China is continuing its program to develop full-flow, staged-combustion methane engines to power the Long March 9 reusable super-heavy launcher. thrust includes advances in overall design and components. Testing includes working prototype and scale components such as igniters, gas generators and draft chambers.

Authors from the Xi’an Aerospace Engine Institute describe China’s progress in developing this and other methane-oxygen engines in a recently published paper. The institute is the main design unit of the Russian Aerospace Exploration Agency at CASC.

Clusters of 26 reusable engines will power the first stage of China’s Long March 9 superheavy launch vehicle, according to designs previously submitted by China’s main space contractor China Aerospace Science and Technology Corporation (CASC). CASC is reportedly targeting 2033 for the giant rocket’s first test flight.

The document states that research began in China in the 1980s, and that metalox engines with 10 and 80 tons of thrust had been developed by this time. The latter has successfully passed hot fire tests, indicating improvements in engine reliability and reusability. The development of metalox engines with a full-flow staged combustion cycle would support China’s plans for future large-scale deep space exploration, including landings on Mars and other targets.

The document claims that the engine is comparable in basic performance to the SpaceX Raptor engine that powers Super Heavy/Starship. As the world’s second full-flow, staged combustion methane engine, it outperforms Blue Origin’s BE-4 and other domestic and international methane engines, the newspaper said. But the newest engines have more thrust.

But the authors highlight the challenges ahead. Full-flow staged combustion engines can provide advantages in terms of reliability and reusability, as well as high thrust and high efficiency. However, challenges include complex system configuration, difficulties in integrated layout and final assembly, and control of the firing process.

They also argue that the country’s foundations for fully developing these engines remain relatively weak. In their opinion, it is necessary to strengthen efforts in the field of relevant technologies to complete a complex and technically complex project. But the goal of quickly reusable, low-cost, high-reliability engines is seen as key to the country’s goals. According to the article, this will become an iconic technology for China’s space sector.

The article also highlights the progress made by Chinese commercial companies in metalox engine production. CASIC’s Mingfeng-1 engine, Landspace’s Tianque engines powering Zhuque-2, and iSpace’s JD-1/Focus-1 variable thrust engine for the reusable Hyperbola series rockets are noteworthy. Longyun engines developed by engine manufacturer Jiuzhou Yunjian and Aerospace Propulsion’s Canglong engines are also on the list.

Landspace, one of the first companies to emerge since China opened its space sector to private capital, operates Zhuque-2, the first and so far only metalox rocket to reach orbit. The startup is also currently planning a metalox rocket made of stainless steel. This vehicle, called Zhuque-3, will be able to send 20 tons if it is disposable and 16.5 tons if it is reusable into low Earth orbit.

Meanwhile, iSpace recently conducted stage jump tests for Hyperbola metalox rockets. In the near future, the company plans to continue testing at the mileage level.

China’s breakthrough in methane engines, progress in the United States, and SpaceX’s demonstration of reusability have changed the long-term direction of China’s space transportation plans. The super-heavy Long March 9 rocket was to be equipped with gas-oxygen engines with a capacity of 500 tons, according to plans dating back to 2011. These engines are in a much more advanced stage of testing. However, these will form the basis of the one-time launch system.

Newer designs introduced in 2022 and 2023 show the Long 9 March design using metalox engines without boosters. Another distant option looks like the Super Heavy/Starship stack.

China is also developing a heavy three-stage rocket specifically to send Chinese astronauts to the moon by 2030. This rocket will be powered by upgraded Kerolox engines based on the Long March 5. The first stage and the two-stage LEO version of this rocket could potentially be recovered and reused.