J-20 - physical parameters and other overflow from main thread


Equation

Lieutenant General
I don't read Mandarin unfortunately. Nonetheless, apples and oranges comparisons by nominally credible sources which should have known better and that even this "amateur" was able to catch have actually happened before. You may not be able to fathom that, but it is what it is.



"It" said - does that mean the interviewer (you indicated earlier that it was an interview of sorts) said so, or is the Chengdu official quoted verbatim? Is the official named and his function revealed?



All of these are not unusual, I was not pulling them out of thin air (quit projecting your own modus operandi on others). As I indicated, F-22 OEW was widely quoted as ~14t (which is what the public domain developmental target was) until the actual figure was declassified a few years ago. Bare airframe weight without equipment & engines is often the basis for those handy structural materials percentage figures you see for various aircraft.

Again, just because you were not aware of it doesn't mean it doesn't exist or that it's nonsense.



Given the ignorance and attitude that you've displayed toward me in this discussion, forgive me for not taking your word for anything without actual evidence or corroboration from more trustworthy individuals...



Are you Chengdu's professional design team? They have not supplied proof that is in any way accessible to me, so while I would much prefer to hear their input, I'm regrettably stuck with arguing among amateurs - and you certainly haven't provided anything which would change my appraisal either.
So you don't read Chinese and you're getting cheeky about Chinese translations? LOLOL It's not at all an apples to oranges comparison; it compared J-20's 15-16 tons directly to F-22's 19-20 tons. If you read Chinese, you would know this. Where do you even get your translation from if you can't do it yourself? Let me see it and I'll tell you if it's right. We might be having this back and forth because you can't even read a language but insist on what it says?? LOL



"It says" meaning the article reads. It did not quote which Chengdu official the information was derived from. If it did, if it said, "In an interview with Dr. X, material science director, it was disclosed that J-20's weight was controlled to 15-16 tons," then I'd say that's very very solid and this conversation is very very stupid. If that were the case, I would fully believe in the 15-16 ton number unless there was solid evidence that it was not the case. But because the article simply said that its sources in Chengdu said that J-20's weight was controlled to 15-16 tons, I hold some reservations.



Yeah, empty structural weight might not be unusual if it was standing alone, but when compared directly to the weight of an operational F-22, that strongly indicates that we are talking about operational J-20 as well. Bench press, squat, dead lift are all common measures of strength, but they don't compare 1 person's bench press to another person's squat!



You don't read Chinese but you doubt me when I tell you that the article said that J-20's weight was controlled to the 15 ton range as F-22 is in the 19 ton range? LOLOL Every Chinese person will translate it for you as such; maybe you think they're all unreliable. Maybe you should get your reliable translation from Brat LOLOL. It will be more reliable than your "calculations."



Anyway, when it comes to undisclosed aircraft weight, neither or us can prove the other one ignorant. But here, I can. If you dare, make a bet with me. If my translation is accurate, then this is the last post you make on J-20's weight. If my translation is not, then this is the last post that I make. Your confidence in calculating things that cannot be proven is very high; let's see how high it is when applied to something that can be proven. Only take this bet if your confidence is real, but you can leave it if you know you're wrong but just like to keep talking.
 

Tirdent

Junior Member
Registered Member
So you don't read Chinese and you're getting cheeky about Chinese translations? LOLOL It's not at all an apples to oranges comparison; it compared J-20's 15-16 tons directly to F-22's 19-20 tons. If you read Chinese, you would know this. Where do you even get your translation from if you can't do it yourself? Let me see it and I'll tell you if it's right. We might be having this back and forth because you can't even read a language but insist on what it says?? LOL
Not insisting on anything - just trying to figure out a source which I don't have direct access to by asking questions. As the original source is a jpeg image (so getting even a machine translation is pretty laborious) and given my lack of Mandarin, there's little point for me to translate it myself - I have nothing to show you. If you dropped the aggression and hysteria and actually read what I wrote, you'd realize that I am prodding for info to get an idea what that document is or isn't.

