The Academy of Aerospace Propulsion Technology, a subsidiary of the China Aerospace Science and Technology Corporation, has released three commercial liquid rocket engines. The three new engines boast high reliability, high cost-performance ratio and re-usability. Among them, the YF-102 is the country's first open-type liquid oxygen-kerosene engine, and made its maiden flight on April 2 as the engine used for China's first commercial liquid-fueled carrier rocket, Tianlong-2. The other two rocket engines are the YF-102V and the YF-209, which are still in the development stage.