Long March 9 - 2021 Iteration
China's new generation heavy-lift carrier rocket, which is capable of carrying a 100-ton payload to the Moon, has basically concluded its feasibility studies and entered the last phase of getting state approval, according to Luan Enjie, former head of the China National Space Administration. Luan, who is also an academician from the Chinese Academy of Engineering and first commander-in-chief of China's lunar exploration mission, revealed the progress during an interview with state broadcaster China Central Television which was aired on 28 February 2021. The feasibility study of the new rocket has basically concluded, and is entering the final stage for state approval, Luan said. "We are working toward initiating research work of the heavy-lift launch vehicle within the 14th Five Year Plan period (2021-25)," he said.
"State approval of the new heavy-lift launch vehicle, which is highly likely to be the Long March-9, will clear the fog for future manned lunar missions," another Beijing-based space expert who asked not to be named, told the Global Times on 01 March 2021. The Beijing expert also predicted that if China wants to launch the new heavy-lift rocket by around 2030, the project will probably get state approval within the next two years, as the research work for Long March-5 took about 10 years after being approved.
On 24 June 2021, Long Lehao, academician of the Chinese Academy of Engineering and Chief Engineer of Long March Rocket, gave a speech entitled "Long March Rockets and China's Aerospace" at the University of Hong Kong, revealing many new developments in China's aerospace. In particular, the latest "21 version" Long March 9 design plan was aimed at the world's most advanced level, comparable to SpaceX's starship under development, and has become one of the strongest heavy-duty launch vehicles in the history of the world.
Long Lehao compared the 2011 version of Long March No. 9 with the 2021 version. The 2011 version of the Long Nine has three versions, namely the Long March Nine with 4 boosters, the Long March 9A with 2 boosters, and the Long March 9B with the "polished pole" version with no boosters. The first stage has four YF130 liquid oxygen kerosene engines with a thrust of 480 tons, and two YF130 boosters. The second stage uses two YF90 liquid hydrogen and liquid oxygen engines with a thrust of 220 tons. The research and development progress of YF130 and YF90 are relatively smooth.
The 2011 version of Changjiu achieved 140 tons, 100 tons and 50 tons of low-earth orbiting capabilities by changing the number of boosters. However, the biggest problem with the 2011 edition of Changjiu was that it was not reusable. Today, when spacecraft reusable technology was popular, as a heavy-duty launch vehicle put into use in the 2030s, if it was still used for a second time, it would inevitably cause the problem of excessive use cost.
In contrast, the booster class of Space X's starship was called "Super Heavy", and the upper stage was often referred to as the Starship. The super heavy-duty uses 28 (maybe 20 in the future) Raptor liquid oxygen methane engines with a thrust of 300 tons, and the Starship uses 6 Raptor engines, which can send loads of 100 to 150 tons into low earth orbit. In terms of low-orbit transportation capabilities, Changjiu and Starship are similar; but in terms of operating costs, there may be a huge gap between the two.
The arrangement of the 2021 Changjiu first-stage engines has 16 YF135 engines in a ring shape, with 9 units in the outer layer, 6 units in the middle layer and 6 units in the inner layer. In terms of current technology, a feature of reusability was the use of a large number of engines in parallel. Due to the reuse of rockets, the reliability of the engine would inevitably decrease. Therefore, it was inevitable that engine failures occur during launch. When a large number of engines are used in parallel, such as 16 engines in parallel, if one engine fails, the engine can be shut down while other engines adjust their thrust output to still complete the task. In this way, the engine in question can be replaced during the next launch.
The model name of the YF135 engine was the first public appearance. As of 2021, it was only known that its single combustion chamber has a thrust of 360 tons, and it was said that the thrust was adjustable between 30% and 110%. As to whether YF135 uses kerosene or methane, it was still unclear, but kerosene was most likely because the technology of kerosene was relatively thorough. If Changjiu really intends to make its first flight between 2028 and 2030, it would be unrealistic to develop a 350-ton high-thrust liquid oxygen methane engine. Even so, China should develop high-thrust liquid oxygen methane engines in the future.
The 350-ton thrust of the YF135 single combustion chamber was technically very impressive. YF130 has two combustion chambers providing 480 tons of thrust, and a single combustion chamber was 240 tons, so it was technically stronger than YF130. The Soviet artifact RD-180 was also a dual combustion chamber. Perhaps YF130 was progressing well to make YF135 possible? Maybe YF135 was formed by upgrading the single combustion chamber thrust of YF130 to 360 tons.
The second and third stages of the 2021 version of Changjiu both use 120-ton oxyhydrogen machines, which was conducive to simplifying the engine model and facilitating production and maintenance. It was not initially known if it was modified on the basis of the YF90 technology with a thrust of 220 tons, or on the basis of the YF100 series? Because the YF100 series was 120 tons. However, the engine does not even have a name, indicating that it was still at a very early stage.
From the perspective of Changjiu's positioning, it was mainly to send 150-ton large cargo into low earth orbit, so as to serve the construction of a lunar base and manned fire. In June 2021, China and Russia signed a lunar research station cooperation agreement, which would jointly build a lunar base between 2031 and 2035.
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