[maxglute]

WS15 matches western on raw power, i.e. comparable thrust to f119/f135 (f22/f35). PRC cores lacks CMC which was last (2000s) western hot section revolution, but that's more about efficiency ~10-20% better range. We don't know WS15 maintenance/metallurgical gap - no one really knows if their service/overhaul hours, but even if heresay assumption 30-50% lifepsan, that's something PRC industrial output can circumvent, i.e. simply building 2-3x more engines and iterate/improve. CMC fuel efficiency huge, but issue 20% doesn't buy F35s enough range/endurance in westpac theatre size without tanking in many scenarios etc. PRC gets around that by just making J20 chonky boi with massive internal fuel, worked around efficiency from systems perspective.

[foldr]

I think we're talking slightly at cross purposes. The f119 is an engine that flew in 1997. So while the WS-15 is evidence that China can make modern, well-performing military jet engines, it doesn't show that China has caught up with the West in that particular area.

For civil applications, fuel efficiency is non-negotiable if China is to sell engines outside its domestic market.

[maxglute]

I'm just point out lead in specific area can be made up elsewhere and not indicative of overall lead.

WS15 is basically parity with F135 in terms of trust/kinematics, i.e. PRC is functionally at parity with latest fielded US military engines. US still head in efficiency and (heresy osint) lifespan but those are swap, logistics issues that can be worked around, - 20% fuel efficiency negated by larger airframe to carry more fuel (25% for single engine, 40% for twin) and lifespan by just building a lot of cores. There is something to be said about PRC 4/5 gen are twin/triple engined, i.e. in aggregate, on paper MUCH more trust/perf/power gen than single engine F35 w/F135. And now that PRC MIC aviation is starting to spam airframes, J20 triple digits, J35s about to explode, and we are talking about underlying industrial chain that is on trend to supply 3-4x+ more engines than US per year for airframes (not factoring in spares). Have to view from systems perspective, US engine lead =/= platform lead, and US fundamentally constrain in F35/5th gen fleet as single engine and 6th gen in limited quantities, and tyranny of distance in westpac = 20% efficiency from being 10 years ahead in CMC doesn't give meaningful edge. F35/F135 having 20% more fuel efficiency matters less when J20 bruteforces twin engine by being larger, with ~2x combat radius and ability to carry larger AAs. As long as US not willing to go twin engine with large % of fleet, all the cost/readiness implications, being ahead in particular area of jet engines hard = false sense of security/advantage.

But civil aviation, efficiency at CURRENT high fuel prices is none negotiable. There is cross over point where if fuel prices drop to precedented level lows, PRC can make up TOC of less efficient / lifespan engines on capital side... just having 1/2 cost airframes and maintenance packages can weather efficiency buffer over lifetime. But that is going to be very real struggle.

[foldr]

We don’t really disagree on any substantial point. However, if we’re going by the F135, that’s an engine that first flew in 2006. If China now has an engine that’s comparable to it it some ways, that means it’s about 20 years behind, give or take.

As you say, militarily speaking, engine tech is just one of many factors. Quite possibly, China would beat the US in a real war just in virtue of being able to manufacture more screws.