ArmitageShanks From UK - England, joined Dec 2003, 3645 posts, RR: 15 Posted (10 years 8 months 3 weeks 6 days 7 hours ago) and read 2744 times:
After seeing some of these aircraft with massive wing flex I was wondering does this upward flex cause rubbing, stress on the jack screws or flap tracks? Would the manufacturers design the wings to operate more efficiently with the flex or is it not that big of a deal?
Vikkyvik From United States of America, joined Jul 2003, 10335 posts, RR: 26
Reply 1, posted (10 years 8 months 3 weeks 6 days 5 hours ago) and read 2652 times:
Can't answer your specific questions exactly, but can tell you that wings are designed to flex. If they didn't, there's a good chance they'd just snap off. Remember, the wings are carrying the whole plane through the air - in the case of a 747, that could be 800,000 lbs. That's a lot of stress to put on the wings, and the flex helps them deal with it.
Dw747400 From United States of America, joined Aug 2001, 1265 posts, RR: 1
Reply 2, posted (10 years 8 months 3 weeks 6 days 3 hours ago) and read 2587 times:
I'm sure that the flex puts stress on components, but like all design features, there is a tradeoff to be made. To keep a wing from flexing would require a lot more, heavier structure. By designing a wing to flex, the manufacturer saves a lot of weight. When properly designed, I'd assume the manufacturer is able to minimize the amount of stress the wing flexing puts on sensitive components.
QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 25
Reply 4, posted (10 years 8 months 3 weeks 6 days 2 hours ago) and read 2560 times:
Sure wing flex stresses various structures and structural components, but as Dw747400 said, aircraft wings are designed with that in mind. Simple proof are all sorts of statistics reassuringly telling you the 8 to 10-odd meters a wing can be displaced from it's normal position without breaking...
Aircraft can certainly be designed with minimum stress from wing flexing in mind, but the way in which wings are designed and reinforced doesn't necessitate any drastic measures at all. Further-outboard engines are very useful wing flex counters, but moving engines specifically for that purpose isn't common (or necessary, usually) at all...
Zak From Greenland, joined Sep 2003, 1993 posts, RR: 8
Reply 5, posted (10 years 8 months 3 weeks 6 days 1 hour ago) and read 2549 times:
actually wing flexx makes wings more stable.
a good example would be the spokes on the wheel of a bike.
if you have an identical set of wheels(rims hubs etc) but on one set you use 2mm spokes that are straight and on the other one spokes that are only 2mm at the last 2cm on both ends and only 1.8mm in the middle, the wheel with the thinner spokes will be more stable.
the reason is simple: the thin spoke will flexx under peak forces and react more or less elastic. the 2mm straight spoke will not allow the wheel to flexx and you will have one or two spokes flexx forever, i.e. break.
i would guess that with wings it is a similar concept.
with material flex in mind during the design phase, you will end up with a more rugged and lighter wing. and i do also think that the wear and tear is actually lower due to the fact that peaks of stress are softened by flex, hence reducing stress.
Buckfifty From Canada, joined Oct 2001, 1316 posts, RR: 19
Reply 10, posted (10 years 8 months 3 weeks 4 days 13 hours ago) and read 2285 times:
On the Airbus, we keep fuel in the outboard tanks for as long as possible to reduce wing loading in turbulence. Also, the ailerons themselves will counteract the wing loading during these moments to keep the wings from touching each other.
I know the latter is an extreme example, but it has happened, like that firefighting C-130 did a couple of years ago.
And as for checking for cracks, all I can think of are plumbers, for some reason...
Klaus From Germany, joined Jul 2001, 21521 posts, RR: 53
Reply 11, posted (10 years 8 months 3 weeks 3 days 12 hours ago) and read 2198 times:
Starlionblue: Klaus, among those maintenance issues you forgot cleaning up vomit and brown-trouser residue from scared pax
Hadn´t thought of that... I´m usually not all that bothered by a few bumps in the road. (Other than a peculiar accumulation of cases where it started just after I had received my first beverage... )
Buckfifty: And as for checking for cracks, all I can think of are plumbers, for some reason...
Okay, that´s an image I didn´t really need...
I was just thinking that it must be a challenge to keep the tanks and all the control surfaces and subsystems intact even with the wings flexing all the time. The high reliability in practice speaks to the quality of wing design and maintenance...