Radar Absorbing Materials and Structures (RAM / RAS), stealth (LO) coatings

[Vanessa1402]

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.

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.

 

[Ronny]

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.

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

The 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 most

 

[quellish]

The 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 most

 

[stealthflanker]

So thickness in order of Centimeters and differing types of coat can be expected.

 

[quellish]

So thickness in order of Centimeters and differing types of coat can be expected.

mm not cm

 

[Ronny]

The green is metal with anti corrosion coating

 

[publiusr]

A "new" coating?

Blocking radio waves and electromagnetic interference with the flip of a switch

Researchers in Drexel University's College of Engineering have developed a thin film device, fabricated by spray coating, that can block electromagnetic radiation with the flip of a switch. The breakthrough, enabled by versatile two-dimensional materials called MXenes, could adjust the...

phys.org

This may yet be a re-discovery. If truly new---maybe a way to give stealth to more conventional airframes?

Space skin

Multi-layered 'space skin' can help future satellites and spacecraft harvest energy

A research team has shown that their innovative nano-coating, called the Multifunctional Nanobarrier Structure (MFNS), can reduce the operating temperatures of space-qualified structures from 120 degrees Celsius to 60 degrees Celsius.

phys.org

 

[paralay]

What will the stealth coating of the aircraft turn into after landing?

 

[AGS-1787]

What will the stealth coating of the aircraft turn into after landing?

That’s a valid point; how much stealth coating effectiveness gets degraded by dirt and water?

 

[paralay]

That’s a valid point; how much stealth coating effectiveness gets degraded by dirt and water?

chipped coating or other damage can significantly increase visibility. For a T-75 fighter with a 0.2 m2 RCS or an F-22 with a 0.3 m2 RCS, this is significant

 

[quellish]

That’s a valid point; how much stealth coating effectiveness gets degraded by dirt and water?

Water/humidity, dirt, and UV all contribute to the degradation of a coating stack. Voids (bubbles) form between layers and then "pop" taking off the coating, etc.

 

[Acatomic]

What will the stealth coating of the aircraft turn into after landing?

STOL on highways, not dirt roads

 

[Scott Kenny]

Fun fact, the inlet of F-35 and F-22 use some sort of RAM with white color, unlike the outer skin

View attachment 679751
View attachment 679752

That's white paint/topcoat. Though it's probably not using Titanium dioxide as the white pigment.

All jet inlets are painted white at a certain point. (Possible exception for the blackbirds due to heat levels) You need to be able to see anything inside the inlets before starting the engine.