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back to article Airbus brews Scandium smackdown for carbon Dreamliner

Having made its first commercial flight on October 26, with a chartered promotional flight to Hong Kong, the new 787 Dreamliner enters regular airline service today. This is of course a great excuse for us to talk about the competition between the differing technologies and market visions favoured by rival aerospace colossi …

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Devil

Fantastic

So now China will hold a gun to the head of the Airbus as much as it does to the heads of electronics manufacturers.

What a jolly good idea - make your design dependent on a material which has a single source which is known to be controlled in a manner that is best described as err... politically motivated.

No thanks, I'd rather go with Carbon Fibre here...

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Bronze badge

Interestingly

Sc doesn't come from China. I actually send Sc into China in fact.

While it's associated with the rare earths you don't actually get it from rare earth ores. Rather, from the wastes of other metal production: tin, tungsten, tantalum, zirconium, aluminium if you like.

I'm in the process of trying to open an extraction plant in Eastern Germany for example.....

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Anonymous Coward

Cheated on by Airbus?

Interesting article, but it rather overlooks the fact that the A350 will have a greater percentage weight in carbon than the 787.

The real competition between the two is Airbus' 'chucks of carbon' construction policy (allowing easy of repair) vs. Boeing's 'huge tracts of composite' approach which is ultimately a little lighter, but very hard to repair.

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+2

One for the article, one for the footnote.

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Yup

That's me. Get on to the editor here to hire me more often then I can lower my scandium prices and still make the mortgage.....

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recycling?

I understand an alloy airframe can be recycled, whereas when a carbon fibre one cannot. But then I might be talking out of my arse there, and even if I'm correct, does this have an impact in terms of end of life disposal that is so big it will influence purchasing decisions?

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Bronze badge

Not important

Value of Al alloy scrap from a plane, maybe $1,000 a tonne, something like that. As against $30 million value for the 300 tonne beast as an airplane?

There is a scrap value, yes, but it's not really germane.

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How about recycling carbon fibre? Does it have a scrap value like aluminium or is difficult and expensive to recycle?

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The strength of carbon fibre comes from the absence of fractures. Often rockets etc. are wound with fibre, and then embedded in epoxy. Once you chop it up, it's useless.

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Bikes

It would interesting to know who your bike manufacturer is, as most to of the line expensive bike frames are carbon. All the frames that the professionals are riding these days are all carbon tubes. Alu frames are very much last century. Weight and design options are great for bikes in carbon (no need to use straight, round tubes) which mean the manufacturers can have a product differentiator. Obviously stresses on bike frames are bit less than an airliner.

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Mushroom

Carbon fibre is so last tuesday for bike frames

Titanium frames are the thing to have now!

But will Airbus or Boeing make an airframe from Ti, or maybe just the rivets?

At least it doesn't crack like c-fibre....

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"At least it doesn't crack like c-fibre...."

Quite right, it cracks like Titanium.

The only aircraft to be made from titanium are the Mig25 and the SR71, I don't know about the Mig 25 but Lockheed don't know how long the SR71 airframe may last as it heat treats itself every time if files.

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The SR-71 doesn't fly

and hasn't flown for the past thirty years. (The USAF never quite got over the fact that the CIA got a Mach 3 airplane before they did, and that the only Mach 3 airplane the USAF flew was a mod of the one the CIA had.)

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IT Angle

It's amazing...

...how you make such a dry subject sound so interesting. Especially the last sentence ;-)

However, one has to wonder: Where's the IT angle? It's all sciencey and boffinesque, yes, but... um... where are the world-dominating terminator-like computers in all of this?

Anyhow, nicely written, thoughly enjoyed it. Even without the T-1000s. Carry on, that man :-)

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If I was a betting man

I'd bet on Airbus, because a. The "Hubs" have a lot of money invested in their infrastructure, and more importantly a lot has been in invested in ground transport links to an from these airports, and b. people like big aircraft because they erroneously think it means more room, when in reality it doesn't, and it takes twice as long to get on and off the damn things. (However, if the likes of RyanAir ever decided to go long haul, I bet the Dreamliner approach would be their choice every time).

The other thing that worries me about the Dreamliner is the longevity and repairability of carbon fibre; I don't know much about Scandium (my hands on aerospace experience is 20-odd years out of date) but I'm still a bit twitchy about composites for so much of a commercial airframe.

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@David Evans

"I don't know much about Scandium ... but I'm still a bit twitchy about composites for so much of a commercial airframe."

