English: Part of the space collection at work, this upper stage engine is for a S-75 Dvina, a high-altitude, command-guided Surface to Air Missile (SAM). It has become the most widely-deployed air defense missile in history. The missile came to the world's attention when it shot down the high altitude U-2 spy plane of Francis Gary Powers as he was flying over the Soviet Union on May 1, 1960. Stalin ordered the rapid development of the S-75 to better the Nike Ajax of the U.S. It featured significantly improved missile technology and raised the altitude limit to 82,000ft.

Technically S-75 refers to the complete battery, the missile itself being known as a V-750. The missile is in two stages, consisting of a solid-fuel booster and a storable liquid-fuel upper stage. The booster fires for about 4 to 5 seconds and the main engine for about 22 seconds, by which time the missile is traveling at about Mach 3.

This is an unfired Isayev S2.720A bi-propellant regenerative thrust chamber developed for use in the second stage of the Soviet S-75M SAM system. This chamber burns a hypergolic mixture of triethlamine/xylidine (fuel) with nitric acid as the oxidizer and is rated at 34 KN static thrust.

Chamber was produced by the Isayev Design Bureau. Alexei Isayev specialized in small-scale, liquid-fuelled rocket engines for Soviet manned and unmanned spacecraft. From 1957 to 1967 his engines powered the rockets carrying the first artificial satellites, the first man in space, and the first unmanned probes to the Moon and Venus. At the same time, in the 1950s, he was working on engines for surface-to-air missiles (SAMs) and air-to-sea missiles. An unusual artifact of the Cold War and a reminder that the space programs were largely an offshoot of military research and development.