Dreamliner 787 Composites Approach Takes Another Big Hit

My personal experience with composite materials, from the point of view of the scale aircraft I fly (35% aerobatics) is that they could be somewhat treacherous in the sense that one can't detect when a part will fail until it's too late. Granted, my 12 kg plane isn't a jetliner but the basic principles may still apply. I'd much rather fly Boeing's Dreamliner if they were to redesign all critical assemblies with titanium. I'd gladly pay the extra $5 for a ticket.

The 787 composite design is not that unique. Scaled Composites, Lookheed, Northrop has made composite aircrafts for years. The key is to get low mass and low cost while making it durable and effective. It will take Boeing a few good engineers some iterations to get it right. (unless they pissed off the good guys and only have program guys and consultants left)

It is very correct of Boeing to delay the 787 inspite of all the commercial and bad publicity for the delay. Unlike some other manufacturers that have known about possibility of structural failures because of control inputs, or possible loss of aerodynamic wing performance because of icing in areas not covered by de-ice boots, and yet proceded without addressing those problems.
Having said this, composite technology may not be ready to be used and any delay to look into resolving these issues is worth it. The potential gains from using composites as in the 787 make it very worth while to spending the effort and resources make it work.

I hate to say this because if it happens its gona mean a lot of people get killed, but I'll bet they will miss something on the dreamliner, it may not show up for a while, but sometime in the first year or two of operation one of these planes is gona experiance wind shear, turbulance, extreme cross winds, etc. that was not modeled correctly. and the composites are gona fail, the big problem with composites is in the way they fail, generaly by shatering (delaminating will usaly end in shatering too), ware as metals will bend or stretch before being torn apart, many times they will only deform but still be flyable, giving a pilot just enough time to get the plane to a safe emergency landing.
Carbon composite materials are a whole differant ball game and I don't think they are ready for the wings and main structure of a commercial airliner.
And I believe, because there just hasn't been as much experiance with these materials, and much of what has been found out is just not avalible to a non-military program, the computer modeling will not completely cover the materials properties and a major failure mode will be missed.
As to someones talking of load limits, I personaly think that the FAA and aircraft manufactuers in general, cut it way too close on these aircraft, the load limits should be higher and special attention should be given to torsional stress.

Zhivagosc does have a very good, and reassuring point, which is that the start of delamination is not the same as a glass window shattering. Yes, it is a failure that would need to be repaired, but it is not, of itself, immediately catastrophic. In other words, no, the plane would not crash if it had that failure. BUT it would need to be repaired, and that would be expensive and take quite a bit of time. Like Smock said, there are a lot of places "to do it wrong" when manufacturing composit assemblies, and a lot of economic reasons to let things slide rather than scrapping an expensive assembly because of some manufacturing process deviation. That is the unfortunate reality. I won't get into the ugly insides of manufacturing plant politics.

there's no question there are people that know how to build such composite structures successfully, but doing so requires a *lot* of deep knowledge in a large number of areas. The notion that Mitsubishi was going to "learn about composites" while doing large carbon-fiber wing panel beggars belief. Just the handling of the raw materials (most likely sheet and ribbon "pre-pregs") is tricky because they come already wetted-out with epoxy. The materials must stay below critical temps all during processing or the epoxy starts hardening before you're ready. And when the laminate structure is done, it goes into a large autoclave where high-pressure and then heat compress the laminate and harden the epoxy.
As you can imagine, there are any number of ways to mess this up without knowing about it before you find out the hard way.

I think it's going to be quite a while before we see composites in critical areas. Look how long it took aeroplane builders(amongst others) to come to grips with metal fatigue. Trimming costs and weight at the same time as finding out about the stuff is WAY too risky.

perhaps they should call it the 'reamliner

If they don't solve these problems now, the first catatrophic composite failure of a 787 Dreamliner will do for Boeing composite aircraft what the Hindenburg did for Zeppelin ridgid airships. DO MORE RESEARCH!!

Anybody have Burt Rutan's phone number?

Do we have any information on how "gracefully" the AL unit fails above the ultimte load limit?...
is there any information about the composit lamination, and in particular, is it a 2 dimensionaly laminating technique or a 3-D as used in nose cones made by FMC in Maine (my FMC info is 20 years old). FMC did Boron, AL and graphite 3-D weavings !!

I think the most important thing is to find out why the composite wing delaminate during the test - is it the design issue (strength inadquacy) or manufacturing problem (weak material adherence) - rather than commenting the technology or the company's decision. The uses of composites in wings and fuselages are fairly new to the industry, there is still a space for research and improvements for the industry.

Perhaps the new carbon nanotube composites will work -- they're supposedly very much stronger than carbon composites.

I don't care who did what when or where- the bottom line is this. Fish or Cut bait- if composites are not going to work and they are too risky- go back to metals. We don't need negative public perception of a composite process casting doubt on the success of everyday safe flight operations.
Put it back in development - it may be ready for dreamliner 797.

Clearly the commentor does not understand the technicalities of the large-scale testing Boeing is conducting. And Design News should not assume the Mitsubishi decision was caused by its Boeing experience. Officially, for Mitsubishi, the decision was due to lead-time for composite materials. Lead-time is often a driver in structural design decisions.

zhivagosc:
You're right in chastising Doug for oversimplifying what happened. But you might want to check your facts too:
"..a stringer from a skin". Count 'em, there are 18x2 = 36.
Also - the stringer / delamination problem reportedly occured just above "limit load", which is the maximum load expected to be seen in service. Boeing have never disclosed what the figure was. These parts need to retain structural integrity up to "ultimate load", which is limit load x 1.5. Note also that boeing tested a wing to destruction, and it passed ultimate load - but they never disclosed by how much.
These are massive problems, and Boeing keeps sweeping them under the carpet. Think about it - the modelling of stresses in this structure don't stack up - over & under engineering in the same pieces? What's going to happen in real life? Even if the part can continue carrying load, how much is that? Composites deteriorate rapidly once delamination occurs and ice/water start to enter and eat away at the structure.
I'm expecting some really really bad news about all this one day. Everyone seems to have an illogical hope that Boeing will nail it soon. Good luck to them, but it's going to take a long time to start understanding and utilizing these materials safely.

"a Mitsubishi-built composite wing for the Dreamliner 787 broke in a stress test." You need to stop reporting incorrect information. Nothing broke. Stresses were higher than acceptable, and there was delamination of a stringer from a skin. The part was still structurally intact, and able to carry load (not broke-unable to carry any load). The extreme loads experienced during flight testing would have stressed the part beyond its capability and potentially broken the part. A more accurate description is "load-limited" since many of the extreme loads are 1.5x normal operating loads. The part did not meet its design requirements and was modified to allow full loading.