Of course, but my point was that if they're happy with the J-20 and they tendered for a fighter that was competitive with the F-22, that should reasonably preclude the J-20 being a 25 tonne giant insofar as being that heavy would dramatically inhibit its ability to meet those requirements. If the J-20 wasn't reasonably successful at delivering on the PLAAF's requirements, I somehow doubt they'd be so happy with it. This is not to say the J-20 must be a 15 tonne lightweight, but that how satisfied the PLAAF is with the fighter should give us some general ideas about how capable it is.
I feel like I'm repeating myself. First, we don't really know how happy they are. (If you disagree, please let me know how we know.) Since they went for a longer plane with a larger fuselage cross section than the F-22, maybe they planned for a heavier plane from the beginning. Regardless of the weight, they can also be happy with other achievements, such as stealth or sensor fusion. I don't take it as a given that the J-20 matches the F-22 in everything just because that was supposedly a requirement (engines, number of missiles in the weapons bay). The J-20 is the only Chinese fifth generation program with military support (in contrast with the FC-31), so in a way, you could say they don't have a choice about being happy. If they aren't happy about something, are they going to complain in the media?
I wasn't rejecting the offer for decorum (I think we've been pretty civil so far). I was pointing out that sometimes the basic assumptions behind certain arguments don't reflect as much technical assessment as subjective judgement. That wasn't necessarily aimed at you, and I don't think that's a particularly shocking observation...If part of assessing arguments in debate is examining the basic premises and assumptions behind their logic, then from time to time we are going to encounter some arguments that aren't rooted so much in objective analysis.
Here's how this part of the conversation looks from my perspective. Among general discussion, you bring in "condescending biases and baseless prejudices." Even if you don't explicitly accuse me of these things, I feel that questioning people's motive is pretty rude, which is what I try to tell you. You reply that you agree, but nevertheless insist. It's like I'm telling you that I don't like being insulted and you say you'll do it anyway (but you aren't insulting me). I won't comment on this anymore (unless necessary).
Just for the record, I'm not American and don't stand for their views or interests ("underestimation of potential adversaries [...] NK ").
I already gave you my answer on claims, and my reasons for it. The answer is yes. On the KLJ-7A specifically, I think there's a gray area in what Henri K. meant by "comparable to the AN/APG-81", but the overall scope of interpretations that claim covers doesn't sound so unlikely. It's not like China's a slouch in its electronics capabilities. That was one of the first technological domains they managed to attain significant parity in.
I don't think there's much grey area. The fourth paragraph has a quote by Wang Hongzhe, identified in the third paragraph as deputy director of NRIET. Three machine translators give an almost identical result: "The KLJ-7a, which makes its first public appearance in this exhibition, has a combat range of 170 kilometers," stresses WANG Hongzhe (王宏哲), "This range is equivalent to (that of the radar of) F-35, and it is mostly achieved on a radar with a much smaller volume E" n comparison. » (By Bing, obviously should say "in comparison".)
I don't think the range of the AN/APG-81 has been published. Ironically, in this case we have the number for the Chinese claim but not the American one. You could probably find something on the lines of "40% percent more range than X, which has twice the range of Y" where X and Y are previous generation radars, but I don't feel like searching. FORBIN has reported some possibilities.
Anyway, let me know what you think of this claim. I think it's false.
Consider the F-22's larger horizontal and vertical tails. Consider also that if the J-20's fuselage cross section were say only .5 m^2 smaller than the F-22's, multiplied across that alone could neutralize half the volume difference if the J-20 shared the same cross section area as the F-22. Or consider that some x percent larger volume could be offset by x percent smaller density. Of course, these are points I've already made multiple times. I'm not saying anything new here.
Just because Trident doesn't agree with me about the thinner wings that doesn't mean he's right. No offense to Trident, but when he made the counterpoint he more or less based it on an eyeball description. These things have to be measured, and given how hard it is get an accurate wing thickness measurement with the photos we have on hand, it's hard to say how the two planes actual wing thickness compares. It looks thinner to me, judging by the thickness of the leading edge, but maybe that's just an optical illusion? That point about precise measurement is also true of the entire exercise more generally. Charitable case scenario or no, a rough estimate is a rough estimate. They're not meant to be taken strictly or at face value. I for one personally think Trident hedged a bit on his "charitable" case, and I have some problems with his approach to getting cross sectional area and how he extrapolates it, but I don't think it's really worth getting into these problems because I don't think the value of the output we get is really all that useful beyond a ballpark figure anyways. Trident himself said as much.
I don't think the purpose of these discussions is "fairness", but "accuracy". At the end of the day I don't really care who gets credit for being right. I want to know what the facts are. If you delve into my posting history though you'll see plenty of estimate attempts on my part, though not of volume. This is in part because I don't think anyone could do a volume estimate justice without at least using some kind of 3D model. I tend to emphasize accuracy because I presume that's what what we ultimately care about in these discussions, and short of some method that can give us some measure of precision it seems to me trying to do a volume estimate with *very* rough assumptions on a complex shape is a futile exercise, though I do commend those who take their time to give it a try. Anyways, you can believe what you want about the J-20's dimensions or weight. The evidence is loose enough right now where there really is no right answer (except length and maybe wingspan).
I won't comment on specifics about the volume. It is indeed a lot of work to perform a full estimate.
However, there are two members who say they've done it and have posted their results on this thread: Totoro (page 39, +20%) and Trident (doesn't provide a volume estimate, only one of mass). Conversely, I find that you were mostly nitpicking or blowing holes in the work of others without providing your own measurements for others to use or critique. This is what was meant by "fair."
Consider also that if the J-20's fuselage cross section were say only .5 m^2 smaller than the F-22's
Is it actually 0.5 square meters smaller? Trident found that it's 0.6 square meters larger. Why should we assume that everyone's measurements were biased in one direction and your counterpoints are somehow better? Why didn't any of your warnings about measurement make the point that the error could be in the other direction?
Anyway, my position isn't that the J-20 weighs 25 tonnes. My view is that it most likely has a similar density to the F-22 and is thus proportionally heavier (maybe 21 to 23 tonnes). Some weight reduction might be plausible, but 6+ tonnes isn't (to me). I think the 15 tonne number is an extreme outlier (if you had queried the members here, how many would have volunteered something like it before the article was posted?). In your first reply to me you said that
Yes, we did, and the short and thin of it is simply that we don't know enough about the source to know for sure how reliable it was. On one hand, the claim was from a trade magazine, so it's atypical of the usual bad sources we're used to, but on the other hand it's not a source we've seen before so we have no history of claims to make judgments with and no context for how reputable, well sourced, connected, and diligent the publication is.
although jobjed described it as
more legitimate than normal so, based on what we know and can know, the probability of the claim's being true is now firmly out of "negligible" territory.
To conclude, I think Chinese technical claims can be wrong and the 15 tonnes number probably is wrong.
