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Chengdu J-20 5th Generation Aircraft News & Discussions

Yes, since it is a scan from a two-page report in "Weapons magazine"

It's not a crack because of two page becoming one picture, but indeed a crack to the fuselage. Maybe it's intentional, to raise the RCS, or J-20 still have a flaw that we don't know?
 
It's not a crack because of two page becoming one picture, but indeed a crack to the fuselage. Maybe it's intentional, to raise the RCS, or J-20 still have a flaw that we don't know?

Here's a modified version ... and NO, that crack is only due to the not yet completely closed or just opening main landing gear door.

J-20 2016 via Weaponsmagazine - 1+.jpg
 
And too much superstition is bad for yours. I smell the stink of a certain wannabe aeronautical engineer on you. What you (and he) missed was that counting surfaces is not how RCS is determined. You (rather he) have also failed to show that if there is an increase in the RCS as a result of the canards and the strakes relative to a configuration with horizontal stabilizers, that this increase is tactically significant.
Actually, regarding the highlighted -- IT IS.

There are three rules, or guidelines, on designing a low radar observable body.

Control of:

- Quantity of radiators.
- Array of radiators
- Modes of radiation

The sphere is the ideal 'stealth' body because it is the most obedient to those three rules. In fact, the sphere is the ideal radar calibration body.

http://www.centurymetalspinning.com/radar-calibration-spheres/
https://en.wikipedia.org/wiki/Lincoln_Calibration_Sphere_1

In radar detection, everything is a radiator. If a structure can reflect a radar signal, it is a radiator.

The sphere has only one radiator -- its body.

Whereas, with something like this...

drYTM21.jpg


You can see multiple protrusions from the main body -- the fuselage.

So regarding rule 1, the higher the count of structures that protrudes from the body, the greater the contribution to total RCS. The problem then become how to minimize that contribution. You can apply radar absorbent materials ( RAM ) but that does not take away from the fact that the structure is a contributor.

Rule 2 -- Array of radiators -- is how the canards are in relation to nearby structures. Whether their relationship is tactically significant or not, we do not know unless the jet is under independent RCS measurement testing and the data is available for all to see. But the problem remains in that the higher the quantity of radiators ( Rule 1 ), the greater the difficulty in applying Rule 2. Not impossible, but greater difficulty.

Rule 3 -- Modes of radiation -- is how radar signals leave a finite structure. In learning about radar principles, students are taught using theoretical infinite surfaces. But that is not real life where everything is finite. A radar signal make contact with a structure. Sooner or later, it has to leave that structure. The higher the count of finite structures, the greater the relationships of these structures in Rule 2, which could lead to higher total RCS.

The point here is that no rule is more important than the other. All three have equal significance.

So if you think that the J-20's eight major protrusions/structures have no bearing on final RCS, we are indeed talking about 'Chinese physics'.
 
@Deino;

EDIT,

Found another image and there is indeed a opening panel on the side. So it is not a crack as it appeared.

24063640826_6ecc996c68_o.jpg
 
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@Deino;

j-20-2016-via-weaponsmagazine-1-jpg.417140


Two page ad or scan has nothing to do with the crack. This is not a scanning artefact. Th crack doesn't have a pattern and it is ending at an awkward position. From the look of it, it really feels like a crack.


No ... I'm really surprised no-one sees it too: it looks only like a crack it is due to the not yet completely closed or just opening main landing gear door.

On the older prototypes the front part of the door was always open, when the gear was down, however on the revised ones and LRIP-birds it always closes again soon after the gear is down or only opens just a moment before the gear is taken in again.

So it is not a crack. The front door is just not fully closed.

Deino

J-20A yellow - 20170112.jpg
 
Metal istarhan crack nahe hota :P paper scan lag raha hey magazine ka

Translation for international readers: Metal does not cracks like this and the line indicates paper scan from magazine.

@Stealth kindly use English so that readers see it appropriate.

Regards,
 
Asok ... is that a question asked in earnest ???:fie:

Yes, I don't remember seeing this pic or camouflage scheme before. It's not bad, consider every other Chinese planes, looks like that. This is the color of Chinese sky.
 
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