RD-191
The RD-191 (Russian: Ракетный Двигатель-191, romanized: Raketnyy Dvigatel-191, lit. 'Rocket Engine 191') is a high-performance single-combustion chamber rocket engine, developed in Russia and sold by Roscosmos. It is derived from the RD-180 dual-combustion chamber engine, which itself was derived in turn from the four-chamber RD-170 originally used in the Energia launcher.