Chang Zheng    CZ-3A /-3B /-3C

China National Space Administration * China Academy of Launch Vehicle Technology (CALT)* China Aerospace Science and Technology Corporation (CASC)

Durch Hinzufügen einer kryogenen dritten Stufe mit einem Schub von 44,15 kN entstand aus der CZ-2C die CZ-3. Sie wurde erstmals 1983 von Xichang gestartet. Eine schubstärkere CZ-3+ wurde seit 1988 eingesetzt und 1990 erstmals auch zum Start eines ausländischen TV-Satelliten ASIASAT genutzt.

Seit 1994 gibt es eine CZ-3A mit einem deutlichen Leistungszuwachs. Die erste Stufe wurde zunächst verlängert (+ 2,56 m) und das Treibstoffassungsvermögen damit um ca. 26 t erhöht. Für 1. und 2. Stufe wurden leistungsfähigere Triebwerke verwendet (YF-21B bzw. YF-24B). Dann wurde die kryogene dritte Stufe wesentlich verbessert. Durch Erhöhung des Tankdurchmessers von 2,25 auf  3,0 m konnte die Treibstoffmenge etwa verdoppelt werden (von 8,50 auf 18,0 t). Die 4 kleinen Triebwerke YF-73 wurden durch stärkere Triebwerke YF-75 ersetzt.

Eine andere seit 1996 eingesetzte Variante CZ-3B erhielt zusätzlich vier 16,33 m lange Starthilfen mit je 41 t flüssigem Treibstoff (UDMH/N2O4) und einem Einkammertriebwerk YF-20D. Die Tanks der zweite Stufe wurden verlängert (+ 1,58 m) und die Treibstoffmenge um etwa 14 t erhöht. Der Durchmesser der Fairings wurde von 3,35 (CZ-3A) auf 4,00 m erweitert. Eine als CZ-3C bezeichnete Variante mit nur zwei Boostern wurde inzwischen ebenfalls eingesetzt.

The development of CZ-3A launch vehicle was started in 1980s, based on the flight proven technology of CZ-3. The main mission of these launch vehicle is to launch China's communications satellites. In February of 1994, its maiden flight was successfully performed. The first and second China's DFH-3 communications satellites were successfully orbited by CZ-3A in November, 1994 and May, 1997. In July, 1999, Alenia Aerospazio selected the CZ-3A to provide launch services for its Satelcom-1 communications satellite which is scheduled to launch in 2001. In October,2000, CZ-3A 5th flight was a success.
CZ-3A is a 3-stage launch vehicle developed on the basis of CZ-3 and CZ-2C. Its third stage is powered by cryogenic propellants, namely, liquid hydrogen and liquid oxygen. It is specially dedicated for launching different spacecraft for GTO missions. Its launch capability for GTO mission is 2600 kg. The fairing static envelope is 3 m in diameter.

To meet the demand of worldwide communications satellite market, the development of CZ-3B launch vehicle was started in 1986, based on the flight proven technology of Long March launch vehicles. In April of 1992, Intelsat executed a launch services contract with CGWIC to use an CZ-3B to launch Intelsat 708 communications satellite. It indicated that the CZ-3B development entered a new development stage and the CZ-3B configuration had been acceptable by world launch services industry.
Unfortunately, the maiden flight of CZ-3B launch failed because the inertial reference altered. After investigation and corrections to the failure of the maiden flight, the CZ-3B launch vehicle achieved four consecutive successes in 1997 and 1998. The CZ-3B launch vehicle has been proven to be a mature powerful launch vehicle in the Long March family.
CZ-3B launch vehicle is the most powerful launch vehicle in Long March fleet based on the CZ-3A as the core stage with four liquid boosters strapped on the first stage. The development of CZ-3B has been made upon the extensive heritage of the mature and flight proven technology of Long March family of launch vehicles. It is specially dedicated for launching heavyweight communications satellite for GTO missions. The GTO launch capability of CZ-3B is 5,200kg.
 

CZ-3A Launch Vehicle
is a large-scale three-stage liquid launch vehicle. A powerful cryogenic third stage has been developed to enable CZ-3A to present greater GTO capability. The typical GTO launch capability of CZ-3A is 2.65 tons. By adopting flexible and advanced control system, CZ-3A can provide large attitude-adjustment and orientation before SC/LV separation, and adjustable SC spin-up rate at the separation. Therefore CZ-3A is of great adaptability. CZ-3A has paved the way for the development of CZ-3B and CZ-3C, and has become the basic type of Chinese GTO launchers.
CZ-3A is mainly used for GTO missions, but also can be used for LEO, SSO and polar orbit missions, or dual-launch and multiple-launch missions.

