The R-7 Semyorka (Russian: Р-7 Семёрка), officially the GRAU index 8K71, was a Soviet missile developed during the Cold War, and the world's first intercontinental ballistic missile.
- Type: Ballistic missile.
- Origin : Soviet Union.
- In service : 9 February 1959 – 1968.
- Mass : 280 metric tons.
- Length : 34 m (112 ft).
- Diameter : 10.3 m (34 ft).
- Propellant : LOX/T-1.
- Range : 8,000–8,800 km (5,000–5,500 mi).
- Engine: RD-107 4x 907.4 kN (203,992 lbf), RD-108 1x 907.4 kN (203,992 lbf), Vernier 12x 38.259 kN (8,601 lbf).
The R-7 made 28 launches between 1957 and 1961, but was never deployed operationally. A derivative, the R-7A, was deployed from 1959 to 1968. To the West it was unknown until its launch (later it would get the NATO reporting name SS-6 Sapwood). In modified form, it launched Sputnik 1, the first artificial satellite, into orbit, and became the basis for the R-7 family which includes Sputnik, Luna, Molniya, Vostok, and Voskhod space launchers, as well as later Soyuz variants.
The widely used nickname for the R-7 launcher, "Semyorka", means "seven" in Russian.
The R-7 was 34 m (112 ft) long, 10.3 m (34 ft) in diameter and weighed 280 metric tons (280 long tons; 310 short tons); it had two stages, powered by rocket engines using liquid oxygen (LOX) and kerosene and capable of delivering its payload up to 8,800 km (5,500 mi), with an accuracy (CEP) of around 5 km (3.1 mi). A single thermonuclear warhead was carried with a nominal yield of 3 megatons of TNT. The initial launch was boosted by four strap-on liquid rocket boosters making up the first stage, with a central 'sustainer' engine powering through both the first and the second stage. Each strap-on booster included two vernier thrusters and the core stage included four. The guidance system was inertial with radio control of the vernier thrusters.