J-20... The New Generation Fighter III

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Quickie

Quickie

Colonel
paintgun said:
the picture was not tempered with in any condition, maybe just the setting of the (crappy) camera, or lost information in jpeg compression, causing it to change hue
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The reason I'm skeptical that it's due to a camera setting effect or that of software imaging is because, if that's the reason, the whole picture including the hue of the buildings in the background, will be affected. I don't remember the paint of the buildings as being darker than the dark grey of the J-20. It's still possible the colour of the J-20 was doctored though, but I can't be sure of this.
 
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paintgun

Senior Member
the dead giveaway for me was the background vegetation, it is a very blue hue
and the grasses on foreground appear almost purple-ish, because again red/orange hue+blue = purple, but it's actually gray on that picture

you can try any color picker/eye drop tool and see what the real colors are if you want to see it for yourself, or see if im wrong

if the picture was tempered, the culprit would be wise to isolate the hue change just on the J-20 as you say, but perhaps he is just being lazy, or perhaps it is not tempered at all, just a crappy camera

the J-20 being lighter compared to the background building is also natural
 
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Centrist

Junior Member
In early photos it seemed that the J-20 was dark green. Now it seems to be grey. It does seem to change. There are many factors that could cause this...
 
Quickie

Quickie

Colonel
It doesn't seem like the picture had had its colour manipulated either, at least not in a high degree as I can still see some of the primary colours like the red, yellow, blue and green. It could also be the layer of painting just behind the dark grey, i.e. the J-20 was in the middle of a paintjob.
 
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cataphract

New Member
Martian said:
J-20 Mighty Dragon DSI and S-duct design is superior to F-22 S-duct-only design

The J-20 Mighty Dragon is a truly modern design. The old F-22 Raptor really shows its age when we compare the S-ducts for the world's two premier stealth fighters.

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J-20 Mighty Dragon incorporates advanced DSI to dramatically increase the stealthiness of its S-duct design.

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J-20's combined DSI and S-duct design forces radar waves to travel a circuitous path of five reflections before they can strike the engine fan blades.

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Lacking an advanced DSI, the F-22 is helpless from preventing radar waves in traversing the shortest path to reach the F-22 engine fan blades in only two reflections.

The following calculations will show the massive advantage in the stealthiness of the J-20 S-ducts, when compared to the F-22.

The effectiveness of RAM coating is a 99.684% reduction (or 0.00316 left) in radar energy (see citation below). For radar energy entering the J-20 S-duct, it must undergo a minimum of five reflections before it strikes the engine fan blades. The shortest path to exit the J-20 S-duct is to reverse course and escape in another five reflections. The total minimum number of reflections is ten.

To calculate the amount of the original radar energy that entered the J-20 S-duct and was able to egress/reflect out of the S-duct after striking the engine fan blades, we have to reduce the original radar energy by 10 reflections from the RAM coated S-air duct walls.

Amount of original radar energy that can escape J-20 S-duct = (0.00316) ^ 10 = 9.93 x 10E-26

Since incoming radar waves can escape the F-22 S-duct in only four reflections, the attenuation of the enemy radar waves is inferior to the J-20 by many magnitudes.

Amount of original radar energy that can escape F-22 S-duct = (0.00316) ^ 4 = 9.97 x 10E-11

The effectiveness of the J-20 DSI and S-duct design is approximately 1 x 10E15 times better than the F-22 S-duct-only design or 1,000,000,000,000,000 times stealthier.

Admittedly, the amount of radar energy escaping from the S-ducts of the J-20 and F-22 are both extremely low and virtually undetectable. Nevertheless, from a stealth design standpoint, the J-20 is clearly far superior.

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Citation for RAM coating reduction of 99.684% reduction in radar energy.

From my February 12, 2011 post:

Revised final estimate for J-20 canards' radar return energy is 1.035 x 10^-17

I find Gambit's arguments for a -25 dB reduction, instead of -50 dB, from RAM coating to be convincing. I have revised my calculations for the effect from China J-20's canards. Quickie is correct that -25 dB is equivalent to 99.684% reduction (e.g. 10^2.5; take inverse; and convert to percentage). Thank you to Delft for highlighting the issue.
...
After hitting the canards, we know that 99.684% of the reflected energy is reduced by the military-grade RAM. (See
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) This means that only 0.00316 (e.g. 1 - 0.99684 = 0.00316) of the impacting radar energy survives contact with the canard's RAM surface.
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f22cutaway.gif


1stly, as you can see, the F-22's intake duct isn't as you assumed. It is in fact closer to the F-35's intake duct of a continuous curve structure.
2ndly, you failed to account for duct geometry that would eliminate the reflected waves.
3rdly, you failed to account for the fact that DSI, being a round bulge structure outside of the aircraft scatters significantly more EMR more evenly. Thusly increasing overall rcs from sides.

