J-20 design is not compromised. But any design is the result of tradeoffs, J-20 designers simply had made the best possible design choices and tradeoffs based on China's requirements and circumstance.
China Flanker Thread II
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J-20 design is not compromised. But any design is the result of tradeoffs, J-20 designers simply had made the best possible design choices and tradeoffs based on China's requirements and circumstance.
Trouble is, it's not accurate in key respects. The oft-claimed increased composite content in the Chinese Flankers has never been conclusively proven, with people generally relying on primer colour when pressed. More room for fuel? More than 11500kg? And while the J-16's AESA radar is better, the Su-35 seems to have a more comprehensive EW suite, with LWR, spherical MAWS coverage and very powerful ECM. Add the "AI copilot" (for which probably read, sensor fusion) in the Su-35 that apparently impressed even the Chinese, and it is questionable whether there is such a big gap in avionics at all. There's more to it than the radar alone - the F-15C had a better radar than the contemporary Su-27S, yet with intra-flight data-link and IRST the Russian avionics suite as a whole was competitive.
Engines? Well, the Izd. 117S has TVC in operational service and its TBO and life are reportedly still double the WS-10's. That's no "marginal" difference.
Some questions
The composite content has never been proven, but my understanding is that this was inferred from the capability of China to produce complete airframes without the inner workings of the Russian titanium-working (of which Russia is the leader). Since Titanium has higher yield strength, it cannot be easily substituted with aluminum or steel at a Kg per Kg basis. Do you know how much of the base Su-27 is using Titanium?
Could you elaborate some of the extra EW and ECM capabilities of Su-35 vs. J-16?
Are we looking at a doctrinal divergence where Russia is trying to load in extra capabilities on an individual platform vs offloading into specialized platforms? China seems to be more going with an American style doctrine of aircraft specialization (J-16D like EF-18, the many Y-8/9 EW/ELINT versions accompanying flights in the Taiwan Strait, etc.)
There are multiple things wrong with the video... frankly the J-16 and Su-35 one was probably the truest.
The same Chinese language insider post from Yankee (a summary of which could be found here: ) that described the AI/duel-mode being neat was also the same post that wrote the J-16 as being superior to Su-35 in terms of the primary radar and in terms of ESM and ECM.
Regarding the use of composites, I don't think that was often attributed to primer colour -- rather it was part of the consistent set of rumours going back over a decade. If the rumour is true, it is likely about a decade out of date.
In any case, the video itself is fairly average was already discussed some time ago (I believe in the PLAAF "breaking news" thread) and my response to the video was posted as a Twitter thread as well.
I don't see why we need to bother by it.
We all know there had been a long-running debate/discussion at SDF and elsewhere about if or why China should import Su-35 from Russia. Among all the arguments for the import (or why), there was one camp that suggested the primary reason being for the engine 117S with TVC. I never believed that and still don't think that's the primary reason.
Yankee's extensive list can be considered as PLAAF's rather comprehensive evaluation report on Su-35 ex post, with considerable credibility. In other words, only the first bullet is the original primary reason (or part of) for the acquisition of Su-35. The rest of the points are the evaluation results after they had put their hands on and operated Su-35 extensively.
The conclusion was that 117S turned out to be the most impressive subsystems on Su-35, particularly from the angle of marrying an advanced Flanker variant with powerful TVC engines. That's probably one of the key takeaways and learning, more than an engine with TVC per se.
You can be very interested about a plane’s engine, enough to want to study it, without being at all interested in using the engine.
That is an even weaker line of reasoning. Relying on primer colour can at least actually give good results if you assure yourself that the material distribution makes sense with some engineering judgement and cross-reference with other sources. It does work really well on KNAAPO built aircraft - including the Su-35 - for example (medium grey vs. yellow). Yet the resulting composite disposition in Chinese Flankers is not consistent with any logic, things very difficult and expensive to make out of composite would be green, with the low-hanging fruit still yellow. And, perhaps most fatally in fact, the implied composite/metal content varied wildly between individual airframes.
In the past few years, high-quality close-up photos of modern Chinese Flanker derivatives have also revealed that the structure is very close to the basic Russian design. The rivet patterns, indicating where the skin is fastened to the internal structure, are more similar to the basic Su-27 even in the J-16 than on the Su-35 (which has a significantly altered nose and central fuselage). You don't get massive weight reductions (I think the rumoured saving was several hundred kilograms, bringing OEW below 16t) with minor surgery that does not manifest in externally visible differences.
And for a derivative version as opposed to a clean-sheet design, the cost-effective scope for deep structural changes is pretty limited anyway - the effort for qualification testing significant changes would be prohibitive. It is for very good reasons that the Su-35 avoids more composites, the more you deviate from the basic model, the more your cost-saving over a new design diminishes.
In any case, the manufacturing technology for the titanium parts would have needed to be among the tech transferred for the license-built J-11A as a 1:1 Su-27 copy. So I don't quite see what the basis of the whole inference is?
Quite a lot - around 30% IIRC. But that's irrelevant - it is the weakest of arguments, as pointed out above. All in all, the increased composite content is an unsubstantiated rumour which is at odds with some fairly strong circumstantial evidence. I rate the probability of it being true as so low as to be not worth considering.
Well, as I said, the Su-35S has a more comprehensive sensor suite in the EO regime at least, with 6 MAWS sensors (as opposed to only 2 or 4) giving true all-round coverage, no matter where the threat is coming from. It also has laser warning receivers to detect enemy IRSTs using laser ranging, I'm not aware of such a system on Chinese Flankers at all.
Even in the RF spectrum, there are valid reasons to believe the Su-35 has certain advantages, for example its ESM arrays are significantly larger. And yes, size DOES matter here, because it is constrained by the physics of wavelength - you cannot miniaturize a L-band emitter-locating receiver into a thimble radome. While Chinese superiority in microprocessors may reduce the weight and increase the performance of their back-end electronics boxes, they cannot overcome the bandwidth limitations of small antennas.
RF ESM/ECM is the one area where I'm surprised by the Yankee summary, incidentally - that source is in fact where I got the "AI copilot" thing from. Almost everything else agrees pretty well with what you'd expect based on the known or reasonably well-inferred capabilities. For example the IRST on the Su-35 is indeed not the greatest, it is supplied by a different company than on previous Flankers which has its strong suit in FLIRs. Probably the better imaging performance for improved A/G capability was a deliberate trade-off for better multirole versatility.
I can only conclude that Russia dumbs down the ESM/ECM software for export, in a similar manner to the original J-11s and Su-30MKKs coming with the downgraded Gardeniya jammer in place of the Sorbtsiya for domestic use.
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The Su-35s certainly could be a downgraded ESM/ECM suite, but at the same time the idea of J-16 featuring a slightly more capable ESM/ECM suite compared to Su-35 isn't exactly beyond the pale either, considering when each aircraft was respectively developed and the capability of the relevant industry domains in each country of the time.
If anything I would expect J-16, J-10C and J-20 to all field a similar generation of ESM/ECM capabilities to one another.
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