ChangZheng 4 (Long March 4) Space Launch Vehicle

Last updated: 7 February 2007

The ChangZheng 4 (CZ-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 CZ-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 CZ-4A has carried out two launch missions, the CZ-4B six launch missions, and the modified CZ-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 CZ-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 CZ-4’s first and second stages are essentially identical to those of the CZ-3. The third stage of the CZ-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.

As the CZ-3 became fully successful, the basic variant CZ-4 programme stopped in 1982. Based on its design, SAST introduced the CZ-4A in the mid-1980s for the polar and sun-synchronous orbit missions. The CZ-4A is generally identical to the CZ-4, but with a slight lighter lift mass (CZ-4: 248,926kg; CZ-4A: 241,092kg). The launch vehicle is capable of delivering a 1,500kg payload into the sun-synchronous orbit. The CZ-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 CZ-4A on 3 September 1990.

SAST began to develop an improved CZ-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 CZ-4B missions from Taiyuan Satellite Launch Centre (TSLC), sending 8 satellites into orbits successfully.

Modifications on the CZ-4B included:

• A larger satellite fairing
• Replacing the original mechanical-electrical control on the CZ-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 CZ-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 CZ-4 carries UDMH/N2O4 for all stages. The CZ-4 first stage uses the same power plant as the CZ-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 CZ-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

Typical Flight Sequence (CZ-4A in SSO Mission)

• T + 0 sec: Launch vehicle lifts off
• T + 147.866 sec: First-stage engine shuts down
• T + 151.766 sec: First-stage is separated from the launch vehicle
• T + 166.766 sec: Satellite fairing jettison
• T + 273.718 sec: Second-stage main engine shuts down
• T + 284.718 sec: Second-stage swivelling venire motor shuts down
• T + 285.718 sec: Second-stage separated from the launch vehicle
• T + 286.918 sec: Third-stage engine ignites
• T + 603.968 sec: Third-stage engine shuts down
• T + 617.468 sec: Third-stage correction motors shut down
• T + 658.468 sec: Satellite is separated from the launch vehicle
• T + 658.668 sec: Third-stage begins retrofire

Specifications

Launch Records

Gallery