J-20 5th Gen Fighter Thread VI

[Engineer]

Do you understand how asinine your claim is? By the same logic, since Lockheed aerodynamicists wrote internal papers on how the F-35 is supposed to get 5G sustained at altitude, the F-35 is a supermaneuverable fighter that can turn circles within any other aircraft. There is a wide difference between an aircraft design document and an actually-implemented aircraft.

I didn't make a claim. I pointed out a fact, so the level of asinine in my argument is zero. While there are indeed differences between wishes and actual implementation, they don't dismiss the fact that the intended role of the J-20 is a manoeuvrable air-superiority fighter. Using your F-35 example, just because the original requirements weren't 100% achieved, that doesn't suddenly make F-35 a bomber or an interceptor.

Aside from fallacies and pathetic excuses, haters have provided absolutely no proof that J-20 isn't a air-superiority fighter. The fact that certain hater now resort to calling everyone he disagrees with "fanboy" only further demonstrate how his arguments have nothing of substance.

 

[latenlazy]

Is that a relevant criticism of my argument? The F-35's original specs indicated that it should be capable of 5G sustained turn at altitude and speed. As it turns out, the aircraft was overweight and the requirements postulated by the Pentagon were downgraded to 4.2 G, if memory serves.

What we know right now is that the J-20 was intended to be supermaneuverable without resorting to TVC or having high thrust engines, and we already know that there's one disappointment: the aircraft is supposed to be able to supercruise with engines as is, but rumors as they come claim that the aircraft needs upgraded engines to supercruise.

It is. The credibility of the conclusions one can draw from a design study is different if an objective is explicitly stated vs if some performance parameter is merely described. The latter tells you what a design on paper attained, but the former tells you what an essential focus of the design was. Also, we know with the case of the F-35 the fighter ended up being overweight because the requirements kept shifting dramatically after the demonstrator design, and in specific ways that would naturally fit with a final design being overweight from their initial spec’ed performance. I don’t think we have any indication of this being the case for the J-20, especially since, it seemed the J-20 did not seem to face nearly the same overburdened shifts in design requirements the F-35 did along its development history.

Which “rumours” claim that the aircraft needs upgraded engines to supercruise? Sources?

 

[Engineer]

The wing is measure as an airfoil, from wing root chord to wing tip chord, that is called exposed wing, however as airforce brat said that does not tell you the whole concept because aircraft have two wings one for each side plus they have a center of gravity, therefore you can use the squared wing span to generate an area where the wing is acting thus part of the fuselage will fall under that area that is called reference wing area.

To calculate an area of an exposed wing you have to consider wing type for example Su-27 has a compound wing and your calculation you did, does not include the Lex for Su-27 and the pancake which also is an airfoil and you did not include part of the J-20 trailing wing extension and lex.

Some companies also include the horizontal stabilizers.

Wrong as usual.

What you included as wing for the Su-27 -- the LERX and tunnel area, aren't part of the wing at all. They belong to the fuselage. Here is an image of a Su-27 to proof it with wings detached:

If you were to calculate reference wing area, then the entire wing from one side to another is considered. Yet you tried to use silly accounting trick, using one standard of measurement for the Su-27 and another standard for J-20 to hide the fact that Su-27 is inferior. That's Fallacy of Equivocation.

 

[Engineer]

i will put it easier, longer fuselage does it have more volume? if it has more volume why? why that need to have extra volume?

why you will add extra volume? see the drawing you originally posted and the J-20 is as wide in fuselage cross section as an F-22 and from wing chord rood to wing tip chord its wing is shorter look at the top view and the wing also is smaller that will impact wing loading.

The answer is simple, J-20 carries very likely more fuel, more fuel impacts weight, more volume does the same, the J-20 is very likely with WS-15 is a much longer range aircraft than F-22, with Al-31 that extra volume will give it similar range if not more than an F-22.


Why? the J-22 is designed to operate with a very long range, it makes sense if it has to fly over continental Asia or the west pacific ocean

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longer Fuselage longer S inlet ducts, longer fuselage wider space between intake lips and jet nozzle pipes therefore you can store more fuel easily

Longer fuselage for the same width means higher fineness-ratio. For the same fuselage cross-sectional area, higher fineness-ratio translates to lower supersonic-drag.

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To achieve supercruise, there are two approaches: increase thrust as F-22 did, or reduce drag. J-20 takes the latter approach. It's a simple trade-off.

 

[Engineer]

thinner wings do generate more lift or less lift?
Do the An-124, C-5, A-380 or B-747 do they have thin or thick wings with lot of camber?

...

tell me which aircraft has better TWR J-20 or F-22?
If it has thinner wings, smaller wings, and higher swept do you think it will generate more lift at slow speeds?

Have you ever seen aircraft that operate at 500-600 km/h do have they thin or thick wings, lot of sweep or little swept wings?
Example A-10 or su-25? do they have wings like J-20?


where is the higher instantaneous turn rate at 600 km/h or 1900km/h for F-15?

where is the higher G load F-15 can get at 600km/h or 1800km/h?

