History of Chinas's YF-21/24 rocket engines

 

The YF-20 is a Chinese liquid rocket engine burning N2O4 and UDMH in an gas generator cycle. It is a basic engine which when mounted in a four engine cluster forms the YF-21. The high altitude variant is known as the YF-22 and is  paired with YF-23 verniers to form the YF-24 propulsion module for second stages. Over time several improvements to the engine performance has been achieved. Finally, the engine YF-24 of the second stage was in 1991 for the first time replaced by a significantly upgraded engine version with an extended nozzle on the main engine (CZ-2E, -2F) . Obviously, the engine YF-24 replaced by the engine YF-24E for all versions since the year 2002.
The Verniers for the YF-24 engine were used in three variants over time. The first YF-23 is characterized by a long combustion chamber compared to the following YF-23B. An uncooled composite nozzle is characteristic of the current variant YF-23F. This variant has been used latest since 2012.
 


Timeline

 

Booster

Stage 1

 Stage 2   +Verniers (4)

Launcher CZ-2

Launcher CZ-3

Launcher CZ-4

 YF-20B  

CZ-2E

 CZ-3B  
 YF-20C    CZ-2F/SZ, CZ-2F/TG  CZ-3B+, CZ-3BE, CZ-3C, CZ-3CE  

 4 x YF-20

 = YF-21

 

FB-1, CZ-2

 

 

 4 x YF-20A

 = YF-21A

 

CZ-2C

 CZ-3  

 4 x YF-20B

 = YF-21B

 

CZ-2C+, CZ-2CS, CZ-2D, CZ-2E

 CZ-3+, CZ-3A, CZ-3B  CZ-4A, CZ-4B
 4 x YF-20C  = YF-21C  

CZ-2F/SZ, CZ-2F/TG

CZ-3A+, CZ-3B+, CZ-3BE, CZ-3C, CZ-3CE  CZ-4B+, CZ-4C
 CZ-2CS, CZ-2CS-4, CZ-2D-4
 YF-22  -  = YF-22

FB-1

   
 YF-22  4x YF-23  = YF-24

CZ-2

   
 YF-22A  4x YF-23  = YF-24A

CZ-2C

,CZ-3  
 YF-22B  4x YF-23B  = YF-24B

CZ-2C+, CZ-2CS, CZ-2D

CZ-3+, CZ-3A, CZ-3B

 CZ-4A, CZ-4B
 YF-22E ( l.n.)

 4x YF-23B

 = YF-24D

CZ-2E, CZ-2F/SZ, CZ-2F/TG

 CZ-3A+, CZ-3B+, CZ-3BE, CZ-3C

 CZ-4B+, CZ-4C

 CZ-2CS, CZ-2CS-4, CZ-2D-4
 YF-22E ( l.n.)

 4x YF-23F

 = YF-24E  CZ-2F/SZ, CZ-2F/TG

 CZ-3A+, CZ-3BE, CZ-3CE

 CZ-4B+, CZ-4C

CZ-2CS-4, CZ-2D-4

DaFY-5-1

DaFY-6-2

DaFY-20-1

DaFY-21-1

another term for engines

 

Photo Gallery

  YF-20/21


YF-20 (Booster)


   
   
YF-20

           
YF-21 (FB-1, CZ-2)
Note: Different combustor head and exhaust pipe to YF-21A etc


YF-21A etc  (four YF-20A engines)

     
YF-21A etc

  YF-22/24



YF-24 flow scheme



YF-22 without verniers (FB-1)

  
YF-24B (YF-22B with YF-23B verniers)


    

YF-24D ( =YF-22E  l.n.+ YF-23B verniers)


YF-24D (YF-22E  l.n. + YF-23B verniers)

    
YF-24E (=YF-22E  l.n. + YF-23F verniers

   YF-23 (Verniers)



YF-23



YF-23B


YF-23F (composite nozzle)



YF-23F