RD-701 (Russian: Раке́тный дви́гатель 701, Rocket Engine 701) - liquid-fuel rocket engine developed by Energomash, Russia. It was proposed to propel the reusable MAKS space plane before cancellation of this project. The RD-701 is a tripropellant engine that uses staged combustion cycle afterburning of oxidizer-rich hot turbine gas. This engine has two modes. Mode #1 uses three components: LOX as an oxidizer and a fuel mixture of RP-1 / LH2 which is applied for near earth surface conditions. Mode #2 also uses LOX, with LH2 as fuel in vacuum where atmospheric influence is negligible.