Long March 7

The Long March 7 (Chinese: 长征七号运载火箭), or Chang Zheng 7 in pinyin, is a Chinese liquid-fuelled medium-lift launch vehicle from the Long March family. Developed by the China Aerospace Science and Technology Corporation, it had its first successful flight on 25 June 2016. This rocket is known as Bingjian, which means "the Ice Arrow".

Long March 7 was created to replace the Long March 2F and was expected to become a very important rocket for China, handling about 70% of all launches. It plays a big role in the Tiangong space station program by launching the Tianzhou cargo spacecraft that bring supplies to the space station. Although it was first meant to carry astronauts, this job is now being taken over by a new rocket called the Long March 10A.

The Long March 7 has special fuel called kerolox in its main parts and uses engines called YF-100 to take off. It also has engines named YF-115 for its second part of the flight. A newer version, the Long March 7A, added a third part with YF-75 engines, and helped create another rocket called the Long March 8.

History

The Long March 7 project began in 2008 when a development team was formed at CALT. The team planned to update the Long March 2F by changing its fuel and improving its engines. However, this change led to many new challenges, making the project more complex.

Later, the project for the Long March 5 was also changed to include different versions of rockets. Because of this, the teams decided to combine the projects for the Long March 2F and the Long March 5. This helped mix the reliable parts of the Long March 2F with new technologies from the Long March 5.

In 2010, the project was officially named the Long March 7. It needed eleven new major technologies and was the first time the whole process was developed using digital design and manufacturing.

The first flight of the Long March 7 happened successfully on June 25, 2016, at 12:00 UTC from the Wenchang launch pad. It flew in the LM-7 version with the new Yuanzheng-1A upper stage and completed its mission well.

Design

The Long March 7 is a medium-lift rocket that is part of a new family of rockets. It is based on the reliable Long March 2F rocket and uses LOX and kerosene instead of older, more dangerous fuels. This makes it safer and cheaper. It can carry about 5,500 kg into a special orbit called Sun-synchronous orbit.

The Long March 7 shares some parts with other rockets like the Long March 5 and Long March 6, but it was built by different teams. It can be changed by adding boosters or extra stages to carry more weight or reach higher orbits. This makes it very flexible. The rocket can carry between 4,000 kg and 13,500 kg to low Earth orbit, depending on its setup.

The rocket uses special engines and control systems that were developed locally, making it a good base for future rocket designs.

2013 proposed variations

In a paper published in Manned Spaceflight, the Long March 7 was described as a family of different rockets. These rockets would have names starting with CZ-7##, where the first number showed how many main parts the rocket had (either 2 or 3). The second number showed how many extra rockets helped it lift off (0, 2, or 4). If these extra rockets were a special solid type, an S would be added.

Some versions could have a different second part of the rocket using LH/LOX fuel and special YF-75 engines, marked with (HO). Some could also have an extra part at the top, called the Yuanzheng-1A, marked with /SM.

For example, the version that first flew was called CZ-724/SM because it had two main parts with RP-1/LOX fuel, four extra liquid rockets, and the Yuanzheng-1A top part. A CZ-720 would have two RP-1/LOX parts and no extra rockets. A CZ-724S(HO) would have a RP-1/LOX first part, a LH/LOX second part, and four solid extra rockets. A CZ-732 would have two RP-1/LOX parts, a LH/LOX third part, and two liquid extra rockets.

The paper also talked about what kind of fuel each part could use. In some versions with no extra rockets, the second part would use RP-1/LOX fuel but only two YF-115 engines instead of four.

CZ-7A variant

Since 2020, a new version called the CZ-7A has been added to the CZ-7 family. This version uses the same first two parts as the basic CZ-7 but adds a third part with special engines that use very cold fuels. The design of this third part comes from another rocket called the Long March 3B.

The first CZ-7A flight happened on March 16, 2020, but it did not go as planned. The exact reason for this problem was not explained right away. The next flight of the CZ-7A happened successfully on March 11, 2021, carrying a satellite called Shiyan-9 to test new space technologies.

Launch Statistics

Launch outcomes :

List of launches

Main article: List of Long March launches