Vanessa1402
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How thick is the Radar absorbing coating of fighter?. Is it 1 mm? 2 mm? or 4 mm?
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I don't know about thickness but current RAM allegedly can reduce reflection by 6-10 dB
Would you mind me asking where you get that from? and by large aircraft, do you mean like B-2 or F-18 E/F?I don't know about thickness but current RAM allegedly can reduce reflection by 6-10 dB
There are a lot of different variables at work - frequency, etc. - but ~-20db is more typical for modern aircraft. And that is approaching the theoretical and practical limits of RAM.
The depth of the coating stack on a given aircraft will vary. In some areas it will be deeper than others. Maybe the angle to a ground threat radar means that it needs to be deeper in one place. Or maybe in an area where energy striking another surface collects / focuses. Or the whole stack is deeper / more complex because of the properties of the underlying structure (i.e. the structure is plastic and needs several layers of other stuff to reflect and absorb, etc.).
On one modern, large aircraft the layer of magnetic RAM in the coating stack varies from 0.5mm to 2.25mm
What is that image?. Is it the skin of the F-35 or something else?. Does the number represent the thickness in mm or nanometer?it's extremely inconsistent even on small partsI asked this because even on the same aircraft, the thickness of the radar absorbing material seem extremely inconsistent
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imho, the energy to be absorbed will be the same as it is on the same fighters, both the wing and fusalage are exposed parts.@Vanessa1402 : It depends on how much energy need to be absorbed. Hence the relative geometry of the plane regarding the said panel is driving the RAM thickness.
this is F-35 DSI bulb area; of course, RAM thickness numbers are deliberately distortedWhat is that image?. Is it the skin of the F-35 or something else?. Does the number represent the thickness in mm or nanometer?
How do you know that is the RAM thickness and not the full skin thickness?
Can you tell us where that screenshot come from?it's extremely inconsistent even on small partsI asked this because even on the same aircraft, the thickness of the radar absorbing material seem extremely inconsistent
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On the F-35 those are carbon skin panels. They may or may not have a coating of RAM applied.No, I mean the gray panel, like in this photoIf you mean the green panels, no those are coated in primer. They have an edge treatment that is conductive or impedance matching.
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To be fair though, isn't carbon fiber itself also absorb radar wave?On the F-35 those are carbon skin panels. They may or may not have a coating of RAM applied.
I would double down on that one Very curious to see where those comes from.Can you tell us where that screenshot come from?it's extremely inconsistent even on small partsI asked this because even on the same aircraft, the thickness of the radar absorbing material seem extremely inconsistent
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It can reflect or absorb depending on how it is constructed. On the F-35 the skin panels reflectTo be fair though, isn't carbon fiber itself also absorb radar wave?On the F-35 those are carbon skin panels. They may or may not have a coating of RAM applied.
Afaik, the carbon fiber skin (Graphite exposy or/and BMI) are the one with the green primerOn the F-35 those are carbon skin panels. They may or may not have a coating of RAM applied.No, I mean the gray panel, like in this photoIf you mean the green panels, no those are coated in primer. They have an edge treatment that is conductive or impedance matching.
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Count me in, I also want to knowI would double down on that one Very curious to see where those comes fromCan you tell us where that screenshot come from?it's extremely inconsistent even on small partsI asked this because even on the same aircraft, the thickness of the radar absorbing material seem extremely inconsistent
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Where are these pictures from?Afaik, the carbon fiber skin (Graphite exposy or/and BMI) are the one with the green primerOn the F-35 those are carbon skin panels. They may or may not have a coating of RAM applied.No, I mean the gray panel, like in this photoIf you mean the green panels, no those are coated in primer. They have an edge treatment that is conductive or impedance matching.
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Isn't that a bit counter productive for stealth aircraft?.It can reflect or absorb depending on how it is constructed. On the F-35 the skin panels reflectTo be fair though, isn't carbon fiber itself also absorb radar wave?On the F-35 those are carbon skin panels. They may or may not have a coating of RAM applied.
