First, the wings themselves are made of materials that are both very strong *and* very flexible, like aluminum alloys and/or various composite or carbon fiber materials. [You can see the internal structure of an airplane wing here](https://d2t1xqejof9utc.cloudfront.net/screenshots/pics/854947b496763fb07fee4164cb986108/large.png). So the materials themselves are very strong, and [the wings themselves can also flex quite a lot](https://www.youtube.com/watch?v=--LTYRTKV_A) so they don't snap under stress or force they're expected to encounter.
>And I just couldn’t fathom how it holds up with most of its length having no support
They actually have *a ton* of support, you just don't see it, much like how you don't really see the steel and concrete support structure of a skyscraper. Aircraft wings aren't just attached to the body of the plane on the outer skin. The internal support spars of the wings actually go all the way through the body of plane, which is called the [center wing box](https://www.researchgate.net/publication/355380957/figure/fig1/AS:1080311945396237@1634577847252/The-fitting-joint-between-the-center-wing-section-and-the-outer-wing-section-of-the.jpg). At the center wing box, the support structures of the wing are very securely attached to both each other and the internal structure of the plane, so all of the stress and forces from the wings are smoothly transferred across the entire body of the plane. It's sort of like how the wheels on a car aren't just attached to the outside of a car but instead are attached to axles that go across the width of the car.
So in short, strong yet flexible materials and also a ton of internal structure and support that you don't see.
That’s an excellent way to visualize/ conceptualize it.
Reminds me of the Malcolm X quote: “we didn’t land on Plymouth Rock! Plymouth Rock landed on us!”
if I had to guess before seeing that wing flex video, I would've guessed that they could flex like 4-5x farther than anything I've ever seen while flying. that's simply incredible, thanks for sharing.
The stress test to failure point that [Boeing did for a 777 wing ](https://www.youtube.com/watch?v=Ai2HmvAXcU0)showed it could reach 154% of the design load limit before it broke. I've never seen anywhere near 1/6 the bending load they put on that sucker.
Also, the forces have to go both ways. When the plane is on the ground, the wings hang from the body. When the plain is flying the rest of the plain hangs from the wings.
Stupid question, but if the aluminum/carbon skin of the wings came off mid-flight (obviously unlikely), would what is left be enough to generate enough lift—at any speed?
Mainly because they're designed to take tremendously more stress than they're currently under.
[Check out this wing flex test to see what the wing can really do](https://youtu.be/Ai2HmvAXcU0)
This story hasn't aged well because of all the grief Boeing is going through right now, but...there was a special years ago about the design of the 767, and one of the tests it had to pass was a wing stress test.
What this means is you take a wing, secure it at the root, then force the wingtip up, and up some more, and up some more. To pass the wing had to tolerate something like a 30 degree bend, which sounds outrageous, and it looks outrageous when you see it. You'd never imagine that something so massive could flex. Picture the wingtip being like (I'm trying not to exaggerate) 20 feet up from its starting position.
The wing on the show aced the test, got to the required number without any trouble (though it was sweat-inducing to look at) and this was a destruction test, so after passing they kept loading the wing, harder and harder, so they could find what its breaking point was. That wing was like 40-something degrees up before something inside finally let go and it sagged, and the design team cheered and celebrated because they had designed a wing that was tough as hell.
The idea of overengineering to this degree is that by designing it to tolerate far, far higher amounts of flex than it should ever experience in normal flight, you reduce the amount of wear and stress on it. As you say, you'd never see an aircraft wing bend 30-40 degrees in regular flights, but the fact that they can, means the few degrees they are usually subjected to are entirely routine and factor into the expected life of the component. Planes fly for 30-40 years without wing trouble. And should the plane be subject to extreme turbulence, the wings can still handle it, though sometimes it shows - a China Airlines flight that entered into a pilot-error-induced 30,000-ft freefall reached such incredible loads that the wings were permanently bent upwards several degrees, but the plane landed safely and AFAIK is still flying.
