J-20 5th Gen Fighter Thread VI

[Air Force Brat]

(cont)

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A radome made of meta-material (Photo: Kuang Chi)

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An air duct for an airplane (Photo: Kuang Chi)

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Antennas made of meta-material (Photo: Kuang Chi)

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An anti-icing board (Photo: Kuang Chi)

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An aircraft structure grid made of meta-material (Photo: Kuang Chi)

With announcements of this type that provide a little more detail on the aircraft, and new variants such as the onboard version and the one with Chinese jet engine vector, the program J-20 we probably still reserved other surprises to come.

To be continued.

Henri K.

Meta- Material is really nothing new,, it has been used to fabricate radomes with the desired properties, and the matt that is applied to inlets, leading and trailing edges on the J-20 and F-22, it is also used for the covers over many of the avionics on the J-20.. Kool Stuff, and it should actually absorb those radar waves, that's the principle, it allows certain frequencies to "radiate" through, while absorbing everything else..

also your post illustrates that meta metarial is conductive and can be charged with current to produce enough heat for very effective deicing,, in fact I would imagine that's exactly what its doing, (besides absorbing radiation), on those leading edges of the inlets, wings and tail surfaces....

 

[Hyperwarp]

Any ideas?

 

[Air Force Brat]

Any ideas?

View attachment 46125

Exactly what I was referring to as avionics covers, we could accurately call them side panels or antennae covers?? or since it is conductive it could be the actual "sensor grid?"

 

[Deino]

Any ideas?

View attachment 46125

IMO not, it has a different shape.

 

[taxiya]

Any ideas?

View attachment 46125

Although they are of different shapes, I can imagine the same purpose.
The demo piece was said to be a "超材料隐身格栅"="meta-material stealthy grid".

The two doors/covers on the J-20 could be (and I strongly believe) air flow bleeding doors for the DSI bump. The opening holes of the doors are in the size of millimeters. That is the worst size for stealth against millimeter Radar wave. Radar waves close to the size of the objects will NOT bounce off like light on a mirror (to other direction), but re-emit from the object to all directions, making the object like a lamp. The only way to deal with this is a material that absorb efficiently. Traditional RAM simply can not do it because itself has a thickness, neither can the LM patented band selective material (micro fiber metal wire laced composite) because the holes of the grid itself are in the same size of the supposed distance between the micro wires, all in millimeter. So here comes the meta-material.

Same bleeding openings on JF-17


Besides the air bleeding doors, the doors on J-20 could also be related to this one. The texts are two blurred, but I can make the first character on the lower line as "天", maybe related to some electrical thing as in "天线".

 

[jobjed]

The opening holes of the doors are in the size of millimeters. That is the worst size for stealth against millimeter Radar wave. Radar waves close to the size of the objects will NOT bounce off like light on a mirror (to other direction), but re-emit from the object to all directions, making the object like a lamp.

Rule of thumb is aperture size should be smaller than 1/6 of the target band's wavelength. X-band has wavelength of 2 - 3.75cm so holes a few millimetres wide is precisely what's needed to counter X-band radar.

 

[taxiya]

Rule of thumb is aperture size should be smaller than 1/6 of the target band's wavelength. X-band has wavelength of 2 - 3.75cm so holes a few millimetres wide is precisely what's needed to counter X-band radar.

Yes, that is X-band, not millimeter band which is less than 10mm. Just asking, what band is AIM-120's radar? Or broadly speaking, any fire control radar working on the Ka band for example?

 

[jobjed]

Yes, that is X-band, not millimeter band which is less than 10mm. Just asking, what band is AIM-120's radar? Or broadly speaking, any fire control radar working on the Ka band for example?

To launch an AIM-120, the launching aircraft has to first successfully track its target, which is not going to happen if the target is a low-RCS aircraft unless the pilot's feeling suicidal.

 

[taxiya]

To launch an AIM-120, the launching aircraft has to first successfully track its target, which is not going to happen if the target is a low-RCS aircraft unless the pilot's feeling suicidal.

First of all, I am not going to insist on my guessing. But I can not agree with this answer, because eventually a low RCS aircraft will face one another. Besides, such aircraft does not have to go suicidally close to launch an AIM-120 type of missile, but rely on the AWACS flying behind while remaining radio silent. The missile will have to lock on the target at its final approach to the cued location (within 10 to 20km). The launching platform may not have to see, but the missile much see the target, right? So if the missile's radar works on millimeter band, the target must counter it, doesn't it?

 

[jobjed]

First of all, I am not going to insist on my guessing. But I can not agree with this answer, because eventually a low RCS aircraft will face one another. Besides, such aircraft does not have to go suicidally close to launch an AIM-120 type of missile, but rely on the AWACS flying behind while remaining radio silent. The missile will have to lock on the target at its final approach to the cued location (within 10 to 20km). The launching platform may not have to see, but the missile much see the target, right? So if (I don't know since you haven't answered) the missile's radar works on millimeter band, the target must counter it, doesn't it?

An active radar-guided AAM picks up the target with its own radar at around 20-30km, and that's against 4th-gen fighters without stealth shaping. Against low-RCS 5th-gens, that range will be much reduced even if the aircraft's shaping is not optimised for K or MMW-band. Before the missile gets close enough to see its target, the aircraft's MAWS and radar will already know an active beam-emitter is fast approaching, allowing the pilot to change his heading so the missile will never get the opportunity to lock on by itself.