at Bolkow GmbH (later Astrium). RD-170, RD-171, RD-180 and RD-191—a series of Soviet and Russian engines used on the Energia, Zenit, Atlas V, Angara and previously on the Atlas III launch vehicles. RD-171 (and its RD-171M successor), -180 and -191 are derivatives of RD-170. RD-0124—a series of oxygen/kerosene engines used in the second stage of Soyuz-2.1b rocket as well as in upper stages of Angara series rockets. YF-100—Chinese engine developed in the 2000s; used on the Long March 5, Long March 6, and Long March 7. AR1—An Aerojet Rocketdyne project partially funded by the United States Air Force as a potential replacement for the RD-180 Russian engine. BE-4—Blue Origin LCH4/LOX engine—using the oxygen-rich staged combustion (ORSC) cycle—planned to be used on the ULA Vulcan launch vehicle, which will replace the Atlas V and Delta IV, first flight test in 2021 and also on Blue Origin's New Glenn launch vehicle, with first flight test no earlier than 2021. RD-253—Soviet engine developed in the 1960s and used on the Proton launch vehicle's first stage. Later variants include the RD-275 and RD-275M. SCE-200—Indian RP-1/LOX main stage engine in development. Hadley—Ursa Major Technologies LOX/kerosene booster engine under development near Denver, Colorado. Rocket Factory Augsburg "Helix" LOX/kerosene engine under development which should power the RFA One near Augsburg, Germany. Launcher E-2 — LOX/kerosene engine under development which should power the Launcher Light launch vehicle. Fuel-rich staged combustion RS-25—US developed LH2/LOX engine in the 1970–1980s, flown on the Space Shuttle through 2011 (with periodic upgrades), and planned for further use on the Space Launch System in 2020s. RD-0120—LH2/LOX engine used on the Energia rocket. LE-7—LH2/LOX engine used on the H-II rocket family. KVD-1 (RD-56)—Soviet LH2/LOX upper stage engine developed for the never-flown upgraded version of the N-1 launch vehicle. Used on the GSLV Mk1. CE-7.5—Indian LH2/LOX upper stage engine, used on the GSLV Mk2 Full-flow staged combustion RD-270—USSR engine under development 1962–1970 for the UR-700 project; never flown. Integrated powerhead demonstrator—Demonstration project for the front part of a full flow engine, with no combustion chamber or other backend subsystems. US project to develop a part of a new rocket engine technology in the early 2000s; no full engine ever built; never flown. Raptor—SpaceX LCH4/LOX engine in development, first flown in 2019 Current/past applications of staged-combustion engines Space Shuttle Angara (rocket family) SpaceX Starship H-II H-IIA H-IIB GSLV Long March 5 Long March 6 Long March 7