Boeing's New 787 Wings — Amazingly Flexible

An anonymous reader writes "Boeing is making the wings of its new 787 out of carbon fiber instead of metal. That means the wings are so strong and flexible that they could bend upward and touch above the fuselage — or come close. The company is expected to deliver the first 787 to All Nippon Airlines in May 2008. 'Boeing has completed static testing of a three-quarter wingbox, but engineers are still considering whether to limit testing of the full wing to a 150% load limit held for 3 sec. or to continue bending it to see when it breaks. 'There's a raging debate within the engineering team to see if we should break it or not,' says [787 General Manager Mike] Bair.'" They have come a long way in wing flexibility.

Comments

I hope they test it!

[chris098]

From the article:

No one's ever really tried that before, so testing is critical.

Since this seems like such a new concept (please correct me if I'm wrong; I don't follow plane technology too much), it would just seem prudent to try bending the wings until they break... how can they make accurate judgments and calculations without knowing exactly how much stress the wings can take before snapping?

Re:I hope they test it!

[timeOday]

Typically, fatigue cracking has been the limiting factor in aircraft structures, and has caused numerous crashes.

That is the issue. It doesn't really matter whether the wings can bend until they touch when they are brand new. What matters is whether they will hold up after billions of tiny deflections, especially if there is a defect deep inside or as they get chipped, etc.

Re:I hope they test it!

[Firethorn]

Yes, but from my reading, it's likely that the carbon fiber wing will still be intact after suffering forces that would have reduced the metal wing to a twisted, useless mess.

So, while some failure modes might be worse than traditional aluminum wings, it's also likely to be better in others.

Then it becomes a matter of risk assessment and minimization. A good example would be seatbelts - there is the occasional accident where you'd be better off without the belt, but in the vast majority of accidents you're far better off with it on.

While its great they are so flexible

[N3WBI3]

Does it really matter if, because of how they are bent, you lose lift?

Don't break it

[Broken scope]

A bit of wisdom from a Retired Boeing exec who I forgot the name of.

The story was about one of the earlier Boeing's, they had stressed the wing to like 10 times any theoretical force that could be possibly placed on it during a rather publicized testing of its strength. They test folks were all about trying to break it.

During the process of doing this an exec asked them what they were doing. "Breaking the wing" they replied.
The exec said No, stop the testing.

Why? the testers asked.
Because the headline won't read ,

"Boeing wing breaks at 40 times the stress encountered during possible flight conditions",

Instead it will read

"New wing of new Boeing Jet Breaks".

Please note Its been awhile since I heard that story, but I think the point is pretty clear.