empty mass: 6,800 kg
- Thrust (vac): 912 kN
- Isp: 315 s (3.09 kN·s/kg)
- Burn time: 301 s
- Isp(sl): 248 s (2.43 kN·s/kg)
- Diameter: 2.99 m
- Length: 28.00 m
- Propellants: Lox/Kerosene
- Engine: 1 x RD-108-8D75-1959
- Total mass: 267,000 kg
- Total liftoff thrust: 3.89 MN
[edit] Operators
- Soviet Union: The Strategic Rocket Forces were the only operators of the Semyorka.
[edit] See also
[edit] References
The Kremlin's Nuclear Sword, Steven J. Zaloga, Smithsonian Institution Press, Washington and London, 2002.
[edit] External links
- Rocket R-7 from S.P. Korolev Rocket and Space Corporation Energia, a Russian rocket and space contractor
| Russian and former Soviet surface-to-surface missiles |
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The SS designation sequence: |
| List of Russian and former Soviet missiles Missiles |
| Current: |
Ariane 5 • Atlas V • Cosmos-3M • Delta II • Delta IV • Dnipro • Geosynchronous Satellite Launch Vehicle • H-IIA • Long March • Minotaur • Pegasus • Polar Satellite Launch Vehicle • Proton • Rockot • Soyuz • Taurus • Tsyklon • Zenit |
|---|---|
| Planned: | |
| Historical: |
Ariane 1 • Ariane 2/3 • Ariane 4 • Atlas ICBM • Atlas II • Atlas III • Black Arrow • Delta III • Diamant • Energia • Europa • M-V • N1 • R-7 Semyorka • Saturn I • Saturn IB • Saturn V • Saturn INT-21 • PGM-17 Thor • Titan (I, II, III, IV) • Voskhod • Vostok |
