НПО Энергомаш
On March 16, 1976 the Government passed a resolution for the development of Zenit, the RD-171 and RD-120. By April 1976, Yuzhnoye supplied NPO Energomash with the final requirements for the 11D77 first and second stage propulsion. One of the desirable effects of consolidating the first and second stage propulsion on the same designer, was that they could learn their lessons on staged combustion engines on the smaller and simpler upper stage engine, and then apply them to the bigger and more innovative first stage RD-170. NPO Energomash, had already worked on a prototype kerosene / oxygen staged combustion engine in that range, based on the RD-268 hypergolic engine, which was already under serial production with Yuzhmash.