The China Academy of Launch Vehicle Technology (CALT) has announced a major breakthrough in the development of large-diameter stainless steel propellant tanks for its next-generation launch vehicles. CALT, a key player under the China Aerospace Science and Technology Corporation (CASC), recently unveiled prototypes measuring 5.0 meters and 10.6 meters in diameter.
The 10.6-meter tank, a significant achievement, is integral to the development of the Long March 9, a future reusable super heavy-lift rocket intended for ambitious lunar and infrastructure missions. Its design also incorporates concepts for crewed Mars missions. “The success of this prototype marks a major breakthrough in the development of ultra-large-diameter stainless steel tanks and represents a solid first step toward the iterative development of large-diameter stainless steel structures for heavy-lift launch vehicles,” CALT stated in a previous social media post.
CALT’s choice of stainless steel is strategic. The academy highlights the material’s potential for large-diameter cryogenic propellant tanks, particularly in reusable, low-cost, and rapidly manufactured launch systems. However, they acknowledge challenges compared to aluminum alloys, including machining difficulty, susceptibility to buckling, and weld deformation. These challenges required substantial advancements in assembly, welding, and forming technologies.
The 5.0-meter-diameter tank’s immediate application is less clear, though it could relate to the Long March 10 series. CALT stated that the 5.0-meter prototype development marked a breakthrough in its production and manufacturing technology innovation, providing strong support for the smooth progress of major national engineering tasks. The project was also touted as successful exploration of CALT’s innovative development model, featuring rapid iteration with digital empowerment.
China’s growing commercial space sector is also embracing stainless steel. Landspace, for example, is developing the Zhuque-3 stainless steel launcher and is aiming for its first orbital launch in the second half of 2025. Other companies, such as Lightyear Exploration and Space Epoch, are also contributing to this trend.