United States consider Russian rocket engine RD-180 to be the best rocket engine on the world, claim RosCosmos officials.
      
      RD-180 is a two-chamber variant of four-chamber kerosene engine RD-170. The engine owes better specific characteristics, than American analogues have, to closed circuit with reburning of exhaust generator gas in main combustion chambers. The engine is environment friendly – its gas generator has oxidizer-rich medium, thus eliminating coke formation on turbine elements and pollution of environment with unburned kerosene.
      
      RD-180 is exported to America as an integrated engine with its own hydraulic system, driven vector-thrust control, vent system and pneumatic valve activation.
      
      Source: Science News