Low observables versus maintainability tradeoff

overscan (PaulMM)

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On the B-2 we said: "We're so smart there is no way we will have the LO maintainability issues of the F-117".
On the F-22 we said: "We're so smart there is no way we will have the LO maintainability issues of the B-2".
On the F-35 we said....

Joe Reiman, Air Force Logistics Command.
 
Operating from dispersed bases has been a part of the Finnish air force doctrine. Some worry about how that will work out with the F-35.
 
I'm curious how the B-2s are holding up in Australia, they just seem to be parked on the apron without shelter?
 
On the B-2 we said: "We're so smart there is no way we will have the LO maintainability issues of the F-117".
On the F-22 we said: "We're so smart there is no way we will have the LO maintainability issues of the B-2".
On the F-35 we said....

Joe Reiman, Air Force Logistics Command.


In terms of man hours, expense, and complexity, the majority of LO maintenance issues come from the coatings used.

- Normal, non-LO aircraft maintenance
- Damage
- Degradation of coatings

For example, when the maintainers need to access a part inside the aircraft skin panels need to be removed, etc. To remove the panels LO coatings and sealers need to be scraped off carefully by hand. When the panel is put back on, the coatings need to be replaced, gap filler / sealer restored, and the signature verified.

An example of damage would be when a refueling boom scrapes the skin of the aircraft during tanking. The damage needs to be assessed, coatings removed and replaced, etc.

And then there is the degradation of the coatings. Sometimes the coating thins or comes off due to aerodynamic forces. Or moisture and UV combine to create voids or bubbles between the coating layers that are very difficult to detect.

Over time the issues with normal aircraft maintenance have improved. More recent LO aircraft are designed to be easier to access the inside. Fewer panels need to be removed, and panels may have seals that do not require extensive gap fillers, etc. to be applied.

The coatings remain a major problem. They are hazardous materials that are difficult to work with, something DoD would like to change. Removing them is a manual process on most parts of an aircraft. There is not a way to remove only some layers of the coatings, it is all or nothing. Removing just the top coat and magnetic RAM and not the deeper conductive layer is not feasible. There are not good, reliable ways to measure the degradation of the coating layers.

DoD has been working these problems for some time. For example, they tested using lasers to remove coating layers. This sort of worked, but also sort of set everything on fire.

It is certainly possible to develop a VLO aircraft that does not require the use of these coatings. Sacrifices would have to be made in other areas, though, which DoD is probably not willing to accept. Using some of these coatings is a direct result of using exotic or composite materials in the aircraft structure.
 
I am very interested to see how this laser plasma thing plays out. I wonder if its possible to project a large oblique wall to deflect radar away from the projecting craft. All the things that were said about the digital century series seems like it was for a craft designed with only pure aerodynamics in mind.
 
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Then there is this.
Most pertinent related text for mobile users who can't access the article.
Russia’s Roselectronics claims to have made a breakthrough in low observable materials, with a composite capable of absorbing a wide range of radar frequencies.

The company, a unit of state arms manufacturer Rostec, says the lightweight material is composed of glass fibres with a metal core, and is suitable for the manufacture of aircraft parts.

“In the process of creating a radio-absorbing material, several layers of fiberglass were connected to each other,” says Rostec.

“It is based on thin threads with a metal core in glass insulation. Due to its exceptional characteristics, the new material absorbs up to 95% of the incident electromagnetic radiation of radars and significantly complicates the detection of an air object using radar equipment.”

Rostec adds existing stealth coatings require regular restoration, while its new material requires no maintenance.

In the West, early low-observable coatings for types such as the Lockheed Martin F-117 and Northrop Grumman B-2 are understood to require significant maintenance work.

The low-observable skin of the Lockheed F-35, however, is understood to require less maintenance to retain its low-observable qualities. This is a particular consideration given spartan operating environments such as aircraft carriers, from where the short take-off and vertical landing F-35B and carrier capable F-35C operate.

To highlight the durability of the F-35’s low-observable skin, Lockheed’s F-35 factory in Fort Worth, Texas has a doormat made from the jet’s low-observable skin.

Russian aircraft have tended to lag their US counterparts in stealth technology. Russia has developed just one stealth fighter, the Sukhoi Su-57, which is in production for the Russian air force.

In late 2022 Russian news agency TASS said the Russian air force will have 22 Su-57s in service by late 2024. The total fleet is planned to reach 76 tail numbers by 2028.

Rostec makes no mention of whether the new radar absorbent material will be incorporated into the Su-57, or into the developmental Su-75 Checkmate.
 
Btw, is there any pictures of Su-57 in full "low observable appearance". Google results for F-35, J-20, etc. show surface appearances one would expect of a stealth fighter. In contrast results for Su-57 show eye appealing paint jobs but not this distinctive stealth look one is used to.
Or does Sukhoi use completely different means or methods in this regard?
 
Btw, is there any pictures of Su-57 in full "low observable appearance". Google results for F-35, J-20, etc. show surface appearances one would expect of a stealth fighter. In contrast results for Su-57 show eye appealing paint jobs but not this distinctive stealth look one is used to.
Or does Sukhoi use completely different means or methods in this regard?
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The difference between the prototypes and the serial aircraft are very apparent in photos and video. A google search of Su-57 Serial would result in a few photos of the sort.
 

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