RD-843

RD-843 is a Ukrainian liquid-propellant rocket engine that runs on a fuel pair of UDMH and AT . The engine is designed for 5 starts in flight and can deviate up to 10 degrees in each direction ^[1] . The mass of the engine is 16.5 kg, traction - 0.25 tf. ^[2]

The engine was developed by Yuzhnoye Design Bureau for Fiat Avio and is manufactured at the Yuzhmash plant . It uses a combustion chamber from the RD-869 engine of the Soviet R-36M ICBM , designed for operation with a fuel displacement system. The RD-843 was tested in 74 tests, 140 ignitions, reaching a total operating time of 8201 s, which is approximately equal to 12 service life on 4 engines. ^[one]

Now it is used as the main engine of the 4th stage of the Vega launch vehicle ^[3] . As of November 2017, the engine was successfully used at 11 orbital launches. ^[four]

On November 30, 2017, the European Space Agency allocated € 53 million to finance the Vega Evolution program, which provides for the replacement of Ukrainian liquid rocket engines RD-843 (supplied for Vega launch vehicles) with more environmentally friendly German engines. The German aerospace technology agency plans to work with Italians to develop a replacement for the RD-843 ^{[5] [6]} as part of the creation of the new fourth stage AVUM + for the new version of the Vega-C rocket by 2019. ^{[7] [8]}