The successful second flight of an upgraded Soyuz 2-1a launch vehicle with new larger ST payload fairing and Fregat upper stage from Baikonur on 19 October could pave the way for the more powerful 2-1b variant to make its maiden flight by year-end. As well as the 2-1a's digital controls, for improved navigation accuracy, the -1b uses a new RD-0124 third-stage engine and the ST fairing.
Manufactured by the Design Bureau of Chemical Automatics in Voronezh, Russia, the RD-0124 provides 34s more specific impulse than the Soyuz 2's current RD-0110 third-stage engine, improving launch performance.
A successful flight of the ST fairing was key to clearing the uprated 2-1b for its first launch. "The 2-1a enables Starsem to introduce the ST payload fairing to accommodate medium-class geostationary-orbit telecommunications spacecraft," says Arianespace, the major shareholder in Starsem, which markets Soyuz launches.
Source: Flight International