YF-115 is an active LOX/kerosene liquid-rocket engine used across Chinese medium-lift launch-vehicle upper-stage configurations. China Aerospace Science and Technology Corporation’s current 2026 report says YF-115 has undergone more than 100,000 seconds of ground-test qualification and is widely used across multiple medium-lift launchers; exact thrust and cycle values are not asserted here because the bounded sources do not provide them.