Yuanzheng

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.

Yuanzheng

Manufacturer	CALT
Country of origin	China
Used on	Long March rocket family (2C · 2D · 3B · 3C · 5 · 7)
Associated stages
Comparable	Fregat
Launch history
Status	Active
Total launches	29
Successes (stage only)	28
Failed	1
Lower stage failed	0
First flight	30 March 2015 BeiDou I1-S
Last flight	21 March 2024 Yunhai-2 Group 02
Launch date
Yuanzheng
Powered by	1 × YF-50D[1]
Maximum thrust	6.5 kN (1,500 lbf)[2]
Specific impulse	315.5 seconds[2]
Propellant	N2O4 / UDMH

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 lb_f) 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.

Models

Yuanzheng upper stages from left to right: YZ-1, YZ-1A, YZ-1S, YZ-2, YZ-3

History

Yuanzheng was presented in a 2013 paper^[3] and performed its first mission on 30 May 2015. The debut flight of the Long March 7 in 2016 included an improved version called Yuanzheng-1A that can flexibly deploy multiple payloads into various target orbits.^[5] Further variants were later deployed for Long March 5 (YZ-2) in 2016, Long March 2C (YZ-1S) and Long March 2D (YZ-3) in 2018.

Flight No.	Date (UTC)	Carrier Rocket	Stage Model	Serial Number	Launch site	Mission	Result
01	2015-03-30 13:52	Long March 3C	YZ-1	Y1	Xichang	BDS I1-S	Success
02	2015-07-25 12:29	Long March 3B	YZ-1	Y2	Xichang	BDS M1-S / BDS M2-S	Success
03	2016-02-01 07:29	Long March 3C	YZ-1	Y3	Xichang	BDS M3-S	Success
04	2016-06-25 12:00	Long March 7	YZ-1A	Y1	Wenchang	Inaugural Mission	Success
05	2016-11-3 12:43	Long March 5	YZ-2	Y1	Wenchang	Inaugural Mission	Success
06	2017-11-5 11:45	Long March 3B	YZ-1	Y4	Xichang	BDS-3 M1 BDS-3 M2	Success
07	2018-01-11 23:18	Long March 3B	YZ-1	Y5	Xichang	BDS-3 M7 BDS-3 M8	Success
08	2018-02-12 05:03	Long March 3B	YZ-1	Y6	Xichang	BDS-3 M3 BDS-3 M4	Success
09	2018-03-29 17:56	Long March 3B	YZ-1	Y7	Xichang	BDS-3 M9 BDS-3 M10	Success
10	2018-07-29 01:48	Long March 3B	YZ-1	Y8	Xichang	BDS-3 M5 BDS-3 M6	Success
11	2018-08-24 23:52	Long March 3B	YZ-1	Y9	Xichang	BDS-3 M11 BDS-3 M12	Success
12	2018-09-19 14:07	Long March 3B	YZ-1	Y10	Xichang	BDS-3 M13 BDS-3 M14	Success
13	2018-10-09 02:43	Long March 2C	YZ-1S	Y1	Jiuquan	Yaogan 32A, 32B	Success
14	2018-10-15 04:23	Long March 3B	YZ-1	Y11	Xichang	BDS-3 M15 BDS-3 M16	Success
15	2018-11-18 18:00	Long March 3B	YZ-1	Y12	Xichang	BDS-3 M17 BDS-3 M18	Success
16	2018-12-29 08:00	Long March 2D	YZ-3	Y1	Jiuquan	Yunhai-2 01, 02, 03, 04, 05, 06 Hongyan-1	Success
17	2019-09-22 21:10	Long March 3B/E	YZ-1	Y13	Xichang	BDS-3 M23 BDS-3 M24	Success
18	2019-11-23 00:55	Long March 3B/E	YZ-1	Y14	Xichang	BeiDou-3 M21 BeiDou-3 M22	Success
19	2019-12-16 07:22	Long March 3B/E	YZ-1	Y15	Xichang	BeiDou-3 M19 BeiDou-3 M20	Success
20	2021-08-24 11:15	Long March 2C	YZ-1S	Y2	Jiuquan	RSW-01 RSW-02 unknown payload	Success
21	2021-11-03 07:43	Long March 2C	YZ-1S	Y4	Jiuquan	Yaogan 32-02A, 32-02B	Success
22	2022-05-20 10:30	Long March 2C	YZ-1S	Y5	Jiuquan	LEO Test Sat 1/2 Digui Tongxin Weixing	Success
23	2023-07-09 11:00	Long March 2C	YZ-1S	Y3	Jiuquan	Hulianwang Jishu Shiyan 1A Hulianwang Jishu Shiyan 1B	Success
24	2023-11-16 03:55	Long March 2C	YZ-1S	Y9	Jiuquan	Haiyang-3A	Success
25	2023-11-23 10:00	Long March 2D	YZ-3	Y2	Xichang	Hulianwang Jishu Shiyan 2A Hulianwang Jishu Shiyan 2B Hulianwang Jishu Shiyan 2C	Success
26	2023-12-26 03:26	Long March 3B/E	YZ-1	Y16	Xichang	BeiDou-3 M25 BeiDou-3 M26	Success
27	2023-12-30 00:13	Long March 2C	YZ-1S	Y17	Jiuquan	Hulianwang Jishu Shiyan 4A Hulianwang Jishu Shiyan 4B Hulianwang Jishu Shiyan 4C	Success
28	2024-03-13 12:51	Long March 2C	YZ-1S	Y18	Xichang	DRO-A DRO-B	Failure
29	2024-03-21 05:27	Long March 2D	YZ-3	Y3	Jiuquan	Yunhai-2 Group 02	Success

