747 wing tip deflection

[wildrapid47]

Please can anyone tell me the normal wing tip deflection of a 747 when flying .. compared with sitting on the runway. A friend of mine has bet her months salary with someone ..... she said 30 feet .... the other person said 7 feet. The closest wins the money ... they are both mad. I kept out of it !!!

[Mr Levitator]

I'm betting on 7' being closer....... Although I'd have said 10'.

Mr L.

[Charles Darwin]

The wing tips of a large aircraft, for example, might move up and down through more than six feet relative to the fuselage when the aircraft goes from the ground, where the wings only have to support their own weight, to flight, where they support the weight of the entire aircraft.
According to "DESIGN-CENTERED INTRODUCTION TO AEROSPACE ENGINEERING
12. STRUCTURES & MATERIALS

http://www.adl.gatech.edu/classes/dci/structur/dci08.html
I think 6-7 feet are more likely than 20.

[411A]

There really can be no clear winner, as it would most certainly depend on the fuel quantity state while the aircraft was on the ramp.
IE, max fuel, wing tip lower.

On the 707-320B (advanced) it was on the order of 6 feet.
More on the 747, would be entirely possible

And, in case anyone wanted to know, the maximum deflection of the wing tip on the long body 707, without structure deformation was...22 feet.

[HotDog]

During the recent severe wing loading tests of the A380, the wing failed between the outboard and inboard engines at 1.5 times the limit load at a deflection of 7.4 meters or 24.5 feet. The 747-400 wing is slated to snap off at a max deflection of 26ft.

[barit1]

My colleague who flew Boeing B-47 bombers 50 years ago recalls its wingtip deflection (max pos g to max neg g) was on the order of 26 feet. I don't think any Boeing since then has exceeded this flexure.

[Bolty McBolt]

My 747 training notes claim 27 feet

[Capt Fathom]

The 747-400 wing is slated to snap off at a max deflection of 26ft.
Hopefully no one has told the 747-400 wing that!

[MkVIII]

My colleague who flew Boeing B-47 bombers 50 years ago recalls its wingtip deflection (max pos g to max neg g) was on the order of 26 feet. I don't think any Boeing since then has exceeded this flexure.

The B-47 had quite pronouced anhedral on the ground. In flight, the wing indeed developed quite pronounced dihedral, and I don't doubt 26ft at all! (I have a B-47 manual here somewhere in my repertoir of redundant and interesting artefacts).

Finding the amount of in-flight defelction of the B-52 would be interesting as well.

[Capt Claret]

I have a vague recollection of being told, or reading, that the B707 wing tip moved through 14' from no lift, to lift. I'm old the recollection is nearly as old.

[broadreach]

XB-52 wing flexing from http://www.faqs.org/docs/air/avb52_1.html

"The wings were thick, with a chord (ratio of cross-sectional height to width) of 15% at the root, tapering to 8% in the outer wing. They could flex from 3 meters (10 feet) down to 6.7 meters (22 feet) up."

Wildrapid47, about that month's salary, how'd it go?

[PA-28-180]

Anybody know how the 'wing dampener' works on the C-5? And why only the C-5...or has something similar been used on other airframes? Thanks.

[wildrapid47]

Thanks to all for your replies .... seems like 7-10' is the norm but it will snap off at around 26'. Since the bet did not specify the exact conditions I think I have a way to get my friend out of losing a months salary ... It appears they are both right but obviously under very different conditions ...

thanks to all once again.....

[FearlessFreep]

USAF maintenance training for my AFSC (job code) was on the B-52. It was stated that normal wing flex at the tips on the BUFF was +/- 7 feet. So that's a total flex of 14'

The B-52 is a high wing aircraft with an anhedral There are outrigger gear on the wingtips of the BUFF to prevent wingtip strikes. When they were heavily laden both outriggers could be in ground contact but normally they would not be touching the ground. Also there was some differences on the tip tanks that were mounted on the different models that may have had a definite effect on wing flex. One of the other interesting things about the BUFF is that during climbout you would actually have a negative deck angle. It was pretty wild to see them climb out with the nose down!

The 747 is a low wing with a dihedral Two very different design concepts, between the two different aircraft. I would have to say that the wing flex would be very different as well.

Not that I can get all that good of a look at but by observing 74's during takeoff but the wing flex on a 742 does not even come close to that. Have no idea what the normal flex would be on a 74.