Soyuz/Vostok

The Soyuz/Vostok was an interim expendable carrier rocket used by the Soviet Union in 1965 and 1966. Two were launched with prototype US-A satellites.
The Soyuz/Vostok was launched from Site 31/6 at the Baikonur Cosmodrome. It consisted of the boosters and second stage from a Soyuz rocket combined with the third stage of the Vostok-2, and an unknown fourth stage. Along with the Voskhod-derived Polyot, it was built as an interim between the cancellation of the UR-200 development programme, and the introduction of the Tsyklon-2, which took over US-A launches once it entered service.