Chinese Long March 3B lofts Alcomsat-1 for Algeria

by Rui C. Barbosa

China is continuing to pick up its launch cadence via the launch of a new communications satellite for Algeria on Sunday. The Alcomsat-1 satellite was orbited by a Long March-3B/G2 (Chang Zheng-3B/G2) launch vehicle from the LC2 Launch Complex of the Xichang Satellite Launch Center. Liftoff time was recorded at 16:41 UTC.

Alcomsat-1 Launch:

The Alcomsat-1 launch comes several years after it was originally hoped, having initially scheduled for launch in 2014.

The Chinese made Algerian satellite is dedicated to space communications, providing broadcast services, Internet, telephony and VSAT services.

The satellite was developed by the Chinese Academy of Space Technology (CAST) and is based on the DFH-4 platform. Its communications payload is composed of 33 operational transponders (19 in Ku band, 12 in Ka band and 2 in L band). The satellite will operate for 15 years on the geosynchronous orbit. Launch mass is around 5,200 kg.

Alcomsat-1 will be operated by the Agence Spatiale Algérienne (ASAL).

As part of the contract assigned with the China Great Wall Industry Corporation for the development, manufacture, launch and orbital delivery of Alcomsat-1, two ground control stations were built in Médéa and Ouargla, Algeria. The two station will be used to control the satellite and will be operated by Algerian trained in China.

The DFH-4 (DongFangHong-4) platform is a large telecommunications satellite platform of the next generation. It provides high capability in output power and communication capacity ranking with international advanced satellite platforms.

The applications for the DFH-4 platform isn’t limited to high capacity broadcast communication satellites and can be used as a tracking and data relay satellite, regional mobile communication satellite, etc.

Image result for Chinese DFH-4 platformThe platform comprises propulsion module, service module and a solar array system. It has a payload capacity of 588 kg and an output power of 10.5 kW by the end of its lifetime. Its design lifetime is 15 years and its reliability by the end of its lifetime is more than a 0.78 industry ratio.

The platform is equipped with 22 Ku-band transponders (four 54MHz and 18 36MHz), 3 receiver antennas, and two transmission antennas.

The DFH-4 can support the transmission of 150~200 TV programs simultaneously to ground users using a 0.45 meters antenna device. The DFH-4 satellite also features strong capabilities against hostile disturbance and jamming. The satellite’s power supply includes two 6 meters solar panels.


Established in 1980, the China Great Wall Industry Corporation (CGWIC) is a commercial organization authorized by the Chinese government to provide satellites, commercial launch services and to carry out international space cooperation.

As the professional company promoting international cooperation for China’s space industry, CGWIC is devoted to the internationalized development of China’s space industry.

CGWIC has developed into a system integrator for space products and services. It can meet customer’s multi-directional needs by providing comprehensive solutions for commercial launch services, satellite export, satellite ground tracking and control station construction, satellite applications, project financing, project insurance and technical training, etc.

Through extensive international cooperation, CGWIC enjoys an excellent reputation in the international aerospace industry, the financial community and the insurance industry.

In addition, CGWIC is actively involved in the international marketing of civilian products and services utilizing space technology and provides high quality products and specialized services in diversified fields including satellite technology applications, green energy, information & electronic products, petroleum & petrochemical equipment, new materials, consulting services, international trade, international exhibition, international logistics, project contracting, international bidding, etc.

The Algerian Space Agency (Agence Spatiale Algérienne – ASAL) was established on January 16, 2002, in Bouzareah, Algiers.

The main objectives of the ASAL are to propose to the Algerian government the elements of a national strategy in the field of space activity and ensure their implementation in the establishment of a space infrastructure to strengthen Algerian national space capacities.

Launch vehicle and launch center:

Alcomsat-1 was orbited by a Long March-3B/G2 (Chang Zheng-3B/G2) version of the Long March-3B.

Developed from the Long March-3A, the Long March-3B features enlarged launch propellant tanks, improved computer systems, a larger 4.2 meter diameter payload fairing and the addition of four strap-on boosters in the core stage that provide additional help during the first phase of the launch.

The rocket is capable of launching a 11,200 kg satellite to a low Earth orbit or a 5,100 kg cargo to a geosynchronous transfer orbit.

The LM-3B/G2 (Enhanced Version) launch vehicle was developed from the LM-3B, increasing the GTO capacity up to 5,500kg. The LM-3B/E has nearly the same configurations with LM-3B bar its enlarged core stage and boosters.

The first launch of the LM-3B was the infamous ‘St. Valentine Day Massacre’ and took place on February 14, 1996, but ended in failure. In this day the first LM-3B launcher failed 2 seconds after liftoff and crashed in a nearby village killing an untold number of people.

