J-20 5th Generation Fighter VII


Inst

Senior Member
Can you please provide the link or whatever of the referred “good measurements” of j-20? I saw several different version from 20.1 to 20.4 now to 20.88, all claims to be precise measurement...

and also for the su-57, if there is any good source, even wiki has different number in the same page... terribly confusing...

You have the source picture, and the other aircraft are J-16s (Su-30MKK clones). It's satellite, and the standard mistake working with the picture is not compensating for perspective (you need to use the centralized J-20 and a centralized J-16).
 

stannislas

Junior Member
Registered Member

You have the source picture, and the other aircraft are J-16s (Su-30MKK clones). It's satellite, and the standard mistake working with the picture is not compensating for perspective (you need to use the centralized J-20 and a centralized J-16).
yeah, I saw that thread, and like I guessed it's the same picture, the 20.1 and 20.4 m measure from other people is also from this image as well...

Also, this is definitely not from satellite, very like DJI fly over. Depends on where the picture was taken and the lens, given the height of the picture was taken, the angle error could be much bigger than you think, 5-10% is even possible...
 

Inst

Senior Member
yeah, I saw that thread, and like I guessed it's the same picture, the 20.1 and 20.4 m measure from other people is also from this image as well...

Also, this is definitely not from satellite, very like DJI fly over. Depends on where the picture was taken and the lens, given the height of the picture was taken, the angle error could be much bigger than you think, 5-10% is even possible...
Perhaps, but this is the closest we'll get to overflight. IIRC, the main errors made were based on perspective distortion, i.e, using the J-20s on the side or the J-16s on the side to do measurements (i.e, 20.1 / 20.4)

However, this is the closest we'll get to good measurements; i.e, the background is flat, the planes are on the same plane orthogonal to the viewer, etc. Software could possibly derive closer estimates than what we already have.
 

Inst

Senior Member
Relative to the main plane, the center J-16 is positioned almost exactly the same as the central J-20. So we could do length vs length measurements there. IIRC that's how the numbers were derived.
 

stannislas

Junior Member
Registered Member
Perhaps, but this is the closest we'll get to overflight. IIRC, the main errors made were based on perspective distortion, i.e, using the J-20s on the side or the J-16s on the side to do measurements (i.e, 20.1 / 20.4)

However, this is the closest we'll get to good measurements; i.e, the background is flat, the planes are on the same plane orthogonal to the viewer, etc. Software could possibly derive closer estimates than what we already have.
don't get me wrong, appreciate you provide the source, and I agree this might be the closest we could get atm in terms of the references.

But still, we could measure slightly better than this, based on the angle differences the J-16 is opened, the center of the picture in Y-axis is roughly aliasing withe the left intake of the J-16 in the middle, I don't want to measure exactly how many pixels that is but let's just say roughly 10% may occur, so the average error in width is roughly 1-2% + pixel error for a quick estimation from your measurement, and that's assuming you are using the J-20 in the middle...

To do a more precise estimation, we could roughly reverse out the height of the camera using the same idea above, and this is Step 1.

For Step 2, we need the original picture (if I'm not wrong this is a cut from a larger picture) with ISO and other information of the picture (I have DJI Mavic myself, the lens is definitely more a fisheye, so boundary stretch is big).

But assuming the X and Y axis has the same angel error (unlike, but...), and ignoring the lens stretching, for now, based on the rough length/width estimation, you might looking for a 2-4% or even 6% error in length... that's from 20.04 to 20.46 after the error compensation.

But of course, this is a very quick estimation here, and I'm not sure exactly how many % the error exactly is, just think it should be slightly more accurate the 20.88 you got from raw pixel measurement.

Relative to the main plane, the center J-16 is positioned almost exactly the same as the central J-20. So we could do length vs length measurements there. IIRC that's how the numbers were derived.
yes, but the stretching and angle error on two jets are still different, not exactly useful to say...
 

latenlazy

Colonel
don't get me wrong, appreciate you provide the source, and I agree this might be the closest we could get atm in terms of the references.

But still, we could measure slightly better than this, based on the angle differences the J-16 is opened, the center of the picture in Y-axis is roughly aliasing withe the left intake of the J-16 in the middle, I don't want to measure exactly how many pixels that is but let's just say roughly 10% may occur, so the average error in width is roughly 1-2% + pixel error for a quick estimation from your measurement, and that's assuming you are using the J-20 in the middle...

To do a more precise estimation, we could roughly reverse out the height of the camera using the same idea above, and this is Step 1.

For Step 2, we need the original picture (if I'm not wrong this is a cut from a larger picture) with ISO and other information of the picture (I have DJI Mavic myself, the lens is definitely more a fisheye, so boundary stretch is big).

But assuming the X and Y axis has the same angel error (unlike, but...), and ignoring the lens stretching, for now, based on the rough length/width estimation, you might looking for a 2-4% or even 6% error in length... that's from 20.04 to 20.46 after the error compensation.

But of course, this is a very quick estimation here, and I'm not sure exactly how many % the error exactly is, just think it should be slightly more accurate the 20.88 you got from raw pixel measurement.



yes, but the stretching and angle error on two jets are still different, not exactly useful to say...
You can use the multiple J-16s to adjust for lens stretch in theory. May need a pretty advanced piece of software to adjust the image to normalize spatial dimensions using three fixed size objects though.
 

Phead128

Junior Member
How can Rafale, a platform that was introduced in 2001? even with marginal upgrades, can be more advanced than J-20 which was introduced in 2017?

That's almost two decades difference, whereas there is limits to what France can upgrade in a frame, whereas China has the luxury of reinventing the frame to accommodate newest/latest technology including future upgrades.
 

Figaro

Junior Member
Registered Member
How can Rafale, a platform that was introduced in 2001? even with marginal upgrades, can be more advanced than J-20 which was introduced in 2017?

That's almost two decades difference, whereas there is limits to what France can upgrade in a frame, whereas China has the luxury of reinventing the frame to accommodate newest/latest technology including future upgrades.
Remember this is coming from the same group of people who believe they can fight a 2.5 front war against China and Pakistan ...
 

stannislas

Junior Member
Registered Member
You can use the multiple J-16s to adjust for lens stretch in theory. May need a pretty advanced piece of software to adjust the image to normalize spatial dimensions using three fixed size objects though.
you are right, but like what I said, given a rough estimation over the number @Inst claimed according to the pixel counting should give a length closer to the real thing... but still an estimation
 

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