I see. So theoretically if the WS-15 is successfully produced it could make FC-31 a single engine aircraft like the F-35?FC-31 is not a large heavyweight fighter, it’s medium sized. WS-10 is a larger engine, and in a twin engine configuration would be for a large fighter. For example, the medium-weight J-10C uses a single WS-10B.
Hopefully someone on the forum can recommend some good books/materials for you to read to further your understanding of military aviation?