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 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.
==Versions== 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. YF-20: Core engine. Flown originally on the Feng Bao 1 and Long March 2A. YF-20A: Core engine. YF-20B (a.k.a. DaFY5-1): Core engine, also used on the boosters. YF-20C: Core engine, also used on the boosters. YF-20D: Core engine, also used on the boosters. YF-20E: Core engine, also used on the boosters. YF-22: Upper stage version with enlarged nozzle are ratio. Flown originally on the Feng Bao 1 second stage with no verniers, and on the Long March 2A with the YF-23 verniers as the YF-24. YF-22A: Upper stage version. YF-22B (a.k.a. DaFY20-1): Upper stage version. YF-22C: Upper stage version. YF-22D: Upper stage version. YF-22E: Upper stage version. YF-25: Booster stage version.
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