Long March 4
Long March 4 rocket family or Chang Zheng 4 rocket family is an expendable launch system within the Long March (rocket family) and is operated by the People's Republic of China. Three configuration variants currently exist: Long March 4A, Long March 4B, and Long March 4C.
History
The Long March 4 rocket was originally developed as a backup to the CZ-3 for launch of the geostationary satellites, but was later adopted for the launch of remote-sensing satellites into sun synchronous orbits. CZ-4 was developed by the Shanghai Academy of Spaceflight Technology.CZ-4 is built on the design of the CZ-3C vehicle using its first two stages. The third stage adopts a UDMH/N2O4 storable propellant system using two gimbaled rocket engines as opposed the LH2/LO2 stage third stage employed on CZ-3C.
The Long March 4A has a length of 41.9 meters and a maximum diameter of 3.35 meters.
The Long March 4B was introduced in the late 1990s for the launch of the Ziyuan 1 (CBERS 1) remote-sensing satellite. The CZ-4B is of similar design to the CZ-4A but adopts an updated payload fairing 8.48 meters in length and 3.35 meters in diameter to house large remote-sensing satellites.
The Long March 4C was introduced in 2006 for the launch of Yaogan 1 reconnaissance satellites. The CZ-4C features an improved third-stage with multiple re-start capability to launch heavier satellites and multiple satellites on a single vehicle. Improvements include a third-stage using the YF-40A engine with multiple restart capability, enhanced propellant management, new flight computer and guidance systems, and an automated launch control system.
Launch history
Launch statistics for the Long March 4 rocket family.| Derivative | Status | First flight | Launches | Successes | Failures | Partial failures |
| Long March 4A | 6 September 1988 | 2 | 0 | 0 | 0 | |
| Long March 4B | 10 May 1999 | 54 | 53 | 1 | 0 | |
| Long March 4C | 26 April 2006 | 58 | 56 | 2 | 0 |