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.