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The Long March 3C Carrier Rocket

09-25-2010 16:10 BJT

The Long March 3C (CZ-3C) is a large three-stage liquid strap-on carrier rocket. It consists of a CZ-3A, which is used as the core-stage after being modified, and two liquid roll boosters. The CZ-3C is one of the Long March 3 series carrier rockets after the CZ-3A and CZ-3B. It is almost the same as the CZ-3B in terms or their structure and subsystems, except for two roll boosters tied on the first-stage. The launch of the CZ-3C has broadened the scope for users to flexibly choose the Long March rockets according to the quality and mission of the payload.

The CZ-3C is mainly used for launching satellites into geosynchronous orbit, with its GTO carrying capacity being 3.8 tons. The CZ-3C is nearly 55 meters long and its take-off mass is 345 tons. The diameter of its first and second-stage is about 3.35 meters and that of boosters is 2.25 meters, and the diameter of the third-stage is 3 meters. The maximum diameter of the satellite fairing is 4 meters. The first-stage, boosters, and second-stage use the UNMH and N2O4 as propellant while the third-stage uses LH2 and LOX which have higher efficiencies.

The CZ-3C consists of the rocket body, power system, control system, telemetry system, external testing security system, sliding section propellant management and attitude control system, cryogenic propellant utilization system, separation system, and auxiliary systems.

The CZ-3C has officially been put into the international commercial satellite launching service market.

Description of the rocket's structure

First-stage

The first-stage is about 23 meters long and is equipped with the oxidant box full of liquid N2O4 in its upper part and the incendiary agent box full of liquid UDMH in its lower part. The first-stage is equipped with the engine DaFY6-2, which is composed of four parallel-connected liquid engines N2O4/UDMHs, with each having thrust power of 75 tons. The nozzle of each engine N2O4/UDMH can be driven by the servo mechanism to control the flight attitude of the rocket in a one-way swing posture, with the maximum swing angle being 10 degrees.

Roll boosters

Each of the roll boosters is about 15 meters in bundling length and is equipped with the oxidant box full of liquid N2O4 in its upper part and the incendiary agent box full of the liquid UDMH in its lower part. Each of the two boosters is equipped with an engine DaFY5-1 which has a thrust power of 75 tons. Its nozzle is fixed.

Second-stage

The second-stage is almost 10 meters long and is equipped with the oxidant box full of liquid N2O4 in its upper part and the incendiary agent box full of the liquid UDMH in its lower part. It is equipped with an engine DaFY20-1 which has a thrust power of 75 tons and unfixed engine DaFY21-1which has four small nozzles and the thrust power is 4.8 tons. The main engine jet pipe is fixed and the unfixed engine jet pipe can perform a one-way swing, with the maximum swing angle being 60 degrees, to control the flight attitude of the rocket body.

Third-stage

The third-stage is about 12 meters long and is equipped with the oxidant box full of LH2 in its upper part and the incendiary agent box full of LOX in its lower part. The third-stage uses the hydrogen engine YF-75 and has a second-start capability. It is made of two parallel-connected single-tube engines, with each having a thrust power of 8 tons, and can be driven by servo mechanism in a two-way swing posture, with the maximum swing angle being 4 degrees, to control the flight attitude of the third-stage rocket body.

Satellite fairing

When the rocket flies through the atmosphere, the satellite fairing at the top of the rocket can protect the satellite from interference and provide a safe environment for the satellite. The satellite fairing of the CZ-3C is composed of the top, bi-pyramid section, cylindrical section and the inverted taper. The top is made of fiberglass and has good wireless penetration features. The bi-pyramid and cylindrical sections are made of iron honeycomb material and the inverted taper is made of a chemical alloy material. If necessary, the wireless penetration window and the operating window can be opened on the cylindrical and bi-pyramid sections. The fairing of the CZ-3C is about 10 meters long, with the maximum external diameter being 4 meters and static envelope diameter being about 3.7 meters.

Butt joint of satellite and rocket

The CZ-3C can provide a variety of mechanical interfaces but normally only provides the standard 937B and 1194 mechanical interfaces. The bottom of the satellite and the upper part of the rocket's payload holder are jointed together and locked by belts.

The standard GTO parameters represent the parameters of satellite orbit when the satellite is separated from the rocket. Users can choose different paths based on the needs of satellite and the carrying capacity of the rocket. If the carrying capacity allows, the CZ-3C could send the satellite into a low-inclination orbit or a super-GTO, thus to extend the time limit of the satellite in orbit.

Carrying capacity

The carrying capacity of the CZ-3C in standard GTO is 3.8 tons. The standard GTO parameters and injection accuracy are as tabled below:

Flight timing

Task description

The CZ-3C rocket is able to send satellites into the GTO. When implementing a typical GTO mission, the first and second subsets of the CZ-3C rocket will first send the combination of the satellite and the third subset into a circular parking orbit, and then the third subset will launch a more than 600-second flight in the gliding section. The third subset will turn on its engines again to send the combination into the target GTO after the combination is re-orientated control by the rocket control system. At last, the third subset will be separated from the satellite.

The standard GTO parameters represent the parameters of satellite orbit when the satellite is separated from the rocket. Users can choose different paths based on the needs of satellite and the carrying capacity of the rocket. If the carrying capacity allows, the CZ-3C could send the satellite into a low-inclination orbit or a super-GTO, thus to extend the time limit of the satellite in orbit.

Typical flight timing

 

Operations at launch site

The CZ-3C rocket will be launched at the Xichang Satellite Launch Center (XSLC). The rocket will be transported from Beijing to Xichang in Sichuan Province by train and various tests and operational activities will be launched at the technology center and the launching center of the XSLC, including the four general tests at the technology center, transporting the rocket from the technology center to the launching center, the butt joint of the subsets of the rocket at the launching center, the four general inspections at the launching center, the joint operations of the satellite and rocket, the rocket filling and finally, the launching countdown.

Editor:Zheng Limin |Source: CNTV.cn

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