Long March 4C lofts latest Yaogan Weixing satellite

by Rui C. Barbosa

Confirming the rumors that have circulated over recent days, China has launched another new satellite in the military’s Yaogan Weixing series via the use of a Long March-4C (Chang Zheng-4C) rocket. The mission began with liftoff at 02:31 UTC on Thursday, from the LC9 launch complex at the Taiyuan Satellite Launch Center.

Chinese Launch:

As per usual, Chinese media is referring to the new satellite as “a new remote sensing bird that will be used for scientific experiments, land survey, crop yield assessment, and disaster monitoring”.

However, as was the case in the last launches of the Yaogan Weixing series, western analysts believe this class of satellites is used for military purposes.

A Y-W SatelliteThis latest launch is believed to be of a satellite in the YG-8/15/19/22 series, understood to be the fifth electro-optical, third generation satellite equipped with a high-resolution wide-angle observation system and based on the Phoenix Eye-2 bus.

Also known as Jianbing-9, this type of satellite operates on a typical 1,200×1,200 km x 100.3 degree SSO orbit. The satellites are built by Shanghai Academy of Spaceflight Technology (SAST).

Yaogan-27 was launched by a Long March-4C launch vehicle. With its main commonality matched to the Long March 4B, the first stage has a 24.65 meter length with a 3.35 meter diameter, consuming 183,340 kg of N2O4/UDMH (gross mass of the first stage is 193.330 kg).

The vehicle is equipped with a YF-21B engine capable of a ground thrust of 2,971 kN and a ground specific impulse of 2,550 Ns/kg. The second stage has a 10.40 meter length with a 3.35 meter diameter and 38,326 kg, consuming 35,374 kg of N2O4/UDMH.

It includes a YF-22B main engine capable of a vacuum thrust of 742 kN and four YF-23B vernier engines with a vacuum thrust of 47.1 kN (specific impulses of 2,922 Ns/kg and 2,834 Ns/kg, respectively).

2015-08-27-081458The third stage has a 4.93 meter length with a 2.9 meter diameter, consuming 12,814 kg of N2O4/UDMH. Having a gross mass of 14,560 kg, it is equipped with a YF-40 engine capable of a vacuum thrust of 100.8 kN and a specific impulse in vacuum of 2,971 Ns/kg.

This launch was the 220th Chinese orbital launch, the 208th success and the 207th launch of the Long March launch vehicle family.

It was also the 53rd successful orbital launch from the Taiyuan Satellite launch Center, the 2nd launch from this space center in 2015 and the 4th orbital launch for China this year.

Launch took place from the Taiyuan Satellite Launch Center (TSLC). Situated in the Kelan County in the northwest part of the Shanxi Province, TSLC is also known by the Wuzhai designation. It is used mainly for polar launches (meteorological, Earth resources and scientific satellites).

Z114The launch center has two single-pad launch complexes, a technical area for rocket and spacecraft preparations, a communications centre, a mission command and control centre, and a space tracking centre.

The stages of the rocket are transported to the launch centre by railway and offloaded at a transit station south of the launch complex. They were then transported by road to the technical area for checkout procedures.

The launch vehicles were assembled on the launch pad by using a crane at the top of the umbilical tower to hoist each stage of the vehicle in place. Satellites were airlifted to the Taiyuan Wusu Airport about 300km away and then transported to the centre by road.

The TT&C Centre, also known as Lüliang Command Post, is headquartered in the city of Taiyuan, It has four subordinate radar tracking stations in Yangqu (Shanxi), Lishi (Shanxi), Yulin (Shaanxi), and Hancheng (Shaanxi).

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