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), and later (1999) were also added new Verniers. Obviously, the engine YF-24 replaced by the engine YF-24E for all versions since the year 2002.


Engine history

 

Booster

Stage 1

 

 Stage 2

 +Verniers (4)

 

Launcher

 YF-20B -

-

- - -

CZ-2E, CZ-3B

 YF-20C -

-

- - -  CZ-2F, CZ-3B+, CZ-3BE, CZ-3C, CZ-3CE
 DaFY-5-1  

 

     

another term for booster engine

-

 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/SD, CZ-2D, CZ-2E

-  4 x YF-20B  = YF-21B - - -

CZ-3+, CZ-3A, CZ-3B, CZ-4A, CZ-4B

-  4 x YF-20C  = YF-21C - - -

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

-  4 x YF-20C  = YF-21C - - - CZ-2F/SZ, CZ-2F/TG
-  4 x YF-20C  = YF-21C - - -

CZ-3A+, CZ-3B+, CZ-3BE, CZ-3C, CZ-3CE, CZ-4B+, CZ-4C

 

 DaFY-6-2

       

another term for first stage engines

- - -  YF-22  -  = YF-22

FB-1

- - -  YF-22  YF-23  = YF-24

CZ-2

- - -  YF-22A  YF-23  = YF-24A

CZ-2C, CZ-3

- - -  YF-22B  YF-23B  = YF-24B

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

- - -  YF-22B  YF-23B  = YF-24B

CZ-3+, CZ-3A, CZ-3B, CZ-4A, CZ-4B

- - -  YF-22E ( l.n.)

 YF-23B

 = YF-24D

CZ-2E

- - -  YF-22E ( l.n.)

 YF-23F

 = YF-24E CZ-2F/SZ, CZ-2F/TG
- - -  YF-22E ( l.n.)

 YF-23F

 = YF-24E

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

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

CZ-3A+, CZ-3B+, CZ-3BE, CZ-3C, CZ-3BE,  CZ-4B+, CZ-4C

       DaFY-20-1    

another term for second stage engine

         DaFY-21-1

 

another term for Vernier engines

 

Photo Gallery

  YF-20/21


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


YF-21 & YF-24 engine family


           
YF-21A



Single YF-20B (Booster)



YF-21B

  YF-22/24



YF-24 flow scheme



YF-22 without Verniers (FB-1)


  

YF-24B


    

YF-24D (CZ-2E)



YF-24E



YF-24E

   YF-23 (Verniers)



YF-23



YF-23B



YF-23F


YF-23F