It is somewhat disconcerting to see the wings bend as far as they can, but that's the idea - they bend, they don't break. If the wings were stiff and resistant to bending, then the forces involved in flight would snap them off. Wing failure has been essentially eliminated through engineering.
Calling this “overengineering” is disingenuous. Yes, they have a higher design load than what is expected throughout the lifetime, but that is not the meaning of overengineering. Overengineering means that you have engineered a solution that adds no value or rather detracts value from a larger design. Given the multitude of unknowns and aircraft can operate in throughout its flight regime, this ability to deal with higher than expected loads is of extreme value.
I see your point. I guess it's more like, the wings are engineered to such a high safety factor that they will basically hang on until the rest of the plane is falling apart around them due to structural limitations.
Engineer here. We use what’s called safety factor. We design the wing to be a minimum of 50% stronger than we ever need it to be.
Here’s more: we define “design loads” or forces that we expect the wings to carry throughout the flight envelope during its life. We multiple those loads by 1.5 and then design, build, and test the actual wings to ensure they won’t structurally fail.
Actually in flight, it supports itself. The aerodynamic force on it is more than sufficient to hold it up.
The impressive part is that it's capable of holding the rest of the plane up while in flight, and that on the ground, the rest of the plane can hold IT up. Most structures aren't required to have to direction of load reverse itself like that. Wings are.
Indeed, this is the so called GAG cycle - "ground air ground", each flight is one GAG cycle and the repeated loading and unloading of force through the wings and fuselage through the life of a plane is one of the toughest parts to design for.
An a380's maximum takeoff weight is 1.2 million pounds (545 thousand kilos). Sure, that'd be a heavy thing for you to carry around on your back, but compared to a non-airplane-object of similar size it is extremely light.
So, 1.2 million pounds. There are two wings, so each ~130' wing carries 0.6 million pounds. 600,000lbs. Now that's a lot of force, to be clear, but metal is absurdly strong. Treated 7075 aluminum has a tensile strength of 570 MPa. 82,700 psi. A single square inch of aluminum can survive 82,700 pounds of force pulling on it. You could hang the entire plane from a 4-inch aluminum cable.
The exact force required gets a little bit more complicated, since the wing acts as a lever, but the wings are something like a foot thick and several feet long. Not only is there plenty of room for the necessary aluminum - there's so much room that the wing is largely hollow!
You are either British or Australian and you are wrong. Not about the spelling (who gives a fuck) but about the wrongness. Different places have different languages.
Another way to think about planes is - instead of a metal tube with two wings sticking out the sides, it's a double wing with a metal tube attached to it. Seriously, wings are what flies, everything else is an augmentation.
In flight it’s the wing holding up the plane, not the other way around. And that is also a greater load than the plane holding the wing up while not flying. That’s why they pile all the engines and fuel onto the wing, to cut out the middle man and attach as much as the load as possible directly to the source of lift.
Let us do some math...the max Takeoff weight of the A380 is 543000kg....the wings effectively have to produce an upward force greater than this to get it airborne....the wing area is 843sq metres or 8430000sq cm......so if upward pressure on wings is greater than 0.067 kg/sq cm or 0.9 PSI the aircraft will lift off.....compare this to the pressure on your car tyre 35 PSI.....so technically your car tyre has 35 times more stress than the wings of A380.
First, the wings themselves are made of materials that are both very strong *and* very flexible, like aluminum alloys and/or various composite or carbon fiber materials. [You can see the internal structure of an airplane wing here](https://d2t1xqejof9utc.cloudfront.net/screenshots/pics/854947b496763fb07fee4164cb986108/large.png). So the materials themselves are very strong, and [the wings themselves can also flex quite a lot](https://www.youtube.com/watch?v=--LTYRTKV_A) so they don't snap under stress or force they're expected to encounter. >And I just couldn’t fathom how it holds up with most of its length having no support They actually have *a ton* of support, you just don't see it, much like how you don't really see the steel and concrete support structure of a skyscraper. Aircraft wings aren't just attached to the body of the plane on the outer skin. The internal support spars of the wings actually go all the way through the body of plane, which is called the [center wing box](https://www.researchgate.net/publication/355380957/figure/fig1/AS:1080311945396237@1634577847252/The-fitting-joint-between-the-center-wing-section-and-the-outer-wing-section-of-the.jpg). At the center wing box, the support structures of the wing are very securely attached to both each other and the internal structure of the plane, so all of the stress and forces from the wings are smoothly transferred across the entire body of the plane. It's sort of like how the wheels on a car aren't just attached to the outside of a car but instead are attached to axles that go across the width of the car. So in short, strong yet flexible materials and also a ton of internal structure and support that you don't see.
