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. ==References==