Further test firings

Even as the Zenit was slowly overcoming its teething problems, tests continued of the RD-170 in preparation for the first flights of the Energiya rocket. In November 1985 the engine was test-fired for the first time as part of an Energiya strap-on booster “modular section’’ at NIIkhimmash’s IS-102 test stand. In all, the RD-170/171 underwent fifteen test firings as part of a Blok-A or Zenit first stage at NIIkhimmash. By the time of Energiya’s maiden launch in May 1987, a total of 148 RD-170 engines had undergone 473 test firings totaling 51,845 seconds. By early October 1988, only weeks before the first attempted launch of Energiya-Buran, these numbers had increased to 186 engines, 618 test firings, and 69,579 seconds of accumulated burn time.

Test firings of the RD-170 continued after the two flights of Energiya and were mainly aimed at further improving the engine so that it could be reused on as many as ten Energiya missions, a capability that was demonstrated by 1992. Meanwhile, PO Polyot’s serial production plant in Omsk opened its own test-firing stand at Krutaya Gorka (55 km north of Omsk), carrying out six tests of RD-170 engines beginning on 29 December 1990. The test stand was reported to be the scene of a major explosion on or around 20 November 1991, which probably rendered it useless for further test firings [3].

When the Energiya program was canceled in 1993, a total of 14 flightworthy RD-170 engines had already been installed on Blok-A strap-on boosters awaiting their missions at Baykonur’s Energiya assembly building. In 1996-1997 the engines were removed and shipped back to Energomash to be modified as RD-171 engines for use in the Zenit rocket as part of the Sea Launch program [4].