J-20 - physical parameters discussion and other overload from main thread


Inst

Senior Member
Clearly, you don't have much knowledge in engineering, especially in civil engineering. How could you assume the brick is exactly is 5x4m, the process for you to get those numbers is pretty unreasonable, based on " relatively standard ", what standard? Like I repeated many times, it's a construction material, I won't be surprised if their error to be more than 10cm differences between each. And if you won't read what other people wrote then, I'm done discussing this with you.

Also, more importantly, known how runway is constructed, those are not actually "brick", normally they will do the entire runway in concrete and after the concrete is dry, they use some machine to cut out each channel for the concrete to be able to expand in the summer and shrink in the wintertime. And if you have any idea about the civil engineer, trust me, their minimal error is measured in cm, whereas 1mm (mostly even much less) in jet production.

So I will say your pixel measure will be much accurate than the grid approximation, just need some additional error correction to get the estimation more reliable.
Brick was the term you used. I actually assumed these were concrete blocks. If your point is that there's divider lines, well, it's notable that they seem uniform with a 5:4 length / width ratio. At the scale of the picture, likewise, 18 pixels = approximately 1 meter if we assume 5mx4m, perhaps 16-17 pixels = 1 meter. A cm error wouldn't be visible in that picture.

Measuring different square units, it seems as though the rectangle size is uniform.

===

Also, I'll point out that this is a military runway and therefore can't be expected to be built similarly to civilian runways. It, in contrast, has to be hardened against explosives (because explosives will be used against the runway) and be built in such a way that mines laid onto the runway to impede repair can be easily removed.

Here's another shot of PLA runway material.

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Christ, are we now discussing pavement?

An old introduction to airfield pavement:

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artificially covered surface for,ensure uninterrupted year-round operation.&text=The principal type of monolithic,longitudinally with high-strength wire.
 
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stannislas

Junior Member
Registered Member
Brick was the term you used. I actually assumed these were concrete blocks. If your point is that there's divider lines, well, it's notable that they seem uniform with a 5:4 length / width ratio. At the scale of the picture, likewise, 18 pixels = approximately 1 meter if we assume 5mx4m, perhaps 16-17 pixels = 1 meter. A cm error wouldn't be visible in that picture.

Measuring different square units, it seems as though the rectangle size is uniform.

===

Also, I'll point out that this is a military runway and therefore can't be expected to be built similarly to civilian runways. It, in contrast, has to be hardened against explosives (because explosives will be used against the runway) and be built in such a way that mines laid onto the runway to impede repair can be easily removed.

Here's another shot of PLA runway material.

Please, Log in or Register to view URLs content!

Christ, are we now discussing pavement?

An old introduction to airfield pavement:

Please, Log in or Register to view URLs content!
artificially covered surface for,ensure uninterrupted year-round operation.&text=The principal type of monolithic,longitudinally with high-strength wire.
ok, :rolleyes:, let's just stop here, I feel wasting of time continues the discussion on how to construct a runway, you are free to believe whatever you like and deny whatever you like, such as whether they are built in different ways.

Oh, there are international standards about runway pavement applies on both civil and military runway... But of course, in your mind, the Chinese would like to waste time and money to achieve the same outcome in a different way, sure...
 

Inst

Senior Member
You know the easiest argument you have is just to argue that the method I'm using would end up making the J-16 off its known dimensions, right? The closest I can get is 0.7% if you go there.

Otherwise, we have relatively canonical dimensions, 20.88 length vs 12.95 wingspan.
 

stannislas

Junior Member
Registered Member
You know the easiest argument you have is just to argue that the method I'm using would end up making the J-16 off its known dimensions, right? The closest I can get is 0.7% if you go there.

Otherwise, we have relatively canonical dimensions, 20.88 length vs 12.95 wingspan.
Also like I repeated so many times, I'm ok with the way you count the pixel. But on top of that, You need to do an error correction which you keep refusing to do so.

Based on how you did the wingspan, given the center of the camera is highly likely at somewhere around the left intake of the middle J-16, just by quick calculation you can tell there is a roughly 1-2% error estimation on that. And similarly, because we are not sure exactly where the camera center is, but applying the similar approximation, a rough 2-4% estimation is expected.

Also, the grid estimation is on how much the photo distorted is meaningless, there are just too many unknown there, "brick" size, channel size, the error of each, and etc. Thus using the grid to 0.7% is simply meaningless. We are talking about the difference on the decimeter scale, and you are trying to us measure it with something that could have decimeter error, seriously?
 

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