"It says" meaning the article reads. It did not quote which Chengdu official the information was derived from. If it did, if it said, "In an interview with Dr. X, material science director, it was disclosed that J-20's weight was controlled to 15-16 tons," then I'd say that's very very solid and this conversation is very very stupid. If that were the case, I would fully believe in the 15-16 ton number unless there was solid evidence that it was not the case. But because the article simply said that its sources in Chengdu said that J-20's weight was controlled to 15-16 tons, I hold some reservations.
See, that's not an unreasonable way of looking at it, and a fairly constructive answer to what I was trying to find out. Beyond what you're saying here, I merely pointed out that there are in fact a couple more than the one reason to have reservations which you mentioned yourself. And while a quote from a named official would have elevated its credibility (less potential for misinterpretation by the author), the maxim "if it sounds too good to be true it probably is" applies even then.

Yeah, empty structural weight might not be unusual if it was standing alone, but when compared directly to the weight of an operational F-22, that strongly indicates that we are talking about operational J-20 as well. Bench press, squat, dead lift are all common measures of strength, but they don't compare 1 person's bench press to another person's squat!
Believe it or not, people - including sources who know better with absolute certainty - do make horribly blatant apples to oranges comparisons. I can immediately think of several instances involving statements by Lockheed-Martin, Eurofighter and Boeing (frequently by named people) that were misleading - intentionally or not - to a similar degree. With a data point that is such an outlier as this OEW claim it is always a good idea to adopt a healthy dose of skepticism and cross reference for additional perspective with other available information - which is exactly what I did.

Anyway, when it comes to undisclosed aircraft weight, neither or us can prove the other one ignorant. But here, I can. If you dare, make a bet with me. If my translation is accurate, then this is the last post you make on J-20's weight. If my translation is not, then this is the last post that I make. Your confidence in calculating things that cannot be proven is very high; let's see how high it is when applied to something that can be proven. Only take this bet if your confidence is real, but you can leave it if you know you're wrong but just like to keep talking.
I *would* like to see a decent translation of that article, yes. Since an even accurately translated apples to oranges comparison remains misleading and by admission you're in fact not 100% confident in the source yourself, what you're proposing is nonsense. Your linguistic ability has no bearing on the credibility of my calculations whatsoever - that's a non-sequitur of epic proportions.

Since neither of us can conclusively disprove the other on the question of OEW, I'm happy to agree to disagree, but your attempt to link two completely disparate issues here is just laughable.
 

Equation

Lieutenant General
Not insisting on anything - just trying to figure out a source which I don't have direct access to by asking questions. As the original source is a jpeg image (so getting even a machine translation is pretty laborious) and given my lack of Mandarin, there's little point for me to translate it myself - I have nothing to show you. If you dropped the aggression and hysteria and actually read what I wrote, you'd realize that I am prodding for info to get an idea what that document is or isn't.



See, that's not an unreasonable way of looking at it, and a fairly constructive answer to what I was trying to find out. Beyond what you're saying here, I merely pointed out that there are in fact a couple more than the one reason to have reservations which you mentioned yourself. And while a quote from a named official would have elevated its credibility (less potential for misinterpretation by the author), the maxim "if it sounds too good to be true it probably is" applies even then.



Believe it or not, people - including sources who know better with absolute certainty - do make horribly blatant apples to oranges comparisons. I can immediately think of several instances involving statements by Lockheed-Martin, Eurofighter and Boeing (frequently by named people) that were misleading - intentionally or not - to a similar degree. With a data point that is such an outlier as this OEW claim it is always a good idea to adopt a healthy dose of skepticism and cross reference for additional perspective with other available information - which is exactly what I did.



I *would* like to see a decent translation of that article, yes. Since an even accurately translated apples to oranges comparison remains misleading and by admission you're in fact not 100% confident in the source yourself, what you're proposing is nonsense. Your linguistic ability has no bearing on the credibility of my calculations whatsoever - that's a non-sequitur of epic proportions.

Since neither of us can conclusively disprove the other on the question of OEW, I'm happy to agree to disagree, but your attempt to link two completely disparate issues here is just laughable.


So you're saying there is some small chance out of error that it might be an apples-to-oranges comparison. You can say so and that's fine, but you have absolutely no reason to insist that that's the case. You are repeatedly saying that it's an apple-to-oranges comparison as if there was evidence in the text of it when actually, there's evidence in the text that it's not. As I said before, the text is very clear; the only skepticism is whether the reporter could have made a mistake and confused OEW or prototype weight with operational weight (thus accidentally making an apples-to-oranges comparison). There is no indication of that and the rest of the article did not contain any outstanding errors that would suggest that the reporter is ignorant of the field.



