...as i said, any >18t flanker(which is over 10% and sometimes 20% over original) with AL-31FN engines is underpowered. More so in the naval context.
There's ultimately a big reason why Russia rn advertises plug in 14.5t engine into the old 905mm slot for land applications (where failure doesn't send you under the carrier) - as this lack of power is acutely felt even in land operations. Most heavier flankers, for example, can't go over M=1.8 due to drag. Which should tell a thing, as vanilla was good for M=2.35, and that was limited by the canopy, rather than engines.
My point is, if AL-31 was chosen over WS-10H in these circumstances in a naval context, WS-10H was (hopefully in past tense) indeed TF-30 level bad.
Not that I disagree with everything you said, but TWR decrease is only one of several reason for the max Mach number decrease. You would note that most of the lower Mach number flankers have canards/twin cockpits/both, which adds not only weight but also substantially adds drag.
Plus max Mach number isn’t really a good example for discussing carrier operations as one is about L/D and engine thrust at the upper right corner of the envelope; while the other is about those at the lower left. An aircraft can definitely excel at one and fail miserably at the other (looking at you super hornet)
(Coming from the post below) I derive it from AL-31 being a rather so-so engine for a naval flanker. It works reliably, available, and very well understood by China, but otherwise it is rather...weak for the application in question.
Granted, but weak is two-fold, and I’m not sure everyone’s using the same definition here.
If we’re talking about low thrust then it only really affects safety in very select conditions AKA takeoff, landing, bolter or arresting wire failures. All of these risks can be eliminated or at least mitigated with proper use and operating guidelines. Want to make sure it has enough thrust to stay in the air? Reduce the takeoff weight and max landing weight. Yes it reduces the combat effectiveness of the aircraft, but that’s a less serious issue and not what we’re discussing.
if we’re talking about engine malfunctions (as some seem to be doing) then honestly neither the AL-31FN nor WS-10 (we have very little info on the ws-10h sadly, so mainly just talking about regular WS-10 variants) have a stellar track record: one shows increasingly poor craftsmanship in recent years while the other was catastrophically bad in terms of reliability for the better part of a decade. WS-10 being considered reliable and “good” is a relatively recent thing and I’m not surprised if the WS-10H is still in the processing of transforming from a death trap into an actual usable reliable naval engine. So currently neither choice is perfect, and keep using the AL31FN (picking and choosing those without underwears in their combustors, presumably) while undergoing testing of WS-10H seems as good a choice as any to me.
