A Look at China's Reusable Super Rocket

Tracking the evolution of the ChangZheng 9

I support any and all innovations that improve access to space. Private companies in the United States, led by SpaceX, are leading the charge, developing reusable platforms that will make space travel immensely more affordable. Across the ocean, China also embracing a reusable future and is quietly developing what is perhaps the only real competitor to SpaceX’s Starship.

Information is sparse, often mistranslated, or misinterpreted. In this article, I will do my best to piece together what Chinese engineers are working on, with an exclusive look at the history and future of this evolving rocket. My findings suggest that Chinese engineers are more ambitious than most of their Western counterparts.

~2006 The ChangZheng 9（长征9号）Emerges

Development of China’s super heavy-lift rocket, known as the Long March 9 (LM-9), or ChangZheng-9 (长征九号/CZ-9) in Chinese, can be traced back to the early 2000s. Note, these were conceptual studies and were not officially endorsed by the Chinese leadership. They nonetheless illustrate that China has long had an interest in fielding a super-heavy lift rocket that would enable crewed lunar and potentially Martian missions.

The earliest diagram I found dates from ~2006. The LM-9 was conceptualized by the China Academy of Launch Vehicle Technology (CALT), an institute under the China Aerospace Science and Technology Corporation (CASC), the prime state-owned rocket contractor.

This diagram suggested two design options for the LM-9. Both feature a single 9-meter diameter core with up to four strap-on boosters. The Option “A” design features four 3.35-meter diameter kerosene-fueled boosters, each powered by a single “YF-650” engine. The core stage is also kerosene-fueled and powered by another four “YF-650” engines. The upper stage is apparently hydrogen-fueled and propelled by two “YF-220” engines.

The Option “B” version was slightly taller and utilized four solid-fueled strap-on boosters. Instead of kerosene, the first and second stages both burned hydrogen, with the first powered by five “YF-220” engines and the second by a lone “YF-220.” Both designs would be able to loft some 130 tons into Low Earth Orbit (LEO), roughly the same as the Saturn V.

You’ll notice that I placed quotation markets around the engine names. This is because I can find little information to support the authenticity of this nomenclature. Rather, the naming appears to be a placeholder for possible future engines and the number refers, not to a model number, but to the total engine thrust. That is, the “YF-220” simply refers to an engine that produces roughly 220 tons of thrust, and the “YF-650” produces roughly 650 tons.

~2011 Option A Wins

As we can see from this screenshot, apparently captured from a presentation at the CASC around 2011, it was clear that the LM-9 “Option A,” with liquid-fueled boosters, had won out. This is likely due to China’s relative inexperience in solid-fueled rockets at that time.

Additionally, the design had changed in other ways. The boosters had become larger, at 5 meters in diameter, possibly to take advantage of the tooling and infrastructure from the LM-5 rocket, which was also under development at that time.

The engines on the boosters and core stage had reduced thrust capacity, now down to 480 tons each. To compensate, the engines were now paired up on the boosters. The same 480-ton engine was placed fourfold on the core stage, with the second stage still powered by twin 220-ton thrust hydrogen-fueled engines. Notable, the LM-9 now featured a (likely optional) third stage using 4 25-ton engines.

In all, the rocket would be able to loft some 50 tons to the Moon, or about 8 tons more than NASA’s proposed SLS Block 1B.

~2019 The Design Solidifies

By 2019 it’s clear that engineers were close to finalizing the LM-9’s design. The 480-ton and 220-ton engines now had formal names, the YF-130 and YF-90 respectively. Development of these engines was well underway. The YF-130 engine follows in the footsteps of the advanced Russian RD-180, featuring dual chambers and nozzles. The YF-130, however, was significantly more powerful than its Russian counterpart.

Again, the rocket’s capabilities expanded, with it now estimated to loft up to 180 tons to LEO and some 65 tons to the Moon. It was also recognized that the LM-9 would come in several variants, including an “A” version with only two boosters, and a “B” version with no boosters.