That's the same feeling I get. I'm not a materials expert by any stretch of the imagination, but I seem to recall hearing about the structural robustness of metal skinned aero-frames over the years - things like the metal tearing, not disintegrating, and rivets not just being a point of weakness but also a termination point for tears etc. Metal just seems to fail quite nicely to me....

The only times i've seen composites let go (and, yes, it does take a fair bit as long as you don't dink it in the wrong direction) it has been pretty much catastrophic - not an appealing vision for me as an aircraft passenger.

Is there anybody here with any materials background who could shed any light on the merits, or otherwise, of the two approaches with regard to material failure ?

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Anonymous Coward

Qualified Aircraft Engineer

At least in my past I was an RAF Engineering Officer, so I'm a little qualified to talk about this. Basically, failure modes of metal skinned aircraft and carbon fibre are both pretty reasonable (so long as you don't do anything really stupid - like overstress the airframe in compression testing on an aircraft with square windows like the Comet). Rivets can terminate crack propagation, but the directional weave of fibre can be fine after impact as well, cracks can't propagate across the weave, although delamination can be an issue. One issue with welding is that there are no places to stop cracks propagating - for example, look at the liberty ships in the second world war. Generally though, crack propagation isn't an issue in airlines since you work hard to maintain the material in a region where it is ductile not brittle.

Personally though, I dislike carbon fibre in a passenger airliner because fibre is a beast to maintain. If you get a bird strike on tertiary structure of a metal skinned aircraft (tertiary structure is non-load bearing structure like most of the skin), you can cut the damaged piece out and rivet in a new piece. With fibre, the same bird strike will delaminate most of that section, a lot of the damage can't be easily seen, and you end up removing huge swathes of material because you are worried damage can have spread a long way. Replacing that material is then a nightmare job.

Personally, I'll avoid Dreamliners if I can until they have at least 10 years of service in them.

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Anonymous Coward

longevity of composite airframes

David,

Take a look at the airframe integrity analysis conducted on a decommissioned Beech Starship. That plane is all composite and pressurized. Don't have a link right now but googling for a bit should get you there...

Something else I have heard repeatedly about the Starship is that its composite hull holds up extremely well even in a high cycle environment (much better when compared to conventional designs). The same can't unfortunately be said about the metal mesh embedded into the wings for lightning protection... corrosion issue and no known way to fix it...

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Go

Hubs Smubs

Boeing is building 737s as fast as they can to support the HUB users.

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Boffin

Airframes are generally pretty low margin

Composites do indeed fail catastrophically when they go, but that's not to suggest that they can't be designed with sufficient margin. While there are some intricacies to composite design, the basic concepts of stress-versus-load still apply.

While you're correct that metal has more capability for plastic (yielding) deformation before failure, it's also the case that aircraft are manufactured right down to the razor's edge of margin. Every extra pound means you have to burn that much more fuel on every trip. I think that the 747's cross-section area between the frames is only something like twelve square inches. So while the metal could conceivably have some strength left after yielding, it probably wouldn't have all that much; and aluminum doesn't yield all that much before failure anyway (only a factor of 1.12 between yield stress and failure stress, versus about 1.67 for cold-drawn stainless steel.)

If you're worried about composites being used as major structures, that ship has sailed (er, that plane has flown?) Airbus has been making composite tails for years--in fact, in November 2001 there was an airliner crash in New York where the tail snapped off due to overstressing (pilots had been improperly trained to seesaw the rudder violently to handle turbulence.)

Ultimately, it seems like it's as you describe--the benefit of composites (or weldments) is that you can reduce the amount of joinery you need, saving that part of the weight. You also get a small benefit from reducing the work at your primary assembly facility (bigger subsections = less time bolting them together) although you're really just spreading the labor out to the subsection manufacturers.

Note that they're still using fasteners to assemble the 787 (in fact there was a big problem with their fastener supply chain--they just assumed that there would always be plenty of aircraft-grade bolts available. Unfortunately, when all the defense-industry work went away, the fastener suppliers went out of business!) They just have to be more careful about it. i.e. instead of just punching a hole with a simple die punch, they have to drill and ream and clean. Instead of just slapping on a rivet and letting everything mush itself into place by yielding, they have to use a special-made washer with a curved face to avoid gouging the composite surface (or spend time countersinking every place there's going to be a fastener.) People have tried to make bonded joints for composite structures and nobody's ever found a way to do it that's as good as a bolted joint without being just as much work. (you have to design specifically to make the bonded joint work--any peel stress will kill it dead, just like ripping a piece of Velcro open versus trying to slide it off.)

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Anonymous Coward

Another Licensed (Civil) Aircraft Engineer

Composites offer a lot of advantages over metal, however in my book metal offers one big advantage over composites, you can repair it by cutting out bits and riveting in a new bit.

I say this as a licensed aircraft engineer who saw 5 brand new aircraft all receive damage from ground support vehicles within 2 months of the aircraft being delivered to the airline and all needed structural repair.

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Thanks for all the information everyone, plenty of food for thought and further study. Cheers

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point to point versus hub and spoke

I've no opinion on Scandium (sorry, M. Worstall) but hub and spoke is the most unpleasant transport system ever invented. The ability to go point to point is, after all, why most of us are so attached to our cars, versus public transport.

Europe to US west coast is about 10 hours, direct. Add a connection and the total time can extend from 12 to 17+ hours, depending on where the connection is (midpoint (east coast) is worst, great circles being what they are). Add that to the requirements for another miserable set of airport security theatre each time you add a connection, and there's simply no contest.

Boeing's onto a winner here, and I say that having flown in a 380 (and then joined the queue for US immigration along with the other 500-odd passengers). Nice plane, crappy idea.

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Anonymous Coward

hubs&poke vs point2point

In practice this is a trade off, surely? Even if you can get a p2p flight between your two desired locations, will there be enough passenger demand for the route to support the flight-per-day you also want? Probably the balance will shift, but by how much?

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Paris Hilton

Only 17 hrs.

As an Alaskan we don't have many Point to Point flights to America. My last flight was 20 hours and changing planes 3 time going down. Going back up I only had to change a plane one and the trip still took 12 hours.

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This applies less less in Europe, where you have high-speed rail everywhere and people are somewhat less attached to cars. If you live in, say, the outskirts of France, then you take the high-speed train to the big hub in Paris and take the plane from there.

Ditto for Japan: you take the shinkansen bullet train to either Tokyo or Osaka, the big international hubs.

Even with the various improvements to airliners, trains continue to be more energy-efficient per passenger, and getting more efficient still. They are also far more environmentally friendlier.

http://files.gereports.com/wp-content/uploads/2011/06/FINAL-3_Transportation1.jpg

Not surprising, therefore, that Airbus has gone with the A380 idea. From a European and Asian POV I think it makes sense and is quite forward-looking. From an American POV it makes less sense, but that may yet change.

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Anonymous Coward

train + plane

I live in France, and neither I nor my frequent-travelling business colleagues would ever take TGV+plane if there's a plane+plane option instead. It makes a long journey even longer, and if the train is cancelled or late (or on strike) you have few options for rerouting. You also need to ensure that your TGV has a flight number, so that the entire end-to-end trip is counted as one journey on one ticket, which pretty much limits you to Air France. If you book train + plane on separate tickets, and the train is late, you're screwed. SNCF will only refund your TGV reservation, and the airline will treat you as a no-show.

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Anonymous Coward

point to point versus hub and spoke

Having spent 20 hours in O'Hare airport due to bad weather, cancelled and late flights (If the world ever needs an enema then O'Hare is were it will be applied) point to point any time, as long as its not ryanair.

Re US immigration; I've never paid for priority boarding, but I'd pay for priority disembarking.

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Unnamed bicycle manufacturer using

I'd very much like to know who's making these Al Sc frames please!

(especially the cheaper non-brand)

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Holmes

It can't be very difficult to find someone with 2 product lines, one of which is advertised as containing Scandium.

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actually...

my 15mins of googling came up with zilch :-(

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Joke

What's wrong with good old British engineering?

Hold the thing together with sticky-back plastic.

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Anonymous Coward

Not so far fetched

I was an apprentice at the BAe factory at Hatfield back at the end of the 80's where we built the BAe 146 feederliner. I used to help out doing factory tours, and the one place we loved to take people was the area where we "glue the aircraft together".

Hatfield had vast experience of the perils of rivets (Comet) and so they used a different method to fix longitudinal stringers to skin panels. This consisted of a kind of double sided sticky tape which was laid between the stringer and the skin, whole sections some up to 20ft x 12ft were laid up like this. The laid up sections were then put into a press at something like 200C and 20ATM pressure for a couple of hours for the glue to set.

Included in each laid up section would be between 30 and 50 test sections which would be cut out and removed. Half of the test sections went into storage, the remainder were subjected to destructive peel and pull tests. Under the pull tests, the sections were able to hold something like 32 TONS per square inch.