Interesting new point: while the F-22's OEW ballooned, it was the first true stealth fighter. The Chinese doubtlessly have studied the case of the F-22 and were probably quite aware of this and thus, I surmise that they likely went into J-20's development with more realistic expectations of its weight. It is improbable that they made the same mistake of underestimating weight by such a severe margin after seeing the American example.



Anyway, you seemed very confident discrediting the source as if you knew what it said. Then, I find out that you don't even understand Chinese! Where's your confidence coming from? If I see a wall of text in Arabic, I'm not going to be making any claims about apples, orange, weight without engines, OEW, etc... But you actually debated with me as though you understood it! You were just imagining what it says so you can make imaginary loopholes in a language that you don't understand to convince yourself that it's not a reliable source. And then, even when I told you what it said, you didn't believe me; you said you wanted a second translation because I'm not qualified?! What a joke! Did you get your second translation? Did you figure out that my translation is accurate yet? LOL



Of course my linguistic capability is completely unrelated to your ability to calculate but this shows me that you are incredibly confident even when you don't understand what's going on, thus, it casts doubts on the quality of everything else you do, including your calculations (and assumptions). In that bet, I did not directly challenge your ability to calculate; I challenged your character in general (which pervades to all your endeavors in life including your calculations) for making claims on things that you clearly do not understand, such as the Chinese language.
 

Deino

Lieutenant General
Staff member
Super Moderator
Registered Member
@Equation

STOP this ranting and even more this personnel mocking against Forbin's bad English.

And for all others too: Either You debate in a civilised manner on topic and without any personal attacks, rants and insults or You better do not post.

Take care of the rules ...

No reply allowed and the next one who gets personnel or off-topic will get a two week time out until 1. January 2018.

Deino
 
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Deino

Lieutenant General
Staff member
Super Moderator
Registered Member
By the way ... I deliberately excluded this discussion out from the regular J-20-thread for those interested in a more technical discussion and I'm happy that I did not visit this one regularly, but after a brief look thru I have the feeling that about 70% of the content is completely off-topic, irrelevant to the J-20 or its dimensions, most of the time a back and forth of already mentioned arguments and a religious-like believe of some that their opinion is better or more worth than others.

:mad:

I think I close this thread or even delete it???!!

Guys, what's wrong?? It's Christmas time .... so calm down, all of You.

Deino
 

Inst

Senior Member
Shall we have another place of exile?

Just curious, what's the agreed-upon specs for the J-20's dimensions? So far, I see roughly 20.95 and 12.88 for wingspan. With 12.88, I'm measuring the weapons bays and I'm getting roughly 2.4-2.5 meters wide, 550 mm deep, and 4.5 meters long.

Weight is, of course, a different mystery.
 

Tirdent

Junior Member
Registered Member
Available material doesn't support giving measurements down to the centimeter, I'd be comfortable with stating 20.9m length, 12.9m span and 75m² wing area at this point.

Your bay dimensions are not far off my own assessment, I got 2.4m wide and 4..4m long (depth is hard to accurately establish with the photos we have, but it looks a good bit deeper than the F-22's - the ~0.6m bay depth of the Su-57 in mind, 550mm is entirely believable).
 

Inst

Senior Member
Looking back at the underlying thread, it's roughly the reverse, i.e, 20.87 + 12.94 for wingspan. My own measurements are 20.84 l 12.93 w.

More surprisingly, the wing area has been overlooked, a recent measurement I took showed about 76 m^2 in terms of effective wing area including LERXed areas. This gives a loaded wing loading of 395 m^2 under 30000 loaded weight and 345 m^2 at 26200 (18,000 empty wight + 60% of 12000 fuel with 1000 kg of munitions). This is inferior to the F-22 and Su-57.

Measurements:

Using this set of coordinates:

Frontal triangle apex:

256 539

Front wingspan

390 659

392 421

Rear wingspan

417 658

419 422

Rear triangle apex

443 541

We get roughly 136 pixels of length for the front triangular segment, 27 pixels of length for the central rectangular section, and 25 pixels of length for the rear triangular segment. Using 402.1 for Flanker length (21.94), and double counting the 27 central rectangular section, we get roughly 75.8 m^2 wing area.

Picture in use:

 

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