The development of the rocket was fairly advanced by this point. Engineers had already forged the 9.5-meter diameter alloy rings and made significant progress on the engines, including assembling the first complete YF-130 and preparing it for a test fire.

2021-An Abrupt Shift

In 2021, China’s authorities gave formal approval to develop the LM-9, but just as the first prototype YF-90 was built, the first YF-130 lit, and barrel sections and domes assembled, CASC engineers unexpectedly tossed a decades’ work out the window.

In an abrupt shift, it was revealed that the boosters were deleted entirely and the core stage further widened. In addition, as we can see in the diagram above, the fuel and oxidizer tanks were revised to save weight, now featuring “common dome” construction as is commonly seen in Western launch vehicles.

The 4 YF-130 engines on the core were replaced with 16 YF-135 engines in a ring configuration; nine in the outer ring and six in the inner ring. Though no details on the YF-135 were presented, the engine is believed to be based on the YF-130, but further improved and essentially cut in half (single nozzle/single chamber) producing some 360 tons of thrust. The second stage, surprisingly, dumps the YF-90, instead opting for four 120-ton hydrogen-fueled engines. The optional third stage would use a single example of the same.

Though not explicitly stated, the new design seems to reflect a concern that the original LM-9 configuration would have been obsolete by the time it flew in 2030. In a world slowly adopting rocket reuse, the LM-9 had no clear path to reusability.

If the LM-9 had retained all boosters, for example, it would have had to land 4 boosters and the core with each flight….a logistically difficult challenge. Cutting the YF-130 in half is, additionally, likely intended to make it easier for the engines to gimbal independently of one another, and make throttling down for landing more feasible.

That said, there are no fins or landing legs on the LM-9, suggesting that engineers had left reuse as a possibility for later upgrades, but didn’t want to “bake it in” to the design from the start,

LM-9 hardware was already well underway before the design was jettisoned.

2022-Reusability Emerges

In 2022 the LM-9 saw yet another complete redesign and this time, a corresponding delay. The first flight was now planned for 2035. Perhaps most notably, engineers dumped kerosene fuel for methane, following in the footsteps of SpaceX and much of the industry. With the change in fuel, also came a change in engines. The first stage now features some 26 unnamed 200-ton engines.

Little is known about these engines other than they are designed to be reused at least 50 times. But an 8-year development slide published by the CASC in 2022 gives us some clues.

The 200-ton engine that powers the new LM-9 appears in the uppermost left and is said to be an “FFSC” engine, or a Full-Flow Staged Combustion cycle engine, much like SpaceX’s Raptor. As rocket enthusiasts know, this is the Holy Grail of engine technology. Additionally, the LM-9 now appears with grid fins, implying that reuse will be baked into the design of the first stage from the very first flight.

With the switch to Methane fuel, a large cluster of FFSC engines, grid fins…etc, you would be forgiven if you got “Starship” vibes from the new LM-9. This is not to say that the LM-9 is, in any way, “copied” from Starship. China is certainly able to develop this technology independently. Likely, what is happening here is that as China pursues rocket reusability, engineers are coming to the same conclusions as SpaceX in terms of broad design choices.

Sunk Cost Fallacy

The LM-9 design will continue to evolve and we may someday see Starship-like fins on the upper stage. What’s important to note here is that China is not falling victim to the “sunk-cost” fallacy that appears to plague government programs in Europe and the United States.

China’s state contractor was willing to forsake a relatively mature design with functioning hardware in favor of a better, cheaper, and modern alternative. The same cannot be said for NASA’s SLS, an anachronism that continues to lumber on, carried only by its own inertia.

The delay of the LM-9 will not meaningfully affect China’s space program as China is working on a parallel super-heavy lift rocket, scheduled to fly in 2026, that will fill the gap. More on that rocket here.

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