The missiles

Abstract

After successfully testing its own hydrogen bomb in 1953, the Soviet Union set out to outflank the American air defences by building a ballistic missile with which to threaten Washington from a securely defended base on Soviet territory. It was recognised that the most effective configuration for a multi-stage missile would be to stack the stages one on top of the other, but the shut down and jettisoning of one stage and the ignition of a large liquid rocket engine in flight were beyond the state of the art. Sergei Korolev, the leading Soviet rocket engineer, therefore opted for ‘parallel staging’ in which ‘boosters’ would augment the main engine to lift the missile into the air and subsequently be released. In that way he would need only to perfect the art of discarding the boosters without disturbing the main stage. To lob the 3-tonne warhead a distance of 8,000 kilometres, Korolev strapped four conical boosters around a core stage, each of which contained a turbopump driven by hydrogen peroxide steam that fed kerosene and liquid oxygen into an engine that had four combustion chambers. Because these engines were fixed, the missile was steered by small vernier engines. The construction of a launch pad on the Kazakh steppe began in 1955.1 In May 1957 the first flight failed when the vehicle exploded in the act of staging. Similar failures in June and July were followed by a successful flight in August that not only staged but achieved the assigned range. On 4 October 1957, to demonstrate the power of this rocket, the Soviets used it to put the world’s first artificial satellite, Sputnik, into orbit. As it was his seventh rocket design, Korolev referred to this missile as the Semyorka, which in Russian means ‘number seven’.2