J-20 5th Gen Fighter Thread IV (Closed to posting)

[escobar]

A very good analysis from NDU

The Chinese Air Force: Evolving Concepts, Roles, and Capabilities:

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There is no question which country has made the greatest strides in developing its airpower capability. Over the last two decades, China’s air force, the People’s Liberation Army Air Force (PLAAF), has transformed itself from a large, poorly-trained force operating aircraft based on 1950s Soviet designs to a leaner and meaner force flying advanced Russian and indigenously produced fourth-generation fighters. This remarkable transformation is still a work in progress, but China has made up a lot of ground in a short time...

 

[Engineer]

An interesting bit of wingloading calculation. Courtesy of Kryptid from secretprojects. What do you guys think?

Well, the presence of canard and LERX really boost the amount of lift that can be generated. If you remember Dr. Song's paper, there is a chart which compares the different configurations.

Assuming an equivalent wing area, J-20's configuration can generate 1.44 times the amount of lift that F-22's configuration can produce (180% versus 125%). There is plenty of margin left to allow the J-20 to have a smaller wing area, heavier airframe, and weaker engines.

 

[vesicles]

Well, the presence of canard and LERX really boost the amount of lift that can be generated. If you remember Dr. Song's paper, there is a chart which compares the different configurations.

Assuming an equivalent wing area, J-20's configuration can generate 1.44 times the amount of lift that F-22's configuration can produce (180% versus 125%). There is plenty of margin left to allow the J-20 to have a smaller wing area, heavier airframe, and weaker engines.

Where is the statistical significance? With no error bars, 160% is too close to 149% to make it statistically significant... The same goes with 160% and 181%. (just trying to be a pain in the butt..)

 

[latenlazy]

Where is the statistical significance? With no error bars, 160% is too close to 149% to make it statistically significant... The same goes with 160% and 181%. (just trying to be a pain in the butt..)

That would depend on the standard error, which we do not have either

 

[vesicles]

That would depend on the standard error, which we do not have either

Yep! that's what I was asking. I don't see any error bars...

 

[Engineer]

Yep! that's what I was asking. I don't see any error bars...

That only exists in science, not applied science.

 

[vesicles]

That only exists in science, not applied science.

You see? I have heard something like that before, mainly about only biology needs statistics while physics and engineering do not need it. While I can understand why organic chemistry does not need it (you either get a compound you want or not), I still can't imagine why engineering does not need statistics... Your machine might not work exactly the same every time. There has got to be a range, hence the need for statistics... I used to do bioengineering and I had to have statistics for all my experiments..

 

[Engineer]

You see? I have heard something like that before, mainly about only biology needs statistics while physics and engineering do not need it. While I can understand why organic chemistry does not need it (you either get a compound you want or not), I still can't imagine why engineering does not need statistics... Your machine might not work exactly the same every time. There has got to be a range, hence the need for statistics... I used to do bioengineering and I had to have statistics for all my experiments..

We do deal with statistics, we just don't deal with error bars.

 

[Air Force Brat]

Well, the presence of canard and LERX really boost the amount of lift that can be generated. If you remember Dr. Song's paper, there is a chart which compares the different configurations.

Assuming an equivalent wing area, J-20's configuration can generate 1.44 times the amount of lift that F-22's configuration can produce (180% versus 125%). There is plenty of margin left to allow the J-20 to have a smaller wing area, heavier airframe, and weaker engines.

Now here, we are dealing in the nebulous netherworld, while you are the mathmatician/engineer, and I highly respect your opinion, theres no way an aft mounted delta is producing that much more lift, or all fighters would be thusly configured. There are good reasons the US and Russia abandoned the aft mounted delta in fighter aircraft, and to be very honest I highly suspect that you would agree with me that the forward fuselage of the J-20 and the F-22 are very similar in shaping and ability to produce lift, so while the canard increases lift on the forward fuse, its inclusion on the J-20 merely brings it into parity with the F-22. The F-22 has massive and far aft mounted horizontal stabs, with the addition of TVC, and its shorter length, and higher thrust to weight ratio, the Raptor's pitch transitions are most impressive. So, while the J-10, Rafael, or Eurofighter "could" be in the same league, there is no way the J-20 is producing that much more lift, and even if it were, agility comes from the ability to transition that lift very rapidly without creating massive amounts of drag. Respectfully, given your obvious credentials and good sence, Air Force Brat.

 

[MiG-29]

Now here, we are dealing in the nebulous netherworld, while you are the mathmatician/engineer, and I highly respect your opinion, theres no way an aft mounted delta is producing that much more lift, or all fighters would be thusly configured. There are good reasons the US and Russia abandoned the aft mounted delta in fighter aircraft, and to be very honest I highly suspect that you would agree with me that the forward fuselage of the J-20 and the F-22 are very similar in shaping and ability to produce lift, so while the canard increases lift on the forward fuse, its inclusion on the J-20 merely brings it into parity with the F-22. The F-22 has massive and far aft mounted horizontal stabs, with the addition of TVC, and its shorter length, and higher thrust to weight ratio, the Raptor's pitch transitions are most impressive. So, while the J-10, Rafael, or Eurofighter "could" be in the same league, there is no way the J-20 is producing that much more lift, and even if it were, agility comes from the ability to transition that lift very rapidly without creating massive amounts of drag. Respectfully, given your obvious credentials and good sence, Air Force Brat.

The F-22 has TVC nozzles increasing turn rates, roll rates, and the tail is no fluke, it is also adding lift on a relaxed stability configuration.

Each design group chose compromisess.

Chengdu opted for canards adding lift at high AoA to the wing but at the expense of killing lift at cruise flight.
The F-22 does not kill lift at cruise flight as J-20 does with canards.
T-50 uses the integral configuration see the patent lift, you can see the central body generates lift, MiG-29 generates 40% extra lift just from the central body fuselage airfoil.
Add the levcon that controls the lift generated by the LEX and increases lift at high AoA

You can see the T-50`s patent about the fuselage lift

all configurations do have advantages and disadvantages, all compromise