The first successful launch took place on August 19th, 1997 when the second LM-3B orbited the Agila-2 ‘Mabuhay’ (24901 1997-042A) communications satellite.

On May 14, 2007, the first flight of LM-3B/G2 was performed successfully, accurately sending the NigcomSat-1 into pre-determined orbit. With the GTO launch capability of 5,500kg, CZ-3B/G2 is dedicated for launching heavy GEO communications satellite.

The rocket structure also combines all sub-systems together and is composed of four strap-on boosters, a first stage, a second stage, a third stage and payload fairing.

The first two stages, as well as the four strap-on boosters, use hypergolic (N2O4/UDMH) fuel while the third stage uses cryogenic (LOX/LH2) fuel. The total length of the LM-3B is 54.838 meters, with a diameter of 3.35 meters on the core stage and 3.00 meters on the third stage.

On the first stage, the LM-3B uses a YF-21C engine with a 2,961.6 kN thrust and a specific impulse of 2,556.5 Ns/kg. The first stage diameter is 3.35 m and the stage length is 23.272 m.

Each strap-on booster is equipped with a YF-25 engine with a 740.4 kN thrust and a specific impulse of 2,556.2 Ns/kg. The strap-on booster diameter is 2.25 m and the strap-on booster length is 15.326 m.

The second stage is equipped with a YF-24E (main engine – 742 kN / 2,922.57 Ns/kg; four vernier engines – 47.1 kN / 2,910.5 Ns/kg each). The second stage diameter is 3.35 m and the stage length is 12.920 m.

The third stage is equipped with a YF-75 engine developing 167.17 kN and with a specific impulse of 4,295 Ns/kg. The fairing diameter of the LM-3B is 4.00 meters and has a length of 9.56 meters.

The LM-3M can also use the Yuanzheng-1 (“Expedition-1″) upper stage. It uses a small thrust 6.5 kN engine burning UDMH/N2O4 with specific impulse at 3,092 m/s. The upper stage should be able to conduct two burns, having a 6.5 hour lifetime and is capable of achieving a variety of orbits.

It will be adapted for use on the LM-3A/B/C series mainly for direct MEO/GEO insertion missions (mostly for the navigation satellites of the Beidou GNSS).

General mission launch sequence for the CZ-3B/G2:

The fuelling of the third stage with LOX and LH2 starts at L-7h. First and second stages, as well as the four strap-on boosters, use hypergolic propellant fuelled earlier. At L-1h 20m is the launch vehicle control system power on and function checkout followed by the telemetry system power on and function checkout.

At L-40m the fairing air-conditioning is turned-off and the air-conditioning pipe is dropped-off. Technicians also proceed with the flight program loading and check-up. The gas pipes for the first stage second and are dropped-off. The pre-cooling of the third stage engines takes place at L-20m and at L-13m takes place the third stage propellants topping.

Between L-15m and L-10m the spacecraft umbilical disconnection takes place and at L-3m the telemetry and tracking systems power is switch-over and the third stage propellant fueling pipe is disconnected.

The disconnection of the gas pipe for the third stage is disconnected at L-2m followed by the control system power switch-over at L-1m 30s. Control system, telemetry system and tracking system umbilical disconnection takes place at L-1m as well as the swinging-off of the rods. The TT&C systems start at L-30s and ignition comes at L-0s.

Eleven seconds after lift-off takes place the pitch-over maneuver. Boosters separation occurs at T+2m 21s followed at T+2m 39s by the separation between the first and second stages. Fairing jettison comes at T+3m 55s.

Separation between the second and third stage takes place at T+5m 44s, with the third stage igniting for the first time. This burn ends at T+10m 12s. The vehicle is now on a preliminary orbit until T+20m 56s when the third stage starts its second burn.

This burn will last for 3 minutes and 6 seconds, ending at T+24m 2s. After the third stage shutdown takes places at T+24m 22s an attitude adjustment before spacecraft separation at T+25m 42s.

The Xichang Satellite Launch Centre is situated in the Sichuan Province, south-western China and is the country’s launch site for geosynchronous orbital launches.

Equipped with two launch pads (LC2 and LC3), the center has a dedicated railway and highway lead directly to the launch site.

The Command and Control Centre is located seven kilometers south-west of the launch pad, providing flight and safety control during launch rehearsal and launch.

Other facilities on the Xichang Satellite Launch Centre are the Launch Control Centre, propellant fuelling systems, communications systems for launch command, telephone and data communications for users, and support equipment for meteorological monitoring and forecasting.

The first launch from Xichang took place at 12:25UTC on January 29, 1984, when the Long March-3 (Y1) was launched the Shiyan Weixing (14670 1984-008A) communications satellite into orbit.

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