about WS-10C ? well entire Chinese nation and aviation enthusiasts knows, J-20 deputy chief designer himself confirmed and said, WS-10C is better than AL-31F.
now come to WS-15. first time state media CCTV officially confirmed about WS-15 under final phase of flying test. and enhance its performance , durability. back in 2021 when first time WS-15 flew on J-20 with one engine, local Chengdu journalist confirmed. that was the breaking news at that time on Chinese social media.
follow my massages on 'Chinese aero engine development' thread. you will find very interesting information. i have my own source as well. thank you