The LV Energia propulsion unit consists of four 4-chamber oxygen-kerosene engines RD-170 (one on each strap-ons of stage I) and four 1-chamber oxygen-hydrogen engines RD-0120 on the core stage II and pneudraulic systems for their operation. Engines RD-170 specially designed for LV Energia are of unsurpassed performance and have no analogs abroad.
All engines are ignited at a liftoff with the engines of stage II ignited ahead (8 s) of the first stage engines. During this period a diagnostics system is executing final checkouts and serves out a "permission" to ignite the first stage engines thus preventing from the LV liftoff with a faulty engine. Wide spectra of controllable engine thrust and oxidizer-fuel mass relation enable to implement the best parameters of the LV motion and synchronous depletion of fuel tanks. In the ascent phase, LV is controlled and stabilized through a thrust vector deflection of engines of stages I and II in two planes. For this, the engine gimbals and high precision vernier thrusters are provided to gimbal each engine of stage II and four engine chambers of stage I. The vernier thrusters are sized to about 50 tf for stage I and 33 tf for stage II and to an accuracy of 1% from the thrusters motion spectrum.