Yuanzheng

Yuanzheng
ManufacturerCALT
Country of originChina
Used onLong March rocket family
(2C · 2D · 3B · 3C · 5 · 7)
Associated stages
ComparableFregat
Launch history
StatusActive
Total launches29
Successes
(stage only)
28
Failed1
Lower stage
failed
0
First flight30 March 2015
BeiDou I1-S
Last flight21 March 2024
Yunhai-2 Group 02
Launch date
Yuanzheng
Powered by1 × YF-50D[1]
Maximum thrust6.5 kN (1,500 lbf)[2]
Specific impulse315.5 seconds[2]
PropellantN2O4 / UDMH

Yuanzheng (Chinese: 远征; pinyin: Yuǎn Zhēng; lit. 'Expedition') is a restartable upper stage developed by the China Academy of Launch Vehicle Technology (CALT) for the Long March rocket family.

The Yuanzheng stage enables the Chinese launch vehicles to deploy payloads directly to high-energy orbits such as medium Earth orbit (MEO) and geosynchronous orbit (GSO). Since the Long March third stage cannot restart, it cannot circularize a GSO or GEO orbit from a geosyncronous transfer orbit (GTO). With its restart capability, Yuanzheng has enabled the deployment of satellite pairs for the BeiDou Navigation Satellite System in MEO and communications satellites in GSO. This eliminates the need for the spacecraft to include a liquid apogee engine or an apogee kick motor.[3]

Yuanzheng has a thrust of 6.5 kN (1,500 lbf) with a specific impulse of 315.5 seconds. It uses the storable hypergolic propellants unsymmetrical dimethylhydrazine (UDMH) and dinitrogen tetroxide (N2O4), and can perform at least two burns within its rated life of 6.5 hours, sufficient to reach the transfer orbit apogee, and perform the circularization burn from there.[4]

Operational variants are designated YZ-1 for Long March 3B and 3C, YZ-1A for Long March 7, YZ-1S for Long March 2C, YZ-2 for Long March 5, and YZ-3 for Long March 2D.

  1. ^ Cite error: The named reference cascqq-20150726 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference b14643-cz3pg was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference masv329-24 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference b14643-yz1 was invoked but never defined (see the help page).