The first stage is 23.272 meters long. It employs storable propellants, i.e. N2O4 (stored in the oxidizer tank) and UDMH (stored in the fuel tank). The first stage is equipped with DaFY6-2 engine, which is composed of four engines in parallel attached to the first stage. The thrust of each engine is 75t. With the help of servo-mechanism, the four engines can swing in tangential directions for attitude-adjustment with maximum deflection angle of 10 deg.
The second stage is 7.826 meters long. It employs storable propellants, i.e. N2O4 (in the oxidizer tank) and UDMH ( in the fuel tank). There are one main engine (DaFY20-1) and four vernier engines (DaFY21-1) on the second stage. The thrust of the main engine is 75t, and the thrust of each vernier engine is 4.8t. The nozzle of the main engine is fixed, and the nozzles of four vernier engines can swing in tangential directions for attitude-adjustment with maximum deflection angle of 60 deg.
The third stage is 8.835 meters long. It employs cryogenic propellants, i.e. LOX (in the oxidizer tank) and LH2 (in the fuel tank.) The third stage uses YF-75 as its engine, which is capable of restarting in the vacuum. YF-75 is composed of two independent single-nozzle engine in parallel, the thrust of each engine is 8 tons. The nozzles of YF-75 can swing in two-directions for attitude adjustment with maximum deflection angle of 4 deg.

The payload fairing consists of dome, forward cone section, cylindrical section and reverse cone section. The dome shell and forward cone section are made of fiberglass structure. The cylindrical section is made of aluminum honeycomb sandwich structure. The reverse cone section is made of chemical-milled aluminum structure. The typical CZ-3A fairing is 3.35m in diameter, and 8.887m in length. The maximum fairing static envelope is 3.0 m in diameter.

CZ-3A can send the SC into the Geo-synchronous Orbit (GTO). For a typical GTO mission, the first and second stages of CZ-3A firstly send the SC/Stage-3 stack into a circular parking orbit. Then, the Stage-3 performs a coast phase flight for about 600 seconds. After the re-orientation, the Stage-3 engine re-starts and puts the SC/Stage-3 stack into the target GTO. Finally, the SC separates from the Stage-3.

CZ-3B Launch Vehicle
is a large-scale three-stage liquid launch vehicle. It takes enhanced CZ-3A as its core stage with 4 CZ-2E strap-on boosters. The GTO launch capability of CZ-3B can reach up to 5200 kg. With many advantages, such as great launch capability, flexible adaptability, good heritages, CZ-3B is the most powerful, most advanced, and most complicated launch vehicle in current China. It represents the highest level of launch vehicle technology in China, and also stands on the frontier of the world aerospace industry.

The first stage is 23.272 meters long. It employs storable propellants, i.e. N2O4 (stored in the oxidizer tank) and UDMH (stored in the fuel tank). The first stage is equipped with DaFY6-2 engine, which is composed of four engines in parallel attached to the first stage. The thrust of each engine is 75t. With the help of servo-mechanism, the four engines can swing in tangential directions for attitude-adjustment with maximum deflection angle of 10 deg.
There are 4 boosters strapped on the Stage-1. Each of the enlarged booster is 16.094 meters long. It employs storable propellants, i.e. N2O4 (stored in the oxidizer tank) and UDMH (stored in the fuel tank). There is a tail fin installed on each booster. And each booster is equiped with DaFY5-1 engine, whose thrust is 75t. The nozzle of the engine is fixed.
The second stage is 9.943 meters long. It employs storable propellants, i.e. N2O4 (in the oxidizer tank) and UDMH ( in the fuel tank). There are one main engine (DaFY20-1) and four vernier engines (DaFY21-1) on the second stage. The thrust of the main engine is 75t, and the thrust of each vernier engine is 4.8t. The nozzle of the main engine is fixed, and the nozzles of four vernier engines can swing in tangential directions for attitude-adjustment with maximum deflection angle of 60 deg.
The third stage is 12.375 meters long. It employs cryogenic propellants, i.e. LOX (in the oxidizer tank) and LH2 (in the fuel tank.) The third stage uses YF-75 as its engine, which is capable of restarting in the vacuum. YF-75 is composed of two independent single-nozzle engine in parallel, the thrust of each engine is 8 tons. The nozzles of YF-75 can swing in two-directions for attitude adjustment with maximum deflection angle of 4 deg.

The payload fairing consists of dome, Bi-conic section, cylindrical section and reverse cone section. The dome shell and forward cone section are made of fiberglass structure. The cylindrical section is made of aluminum honeycomb sandwich structure. The reverse cone section is made of chemical-milled aluminum structure. The typical CZ-3B fairing is 4.0 m in diameter, and 9.56m in length. The maximum fairing static is 3.65m in diameter.

CZ-3B can send the SC into the Geo-synchronous Orbit (GTO). For a typical GTO mission, the first and second stages of CZ-3B firstly send the SC/Stage-3 stack into a circular parking orbit. Then, the Stage-3 performs a coast phase flight for about 600 seconds. After the re-orientation, the Stage-3 engine re-starts and puts the SC/Stage-3 stack into the target GTO. Finally, the SC separates from the Stage-3.