Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Why Do Planes Bend?  
User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 20
Posted (14 years 10 months 11 hours ago) and read 2858 times:

I've always figured that the materials used for planes were fairly stong enough for the liftime requirement.

I remember reading an issue of PopSci (4/98?) where the story was on the now-cancelled HSCT. NASA put a canard in front to prevent the body from bending when the plane rolls on T/O. I also remember watching "The Ultimate Guide to Planes" on the discovery channel where they said that the wing lifts by bending up into the loss of pressure when the plane moves.

*Exactly how does that work and should this bending be allowed to happen?

*If we resist the elasticity, will we loose lift in the process?

*What if we extend the length (not span) of a wing to the nose, would that solve both problems?

I hope these aren't trivial, I'd like to learn something.

The meaning of life is curiosity; we were put on this planet to explore opportunities.
10 replies: All unread, jump to last
User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4300 posts, RR: 34
Reply 1, posted (14 years 10 months 9 hours ago) and read 2780 times:

In turbulence, the 747's wings pretty much flap. Flexibility improves the strength of the aircraft.

Chicks dig winglets.
User currently offline456 From Netherlands, joined Feb 2001, 332 posts, RR: 1
Reply 2, posted (14 years 10 months 8 hours ago) and read 2767 times:

I saw a documentary on the television about the development of an 777, and one issue was that the wings were tested for a whole day by 'flapping'. Also saw that a wing can bend to the floor (!!) WITHOUT breaking of the fuselage.
You can see it as well on some explosions or accidents with airplanes, that the wings MOST of time are NOT broken, and are intact to the fuselage.
Wings are really flexible (must though, for the fuel tanks, as well for iron fatigue (sorry if this is improper english))

User currently offlineAmericawest123 From , joined Dec 1969, posts, RR:
Reply 3, posted (14 years 10 months 7 hours ago) and read 2752 times:

I guess bending is better than snapping?? LOL  Smile/happy/getting dizzy

User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 20
Reply 4, posted (14 years 9 months 4 weeks 1 day 22 hours ago) and read 2720 times:

XFSUgimpLB41X posted:

"Flexibility improves the strength of the aircraft,"

When a read this, a pix of a flimsy, rubber airplane pops in my head. The wings lift the plane as well as itself to the point as if the forward view has the plane smiling (or grinning) on T/O.

I guess I have a hard time visualizing to myself that if a wing or any part of a plane can warp so easily it can still be strong enough to do anything.

A little more clairity would help, what if the wings were looped around and connected to the tailplane, would it still bend? Would it give similar lift? I know the drag would be less since the votices would be guided to the middle as if it were a forward swept wing.

The meaning of life is curiosity; we were put on this planet to explore opportunities.
User currently offlineJwenting From Netherlands, joined Apr 2001, 10213 posts, RR: 17
Reply 5, posted (14 years 9 months 4 weeks 1 day 19 hours ago) and read 2710 times:

If a structure cannot bend, it cannot dissipate forces acting on it, which leads to point-stresses and thus thus greater risk at hairfractures and ultimately failure.
Therefore a measure of flexibility is designed into a structure to allow it to absorb forces acting on it, spreading the load over a greater part of the structure.

I wish I were flying
User currently offlineAir2gxs From , joined Dec 1969, posts, RR:
Reply 6, posted (14 years 9 months 4 weeks 1 day 19 hours ago) and read 2706 times:

They bend, but do not break.

User currently offlineGregg From United States of America, joined Jun 2000, 327 posts, RR: 0
Reply 7, posted (14 years 9 months 4 weeks 1 day 9 hours ago) and read 2686 times:

If planes did not bend, they would break. (If they weren't too heavy to lift off the ground.) You need to have flexibility in large structures. Even tall buildings bend in the wind.

User currently offlineMax Power From , joined Dec 1969, posts, RR:
Reply 8, posted (14 years 9 months 4 weeks 1 day 4 hours ago) and read 2675 times:

It better bend or it will break. Flexible is much too rigid, in aviation you have to be fluid.
- Verne Jobst
Cheers, Max

User currently offlineNotar520AC From United States of America, joined Jul 2001, 1606 posts, RR: 3
Reply 9, posted (14 years 9 months 3 weeks 3 days 3 hours ago) and read 2630 times:

Wings on advanced commercial airliners are usually made as shock absorbers, very helpful in turbulence.


BMW - The Ultimate Driving Machine
User currently offlineLAPA_SAAB340 From France, joined Aug 2001, 409 posts, RR: 4
Reply 10, posted (14 years 9 months 3 weeks 2 days 17 hours ago) and read 2629 times:

Looks like Jwenting pretty much covered the first question  Smile/happy/getting dizzy

All structures will deform to a certain degree under loading. In the case of buildings, bridges and such structures, the deformations are more subtle and you won't notice them with the naked eye. In the case of an airplane wing, the deformation is large enough for you to be able to see it. If you wanted a stiffer wing you could make one, and you wouldn't lose any lift doing so, but you'd have a needlessly heavier wing, your ride would be bumpier in turbulence, and you would also run into the problems Jwenting mentioned earlier.

If you were to extend the chord (the width of the wing) and reduce your wingspan, you'd get a very inefficient wing, as a lot more air from the bottom of the wing would be able to spill over the wingtip to the top. This causes loss of lift near the tips (and don't have a wide wing anymore to begin with!) and you also get an increase in drag, which means you burn more fuel!

I hope this helped!

Top Of Page
Forum Index

Reply To This Topic Why Do Planes Bend?
No username? Sign up now!

Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)

Similar topics:More similar topics...
Why Do Wings Need To Be Longer, Not Wider? posted Thu Mar 8 2007 06:22:51 by CoolGuy
Why Do Sidesticks Make Mech Backup Impossible? posted Sat Feb 24 2007 04:12:35 by Blackbird
Why Do A Wings Climb, B Wings Cruise Better? posted Sun Jan 28 2007 08:54:07 by Art
Why Do UA's 777's Smoke So Much? posted Mon Jan 8 2007 08:59:23 by DeltaJet757
Why Do Airports Have Both 3 And 4 Letter Codes? posted Wed Oct 11 2006 00:28:23 by AirPacific747
Why Do I Never See Turbprops Making Contrails? posted Fri Jun 16 2006 14:37:15 by Ba757gla
Why Do Airlines Furlough posted Sat May 13 2006 22:59:26 by AirWillie6475
Position And Hold? Why Do We Use This? posted Thu Mar 2 2006 21:07:30 by Alias1024
Why Do Old Jet-engines Smoke So Much? posted Sun Dec 25 2005 23:02:10 by TheSonntag
Why Do United Ground Very Young Aircraft posted Sat Dec 18 2004 16:11:24 by Aviation

Sponsor Message:
Printer friendly format