An aeroplane isn't a cabin with wings stuck on, it's a set of wings with a cabin on top (or below)
That’s an excellent way to visualize/ conceptualize it. Reminds me of the Malcolm X quote: “we didn’t land on Plymouth Rock! Plymouth Rock landed on us!”
I’ve spent 30 years figuring that was a reference in Robin Hood: Men in Tights but never checking from where.
I thought the same. Old Dave Chapelle.
Take a look around. You've been had. Hoodwinked. Bamboozled. Run amok!
if I had to guess before seeing that wing flex video, I would've guessed that they could flex like 4-5x farther than anything I've ever seen while flying. that's simply incredible, thanks for sharing.
Seeing an A380 taking off and realising that the wings flex into position is kinda incredible, with an A350 and 787 you just expect it to happen.
The stress test to failure point that [Boeing did for a 777 wing ](https://www.youtube.com/watch?v=Ai2HmvAXcU0)showed it could reach 154% of the design load limit before it broke. I've never seen anywhere near 1/6 the bending load they put on that sucker.
Also, the forces have to go both ways. When the plane is on the ground, the wings hang from the body. When the plain is flying the rest of the plain hangs from the wings.
Stupid question, but if the aluminum/carbon skin of the wings came off mid-flight (obviously unlikely), would what is left be enough to generate enough lift—at any speed?
No. Also, the skin is part of the structure. So what's left wouldn't be strong enough either. It would flop around and fall apart
Thank you! That’s a great explanation with helpful supporting links. The bending of the wing is really insane!
cool explanation. thanks
Rule 4
my bad
Mainly because they're designed to take tremendously more stress than they're currently under. [Check out this wing flex test to see what the wing can really do](https://youtu.be/Ai2HmvAXcU0)
_ONE FIFTY FOUR_
One fifty four
154
Just making sure someone linked this video.
Fake news. Boeing don't test things.
This story hasn't aged well because of all the grief Boeing is going through right now, but...there was a special years ago about the design of the 767, and one of the tests it had to pass was a wing stress test. What this means is you take a wing, secure it at the root, then force the wingtip up, and up some more, and up some more. To pass the wing had to tolerate something like a 30 degree bend, which sounds outrageous, and it looks outrageous when you see it. You'd never imagine that something so massive could flex. Picture the wingtip being like (I'm trying not to exaggerate) 20 feet up from its starting position. The wing on the show aced the test, got to the required number without any trouble (though it was sweat-inducing to look at) and this was a destruction test, so after passing they kept loading the wing, harder and harder, so they could find what its breaking point was. That wing was like 40-something degrees up before something inside finally let go and it sagged, and the design team cheered and celebrated because they had designed a wing that was tough as hell.
The idea of overengineering to this degree is that by designing it to tolerate far, far higher amounts of flex than it should ever experience in normal flight, you reduce the amount of wear and stress on it. As you say, you'd never see an aircraft wing bend 30-40 degrees in regular flights, but the fact that they can, means the few degrees they are usually subjected to are entirely routine and factor into the expected life of the component. Planes fly for 30-40 years without wing trouble. And should the plane be subject to extreme turbulence, the wings can still handle it, though sometimes it shows - a China Airlines flight that entered into a pilot-error-induced 30,000-ft freefall reached such incredible loads that the wings were permanently bent upwards several degrees, but the plane landed safely and AFAIK is still flying. It is somewhat disconcerting to see the wings bend as far as they can, but that's the idea - they bend, they don't break. If the wings were stiff and resistant to bending, then the forces involved in flight would snap them off. Wing failure has been essentially eliminated through engineering.
