ChangZheng 4 (Long March 4) Launch Vehicle

The ChangZheng 4 (or Long March 4 in its translation) is a three-stage, liquid-propellant space launch vehicle (SLV) designed and developed by Shanghai Academy of Space Flight Technology (SAST), based on the FengBao-1 two-stage SLV. The ChangZheng 4 is mainly used to deliver satellites into polar and sun-synchronous orbits (SSO) from Taiyuan Satellite Launch Centre (TSLC) located in central China. So far the ChangZheng 4A has carried out two launch missions, the ChangZheng 4B six launch missions, and the modified ChangZheng 4B (Batch-02) four launch missions, with a success rate of 100%.

After the development of FB-1 launch vehicle, Shanghai Bureau of Astronautics (now SAST) was assigned to develop the ChangZheng 4 for geosynchronous transfer orbit missions. Originally intended as a backup for the CZ-3 designed by 1st Space Academy (now China Academy of Launch Vehicle Technology, CALT), the ChangZheng 4’s first and second stages are essentially identical to those of the CZ-3. The third stage of the ChangZheng 4 was a new development by SAST, featuring a thin aluminium alloy wall interlink and two swinging nozzles. The launch vehicle is capable of delivering a 1,250kg payload into the geosynchronous transfer orbit.

ChangZheng 4B (Chinese Internet)

As the CZ-3 became fully successful, the basic variant ChangZheng 4 programme stopped in 1982. Based on its design, SAST introduced the ChangZheng 4A in the mid-1980s for the polar and sun-synchronous orbit missions. The ChangZheng 4A is generally identical to the ChangZheng 4, but with a slight lighter lift mass (ChangZheng 4: 248,926kg; ChangZheng 4A: 241,092kg). The launch vehicle is capable of delivering a 1,500kg payload into the sun-synchronous orbit. The ChangZheng 4A made its first flight successfully on 7 September 1988, sending China's first experimental meteorological satellite FY-1A into the orbit. Another meteorological satellite FY-1B was successfully launched by a ChangZheng 4A on 3 September 1990.

SAST began to develop an improved ChangZheng 4B with increased payload in February 1989. Originally scheduled to commission in 1997, but the first launch didn't take place until late 1999. From 1999 to 2002, there were five ChangZheng 4B missions from Taiyuan Satellite Launch Centre (TSLC), sending 8 satellites into orbits successfully.

Modifications on the ChangZheng 4B included:

• A larger satellite fairing
• Replacing the original mechanical-electrical control on the ChangZheng 4 with an electronic control
• Improved telemetry, tracking, control, and self-destruction systems with smaller size and lighter weight
• A revised nuzzle design in the second stage for better high-altitude performance
• A propellant management system for the second stage to reduce the spare propellant amount, thus increasing the vehicle’s payload capability
• A propellant jettison system on the third-stage.

The further improved ChangZheng 4B (Batch-02) features three major improvements:

• A remotely-controlled launch control system that integrates a number of functions previously carried out separately, including launch control, system testing, data transmission, telemetry, power supply, etc.
• New onboard computer with better calculation performance and a smaller size power supply
• The previous horizontal test procedure has been replaced by a vertical test procedure to reduce the launch preparation time by 33%

The ChangZheng 4 carries UDMH/N2O4 for all stages. The ChangZheng 4 first stage uses the same power plant as the ChangZheng 3A but is two meters longer. The first stage uses a YF-21B motor consisting of four 75,000kg-thrust YF-20B thrust chambers motors with swinging nozzles. Similarly, the ChangZheng 4 second stage is similar to that of the CZ-3A, with a YF-24F rocket motor consisting of one 75,000kg-thrust YF-22B main motor with fixed nozzles, and a YF-23F swivelling venire motor with four chambers motors (4,700kg-thrust in total). The third stage is a specially designed unit powered by a 98kN YF-40 rocket motor.

Variants

Last update: 20 February 2009