Equation
Lieutenant General
Now coat it, paint it, and stamp it with a new serial number and she is all ready to go.
J-20 5th Gen Fighter Thread VI
- Thread starter siegecrossbow
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Something I’ve been thinking about wrt the J-20’s primer and surface materials is that the surface may actually employ more composites than we think. It took a while for me to pin down why I had a strong feeling that the yellow primer wasn’t necessarily indicative of an all metal exterior, and then I remembered that the early J-10B/C prototypes showed considerable composite use in the fuselage and wings, but production models seemed to be covered from head to tail in the same yellow primer that the J-20 was. Either production J-10B/C models reversed the use of those composites, which I think is unlikely, or the yellow coating is not zinc chromate but some other topcoat that works for both metal and composite surfaces, or perhaps it is zinc chromate on top of a more differentiated layer of coating. If that is the case, I think this will very likely also be true for the J-20.
Absolutely -- I mean, looking at "unpainted" J-20s we can see that every surface is yellow or grey. None of the various shades of green that we've seen on J-10B/C prototypes or even J-11B/15/16/etc aircraft that we've come to associate with composite use.
But I don't think anyone would've believed that it meant the canary yellow unpainted J-20s fielded no composites because we saw no green.
Some people made this argument a while back actually, which is why I put some thought into it in the first place.
plawolf
Lieutenant General
Don’t forget that the J20 uses newly developed Chinese metamaterials designed to counter UHF radar.
Such materials would need to be built onto the surface of the aircraft, and given how delicate RAM is, it makes most sense to apply this metamaterial skin directly onto the fuselage.
The uniform yellow on factory fresh J20s would either be the colour of those metamateiral skin, or a base coat designed to protect it, and probably help RAM and paint adhere to the skin.
Such materials would need to be built onto the surface of the aircraft, and given how delicate RAM is, it makes most sense to apply this metamaterial skin directly onto the fuselage.
The uniform yellow on factory fresh J20s would either be the colour of those metamateiral skin, or a base coat designed to protect it, and probably help RAM and paint adhere to the skin.
Both you and I made this argument a year ago in thread of FC-31.
#4734
and
#4735
In #4737 I tried to demonstrate using Y-20 that there is no connection of color of paint with material.
Surface colour alone is an unreliable indicator of airframe material and this is especially true of stealth aircraft, where there are many more layers of coatings than typical. I absolutely expect the J-20 to have a very substantial composite content despite the uniformly yellow paint.
OTOH this works both ways, the belief that everything painted in green primer on Chinese aircraft is automatically made out of composite is equally misguided. Consider this picture of a Rafale undergoing final assembly:
You could be forgiven for thinking that it supports the view that green means composite, as major composite parts (wing skins, rear fuselage skins, fin skins, forward fuselage skins) are indeed green while virtually all parts known to be metal are yellow. All the same, several parts which are definitely composite are also yellow (rudder, ailerons, elevons).
Then there are these Airbus A320-family airframes:
All of the fuselage is known to be metal, yet various parts are green while others are yellow, because they are supplied by plants all over Europe which may use different primer formulations (so long as it meets the spec, it matters not). Not to mention the yellow fin torque box and rudder on the first one, both of which are actually CFRP parts. And while we're on the subject of Airbus:
The vast majority of the A350 fuselage is composite (and still it is yellow), the only part which is confirmed to be metal is... the cockpit area, which is green.
In the absence of good sources like the Rafale material break-down graphic you have to exercise some judgement on whether the material distribution suggested by surface colour makes sense. On SAC's Flankers for example it frequently does not - I doubt their composite content is nearly as high as is frequently suggested.
EDIT: Yeah, what taxiya says, basically. The Y-20 is indeed another good example.
OTOH this works both ways, the belief that everything painted in green primer on Chinese aircraft is automatically made out of composite is equally misguided. Consider this picture of a Rafale undergoing final assembly:
You could be forgiven for thinking that it supports the view that green means composite, as major composite parts (wing skins, rear fuselage skins, fin skins, forward fuselage skins) are indeed green while virtually all parts known to be metal are yellow. All the same, several parts which are definitely composite are also yellow (rudder, ailerons, elevons).
Then there are these Airbus A320-family airframes:
All of the fuselage is known to be metal, yet various parts are green while others are yellow, because they are supplied by plants all over Europe which may use different primer formulations (so long as it meets the spec, it matters not). Not to mention the yellow fin torque box and rudder on the first one, both of which are actually CFRP parts. And while we're on the subject of Airbus:
The vast majority of the A350 fuselage is composite (and still it is yellow), the only part which is confirmed to be metal is... the cockpit area, which is green.
In the absence of good sources like the Rafale material break-down graphic you have to exercise some judgement on whether the material distribution suggested by surface colour makes sense. On SAC's Flankers for example it frequently does not - I doubt their composite content is nearly as high as is frequently suggested.
EDIT: Yeah, what taxiya says, basically. The Y-20 is indeed another good example.
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Interesting and many birds in the world have a big qty of composites even civils.
But on the pic curious to see Mirage 2000 with Rafale never build simult. in grey with Air Sup cammo can be Mirage 2000C or very possible 2000- 5F last Mirage 2000C upgraded ( on this pic i think ) with especialy RDY radar.
Remains one other possibilty in maintenance C or -5F in a other plant not the Dassault plant
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Do you have a link to back this statement up?
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