|Country of origin||China|
|Designer||Academy of Aerospace Liquid Propulsion Technology|
|Associated LV||Feng Bao 1, Long March 2, Long March 3 and Long March 4|
|Propellant||N2O4 / UDMH|
|Thrust, vacuum||816.3 kN (183,500 lbf)|
|Thrust, sea-level||731.5 kN (164,400 lbf)|
|Chamber pressure||7.1 MPa (1,030 psi)|
|Specific impulse, vacuum||289 seconds (2.83 km/s)|
|Specific impulse, sea-level||259 seconds (2.54 km/s)|
|Gimbal range||±10° (when integrated on the YF-21B)|
|Diameter||84 centimetres (33 in)|
|Dry weight||712.5 kg (1,571 lb)|
|Feng Bao 1 first stage and Long March 2C, Long March 2D, Long March 2E, Long March 3, Long March 3A, Long March 3B and Long March 4A, boosters, first stage and second stage.|
The YF-20 is a Chinese liquid-fuel rocket engine burning N2O4 and UDMH in a gas generator cycle. It is a basic engine which when mounted in a four engine module forms the YF-21. The high altitude variation is known as the YF-22 is normally paired with the YF-23 vernier to form the YF-24 propulsion module for second stages. New versions when used individually for booster applications are called YF-25.
The basic engine has been used since the Feng Bao 1 rocket and has been the main propulsion of the Long March 2, Long March 3 and Long March 4 families.
While the basic engine was used multiple times, it was only used as a single engine for booster application. It is usually bundled into modules of multiple engines.
The relevant modules for first stage application are:
The relevant modules for second stage application are: