Swiss' Entire Boeing 777 Fleet Now Has Shark Skin Technology | Hacker News Reader

Swiss' Entire Boeing 777 Fleet Now Has Shark Skin Technology

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Swiss Magazine post “AeroSHARK: inspired by shark skin” https://www.swiss.com/magazine/en/inside-swiss/sustainabilit...

I haven't thought that air travel can be made significantly better but I think 5 years ago or so I flew the dream liner for the first time and it was so much quieter and so much better because of it.

Anyone knows how long a airplane has to fly to be written of?

Roughly 25 years. The other thing that you probably didn't notice directly but made you feel better is the better pressurization. Newer planes tend to keep higher pressures (since carbon fiber is ridiculously strong), which helps prevent some of the general discomfort of flying.

NB, for any budding bathynauts: carbon fibre is strong under tension, which is precisely the use-case for higher-than-ambient-pressure vessels such as air- and space-craft.

It's far less comparatively strong under compression, which seems to have been the principle failure mode of the now-permanently-submerged Titan.

The failure modes of explosive vs. implosive failure are also relevant. High-pressure implosions tend to collapse the entire hull, whilst so far as I understand, explosive failure, particularly at the relatively low pressure differentials of air and space flight, tend to be localised, and the fibre-reinforced nature of composite materials should reduce damage to the neighbourhood of the initial failure point in many cases. Implosive failure needn't actually penetrate the hull so much as crease it, a mode which CF handles poorly respective to the application.

I think a lot of people have a misconception that keeping pressure in is just as hard as keeping pressure out, while in some ways, it's probably easier to make a space station (keep 1 ATM in) than to make a submarine (keep 500 ATM out.)

Hence sci-fi horrors is like getting sucked out into space through a pinhole.

If a micrometeorite (or other space detritus) puts a pinhole in a wall in the space station, can you plug it by covering it with your finger, without necessarily losing the finger ?

IANASpaceDoctor, but very likely you can, at the possible expense of a space-hickey.

Most of you would still be at the right pressure, and skin is pretty tough stuff.

yeah, this is really one of my pet peeves. Lots of people like to pretend that holding a vacuum is really hard, but if all you need is a gross vacuum, it's only about as hard as going down 40 ft into the water.

Other misconception: That we immediately die in space. You can probably survive a minute or two.

Carbon fibre, like most composites, is also very hard to predict. It's much more complex to model, especially in terms of how it ages, and there's a lot of opportunity for part-to-patt variability, so even extensive testing doesn't necessarily give you an all-clear. It took a lot fo time and money to get carbon fibre to the same level of understanding as metals for use in airlines.

NGL my mind went straight to the Titan after I read "carbon fiber" and "ridiculously strong" in one sentence. Thank you for the clear explanation and for alleviating my anxiety of flying transcontinental again.

I never got the chance to fly in a Dreamliner, but I have been told that its air is also more humid than standard jets (because of the carbon-fiber construction, I think, so metal oxidation isn’t an issue).

> because of the carbon-fiber construction

yes

> so metal oxidation isn’t an issue

no. It's not rust, but that higher pressure air can hold more water at the same relative humidity. The higher pressure air is achievable because carbon fiber has higher tensile strength per weight.

> higher pressure air can hold more water at the same relative humidity

The 787 and A350 cabins have higher relative humidity.

> no. It's not rust,

Citation needed. Corrosion resistance is one of the most advertised benefits of the composite materials in those aircraft[1][2].

1: http://www.lb.boeing.com/commercial/aeromagazine/articles/qt...

2: https://skybrary.aero/sites/default/files/bookshelf/3851.pdf

That makes more sense.

Thanks!

Nice, then finally I won't get nosebleeds on long flights <3

Also, I get headaches on planes. The 10,000-foot altitude air pressure does it.

Really, it's that low on a regular plane? I thought it was more like 6000ft equivalent or so. 10k is high, it's like a third of the altitude they actually fly at.

Edit: it's between 6000 and 8000: https://aviation.stackexchange.com/questions/66563/why-arent...

So around 8000 for the likes of the bog standard 737 and A320 and around 6000 for the cool new carbon fibre ones I guess.

May be right. I was told 10K, but that was probably a number that was rectally-sourced.

10k is the altitude above which oxygen masks are required, and any decompression above this altitude triggers the oxygen masks to drop and pilots to make an emergency decent back down to 10k ft.

The 787 and the A350 are both a delight to fly long haul

I still prefer A380 when I can get one. The extra space is amazing.

Isn't that determined by seat pitch, which in turn is arbitrarily configurable by the airline? What does the model have to do with it?

Given how huge the A380 is, it is more likely to fly less than completely full, which increases the odds that you'll have vacant seat(s) next to you in economy class.

Also, if you want to go for a walk, the distance you are allowed to walk is a lot further.

> Given how huge the A380 is, it is more likely to fly less than completely full

That is quite nice as a passenger, but also a big part of why they're no longer made, and why most airlines are phasing them out...

The A380 has higher ceilings than other planes. Doesn't help the knees but makes it feel a lot more airy.

One thing I dislike about flying a full-ish A380 is the length of time for meal service. It can be over 1 hour that you have to sit with your tray table occupied and seat upright, before your tray gets picked up. If you want to use a laptop or sleep, it feels like forever.

These are Boeings we're talking about.

I assume you mean written off, and the answer is it's generally not about how long, it's about how many "cycles". Plane maintenance is usually required on a schedule based on how many flight hours or cycles, and it's usually the cycles they hit first. A cycle is a pressurization and de-pressurization of the cabin. This is what eventually kills a jetliner, the hull will fracture from the stress. The engines are designed to rebuilt/replaced periodically. The hull cannot be reasonably repaired once damaged.

Airliners are required to do different checks at different stages, and the big one costs millions of dollars and requires them to basically disassemble and rebuild the plane. They even may have to remove the paint to check the hull for issues. Industrialized nations generally will only do this a couple times before the cost is more than the jet is worth (I think this is generally around 20,000 cycles, depending on the plane) then they sell them to a third world airline who doesn't have as strict a regulatory scheme. Even then, they generally live on for quite awhile, our regulatory scheme is designed to get as close to zero risk as possible, not to be economical, and it's hard to argue with the results. This is one of many reasons why there are an order of magnitude more crashes in the developing world, though even still safety is high relative to almost anything other than first world commercial airlines.

"The recently imposed smoking ban on many commercial flights has had one distinctly unhealthy side effect -- it snuffed out the most popular method mechanics used to spot cracks in aircraft fuselages.

... mechanics could count on tell-tale build-up of nicotine around cracks as air escaped from the passenger cabin when the plane pressurized after lift-off."

https://www.upi.com/Archives/1988/05/27/The-recently-imposed...

> haven't thought that air travel can be made significantly better

I wonder if it could be made significantly worse. Leg room has been reduced overtime as far as I can tell. I’m 198cm, and it’s actually hell. I probably need to just pay more and go nearer the front, however this would only solve the legroom problem. The seats are too low and aren’t even close to supporting someone tall. I’m in NZ so everything is far away, and 18+ hour flights are actually awful.

I recently flew on an A320neo and then an A320ceo a few days later, both in similar cabin positions and the difference was incredible. On the neo I could easily talk to the cabin crew without raising my voice, the ceo felt like I was having to shout.

I’m flying on an A380 in a few days, that will be interesting experience after only flying long haul on 777s in the past few years

Love the A380, just try to avoid Lufthansa's one, they tend to be the worst at seat space in economy and service. Emirates is my fav.

It's not just Boeing. The Embraer E195 E2 is also way more comfy than your 737 despite being much smaller

When it comes cases of travel feeling worse, I find it's always worth making sure you adjust the cost for inflation.

Sure, we'd expect certain engineering things to get cheaper over time, but you can also see why some luxury touches got phased--or rather priced--out. :p

62,000 flight hours

Flight hours or flight cycles?

I suspect that pressure hull and wing spars experience the greatest loading and fatigue, and may be differentially influenced by overall flight time and takeoff/landing cycles.

Hours. I remember the incident with an Aloha Airlines 737 where fatigue damage caused the failure of part of the structure. Those airplanes were only used for very short hops, hence a high ratio of cycles/hours. While they were within the 62,000 hour limit, the cycles were very high and were not anticipated in the fatigue calculations.

The criteria might have changed since that incident.

Maintenance schedules are based on hours. Pilot experience is also logged as hours.

It's actually both, specifically because of that incident. (Pretty much any time a commercial jetliner crashes, a rule changes, and it's been that way for decades.) There's an hour number and a cycle number for many maintenances, and whichever comes first triggers the maintenance. Hulls, however are rated for a max number of cycles due to fatigue caused by the pressurization/depressurization and that's the part of the plane that cannot be replaced. So the plane usually gets junked or shipped to a developing world airline due to cycles.

NB: Aloha 243 was what I'd had in mind as well, and was when I'd learnt of the distinction between hours and cycles.

For those unfamiliar, a 1988 airline incident in which a Hawaiian airliner experience explosive decompression, though 94 of 95 occupants survived. The lone fatality was a flight attendant who was sucked out through the hole, and if my memory of the post-incident report stands, actually contributed to much of the fuselage damage by enlarging the initial failure region.

<https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243>

Another of my references are the US B-52 Stratofortress fleet, the youngest of which were built 61 years ago in 1963, for which active status is anticipated to extend into the 2050s. My understanding is that wing loadings/unloadings are the limiting factor, with virtually all other parts of the plane being capable of replacement.

<https://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress>

The overall airframe is rated for 32,500 to 37,500 hours, with aircraft experiencing about 380 flight hours/year. The wing upper service being the lowest limit of body parts indicated here:

<https://www.globalsecurity.org/wmd/systems/b-52-life.htm>

This is my only claim to fame, the pilot is my mom’s cousin. Super nice guy.

Hearing him tell the story first hand was pretty incredible. He saw sky, so knew he had a hole… but had no idea it was so extensive until they landed and he walked back there.

Can you imagine the phone footage we would have had from that it if it happened today?!

The phone footage would be ... portrait mode.

Because of what ?

Higher air pressure (lower cabin altitude) and higher humidity. Both make passengers feel better.

You basically subject yourself to altitude sickness every time you fly. It's actually kind of ridiculous how "unpleasant" flights are, but since they're rare enough we just accept it.

Not really, while its possible to get altitude sickness below 8k ft, its very very rare.

Pretty much every aircraft pressurizes to below 8k feet because of regulations.

Perhaps not technically altitude sickness, but the weariness everyone feels when they get to Denver for awhile.

Some more technical information: https://cleantechhub.lufthansagroup.com/en/focus-areas/aircr...

Most relevant part: “By applying a total of 950 square meters of AeroSHARK riblet film to the fuselage and engine nacelle surfaces of a Boeing 777, fuel savings of approximately 1.1 percent can be achieved.”

Seems hardly worth it ? 1.1%? What about the cost of application and maintenance ? I’m guessing it’s plastic too, which will pollute the environment somehow.

Expectation of success or profit = P(success)reward - P(failure)penalty - opportunity cost (TCO)

Supposed these panels were $100k/plane.

Jet fuel costs $0.36/lbs and a 777 burns about 30 lbs/nm in cruise. Suppose a 777 averages 14,000 nm/day. That's 420,000 lbs/day or $151,200/day. 1% savings would be $1,512/day, so the break even point would be roughly 2 months and would be profitable from then on. Suppose a 2 year lifecycle. That a savings $500k per year per plane.

Put a little more thought and data into your comments if you would be so kind.

Your back of the envelope calculation is off by over 10x, so I'm not sure it's him that needs to put more thought into their comments.

Edit after-the-fact

P(success)*reward - P(failure)*penalty - opportunity cost (TCO)

The plane can carry 45,000 gallons of fuel. 2.1 bucks a gallon. So probably 500 bucks of savings a flight since most flights arent full capacity. 130k flights in '23. So ez 65 million in savings a year.

Worth doing for the environment even if it's cost neutral probably.

What are the effects of this stuff on the environment ?

I’m not saying this is a negative , just that plastic pollution is a huge issue , I can’t see this stuff making the situation much better.

There’s a cost/benefit ratio chart in that link from GP comment.

The ROI appears to be 2 years. Considering the application is relatively easy, this looks like a good deal for airlines.

Very interested to understand what the maintenance would be like, are these thing essentially industrial grade stickers?

That provides more information (and visuals) on the technology itself.

I've spent a few minutes looking for imagery of the film itself, sufficient to show details. There's surprisingly little, and I suspect the manufacturer doesn't want visual details of the skin itself available.

There's a schematic in the link below, which also shows the contrast of the AEROShark film to actual shark skin. The film is more grooves than scales, for those curious.

<https://swiss.newsmarket.com/english/press-releases/swiss-ad...>

>>AeroSHARK replicates this hydrodynamic property on aircraft. It is a "special film" made up of "tiny 50-micrometre riblets that reduce aerodynamic drag during flight."

While it's at this point obviously tested and proven to work, I wonder about the size of that texture in relation to the texture on actual shark-skin, and whether they are working at similar Reynolds numbers.

That headline sounds big, but "entire fleet" in this case is only 12 planes. And those 12 are about half of Swiss' wide-body fleet.

That makes it a tiny airline in comparison to others. For example Lufthansa group (which Swiss is a part of) has 98 wide-body aircraft. Competing Air France group has 165. The US is similar, Delta has 164. The Middle East is on another scale, Emirates has 249...

Still a nice innovation, but as a headline "Lufthansa group tests shark skin on 12 Boeing 777s" would be more realistic.

Lufthansa are also rolling it out across their entire freight fleet.

Which is also only 11 wide body aircraft :-)

I guess Lufthansa is now a fairly small airline then? Years ago it was a big one. Of course I can remember flying Pan Am so doesn’t mean much.

Note they said Lufthansa freight fleet, which is why it's only 11 planes. Lufthansa (the passenger airline) is indeed still a very large airline.

According to Wikipedia it's about 180 widebodies for Lufthansa group

https://de.m.wikipedia.org/wiki/Lufthansa_Group

2200 ton saved for 12 planes is about 1.5milliom usd

Each 777 can carry about 150 ton of fuel.

So they got about 15 fill ups free

It might even compound. Ie if because of the sharkskin you have to take less fuel onboard, then the plane will be lighter and you will consume even less fuel. On long distance flights a significant portion of total plane weight is fuel.

Add the opportunity cost of grounding the plane for about a month to apply the coat, plus the cost of the coating. It can easily outweigh the savings or push the ROI to over many years.

LOL 1 month and minimal costs, for years of reduced fuel costs, someone did the calc above and its ~35m in savings a year seems worth it to me given they list the ROI of the film at 2 years.

> a month.

No, It says a week in the article.

“Each aircraft takes about a week to have its AeroSHARK film applied, which requires high-precision workmanship from our personnel.”

Yeah but planes fly a lot over the span of 25 years or so; granted, they need to be repainted every once in a while. It does add up, is all I'm saying.

That sounds like at least a percent or two in savings per year, which is not too shabby.

BASF quotes 1-1.5%, which is pretty damn good for a one-time, low-cost application.

I guess Swiss is Lufthansa's test before rolling it out to the rest of the group's brands.

Yep - the more detailed page on the Lufthansa site states a 777 sees a 1% reduction in aerodynamic drag (it's a bit less for a 747 at 0.8%)

Still solid for a application thats probably relatively cheap and has a 2 year ROI for ongoing savings

Does this film operate on the same principle as Myth Buster's golf ball car?

https://www.youtube.com/watch?v=VUiGhyHC-1A

2200 tons of kerosene... that number would be much more meaningful with a total to relate it to :(

1 Olympic swimming pool.

"total". As in total consumption of these planes.

Disappointed is not covered in shagreen: actual sharkskin leather.

Shark skin technology. Good. But do they have shark lung technology? Boeing planes are practically amphibious these days...

I'm not flying on Boeing. I make sure I fly only on Airbus.

If it ain't Boeing

I'm not going

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