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Joke

Stick-backed plastic?

pah, real engineers use duct tape. And their other tool is WD40.

As the saying goes...

If it should move and it doesn't use WD40. If moves and it shouldn't, use duct tape.

I'm obviously a poor engineer, in that I also use a 3rd tool - a hammer. And swearing.

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Windows

Hammer?

Hammer and swearing makes it 4 tools.

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Silver badge

Nobody expected that

Our three tools are WD40, duct tape, a hammer, and swearing.

Our four tools ...

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Anonymous Coward

there are 3 reasons why nobody expects the aircraft engineers

WD40, high-speed tape, a hammer, and swearing

there are 4 reasons....

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Silver badge

point to point for me

As someone who used to suffer more than a reasonable amount of time stuck in a sardine tube, one knee inserted up each nostril. I've got to say that I always looked to fly directly. If you couldn't get there directly from Heathrow then it counted as third world. Gatwick, perhaps at a push. To me it was the main reason to live in the SE.

Having to change planes is such a PITA.

The other advantage of smaller planes is that for busy routes you end up with more flights so can choose more convenient times to travel. Hopefully everyone is different and so what is most convenient for me, might not be for someone else.

In practice I think we'll end up with a mixture.

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Bronze badge

Why don't we do ConTrans?

Connected Transfer?

Fedex could deliver the luggage. The pax planes could have more restricted rules on carry on baggage.

For ConTrans, a refuel-probe like chute would extend from below the sending plane and after connection to the receiving plane, passengers would take a "fun slide" into the receiver. If any carry-on bags ARE to be transferred, they could go on a separate chute ride, at the aft end of the plane.

But, this could prove expensive to modify fleets of such a/c. If it were feasible, though, it could prove semi-devastating for the hub and spoke as it exists today. It still might work, though, with ferry planes acting as ConTrans planes. But, it might take out valuable space (assuming that the COnTrans idea relies on FULL feeder planes) as it would require two reinforced, tear-resistant pressurized zones (one for pax, one for bags and crew handlers of bags unless things were strictly laptop and purse bags and medications and diapers --- wait, we wouldn't transfer babies this way, would we?) in the event the transfer tube failed. Might involve the "misadventure" of a few pax from time to time, but if the altitudes are kept sanely low, and speeds to what is deemed safe, and pilots and computers mutually handling and monitoring the above/below (as opposed to any attempts at "alongside replenishment").

Crazy? Maybe, but how crazy were nuclear and other types of airplanes.

Come to think of it, hasn't this idea been posited before, say, decades ago?

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Thumb Up

Superb

Excellent article. These pieces are the main reason I read the Reg. Thanks very much.

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Anonymous Coward

The most a failure of the latter can do is ruin one's crotch

>.<

Unless said failure is whilst you are in a uk bicycle lane ie tailgated by a bus...

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Happy

Bus lanes

If you get tailgated by buses, you're not pedalling hard enough...

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Anonymous Coward

Im not in a hurry...and I'm certianly not doing it for exercise...Cycling can be for transport you know.

anyway I dont know if youv'e been to Nottingham or Sheffield the hills are Long and go on for ages!

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UMIST

It raised a smile to se my alma mater UMIST mentioned. T'was a sad day when it was merged into University of Manchester...

Interesting to see the research going into these issues; I had no idea rivets accounted for so much of a plane's weight.

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Meh

Long-term ageing problems

We didn't know about the long-term metal-fatigue problems with aluminium alloys, until Comet airliners started exploding in mid-flight. We didn't know about the effects of sea salt on them, until the open-top Hawaiian airliner incident. Rolls-Royce once almost got sunk as a company by committing to using carbon-fibre turbine blades in the ill-fated RB211, only to discover the fatigue problems once the things were almost in production. And so on. I can think of a number of similar examples in the history of IT. Even using well-understood materials, Alfa Romeo still managed to have a huge problem with a car whose engine fell out after only a few years.

Manufacturers do of course do accelerated ageing tests, but they have to leave out the passage of real time.

It's anyone's guess whether composites or Scandium alloy will be best for aircraft fuselages. And I'll be a little bit more nervous flying in either, since it'll take more than the rest of my years for these materials to be truly well-understood by the industry.

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Bronze badge

Indeed.....

It's been a decade now since Airbus built a wing out of Al Sc. They're still heating and cooling it, spraying it with salt water, bending it etc....somewhere in a warehouse in Germany I believe it is.

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