You know all you’re amounting to saying is that you insist that you’re right, right? In either case, if you drop the long figures for the J-20, everything falls apart, the aircraft goes to 12.88 wingspan, radome drops to smaller than the F-22. So you either have the large J-20 or a crap J-20. Which do you prefer?

The pro-Chinese posters get triggered when you say anything that suggests that the J-20 is not a purebred air superiority fighter. Suggestions that the J-20 is large implies that it’s an interceptor or striker. In reality, it’s built to fight at higher combat speeds than other combat fighters; with the important side effect that when it’s under-engined, it’s a perfectly adequate interceptor. These guys are incredibly defensive about the J-20; when some bad news appears (such as the Kopp RCS diagrams or the Taiwanese RCS simulation) they tend to brush it aside, even when you’re willing to focus on the positives (high speed maneuverability, better radar, modern sensors).

Let’s put it this way. Assume the Chinese had the WS-15 ready, available, and with TVC, in 2008. Would they have chosen to design the J-20 as it is now? The entire Song Wencong paper is about how the Chinese have had essentially the A6M Zero situation, wherein they’ve had to work with inferior engines. The A6M was a marvel when it came out, but as time passed, it was severely hobbled by its lack of armor, and if the Japanese had the choice, they’d have designed something more similar to Western aircraft. The J-20, likewise, has significant strengths compared to competing aircraft, but it’s still a workaround for the fact that the Chinese have had to work with engine technology that’s roughly 20 years behind the times. A J-20 without the engine limitations would have been a purer stealth design, especially in the IR regime.

That said, I don’t disagree with them when they argue that the “international community” is somewhat jaundiced about Chinese aviation. The initial claims of the J-20 being a striker were completely disproven when Blitzo dragged out the narrow bay depth of the J-20, meaning that it could only be an interceptor or air superiority fighter. They were going on on SDF about how a USN propaganda organ misquoted one of their German experts about the capabilities of the J-20, ignoring the fact that as an American military propaganda organ, it’s not allowed to be overly positive regarding enemy aircraft for fear of sparking fright in its own pilots. The truth is somewhere in between their radical positions: the J-20 is likely to be somewhat less stealthy than Western fighters, less maneuverable in subsonic regimes than Western fighters, but at the same time it has strengths and superiorities over its American counterparts.

About the bigger bay, do you have the figures for the Su-57’s bays? The J-20’s bays are roughly 4.6 meters by 2.2 meters in length, with a depth between 300mm and 400mm. The Su-57’s bays are definitely superior insofar as they can carry far longer missiles than the J-20 (i.e, it’d perform better as an interceptor and striker), but how deep are they?

Haarvarla, STR and ITR are actually quite primitive figures for discussing an aircraft’s maneuverability. STR and ITR matter, of course, but they have to be considered in the context of altitude and speed; for instance, the much-vaunted 26 degree STR often don’t exist at high-altitude, when the thin air means you don’t have enough lift. E-M diagrams seem to suggest most pure 4th generation aircraft range around 15 degrees per second at mach .8 in the 5000 meters environment.

Moreover, while in terms of ITR, most aircraft are G-limited, in terms of STR, aircraft maneuver often at rates 2/3rds or one half of their ITR limit, especially at high speeds.

What the claims of supersonic maneuverability amount to is that the J-20, like the Eurofighter or F-22, can achieve good STR in flight regimes where 4th generation aircraft typically struggle. This implies that, at 10,000 feet, the J-20 can fly in, launch missiles, and fly out, without losing significant amounts of energy, or otherwise maneuver to gain an advantage.

I think we’re back to square 1, unfortunately. The original poster exclaimed this was an L-band AESA, but I assumed he was just exaggerating. The 1760 module TR count in other documents means that this is not the J-11B AESA, it’s something else, although presumably from these figures it’s likely to be Flanker-sized. At the same time, though, the Chinese media claimed 450 km range on the J-11B AESA, so perhaps it IS L-band and the X-band AESA was discarded, or alternately the L-band achieves 450 km detection against 0 dBsm, but the X-band has an inferior detection range.

As for the translation,

Heading: Maximum Detection Range vs a RCS 0.1 m^2 target

Figure 4.5 Greatest Discovery Range at Dissimilar Elevations (RCS 0.1m^2)

Column Headers:

Target Elevation (Meters) / Maximum Detection Range In Normal Early Warning Mode (Kilometers) / Maximum View Line Range [???] (kilometers)

Paragraph:

Considering the F-22 stealth aircraft’s RCS should be 0.4 m^2 [only makes sense if we’re taking L-band, and I still have my doubts there], the radar’s detection range against 0.4 m^2 is shown.

Second table:

Same as above.

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But back to the F-35, so that implies, first, the F-35’s cockpit is so cramped because Lockheed wants to minimize the RCS of the exposed cockpit. Likewise, the F-22, unlike the F-35, can reduce RCS by making the bottom the exposed aspect, so only the edge of the radome would be reflected.

