Long March 2D launches SaudiSAT-5A/B

by Rui C. Barbosa
China launched another orbital mission from its Jiuquan Satellite Launch Center using a Long March-2D (Chang Zheng-2D) launch vehicle on Friday orbiting several satellites along with primary payloads SaudiSAT-5A/B. Launch took place at 04:12 UTC from Launch Pad 94 of the LC34 Launch Complex.

The Piao Chong 1 to 6 (Ladybug 1 to 6), Tianyi X1 to X3 and Weina-1 03 satellites were ride companions of the two primary mission SaudiSAT-5 satellites.

Developed by KACST (King Abdulaziz City for Science & Technology), the SaudiSAT-5A and SaudiSAT-5B satellites are Earth observation and technological demonstration satellites from Saudi Arabia.

The satellites are equipped with an optimized regional hyper-spectral observation system, each satellite having a mass of 200 kg at launch.

The development of the two SaudiSAT-5 satellites resulted from an agreement between the governments of Saudi Arabia and Belarus that is part of a larger effort by Riyadh to build up capacities and the capacity to build their own satellites. This agreement was signed on May 16, 2016, during a visit by representatives of Saudi Arabia to Minsk.

The SaudiSAT-5 team

The agreement for the launch of these satellites was signed between Saudi Arabia and China in January 2016 during a visit by Chinese President Xi Jinping to Riyadh. Also as part of this agreement, China will improve remote sensing facilities and related services. KACST will also work in cooperation with the Chinese navigation system at the level of scientific studies for the development of systems and the use of China’s navigation system.

The Long March-2D (LM-2D) launch vehicle is a two-stage rocket developed by the Shanghai Academy of Spaceflight Technology. With storable propellants is mainly used to launch a variety of low earth orbit satellites.

The development of LM-2D was started in February 1990. From 2002, to meet the demand of SSO satellites, the payload fairing of 3350mm in diameter and attitude control engine for the second stage have been successfully developed; and the discharge of remaining propellant and de-orbit of the second stage have been realized. This launcher is mainly used for launching LEO and SSO satellites.

It is characterized by high reliability, wide application and mature technology.

The LM-2D can launch a 1,300 kg cargo in a 645 km SSO. The rocket is 41.056 meters long and the first, second stages and payload fairing are all 3.35 meters in diameter.
The first stage is the same as the Long March-4.

The second stage is based on LM-4 second stage with an improved equipment bay. Lift-off mass is 232,250 kg, total length 41,056 meters, diameter 3.35 meters and fairing length 6.983 meters. At launch, it develops 2961.6 kN engine thrust.

The first stage has a 27.910 meter length with a 3.35 meter diameter, consuming 183,200 kg of N2O4 / UDMH (launch mass of the first stage is 192,700 kg). Equipped with a YF-21C engine capable of a ground thrust of 2,961.6 kN and a ground specific impulse of 2,550 m/s. Burn time is 170 seconds.

The second stage has a 10.9 meter length with a 3.35 meter diameter, launch mass of 39,550 kg and consuming 35,550  kg of N2O4 / UDMH. Equipped with a YF-24C cluster engine with a main engine vacuum thrust of 742.04 kN and a vernier engine with a vacuum thrust of 47.1 kN (specific impulses of 2,942 m/s and 2,834 m/s, respectively).

The LM-2D can use two types of fairings depending on the cargo. Type A fairing has a 2.90 meters diameter (total launch vehicle length is 37.728 meters) and Type B fairing with a diameter of 3.35 meters – total launch vehicle length is 41.056 meters.

Launch profile of the Long March-2D starts with engine ignition at 1.2 seconds before lift-off. Pitch over maneuver happens at 12 seconds into the flight and the end of the first stage ignition occurs at two minutes 33 seconds.
Stage separation and second stage ignition occur one second latter. At 3 minutes 34 seconds the two parts of the fairing separate from the second stage.

Second stage main engine cut-off takes place at 4 minutes 21 seconds and second stage Vernier engines cut-off takes place at 9 minutes and 10 seconds. Nominally payload separation takes place three seconds later.

The first launch of the LM-2D was on August 9th, 1992 from the Jiuquan Satellite Launch Center orbiting the Fanhui Shei Weixing FSW-2-1 (22072 1992-051A) recoverable satellite.

The LM-2D can use the Yuanzheng-3 (YZ-3) upper stage. This is capable of restarting more than 20 times and operating for more than 48 hours. It is equivalent to mainstream upper stages in the world in terms of performance, such as restart times, in-orbit operation time, independent digital control system, and adaptable behavior for various tasks.

The Yuanzheng-3 upper stage was developed to meet the urgent needs for launch vehicles brought by the growth of small satellites, satellite constellations, electric propulsion platforms, etc. The YZ-3 can also be used on the Long March-4B launch vehicle. It is understood it was not used on this mission.

The Jiuquan Satellite Launch Center, in Ejin-Banner – a county in Alashan League of the Inner Mongolia Autonomous Region – was the first Chinese satellite launch center and is also known as the Shuang Cheng Tze launch center.

The site includes a Technical Centre, two Launch Complexes, Mission Command and Control Centre, Launch Control Centre, propellant fuelling systems, tracking and communication systems, gas supply systems, weather forecast systems, and logistic support systems.
Jiuquan was originally used to launch scientific and recoverable satellites into medium or low earth orbits at high inclinations. It is also the place from where all the Chinese manned missions are launched.

The LC-43 launch complex, also known as South Launch Site (SLS) is equipped with two launch pads: 91 and 94. Launch Pad 91 is used for the manned program for the launch of the Long March-2F launch vehicle (Shenzhou and Tiangong). Launch Pad 94 is used for unmanned orbital launches by the Long March-2C, Long March-2D and Long March-4C launch vehicles.

Other launch zones at the launch site are used for launching the Kuaizhou, Kaituo and the Long March-11 solid propellant launch vehicles.

The first orbital launch took place on April 24, 1970 when the Long March-1 rocket launched the first Chinese satellite, the Dongfanghong-1 (04382 1970-034A).

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