Moe Orca's view on WS-15. He's not the most reliable person, but it's worth hearing him out I think:
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Summery, he says these are his educated guess:
1. 18.5 tons max thrust is bullshit, real stats for WS-15 isn't published anywhere
2. WS-15 stats are likely to be broadly similar to F-119, that is 0.3 BPR, dry thrust 10 tons, wet thrust 15-16 tons, turbine inlet temperature 1900K, TWR 10.
3. You might feel those stats seem pretty disappointing and only slightly better than WS-10, and might even use more fuel than WS-10 at low altitude, but this is an engine optimized for high speed high altitude, under those operating conditions it's a huge step forward compared to WS-10
4. overall tech level same as F-119
In the weibo post he does say the nozzle is all new and looks very good, with strong emphasis on low IR and low RCS. He's also been repeatedly saying comparing sea level wet thrust as the "one stat to rule them all" is not the correct approach to judge engines and you need to know what the thrust curve is like, and we have no idea about thrust curve.
For your consideration.