China has been very agile in developing its super-heavy lift vehicle Chang Zheng 9 (CZ-9). It initially started as a fully expendable rocket, like the Ares V or SLS rockets, but over the years developed into at first a partially reusable concept, and recently, with Starship becoming more real, it changed its design again to become a fully reusable launch vehicle. Today we want to look at the road to that design.
Over the years, head designer Long Lehao, who also managed the Chang Zheng 3 program, has been the most prominent source of updates about the massive rocket, but it also appeared on other stages, such as airshows, and rare updates were provided.
Thanks to people on Weiboo and Cosmic Penguin for doing extended research on CZ-9, the history of its design is available to the public.
The first mention of CZ-9, known internationally as the Long March 9, came in 2009, with two proposed variants. Back then, the vehicle had a diameter of nine meters, with the first version’s first stage using the YF-650 rocket propellant-1 (RP-1) engine. The second version was inspired by the constellation program Ares V and used hydrogen on the center core, with two giant SRBs attached to the side of the body.
After this, and some updates in 2010, it became quiet around CZ-9, as China focused on its other launch vehicles. China started to launch and integrate other more modern rockets, such as the mighty Chang Zheng 5 (CZ-5), or smaller modern adaptions, such as Chang Zheng 11.
It was only in 2021 when CZ-9 shifted into focus again, and since then, it has started a rapid iteration phase, with many designs proposed. In June 2021, the single-body concept, without using side boosters, was mentioned for the first time.
This design would feature two 10.6-meter diameter tanks on the first two stages. The power for the first stage would now be provided by 16 YF-135 RP-1 engines, which produce a thrust of about 360 tonnes each. While reusability was not mentioned in this design, it came in the next step.
In April 2022, at a presentation at the Beijing Institute of Technology, it was first mentioned that CZ-9 might aspire to be at least partially reusable. But that was not the only change, as it set the stage for two different design philosophies. The “Chinese-raptor,” a 200-tonnes methalox engine, was considered to be used. This engine would power the first stage in a 26-engine configuration. Over the coming year, it became clear that this might be a part of an internal debate, of whether the stages should be RP-1 or methane powered.
Around this time, the upgrade to CZ-5, now called Chang Zheng 10 (CZ-10), became the main stepstone to the moon for the Chinese space program. This could cause China to delay CZ-9 more, as it took the pressure out of the program to be necessary for the initial steps to push to the moon.
CZ-10, at this point, followed the design of Falcon Heavy and seemed more like the “final step” to CZ-9 before the country was ready to chase a high-risk concept, such as following Starship and trying to adapt it.
The CZ-9 methalox design was partially rolled back in October 2022, as the initial plan was now to debut CZ-9 with the YF-136 RP-1 engines, and the “Chinese raptor” would be rolled into the design at a later date.
At the beginning of 2023, grid fins appeared for the first time and the liftoff mass and thrust were raised to 4,369 tonnes and 6,118 tonnes, respectively. This would bring the liftoff thrust-to-weight ratio of CZ-9 to about 1.4. At the Zhuhai Airshow, a giant model of the CZ-9 was shown at that time. It showed the rocket with the same diameter on the first and second stages, with a slight increase in diameter in the aft section of the booster.
Over the next months, the transition to the “Chinese Starship” began, as the engine variety in the first and second stages was considerably scaled down. In a presentation in March, both the first and second stages now featured the 200-tonne methalox engine.
In the last update the public got on April 21, the day after the Starship launched for the first time, the design was solidified. The first stage would now feature 30 engines in a 3-9-18 configuration, with three engines being the center engines and 18 on the outside ring. An optional third stage, using the YF-79, also came back to the design to allow for beyond low Earth orbit missions, similar to a kick stage. This design also now features a very Starship-like upper stage, which will allow for the reuse of the second stage, in addition to the already planned reuse of the first stage.
As of now, the debut of this massive rocket is currently planned for 2033, which will not feature reusability at first. In the late 2030s, China plans to debut the partially reusable version of the rocket, with the “Chinese Starship” version not flying before the 2040s. The engine was confirmed to use the full-flow staged combustion cycle for the first and second stages, while the kick stage will utilize hydrolox.
In terms of performance, the three-stage version could bring up to 50 tonnes to lunar transfer, while the first stage reuse version of that rocket could deliver up to 35 tonnes. For the developed two-stage version, up to 150 tonnes could fly to low-Earth orbit in an expendable configuration and 80 tonnes when recovered.
It is unclear which paths Chang Zheng 9 might take in the future, but so far it seems China is very adaptive to the current situation in the global rocket market, especially looking at the industry leader. While it initially looked at NASA to provide designs that would bring the future of rockets, it later changed to closely follow SpaceX designs as they started to take over the leadership in rocket development.
There is a lot of copying design going on here, and China is not even trying to hide it, as Raptor and Starship were mentioned in the past. But in the end, this makes them at least able to catch up to the industry leader, its desired and declared goal.
(Lead image: The future Chinese launch vehicles. Credit: CASC)
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