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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.
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?
You could, instead of downright trying to see how much it will take, try to get it up to 200% (or something, I'm not an aerospace engineer) and see for how long it can hold up to extremes like that. Might be more valuable data. Maybe someone more in the know can elaborate.
Pull them back, let them go, and... BOEINNNNG!
Enter the flapping apparatus! It'll make the passengers feel more comfortable, having their plane flap it's wings!
If any article screams out for a Slashdot poll, this one is it.
1. Chicken out and don't break 'em
2. See how far they go and post it to YouTube
3. Orinthop mode! Pull 'em back and let 'em flap!
4. Cowboy Neal
Learning HOW to think is more important than learning WHAT to think.
You are joking, right? Assembly of the first A350 won't even begin for about 5 years. It's not at design freeze. The 787 is about to roll out, and first flight is in a few months.
Both companies have been using carbon fiber. The 787 uses an unprecedented amount of it. You can't say it's nothing new by citing an Airbus project that doesn't have a scheduled delivery until 2013. http://en.wikipedia.org/wiki/Airbus_A350
The point of the 787 is to fly further, more cheaply. So while costing less to fly, it is also supposed to do to the Pacific what the Boeing 767 did to the Atlantic market. That is, the 767 brought in a revolution of being able to connect mid-sized cities on both continents, rather than forcing people to go through hubs on larger aircraft such as the 747 or DC-10.
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.
You mad
Ladies and Gentlemen, this is your captain speaking... If you take a look out the windows on the left side of the plane, you will notice our right wing....
The above comments are not guaranteed to make sense to anyone other than the author...
The fact that the 787 is a "plastic airplane" will get a lot of play, and having wings that bend, potentially to the point that they will tough, is just the most obvious and mediagenic manifestation of that. But it is just the tip of the iceberg of the innovations.
1) Yes, it's almost completely carbon fiber. This means that the plane can (and is) lighter, so it will be more fuel efficient. Also, it's easy to make complex curved shapes, so the wings and fuselage are slightly more aerodynamic. Because carbon fiber structures are so strong, the windows can be larger, and the plane can be pressurized to a lower altitude (it will be pressurized to 6000' instead of the typical 8000' of today's fleet). There is no corrosion, and little worry about fatigue in composites.
2) The plane is not built in Seattle, although that's where the final assembly takes place. All of the building takes place in multiple facilities around the globe, each producing parts to Boeing's plans. These parts will "snap together" in the Everett plant. The first 787 is being assembled right now, and will roll out on 7/8/7 (just over a week from now.) Apparently the left wing was off by 2 thousands of an inch or so, the right wing was absolutely perfect. Boeing converted three 747's to be gigantic cargo transporters to move all the parts from around the world to Everett.
3) The plane has almost completely electric, without the high-pressure pneumatic systems that older planes had. In particular, the AC systems are electric. This will be somewhat more efficient, and safer.
4) The plan for certification of the plane is borderline insane. The final assembly started a couple of weeks ago, and the plane will be rolled out in a week, the first flight will be in a couple of months, and the first delivery will be in Q2 2008. This is a tiny fraction of the time this process required on previous airplanes -- maybe 1/4 the time of the 777 and even less than that of the latest Airbus. This would be remarkable, even if the plane wasn't revolutionary in every other way, too!
5) Aviation Week and Space Technology visited the final assembly line recently, and were surprised to find that it was almost an empty building. That's not because they weren't ready -- that's because there are almost no tools needed to assemble the plane. They snap together the pieces, install the landing gear, and roll it down the building on its gear installing the various subassemblies. Boeing intends to assemble a plane every three days once they get going, a remarkable and unprecedented schedule.
Anyway -- there are so many revolutions in this airplane that I would have thought it was a scam if it was any other company than Boeing. It remains to be seen if they can meet their goals, but so far things are going remarkably according to the plan they laid out a few years ago.
Thad
I love Mondays. On a Monday, anything is possible.
Engineering ethics dictate that we take reasonable precautions to preserve human life, balancing extreme cases with the economic viability of producing the product in the first place.
l ight_587), where a possible gap in the maneuvering conditions / load conditions / stress analysis the FAA requires and airplane manufacturers design to led to an A300 jetliner to lose its tail in flight.
What reasonable is, depends on which field you look at. The same standards do not apply to structural engineering (buildings), civil engineering (bridges, dams), aerospace engineering (aircraft), electrical power engineering (building wiring, electrical distribution systems), etc etc.
The FAA standards are, they set a specific limit load condition calculation for classes of aircraft (light aircraft are different from jet transports carrying people, etc). That's based on performance, operational usage, and the number of people typically carried. There are load cases for limit loads for gust loading (suddenly hitting a headwind when you're already pulling Gs), wind shear, emergency pull-ups, etc. A speed is established, called maneuvering speed, below which nothing you can do to the aircraft is credibly likely to ever cause the aircraft to exceed the limit loads.
Then, you add a 50% safety factor on top of those loads (failure load >= 150% of design limit load), and demonstrate to the FAA's satisfaction that the aircraft meets that ultimate load. For jet transports carrying people, the demonstration requires that you take it out to the 150% load limit and see if it breaks there.
Now, that ultimate load can be expected to cause permanent damage to the wings. Pretty much any aircraft exceeding the design limit load (100%) will get grounded, and anything approaching 150% is guaranteed to have damage. Since the test to 150% damages the test structure for any aluminum aircraft, the usual assumption is that it's a good idea to just keep testing past 150% until it breaks.
But you just need to prove that it meets the 150% for the FAA to be happy.
Designers try to make the failure point slightly, but not too much, past 150% of design limit load. Because adding weight is expensive (operations costs), and as others have mentioned it doesn't do any good for the wing to be stronger if the fuselage breaks first, etc. The loads are all balanced; it's inefficient for things to fail at different points.
These standards are reasonable, for transport aircraft. We know that because large jets are not falling out of the sky due to wing failures. I can't offhand think of the last one that wasn't due to some external cause (collision, etc). There closest incident recently was the American Airlines 587 crash in 2001 (http://en.wikipedia.org/wiki/American_Airlines_F