C5 and An-124 wings straighten in flight?

[ProPax]

I see this every time C5 Galaxy or An-124 are on the tarmac - their wings are drooped significantly. Do they stay like that in flight or do they straighten out as they generate lift? I tried looking for videos on youtube but couldn't find the definitive answer. Could someone help, please?

[ICM]

I will happily give way to an aerodynamicist on this but, for what it's worth, and based on my time with the C-141 that also had drooped wings on the ground, they certainly straightened out as lift increased. And the effect of the weight of fuel in the wings should also be considered. I could touch the wingtip on the ramp before departure on a flight of four or more hours whereas, after landing, that wingtip would be way out of reach.

[diginagain]

Originally Posted by ProPax

I see this every time C5 Galaxy or An-124 are on the tarmac - their wings are drooped significantly. Do they stay like that in flight or do they straighten out as they generate lift? I tried looking for videos on youtube but couldn't find the definitive answer. Could someone help, please?

You should look for video of helicopter blades in flight.

[charliegolf]

Don't they keep the weight in the wings for a while to avoid the single loud clap before the wings fall off? Wing relieving load or summat?

And is it BS that the BUFF has a call of, 'wings airborne' on the takeoff roll?

CG

[ExAscoteer]

Originally Posted by charliegolf

Don't they keep the weight in the wings for a while to avoid the single loud clap before the wings fall off? Wing relieving load or summat?

We certainly did on the C-130. At high fuel loads you'd use the AUX tank (wing shoulder tank) fuel before the EXT tank fuel; the latter providing the wing bending relief.

[sablatnic]

Gliders do it too:

You Tube

[Compass Call]

sablatnic
looks like an overdose of dihedral :-)

[NutLoose]

You Tube

[NutLoose]

Also have a read off

https://aviation.stackexchange.com/q...cargo-aircraft

[ProPax]

Originally Posted by ICM

I will happily give way to an aerodynamicist on this but, for what it's worth, and based on my time with the C-141 that also had drooped wings on the ground, they certainly straightened out as lift increased. And the effect of the weight of fuel in the wings should also be considered. I could touch the wingtip on the ramp before departure on a flight of four or more hours whereas, after landing, that wingtip would be way out of reach.

Oh, I forgot about that pair! C-141 and its Soviet counterpart Il-76/78.

Doesn't that affect fatigue? That wing weighs tons, literally, and it moves several meters, it seems, with the changes in its own weight. I remember reading that B-52 (?) or some other long-winged bomber was flapping its wings in flight so much that fatigue cracks formed before it even landed. I may be wrong or exhaggerating... a bit.

[twb3]

I was a Loadmaster on the C-5A some time ago. I do recall one takeoff when I was seated in an aft-facing seat in the aft flight deck and noticed that the wing was just visible at the bottom of the window at the beginning of the takeoff roll. By the time we were airborne, the entire window was filled with wing as observed from the same eyepoint.

TWB

[ProPax]

Originally Posted by twb3

I was a Loadmaster on the C-5A some time ago.

A totally unrelated question. (I just never met a loadmaster.) If a loadmaster thinks the load is unsafe but the captain still wants to go, who wins? Is there an official separation of duties and "final word"?

[isaneng]

Captain always wins, clue is in the title.

But I suspect he will be going without his Loadmaster.

Or his other crew.

In all seriousness, after 30 years, I have never known one captain go against safety-related advice from any crew member. And when the Nav left the aircraft with me, he didn't go flying either.

[isaneng]

Proof read before hitting 'Post' Isaneng you donkey. Apologies,'I have only ever known............'

[oxenos]

Gliders do it too:

Clearly that glider had used up all it's fuel

[KenV]

All large aircraft wings bend upward during flight, both those with anhedral (like C-5, C-141, C-17, Il-76, An-124 and other military airlifters.) and those with dihedral (the vast majority of airliners.) And yes, that results in fatigue, but is accounted for in the design. The structural weight added to a wing to prevent fatigue failure is much much much less than the weight that would be need to be added to make the wing rigid in flight. Composite wing aircraft flex even more because composites (almost) don't fatigue. Witness that glider wing.

[B2N2]

There is a very specific purpose to that design anhedral.
It reduces spiral stability aka enhances maneuverability.
The high wing and low center of gravity combined cause some dihedral effect.
So a beast this big won’t get out of its own way without anhedral. That’s basically the not so scientific explanation.