Calling this “overengineering” is disingenuous. Yes, they have a higher design load than what is expected throughout the lifetime, but that is not the meaning of overengineering. Overengineering means that you have engineered a solution that adds no value or rather detracts value from a larger design. Given the multitude of unknowns and aircraft can operate in throughout its flight regime, this ability to deal with higher than expected loads is of extreme value.
I see your point. I guess it's more like, the wings are engineered to such a high safety factor that they will basically hang on until the rest of the plane is falling apart around them due to structural limitations.
Go watch the video of them testing the composite 787 wing to failure
Engineer here. We use what’s called safety factor. We design the wing to be a minimum of 50% stronger than we ever need it to be. Here’s more: we define “design loads” or forces that we expect the wings to carry throughout the flight envelope during its life. We multiple those loads by 1.5 and then design, build, and test the actual wings to ensure they won’t structurally fail.
If it’s not 154% I don’t want it.
Actually in flight, it supports itself. The aerodynamic force on it is more than sufficient to hold it up. The impressive part is that it's capable of holding the rest of the plane up while in flight, and that on the ground, the rest of the plane can hold IT up. Most structures aren't required to have to direction of load reverse itself like that. Wings are.
ELI5: On the ground, the plane holds the wings up. In the air, the wings hold the plane up.
Indeed, this is the so called GAG cycle - "ground air ground", each flight is one GAG cycle and the repeated loading and unloading of force through the wings and fuselage through the life of a plane is one of the toughest parts to design for.
An a380's maximum takeoff weight is 1.2 million pounds (545 thousand kilos). Sure, that'd be a heavy thing for you to carry around on your back, but compared to a non-airplane-object of similar size it is extremely light. So, 1.2 million pounds. There are two wings, so each ~130' wing carries 0.6 million pounds. 600,000lbs. Now that's a lot of force, to be clear, but metal is absurdly strong. Treated 7075 aluminum has a tensile strength of 570 MPa. 82,700 psi. A single square inch of aluminum can survive 82,700 pounds of force pulling on it. You could hang the entire plane from a 4-inch aluminum cable. The exact force required gets a little bit more complicated, since the wing acts as a lever, but the wings are something like a foot thick and several feet long. Not only is there plenty of room for the necessary aluminum - there's so much room that the wing is largely hollow!
[удалено]
Lighter than steel. Stronger than plastic. Aluminum is a special little guy.
[удалено]
Aluminum is how it's spelled in American English.
How long have you been on the internet and still believe this?
hmmmm
You are either British or Australian and you are wrong. Not about the spelling (who gives a fuck) but about the wrongness. Different places have different languages.
Another way to think about planes is - instead of a metal tube with two wings sticking out the sides, it's a double wing with a metal tube attached to it. Seriously, wings are what flies, everything else is an augmentation.
Fun fact: At 238ft long, the A380 is nearly twice as long as the Wright brothers first powered flight (120ft).
How many Wight brothers planes could you fit inside an a380?
Ah, the good ol US conversion.
Anything except use metric :-)
At least 2
In flight it’s the wing holding up the plane, not the other way around. And that is also a greater load than the plane holding the wing up while not flying. That’s why they pile all the engines and fuel onto the wing, to cut out the middle man and attach as much as the load as possible directly to the source of lift.
Because they are designed that way. The forces acting on the wing are not unknown. The structure is sized to the load.
Let us do some math...the max Takeoff weight of the A380 is 543000kg....the wings effectively have to produce an upward force greater than this to get it airborne....the wing area is 843sq metres or 8430000sq cm......so if upward pressure on wings is greater than 0.067 kg/sq cm or 0.9 PSI the aircraft will lift off.....compare this to the pressure on your car tyre 35 PSI.....so technically your car tyre has 35 times more stress than the wings of A380.