And again you continue to assume RAM's effectiveness is 99.684%, a number that simply does not coincide with real world data or examples.

You can have a spherical metal ball with the rcs of 1000m^2, one of the WORST stealth shapes you could have (aside from corner reflectors)

This metal ball would have a radius of 17 Meters, and when coated with you magical RAM, it would have a radar cross section of 3m^2.

if RAM worked that well, you wouldn't need shaping to get an aircraft's rcs down to a golf ball from 1-2m^2.
 
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MiG-29

MiG-29

Banned Idiot
cataphract said:
f22cutaway.gif


1stly, as you can see, the F-22's intake duct isn't as you assumed. It is in fact closer to the F-35's intake duct of a continuous curve structure.
2ndly, you failed to account for duct geometry that would eliminate the reflected waves.
3rdly, you failed to account for the fact that DSI, being a round bulge structure outside of the aircraft scatters significantly more EMR more evenly. Thusly increasing overall rcs from sides.

And again you continue to assume RAM's effectiveness is 99.684%, a number that simply does not coincide with real world data or examples.

You can have a spherical metal ball with the rcs of 1000m^2, one of the WORST stealth shapes you could have (aside from corner reflectors)

This metal ball would have a radius of 17 Meters, and when coated with you magical RAM, it would have a radar cross section of 3m^2.

if RAM worked that well, you wouldn't need shaping to get an aircraft's rcs down to a golf ball from 1-2m^2.
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agree
 
L

latenlazy

Brigadier
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Thanks to =GT at CD

1) Is the spool time supposed to be that long?
2) Is that two elevators on the trailing edge I see?

It also just dawned on me that the J-20 doesn't need the WS-15s for peak flight test conditions so long as the plane's T:W (not the engine's, the plane's) matches specifications.

Also, the bobbing it does while on the runway seems to imply that the J-20 is very back heavy as it is right now.
 
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Lacrimosa

New Member
cataphract said:
f22cutaway.gif


1stly, as you can see, the F-22's intake duct isn't as you assumed. It is in fact closer to the F-35's intake duct of a continuous curve structure.
2ndly, you failed to account for duct geometry that would eliminate the reflected waves.
3rdly, you failed to account for the fact that DSI, being a round bulge structure outside of the aircraft scatters significantly more EMR more evenly. Thusly increasing overall rcs from sides.

And again you continue to assume RAM's effectiveness is 99.684%, a number that simply does not coincide with real world data or examples.

You can have a spherical metal ball with the rcs of 1000m^2, one of the WORST stealth shapes you could have (aside from corner reflectors)

This metal ball would have a radius of 17 Meters, and when coated with you magical RAM, it would have a radar cross section of 3m^2.

if RAM worked that well, you wouldn't need shaping to get an aircraft's rcs down to a golf ball from 1-2m^2.
Click to expand...

Taking real numbers and torturing them until they give him whatever he wanted is Martian's specialty, I won't worry about him.

He's a sort of a less reasonable version of MiG-29, for China.
 
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latenlazy

Brigadier
Lacrimosa said:
Taking real numbers and torturing them until they give him whatever he wanted is Martian's specialty, I won't worry about him.

He's a sort of a less reasonable version of MiG-29, for China.
Click to expand...

Martian throws more tantrums than Mig.

Anyways, there are ways to handle the signal returns from the bump, including making them out of materials transparent to the most difficult frequencies to take care of them with internal structures.
 
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paintgun

Senior Member
latenlazy said:
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Thanks to =GT at CD

1) Is the spool time supposed to be that long?
2) Is that two elevators on the trailing edge I see?

It also just dawned on me that the J-20 doesn't need the WS-15s for peak flight test conditions so long as the plane's T:W (not the engine's, the plane's) matches specifications.

Also, the bobbing it does while on the runway seems to imply that the J-20 is very back heavy as it is right now.
Click to expand...

spool time seems normal for me - flaperon or elevon, i don't know

engine : which means this engine works just fine for airframe testing and validation
i think the prototype is not onto performance testing yet, also no point in testing peak performance if you have to change engine later, and work out the kinks all over again, no point gathering data with interim engine

back heavy = no radar installed
 
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