Consider that if you want to say J-20 is an air superiority

You are contradicting yourself. You identified aircraft that are not air-superiority fighter as having thick wings. Since you agree that J-20 has thin wings, you are essentially agreeing that J-20 is an air-superiority fighter.

you your self are now heading why the western analyst say it is an interceptor,

Western analysts are journalists; art majors. They have no knowledge of flight dynamics. Only fools believe western analysts.

 

[Deino]

Guys ... it's really a bit annoying to discuss - and I'm sure we are again at page 1x - such off-topic issues in the J-20 thread.

PLAESE open a new thread and later I will move this stuff but no longer here.

Deino

 

[Engineer]

relax I am not in the J-20 club nor I am a loyal fan and cheer leader as most of the Chinese expatriate, but i will ask what would happen if F-22 loses its TVC nozzles versus Rafale that has lower wing loading?

Ah, but you are in a club, called the J-20 haters club. That's why even people who are not a fan of J-20 can see the total lack of objectivity in your posts.

No volume is explained unless you consider fuel and weapons bays, however you chose not even aerodynamics, but cheer leading the club, go J-20 one two three go! more volume is not needed unless you need to pack something such a longer S intake duck, longer weapons bays, longer internal fuel tanks. longer engines and ah! i forgot that adds weight, Ah! J-20 is flying with lower thrust yield engine but the club does a bit of cheer leading and thumping of chest haha, that is beyond your logic no volume is explained unless you consider more internal space for stuffing more things, but of course when pride wins intelligence and logic do not work

Cheerleading only works for aircraft like J-20 as the aircraft is living up to expectation of what a 5-th generation fighter should be. Cheerleading doesn't work for fake 5-th generation fighter Su-57.

 

[Julio Ramos]

Guys ... it's really a bit annoying to discuss - and I'm sure we are again at page 1x - such off-topic issues in the J-20 thread.

PLAESE open a new thread and later I will move this stuff but no longer here.

Deino

Thanks.
This never-ending discussions tire us all.

 

[AndrewS]

LOLOL What is this? This an American paper on what American 3D printing could do for the overall weight of passenger airplanes (which have many other parts like entertainment systems, kitchens, first class bar, bathrooms, seats, etc... that are huge weight contributors unaffected by 3D-printing). We are talking about a Chinese-designed military aircraft based on Chinese 3D techniques, which can reduce 40% of the the weight of titanium bulkheads used on certain parts of the frame (source previously provided by Kurotoga), AND on top of that, 3D-printing was only one of several known weight-saving measures implemented on J-20. And finally, if you read your paper, the 7% figure it derived was based off "metal parts." It doesn't even state the savings specifically from titanium, which is the metal in question on the J-20. Your paper is sadly irrelevant.

You so desperately don't want to believe that J-20 can weigh 15-16 tonnes that you are attempting to argue against a secondary source to AVIC, the manufacturers of J-20, by finding any paper written anywhere by anyone about any type of aircraft that can be vaguely interpreted in any way to counter the information that you don't want to believe. Here's the deal:

I gave 15-16 tonne figure for J-20 not from some deluded mental calculation of mine, but because I got it from a report on the words of AVIC and that is the closest and most reliable source he have to date on the weight of the J-20. On top of that, I did acknowledge the chance that the report was wrong, though at this time, it seems to be the most reliable source we have. Haha I can imagine if there was a Russian report saying Su-57 was 14 tonnes, you'd defend it to the death as a reliable figure LOL.

Anyway, I said J-20 weighs 15-16 tonnes (with a source), which you translated into 15 tonnes, then 11 tonnes, now 1 tonne? I see you are moving the goal-post a lot because you find your argument increasingly difficult to defend... tsk tsk.

Now your fantasy of Su-57 being a 6th gen fighter... LOLOL

It is possible that the J-20 is only 15-16 tonnes empty.

China has been publishing a lot more materials science papers than the US+Japan combined in the past decade, as per Nature magazine below

China's blue-chip future

Read more

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Plus the F-22 is 25% composite and the F-35 is 35% composite. But the latest B-787 is 50% composite. It demonstrates that there is still a lot of room for improvements.

"By using composites to manufacture 50% of the Boeing 787’s airframe, the aerospace leader knocked 20% of the weight off the aircraft compared to conventional aluminum designs."

Source

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[manqiangrexue]

It is. The credibility of the conclusions one can draw from a design study is different if an objective is explicitly stated vs if some performance parameter is merely described. The latter tells you what a design on paper attained, but the former tells you what an essential focus of the design was. Also, we know with the case of the F-35 the fighter ended up being overweight because the requirements kept shifting dramatically after the demonstrator design, and in specific ways that would naturally fit with a final design being overweight from their initial spec’ed performance. I don’t think we have any indication of this being the case for the J-20, especially since, it seemed the J-20 did not seem to face nearly the same overburdened shifts in design requirements the F-35 did along its development history.

Which “rumours” claim that the aircraft needs upgraded engines to supercruise? Sources?

I think he's talking about the rumors started by the characters on this forum who eye-balled the size, guessed the operational weight at ~36 tons, and said they think it can't super-cruise LOL.