Versions

Currently, there is known to be five versions:

• Yuanzheng-1 (AKA YZ-1) (Chinese: 远征一号; pinyin: Yuǎn Zhēng Yī Hào; lit. 'Expedition One'): Initial version used with the Long March 3. It could perform missions of 6.5 hours, make two ignitions, perform one spacecraft deployment operation.^[6][7]
• Yuanzheng-1A (AKA YZ-1A) (Chinese: 远征一号甲; pinyin: Yuǎn Zhēng Yī Hào Jiǎ; lit. 'Expedition One A'): Improved version used with the Long March 7. Improved version with mission life extended to 48hs, capability to perform at least 9 ignitions and ability to do 7 different separation events. It also includes improved thermal control system, guidance algorithms and orbit planning for multiple payload deployment missions. It will be used as the base system for future deep space propulsion stages, space tugs and orbital servicing and debris removal spacecraft.^[6][8]
• Yuanzheng-1S (AKA YZ-1S) (Chinese: 远征一号商业型; pinyin: Yuǎn Zhēng Yī Hào Shāng Yè Xíng; lit. 'Expedition One Commercial Version'): Improved version used with the Long March 2C.
• Yuanzheng-2 (AKA YZ-2) (Chinese: 远征二号; pinyin: Yuǎn Zhēng Èr Hào; lit. 'Expedition Two'): New version used with the 5.2 m (17 ft) Long March 5 upper stage.^[9]
• Yuanzheng-3 (AKA YZ-3) (Chinese: 远征三号; pinyin: Yuǎn Zhēng Sān Hào; lit. 'Expedition Three'): New version used with the Long March 2D.

References

1. "New Launch". www.casc11.com (in Chinese). Xi'an Aerospace Propulsion Institute. 2015-07-26. Retrieved 2015-08-02.
2. Norbert Bgügge. "Photo Gallery CZ-3CE". B14643.DE. Retrieved 2015-07-25.
3. Kun, Ma; Wu, Guo; Song, Guan; Zhibin, Ma; Tongyu, Li (2013). "上面级发展现状及趋势分析" [Development Status and Trend Analysis of Upper Stages]. Missiles and Space Vehicles (in Chinese). 6 (329): 24–28. doi:10.7654/j.issn.1004-7182.20130606 (inactive 1 November 2024).{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
4. Norbert Bgügge. "YZ-1 space tug". B14643.DE. Archived from the original on August 25, 2015. Retrieved 2015-07-25.
5. "长征七号首飞成功 空间实验室任务大幕拉开" [Successful maiden flight of the Long March 7 mission Damulakai]. www.spacechina.com (in Chinese). 2016-06-25. Archived from the original on 28 June 2016. Retrieved 2016-06-25.
6. "升级版的中国"太空摆渡车"将带来什么?" [What will enable the upgraded space bus?]. www.chinanews.com (in Chinese). 2016-06-25. Retrieved 2016-06-27.
7. "远征一号上面级" [Yuanzheng-1 Upper Stage]. www.chinaspaceflight.com (in Chinese). 2016-06-07. Retrieved 2016-06-30.
8. "远征一号甲上面级(YZ-1A)" [Yuanzheng-1A Upper Stage (YZ-1)]. www.chinaspaceflight.com (in Chinese). 2016-06-26. Retrieved 2016-06-30.
9. "远征二号上面级：今年发射的"长征五号"火箭将启用新研制上面级"远征二号"" [Yuanzheng-2 upper stage: this year's launch of the Long March 5 rocket upper stage will enable the development of new "Yuanzheng-2"]. www.chinaspaceflight.com (in Chinese). 2016-03-30. Retrieved 2016-06-30.