No.Isn't that a bit counter productive for stealth aircraft?.It can reflect or absorb depending on how it is constructed. On the F-35 the skin panels reflectTo be fair though, isn't carbon fiber itself also absorb radar wave?On the F-35 those are carbon skin panels. They may or may not have a coating of RAM applied.
I don't think you understand my question. For reflection, you can always coat the lowest layer with thin layer of metal. But if the layers on top are RAM, then they can help absorb the radar wave before they are reflected. Thicker the RAM, the lower the effective frequency and also better absorbing capabilityNo.Isn't that a bit counter productive for stealth aircraft?.It can reflect or absorb depending on how it is constructed. On the F-35 the skin panels reflect
You can always reflect more energy than you can absorb. That was the breakthrough in stealth in the 70s, designing to reflect energy away from the emitter. Shape is the cake, materials aren’t even the icing. Shape is all about reflection
The thin layer of metal is a maintenance nightmare. The reflective skin panels are an attempt at a solution.I don't think you understand my question. For reflection, you can always coat the lowest layer with thin layer of metal. But if the layers on top are RAM, then they can help absorb the radar wave before they are reflected. Thicker the RAM, the lower the effective frequency and also better absorbing capabilityNo.Isn't that a bit counter productive for stealth aircraft?.It can reflect or absorb depending on how it is constructed. On the F-35 the skin panels reflect
You can always reflect more energy than you can absorb. That was the breakthrough in stealth in the 70s, designing to reflect energy away from the emitter. Shape is the cake, materials aren’t even the icing. Shape is all about reflection
Why would the layer of metal be a maintenance nightmare if it is underneath the RAM layer and completely shielded from the environment? at least that how it seem on F-22, the conductive coating is below the primer and top coatThe thin layer of metal is a maintenance nightmare. The reflective skin panels are an attempt at a solution.
with the same permittivity and permeability, it would seem logical that thicker layer of RAM will absorb more radiation or at very least have lower effective frequency. I vaguely recall reading somewhere that RAM on F-35 is slightly different as it is imbedded inside the composite and called the fibermatThicker ram doesn’t necessarily mean it absorbs more of the target frequency and it is heavy and difficult to maintain.
Why would the layer of metal be a maintenance nightmare if it is underneath the RAM layer and completely shielded from the environment? at least that how it seem on F-22, the conductive coating is below the primer and top coat
with the same permittivity and permeability, it would seem logical that thicker layer of RAM will absorb more radiation or at very least have lower effective frequency. I vaguely recall reading somewhere that RAM on F-35 is slightly different as it is imbedded inside the composite and called the fibermat
IMHO, that only true for full stealth aircraft like B-2, F-117. Whereas, the radar scattering of semi stealth fighter like F-35, Su-57 aren't very impressive.As I understand it is that Stealth is 80-90% shaping of the plane.You should be able to make a plane out of metal in a specific shape, and it would reflect less then a plane that is not shaped.
The only reason that I can think of that can possibly make a thinner RAM more effective than thicker RAM layer is the reflection at boundary (before the wave enter the material). So if a metal sheet is placed at 1/4 wavelength distance below that RAM surface then it can prevent front face reflection. But even for X-band, that still need pretty thick layer
No, RAM does not necessarily behave that way. Thicker is rarely "better". There is an ideal depth for a given material. Modern aircraft often have several stacked layers of RAM that are meant to work together. For example, a low frequency coating that allows higher frequencies through with some attenuation, and below that a high frequency material.
That would be questionable I think, the full coating these look like 1-2 mm thick at mostThe inlets of the F-22 have about a dozen layers of coating.
That would be questionable I think, the full coating these look like 1-2 mm thick at mostThe inlets of the F-22 have about a dozen layers of coating.
mm not cmSo thickness in order of Centimeters and differing types of coat can be expected.