How thick is the radar absorbing material on F-22/F-35

Discuss the F-35 Lightning II
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optimist

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Unread post16 Jun 2022, 08:28

Carbon composites and CNT carbon nanotube really don't like lightning. CNT didn't have structural approval at the time and was used as some nonstructure on the F-35 and not the carbon composite. With the R&D costs now hitting 80 billion. This might have changed.
Last edited by optimist on 16 Jun 2022, 08:39, edited 1 time in total.
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garrya

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Unread post16 Jun 2022, 08:38

I can find some photos of the F-35 in the factory, it appear that the aircraft has 3 layers
The first yellow layer is the aluminum load bearing structure
Then the green layer on top of it is the Graphite exposy + primer
The gray on top is the RAM

f-35 skin.PNG

gray skin.PNG

gray skin2.PNG

thickness.jpg

material.PNG

skin material.PNG
Last edited by garrya on 16 Jun 2022, 08:59, edited 1 time in total.
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Unread post16 Jun 2022, 08:57

Using CNT cables can save 1200lb in weight too
https://blog.dexmat.com/carbon-nanotube ... st-savings
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zhangmdev

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Unread post16 Jun 2022, 09:18

I remember there are some images of scraping away and hand-applying the coating during the maintenance, which were buried in the "dirty" F-35C at sea, and Netherlands F-35 thread.

https://www.dvidshub.net/image/2643438/ ... spect-f-35

nondestructive inspection apprentice, uses a transducer to check for cracks in the low observable paint on an F-35A
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Unread post16 Jun 2022, 12:09

garrya wrote:
madrat wrote:I can only imagine the coating acts as a regulator of electromagnetic wave energy. In electronics you tame peaks and valleys using batteries or capacitance as a choke.

What you describe is a Salisbury screen, aircraft don't use that type of RAM because it is too thick


If I was doing it then I'd want mass production. It would need to be tolerant of high heat, so it makes sense to embed it in heat tolerant materials. It would need to be thin, so I'm thinking graphene materials. There would need to be an insulator so I'd pick ceramic paint. And I'd need anode and cathodes that are largely stable and heat tolerant, so I'd be thinking my ceramics can absorb them. I'm confident you can apply these materials at 12000 dpi with off the shelf technology. All three layers would be less than 100 microns. Rinse, repeat 3-5 times to tune in your desired choke spectrum. Final product would be equivalent to a single carbon fiber matting. Covering with another layer of carbon fiber doesn't sound feasible because your ceramics would not bond. Perhaps they place the RAM on each carbon fiber layer with enough spacing where bonding layers can still happen. It would end up like a snakeskin doing it that way. Under some circumstances you might peel off. On the positive side, it would take a whole lot of heat application for it to emit in the IR spectrum.
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doge

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Unread post16 Jun 2022, 16:32

The wingskin section thickness of the old earliest F-35 it was manufactured when it had 1 top skin seems to be 9.5 mm. 8)
Current, features 3 top skins.
https://www.compositesworld.com/article ... 35-fighter
Skinning the F-35 fighter
Published 10/19/2009 | 13 MINUTE READ
Fasteneing the all-composites skin on the Lightning II requires machining and drilling technology that is optimized for cost-efficiency.
.
.

Proving tool geometry and materials
When Lockheed Martin first began assessing router and drill tools for F-35 production in its DST machining center (Dörries Scharmann Technologie GmbH, Mönchengladbach, Germany), it used a polycrystalline diamond (PCD) router with braised diamond inserts. It featured straight flutes and produced too much delamination on the composite structures, forcing rework and increased tooling costs. Further, the tools lacked the durability needed for this demanding application — one 0.375-inch/9.5-mm-thick wingskin section typically required 24 tools to rout (this was when the F-35 had one large, continuous top skin to cover both wings; current design features three top skins).

I think I saw an Articles the other day that written in sentence "Average thickness of the entire F-35 skin coating is 1.5 cm" but I quickly closed it and Lost the source. :doh: I cannot recall. (or Maybe I am wrong.) I'm sorry. :notworthy: (It may not be an Articles in English. It may be an Italian Articles, or a Norwegian, Dutch, Danish, Swiss, or Finnish etc... Articles.)
F-35 has Too Many Articles !! :bang:
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garrya

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Unread post17 Jun 2022, 03:04

doge wrote:The wingskin section thickness of the old earliest F-35 it was manufactured when it had 1 top skin seems to be 9.5 mm. 8)
Current, features 3 top skins.
https://www.compositesworld.com/article ... 35-fighter
Skinning the F-35 fighter
Published 10/19/2009 | 13 MINUTE READ
Fasteneing the all-composites skin on the Lightning II requires machining and drilling technology that is optimized for cost-efficiency.
.
.

Proving tool geometry and materials
When Lockheed Martin first began assessing router and drill tools for F-35 production in its DST machining center (Dörries Scharmann Technologie GmbH, Mönchengladbach, Germany), it used a polycrystalline diamond (PCD) router with braised diamond inserts. It featured straight flutes and produced too much delamination on the composite structures, forcing rework and increased tooling costs. Further, the tools lacked the durability needed for this demanding application — one 0.375-inch/9.5-mm-thick wingskin section typically required 24 tools to rout (this was when the F-35 had one large, continuous top skin to cover both wings; current design features three top skins).

