Long March 7A fails during Xinjishu Yanzheng-6 mission

by Rui C. Barbosa

China suffered a launch failure on the first flight of the new version of the Long March-7, the Long March-7A launch vehicle on Monday. Launch from the Wenchang Space Launch Center took place at 13:34 UTC from the LC201 Launch Complex.

According to Chinese news official statements about the launch, “Chinese space engineers will investigate the cause of the failure,” without giving any more details about the reasons or when the failure occurred.

At this time is not possible to determine if this failure will impact the near term orbital launch schedule of Chinese rockets. The problem seems to have surfaced when the 3rd stage was to operate and if this is the case, then this will probably lead to the grounding of the Long March-3B/G rockets.

The Long March-7A represents a new step in replacing the old families of hypergolic fuelled launchers that have been the workhorse of the Chinese space since its inception in the ’60s.

Previous launches of the original Long March-7 (on June 25, 2016, and on April 20, 2017) were successful.

Onboard the Long March-7A (Y1) was the secretive Xinjishu Yanzheng-6 satellite.

The development of the Long March-7 – LM-7 (Chang Zheng-7 – CZ-7) launch vehicle began in May 2010. It was originally designated Long March-2F/H (Chang Zheng-2F/H – CZ-2F/H).

The new launcher is China’s new-generation medium-lift orbital launch vehicle developed by China Academy of Launch Vehicle Technology (CALT). The initial project was to be a modernized version of the CZ-2F to be used on the unmanned and manned flight missions in China’s “Manned Space Program”.

While the LM-7 will be mainly used for orbiting the new Tianzhou logistics cargo vehicle for the modular Tiangong space station, the LM-7A will be used for orbiting satellites in high energy orbits, also replacing the hypergolic launchers of the LM-2, LM-3 and LM-4 rocket range.

The LM-7 is a two stage launch vehicle equipped with four strap-on boosters. Total length is 53.00 meters, the diameter is 3.35 m and a span of 10.05 m, with a gross mass of 597,000 kg. At launch, it develops a lift-off thrust of 7,200 kN. The rocket is capable of orbiting 13,500 kg into a 400 km LEO and 5,500 kg into a 700 km SSO.
The LM-7A version uses a hydrolox third stage derived from the Long March-3B/G3.

Rocket components are transported to the launch site from the industrial city of Tianjin using two dedicated cargo ships, the Yuanwang-21 and the Yuanwang-22. The components are then offloaded at the Qinglan seaport serving the Wenchang Space Launch Centre.

The new rocket is powered by the YF-100 engine, with the first stage using two engines and strap-on boosters using a single engine each. It includes the YF-115 on the second stage using four engines, using kerosene as fuel and liquid oxygen as oxidizer.

The development of the YF-100 began in 2000 at the Academy of Aerospace Liquid Propulsion Technology. The engine was certified by the State Administration of Science, Technology and Industry for National Defense (SASTIND) in May 2012.

It is a staged combustion cycle engine producing 1,199.19 kN at sea-level with a Isp of 2,942.0 N.s/kg (vacuum values are: thrust 1,339.48 kN; Isp 3,286.2 N.s/kg). The YF-100 will also be used on the CZ-5 and CZ-6 launch vehicles.

The YF-115 is also a staged combustion cycle engine. It develops 176.5 kN in a vacuum.

The first-stage is assisted by four strap-on boosters at launch. The boosters are similar to the first stage, but having a 2.25 m in diameter. The boosters consist of an oxidizer tank, an inter-tank ring section, a fuel tank, an engine frame, a tail section and an aerodynamic nose attached to the front end of the booster covering the upper bulkhead of the liquid oxygen tank.

Each booster is powered by a single 1,200 kN YF-100 engine with a swinging nozzle that can be oriented at radial direction only.

Wenchang, China’s new space launch center

Wenchang Space Launch Centre is located in the northeast corner of Hainan Island on the southern coast of China.

The center is equipped with two launch complexes. Launch Complex LC101 is used for the Long March-5 launch vehicle family while Launch Complex LC201 is used for the Long March-7 launch vehicle.

Both pads are similar and are equipped with a fixed umbilical tower, underground flame deflector trenches and ducts. Similarly to what happens at the other Chinese launch centers, the umbilical towers have swing arms to allow technicians to access and inspect the launch vehicle and payload.

The launch pads are served by two vehicle assembly and integration buildings. Launch Complex LC101 is served by Building 501 while Launch Complex LC201 is served by Building 502. Each building is 99.4 meters tall permitting the assembly and testing of the launch vehicle in a full, vertical stacked position.

This is a new approach to the launch vehicle preparation for flight because at the other Chinese launch centers the launchers are stacked and tested for flight at the launch platforms.

After being stacked at the vehicle assembly and integration building at the top of a mobile launch platform, the rocket is rolled to the launch pad.

The journey takes several minutes to cover the 2,800 meters separating the vehicle assembly and integration buildings, and the launch pads.

After arriving at the launch pads, the mobile structure is then placed above the flame trench and the necessary umbilical connections between the fixed structures and the mobile platform are established ahead of the flow to launch.

The new launch complex provides additional versatility that isn’t available at the other three launch sites. Wencheng also allows for an increase in performance for the launch vehicles gained from Earth’s rotational because is closer to the Earth equator. This reduces the amount of propellants required for the satellite’s maneuvers from the transit orbit to GEO.

Also, the launch vehicle can fly from the launch site to the southeast direction into the South Pacific, avoiding the possibility of rocket debris falling into any populated area – which has occurred during numerous Chinese launches.

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