While we’re at it, do you have any information on the f-35’s AESA? hornetfinn on F-16 did an estimate proposing a 350-450 km det range vs 0 dBsm on the APG-81, and this sort of information is hard to find. GarryA, if you’re here, you can look at the article I linked that claims the APG-77 has 100 mi operating range, but there’s no RCS figure attached to it so we can’t determine whether or not I can dig 400-500km vs 0 dBsm ranges out of the APG-77v1. Been trying. Also, did anyone mention a claim that the J-11B’s AESA radar is capable of 450 km det vs 0 dBsm yet? It’s actually pretty radical, and suggests that with radar advances like photonics for noise reduction and GaN, current X-band stealth can be partially defeated; an estimate suggests that future photonics radar would be able to get 100 km detection vs -50 dBsm.

A few other things:

First, while doing research on this subject, I found a simulation claiming that the F-35 was capable of achieving -25 dBsm through shaping alone, about the same as the F-22. But once you add RAM to it, you can achieve a further 25 dB reduction to obtain -50 dBsm. But the RAM reduction figure I’ve been unable to obtain.

For instance, consider this:

http://www.panashield.com/emc_absorbers.asp

Is it possible that RAM is actually more potent than we’ve been led to believe? There were rumors of a report that the USAF was hunting for -70 dBsm screws, purportedly for next-generation aircraft, but is it possible we’re already at the -70 dBsm point?

@CastleBravo: I did approximations of the F-16A v F-18C; it appears that you’d need a square increase in thrust to compensate for a linear increase in weight. I.e, C/D is listed as having 10% less STR, but about 15% more thrust than the F-16A and 13% more weight (all off the top of my head). Using this model, an Su-35 could be expected to be about 13% less maneuverable STR than the Su-27, ignoring aerodynamic retrofits. I’d guess this is the result of weight affecting both T/W and wing loading, and the scalar changes to both being multiplied.

@haarvarla: The point about identical ranges does stand, however. Assuming both the F-35 and the F-16 take a mission to ~600 nm, the F-35 will have 60% or so fuel left, while the F-16 will have dropped drop tanks and have about 80% fuel. Using a linear model, we get about 7% less STR on the F-16; using E/M curves we get 15.35 degrees / second at mach .8 at 15000 ft from 16.5 at 60% fuel. In reality, I suspect the square model is more accurate; which drops us to about 14.28 degrees.

gta4, also, is a fanboy, more or less; he’s essentially the American version of all those China stronk folks, he wants to inflate up the F-35’s capabilities, when we know it’s already decisive BVR vs 4th gens using 60-70G BVR missiles. Seriously, selling the F-35’s pedal turn as a sustained turn capability? Ewww.

Also, in general, I don’t see why people are making such a huge fuss about either the F-16’s agility or the F-35’s agility. Neither are too agile by modern standards; the F-16 was a 4th generation plane that got bogged down with thrust increases and weight increases, while the F-35 is not intended as a F-22-style dogfighter. In reality, in an actual combat situation, the F-35 will be able to exploit its stealth and detection advantage against almost all opponents, and WVR in the era of HOBS is almost a type of suicide warfare; winning is when you send 1 fighter against 2 of theirs, and everyone involved is shot down.

Another thing I want to mention is that if you are using US / Russian engines as the benchmark for Chinese engine performance and claim that it is absurd for China to match or exceed the US and Russia, you are wrong.

Russia has an R&D complex and significant experience with turbofans, this is true, but on the other hand, Russia is out of money; even with the Ukraine war Russia is facing budget cuts both to procurement and R&D. China, on the other hand, does not necessarily have a mature R&D complex, but China is flush, or at least was flush, with money, and a 10.4 trillion dollar economy can be dumped into engine R&D with ~2.2% of GDP being dedicated to military budgets.

This is an advantage, and it is not necessarily sufficient to surpass the United States, but if you compare what’s going on with the United States and Russia, the United States as a cutting edge nation is 1-1.5 generations ahead of Russia. They already have a 190+kn engine installed onto the F-35, with tests under certain conditions showing 220+ kn, for an engine with roughly the dimensions and weight specs of the 117S. That’s to say, for China to catch up to 180 kn means that it will possibly be equal to Russia or surpass Russia, but it will not be able to surpass the United States. If you look at the ultimate result being roughly 80% of American performance, then 150 kn, as you stated, is in reach, but so is 176 kn if you look at the F135 under certain performance conditions.

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This is to say, I am not saying that it is probable, but I am saying it’s possible. I still think it’s unlikely for the WS-15 to be ready at a radically early date, around 2016 or 2017, but there is nothing stating that it is impossible for the WS-15 to return to baseline from the WS-10 as an outlier.

Putting it another way, out of all the way the WS-10 project could have performed, it performed roughly between the 10th and 33th percentile; it didn’t manage to kill all its researchers and for that we can be thankful, but it’s turned out to be a huge money-pit. Extrapolating from the WS-10 project to the WS-15 project, we can assume that on average the WS-15 project will perform around the 50th percentile, so the WS-15 will represent consequently a quantum leap over the WS-10 simply because the WS-10 project ended up being so bad.

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To finalize the formulation, the WS-15 will likely be ready around 2019 or 2020. If the final performance under afterburner is only around 150 kn, it won’t be disappointing, but if the final performance under afterburner is around 180 kn it won’t be a surprise either. You may be free to believe that China will be stuck in the low-range of possible WS-15 performance values, but considering massive Chinese budgets and aggressive Chinese cyberespionage, it’s perfectly possible that the WS-15 will be comparable to the F135 in total thrust.

Jessmo23: Refute your own arguments. All the information you need is in Google, I will no longer waste time with you. Have fun!