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CZ-3 Space Launch Vehicle

Long March 3 (LM-3) is a three-stage launch vehicle, primarily fintended or sending spacecraft into Geosynchronous Transfer Orbit. The development of the first and second stages of LM-3 is based on the first and second stages of LM-2C. The 1st and 2nd stages of an LM-3 launch vehicle, based on the LM-2C, are designed and manufactured by the Shanghai Academy of Spaceflight Technology. Most of the technology and flight hardware used in LM-3 have been qualified and proved by LM-2C. The third stage of LM-3 was newly developed. It is powered by a cryogenic engine, using liquid oxygen and liquid hydrogen as propellants.

The CZ-3 launch vehicle was introduced in 1984 to provide the PRC with its initial GEO mission capability. The vehicle also marked the first use of a high technology upper stage and led to China's entry into the commercial space launch services market. The CZ-3 is a 3-stage launch vehicle with the first two stages essentially identical to the CZ-2C. The third stage utilizes a restartable, liquid oxygen/liquid hydrogen engine designated YF-73. The GTO capacity of the CZ-3 is 1.5 metric tons (References 159, 164, 180-184).

The inaugural flight from the Xichang Satellite Launch Center of the CZ-3 on 29 January 1984 failed when the third stage did not restart to maneuver from a LEO parking orbit to GTO. The payload was an experimental communication satellite. During this flight, the third stage engine thrust was lost after engine restart. This caused the satellite to be placed into an elliptical orbit. However, most of the test and experimental investigations planned for the flight were carried out. A rigorous analysis was made for the launch vehicle telemetry data and the cause of the malfunction was identified as being an abnormal mixture ratio in the gas generator for the third stage. This caused the gas temperature to reach a high level to make the turbine shell burn out, resulting in the loss of thrust. The third stage engine was modified and four ground tests were carried out.

The next six missions (April 1984 - April 1990) were successful. On 8 April 1984, seventy days after the test flight, a Long March 3 with the modified third stage engine was launched. It was a perfect success. After that, several chinese communication satellites were launched by LM-3. On 7 April 1990, the seventh launch of LM-3 was carried out, delivering the first foreign communication satellite, AsiaSat 1, into a predetermined GTO. It was a total success and marked the real entrance of Long March launch vehicles for China into the international commercial launch service market.

Only one CZ-3 mission was attempted during 1991-1993, and this flight resulted in the stranding of a domestic PRO communications satellite in the wrong orbit. The eighth launch of LM-3 was conducted on 28 December 1991, and orbital insertion into the planned LEO was accomplished. However, when the third stage was reignited, a propellant pressurization malfunction caused a premature shut-down. Therefore, the satellite did not enter into the specified GTO, leaving the payload with an apogee of only 2,450 km instead of nearly 36,000 km as required. Analyses on flight telemetry data and tests indicated that the source of the failure was due to a speedy drop in pressure inside the the helium gas sphere for engine control caused by a leakage in the piping of gas feed. Measures have been taken to eliminate the possibility of this type of failure in the later launches.

On July 21, 1994, LM-3 with some improvement for APSTAR-1 mission, was successfully launched. To raise the launch reliability, the main measure on APSTAR-1 mission of LM-3 was taken, such as the leak-proof methods for gas feed pipes, more gas vessels for 3rd stage engine control and more gas vessels for 3rd stage pressurization. On July 3, 1996, LM-3 once again sent another APSTR-1A into GTO successfully.

LM-3 prematurely shut off for 48 seconds on August 18, 1996, during its ChinaStar-7 mission. The Hughes HS-376 satellite called the ChinaSat-7 (Zhongxing 7) was left in an unusable orbit due incomplete burn of the third stage of the rocket. The root cause of this falure is deflagration occurred occasionally at LH2 injector area of gas generator, which was caused by frozen oxygen due to inadequate of gas purging during coast flight. The corrective measures had been passed the review and implemented on LM-3 series launch vehicles.

A successful launch of a LM-3 occurred on 03 July 1996, launching China's communications satellite Apstar 1A. The People's Republic's space program showed strong signs of recovery during 1997, launching a CZ-3 from Xichang on 10 June 1997 carrying the country's first geosynchronous weather satellite (Feng Yun 2).

LM-3
	Background Information First Launch: January 1984 Flight Rate: 2-3 per year Launch Site: Xichang Space Launch Center, China Capability: 3,100 lb to GTO, 31.1 degrees 11,000 lb to LEO 2,100 lb to Earth Escape Trajectory History Chinese rocket program started in the late 1950s Evolved from Chinese surface-to-surface (CSS) series IRBMs LM-3 is enhanced version of the LM-2; addition of a cryogenic upper stage Description Three-stage liquid fueled vehicle Stage 1 consists of four YF-20 motors burning UDMH/N2O4 providing a total thrust of 625,800 lb Stage 2 uses one YF-22 engine burning UDMH/N2O4 providing a total thrust of 172,100 lb Stage 3 uses one YF-73 engine burning LOX/LH2 providing a thrust of 9,900 lb Profile Length: 144 ft Launch Weight: 444,400 lb Diameter: 11 ft Liftoff Thrust: 625,800 lb Payload Fairing: 19.2 ft x 8.5 ft