The Long March 12B (Chinese:长征十二号乙运载火箭;pinyin:Chang Zheng 12B, abbreviated LM-12B or CZ-12B), is a Chinese reusable medium-lift to heavy-lift launch vehicle. The rocket has two stages and its first stage is designed to be reused after stage-recovery via propulsive landing. Both stages of the rocket will use kerosene and liquid oxygen (LOX) for propulsion. The rocket is being developed by the China Aerospace Science and Technology Corporation Commercial Rocket Co., Ltd. (CACL), operating under the state-owned China Aerospace Science and Technology Corporation (CASC). The first flight of the rocket was conducted successfully on 1 June 2026.

History

CACL has described the CZ-12B as a 4-meter-diameter class rocket using a kerosene and liquid oxygen propellant mix, unlike the CZ-12A which uses methane and liquid oxygen. CACL further describes the CZ-12B as having a “20-ton-class low Earth orbit carrying capacity”, this is likely in an expendable mode.

A static fire test of the rocket's first stage occurred on 16 January 2026 at the Dongfeng Commercial Space Innovation Test Zone within the Jiuquan Satellite Launch Center in northwest China. The first launch of the CZ-12B occurred on 1 June 2026; the mission was a success and placed the 08 Group of the Qianfan Constellation into polar orbits.

Design

The diameter of the CZ-12B rocket is determined by three factors during the design stage: (1) the requirement to accommodate nine engines in the rocket's first stage in order to increase payload capacity, (2) available options for transporting the manufactured rocket stages from the factory to the launch site, and (3) the rocket's length to diameter ratio. In particular, the relative ease of transporting the stages by road rather than by rail, coupled with the size of the YF-102R engines, constrained the rocket diameter to between 4.2 and 4.5 metres. Additionally, considerations such as the rocket's vibrational mode and structural response to external loads during launch prompted the design team to choose a length-to-diameter ratio of about 16 with an overall rocket length of about 72 metres. These design choices resulted in the team ultimately choosing a rocket diameter of 4.37 metres for the CZ-12B from the "preferred number system" (a list of preferred rocket diameters determined via calculations and modeling).

According to Shan Lei of the China Aerospace Science and Technology Corporation, the design team selected the YF-102R and YF-102RV for the CZ-12B due to the robustness and relative simplicity of the engines' open cycle design (as compared to engines based on the staged combustion cycle) which speeds up the development process at the expense of some degree of engine efficiency. In addition, these engines have the capability for multiple restarts and allow for a wide range of thrust adjustments which open up the prospect for stage recovery and reuse: the YF-102R engines use a high-flow-rate needle-type injector to inject propellant through the central needle for mixing and combustion which is a relatively simple method that facilitates thrust adjustment. Finally, the compact layout of the nine engines first-stage CZ-12B design also argues for the choice of the YF-102R because it uses a 'post-pump oscillation mechanism': “The turbopump doesn’t swing; only the thrust chamber section swings. The swing mechanism is small, so it occupies less lateral space,” said Shan Lei.

Launch statistics

  • Failure
  • Partial failure
  • Success
  • Planned

List of launches

FlightLaunch (UTC)PayloadOrbitLaunch siteOutcomeBooster recovery
Y11 June 2026 08:40Qianfan Polar Group 08PolarJiuquan, CZ-12 padSuccessNot attempted
First flight of the CZ-12B. First stage recovery was not attempted.

See also