The Longyun (Chinese: 龙云; pinyin: Lóngyún, lit. Dragon Clouds) is a gas-generator cycle rocket engine burning liquid methane and liquid oxygen developed by Jiuzhou Yunjian.
History In 2018, the gas generator test for the Longyun engine was completed. The engine completed multiple start-up hot test runs in May 2021. In October 2021, launch startup Rocket Pi signed a deal to use the Longyun engine to power its Darwin-1 reusable launch vehicle. Space Epoch conducted a ground test of a 4.2-meter stainless steel stage powered by the Longyun engine in January 2023. In April 2024, Longyun passed a long duration hot firing test with the servo mechanism rotating to the maximum angle of ±8°. The engine has also reportedly passed the customer acceptance test. On December 23, 2025 the Longyun-70 engines were used on the first flight of Long March 12A rocket. The rocket successfully deployed its payload, but an attempt to land its first stage failed.
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