I think I saw an Articles the other day that written in sentence "Average thickness of the entire F-35 skin coating is 1.5 cm" but I quickly closed it and Lost the source. :doh: I cannot recall. (or Maybe I am wrong.) I'm sorry. :notworthy: (It may not be an Articles in English. It may be an Italian Articles, or a Norwegian, Dutch, Danish, Swiss, or Finnish etc... Articles.)
F-35 has Too Many Articles !! :bang:


I think that thickness also included the Graphite exposy layer (the green one) and not just the RAM layer (the gray one)
E653AFC1-43CD-45C9-8A34-FEEE244F954F.jpeg

wing skin thickness.jpg


RAM in some area seem pretty thick but RAM in wing seem quite thin
body thickness 2.jpg

body thickness.jpg
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Unread post17 Jun 2022, 03:33

My uniform/work gear recognition is not so good, however maintainer with HAMMER does not have BOOTIES, what service is HE? USAF I guess - judging from the 'loading ammo' photos. download/file.php?id=38114

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Unread post18 Jun 2022, 01:16

Civilian artisans fix F-35C stuff onboard CVNs these days. ACE. I guess the F-35C has a thick skin? RRT. Whatever.
FRCE’s F-35 Rapid Response Team makes global impact on flight line readiness
17 Jun 2022 NavAir

"...Based at Fleet Readiness Center East (FRCE), RRT members can deploy at a moment’s notice to any location, from a Marine Corps Air Station halfway around the globe to a Navy aircraft carrier afloat in the Indo-Pacific region....

...For Strike Fighter Squadron 147 (VFA-147), the Navy’s first non-training F-35 squadron, the RRT deployed to the USS Carl Vinson, afloat in the Indo-Pacific region, to assist with repairs to an F-35C. The RRT’s expertise helped facilitate a repair aboard the ship that wouldn’t have been possible otherwise.

“VFA-147 squadron personnel performed a majority of the repair work. The RRT removed a permanent skin panel, prepared it for reinstallation and installed it back on the jet,” explained Lt. j.g. Oliver Williamson, VFA-147 maintenance material control officer. “Some work on aircraft require depot artisans and their knowledge of in-depth aircraft repair in reference to work not normally performed by organizational technicians. This type of work is critical when a situation arises where this type of expertise is required.”...

...“Having an RRT that can deploy within 72 hours to fix any variant of F-35 anywhere in the world is not only value added to the F-35 enterprise, it also shows FRCE’s dedication to support,” he said. “Our FRCE RRT artisans are truly the most dedicated, highly-skilled depot F-35 artisans there are. The majority are veterans so they understand what it is like having an aircraft down awaiting maintenance and the value of expeditious repair capability to get that asset back up and in the fight....."

Photo Captions: "Steven Cope, left, and Joe Shanda, both members of the Fleet Readiness Center East (FRCE) F-35 Rapid Response Team (RRT), perform maintenance on an F-35C for Marine Fighter Attack Squadron 314 (VFMA-314) aboard the USS Abraham Lincoln, underway in the Indo-Pacific region. The FRCE artisans deployed to the aircraft carrier to assist with fixes that were beyond the scope of the organizational-level repairs provided by squadron maintainers. (Photo courtesy of Marine Fighter Attack Squadron 314)"


https://www.navair.navy.mil/sites/g/fil ... 7-1001.JPG
&
https://www.navair.navy.mil/sites/g/fil ... 7-1002.JPG
&
https://www.navair.navy.mil/sites/g/fil ... 7-1003.JPG

Source: https://www.navair.navy.mil/news/FRCEs- ... 72022-1044
Attachments
220606-N-AC707-1001.jpeg
220606-N-AC707-1002.jpeg
220606-N-AC707-1003.jpeg
F-35CartisanBOOTs.jpg
Last edited by spazsinbad on 18 Jun 2022, 01:46, edited 1 time in total.
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Unread post18 Jun 2022, 01:40

This isn't the laser projection to place additional RAM sections. That I referred to earlier, but since 2015 this is how they fasten the skin.
https://www.youtube.com/watch?v=LvD2-_Tl7j4
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Unread post18 Jun 2022, 19:39

Those panels are substantial thickness. Must not be solid composites or they'd be much too heavy. Must be something with considerable stiffness. And must be something that had to be pre-drilled with considerable accuracy and consistency. The panels are probably a sandwich with a layer of carbon-based foam or aerogel. That would also be an excellent way to store energy, due to their exceptional capacitance which is mostly inflammable and otherwise inert. That would offer great stiffness and lighness by volume, but the cost would be high. That would give you awesome potential for absorbing electrical energy across the entire skin. The downside is radiation goes right through it. So you still need a surface to latch on to wave energy before you could absorb it. It is also would help explain the need to retain your aluminum skin to build everything on top. The wizardry would be in the fasteners and grounding. And you still need a layer of RAM on top that feeds your capacitor, and a way to discharge that build up of energy without radiating your position.
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Unread post19 Jun 2022, 05:22

Fastener Inspection Live Link System, the new approach automates many of the steps used by mechanics to verify, select and insert the thousands of fasteners used to attach composite panels to the contoured frame of the F-35 aircraft.

https://www.globalfastenernews.com/fast ... -news-usa/

Orbital ATK made those "access covers", meaning they are removable. Holes for fasteners were fabricated into the parts.

https://kutv.com/news/local/orbital-atk ... osite-part

Those have little to do with the "radar absorbing material".
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Unread post22 Jun 2022, 01:14

Copper mesh is in all kinds of aircraft composite. Nothing special about it.
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Unread post24 Jun 2022, 22:34

There's only one reason someone would ask a question like that, and it's not to benefit us.
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