Composites are winners. The tensile strength to weight ratio of composites versus aluminum is remarkable. Indeed, the next several aircraft designed for the commercial aviation markets will not only be composite based but, also, new, supplementary nano technologies will give successive levels of improvement with each generation.

 

Think about it this way. Big pieces are better. The fewer seams, rivets and other junctional elements that you have in a design the better. Interfaces are where failure occurs. This is where the 787 really offers a transitional technology change for the industry.

 

The 787 has not been an easy development task for Boeing. They found out that too many major componet sub contractors is a mistake (notice the reduction is non-Boeing suppliers of key pieces) and they suffered all of the Murphy problems that accompany something new. However it will fly next month and the 787 will put Airbus in a bind that it may not get out of.

 

This is THE way to reduce weight (and, therefore reduce fuel consumption) without reducing strength.

 

Best,

wjr

Though I agree with wjr a good bit,

I still wonder if it was so wise for Boeing to take on such a big composite project so soon.

 

Would it have been a better idea to start with smaller designs (say, a mostly-composite 737-sized airframe), or even something more along the lines of Bombardier's or Embraer's regional commuters?

This might've been a better approach to build public confidence in the concept of mostly- or even fully- composite (minus engines and wiring, obviously!) aircraft.

 

Like wjr mentioned: it would only take one catastrophic mid-air structural failure to seriously destroy any faith in Boeing about their composite ideas.

 

I've always been a fan of Burt Rutan and what he's achieved with his crew at Scaled Composites.

However, their majority of homebuilts and small personal aircraft (recreational and luxury) don't even come close to the stresses that a larger widebody design will experience.

 

Then again, seeing what's been achieved with his Tier One program (Spaceship One and its White Knight mothership),

if composites can withstand those rigorous environments, then designing a dependable commuter aircraft obviously isn't beyond reach.

 

I just wonder if Boeing was wise in jumping in headfirst right into the large aircraft market, when perhaps instead it may have been a more cautious approach to start smaller and work up from there: unforeseen engineering and manufacturing disasters would be more forgiven in a regional aircraft with maybe only several dozen people lost, rather than a couple hundred in a widebody halfway across an ocean (except, of course, to the families of those lost).

 

Not that these last incidents with Airbus designs have the world screaming bloody murder at Airbus,

it's just that one major catastrophe with an all- or mostly- composite aircraft might get the US FAA, and others, questioning if such new ideas are worth air service certification when there may still be a lot of misunderstoods with composite materials.

 

Worst case scenario: we could get some post-disaster investigation committee, whose advisors know jack squat about real engineering science, convincing the general public and governments that these composite aircraft just aren't safe enough.

(Lord knows we see more than enough scientifically-illiterate mouths open up on everything else, from global warming to stem cells to exotic matter expirements in powerful particle colliders might turn the Earth into a black hole, yada yada...)

 

Boeing knows plenty about building durable aircraft out of mostly metal with composite parts thrown in, so it still shouldn't be their death knell if a Dreamliner "de-laminates" in mid-air (several might raise flags, though): they can always resort back to tried-and-trusted methods and slowly work up from there until a lot more of composites' shortcomings and deficiencies are better understood and can be more easily compensated for.

 

However, a few years in service with barely even minor safety and maintenance issues might be all it takes to encourage more faith in composite construction.

I do hope Boeing's Dreamliner does succeed and doesn't turn out to be a nightmare instead.

The question should not be the strength of the materials, but their long term safety in this application.  The desired characteristics should include long fatigue life, ease and quality of in-life inspection, and predictable failure modes.  Commercial aircraft need to have a reliable service life in excess of 30 years to be successful.

Dogtag is quite correct that Boeing is taking a large risk. While there are technical risks, though, I suspect that delamination won't be a problem as one of the key QA/QC steps that Rutan overcame was measuring this. So I suspect that Boeing is all over it.

 

What I find interesting was the question about longevity of the materials. I can discuss this a bit theoretically but there are so many potential engineering issues at implementation that the variables are simply too great and my knowledge of them simply too small to do much good here.

 

Briefly and theoretically, organization of materials is good. The greater and the more finely grained the organization the better -- if you can control that organization. Very advanced materials like graphene illustrate this point quite nicely. They are highly structured at the molecular level (where, indeed, such a structure dictates a certain atomic configuration as well), they are immensely strong and they are very difficult to work with. If you could build a wing from graphene laminates then it is possible that it could be a few millimeters thick and be stronger than any wing ever built.

 

What's really interesting about even the rather crude composites that we currently use is that they simply don't wear out in the the normal sense within designed stress loads. Whatever binder (glue) is used in the wrap will be the key element of wear and, if done correctly, the binder need never "see" stress. Indeed, I suspect that the key wear element will be oxidization or some other chemical event in the binder.

 

Oh, well, just some blatherings but believe me in one regard. Metals, as they are used today in aircraft, will be looked at like wood and canvass in another generation of so.

 

Best,

wjr

if you look at materials sciences advances that have been made with respect to armoured vehicles, submarines, UAS platforms, USV platforms, combat aircraft and hypersonic systems, then composites are definitely here to stay - and I seriously doubt that its the composites that are the issue.  It all gets down to the engineers and the designs.  If the engineers have stuffed up, then it doesn't matter if it was made out of titanium .

Doggtag brought up and interesting point: it would have likely been better if Boeing would have had the option to build an all composite 737 as their first. It still would have been a big seller. Pity they really needed to build a larger aircraft at the time. Regardless, Boeing has the opportunity to be the leader in this technology. With great risks can come great rewards. There will likely be a composite 737 class at some point. Boeing may also be setting themselves up for the military's composite cargo craft in the future. I would expect a CH-47 variant or equivalent with an all composite hull at some point as well.

 

I like the brief mention of nano-tech. This will no doubt bring substantial performance gains to composites in the future.

As suggested, the binder is the issue.

 

Are we living a real life "No Highway In The Sky"?

 

signed,

 

J. Stewart