eli5: Why is it not possible to build bird-like attachable wings that account for body proportions to allow humans to fly or glide around?
In: 2102
Thus, an average adult male human would need a wingspan of at least 6.7 meters to fly. This calculation does not even take into account that these wings themselves would be too heavy to function.
Because of the Square Cube law.
Basically, the way bird wings generate lift is a function of it’s surface area.
However, bird wings aren’t weightless, so the wings need to generate enough lift to lift themselves and the rest of the body up.
As the body gets heavier, the wings need to get correspondingly bigger, and bigger wings mean heavier wings.
That eventually results in getting something so heavy that you effectively can’t scale that design up enough to continue working.
If you try and fix it by using lighter materials then they tend to not be strong enough to stand up to the stresses of using them.
Also, giving people man power capable personal flight would be such a fucking legislative nightmare of liabilities
You got some amazing responses, but I still want to give my 2 cents, even though it’s redundant
>Why is it not possible to build bird-like attachable wings?
It kinda is, we call it hang glider.
>to allow humans to fly or glide around?
Like a wing suit? So again, we can, just probably not how you envisioned.
Why no flappy? Bones not hollow, too fat, pecs too small to flappy.
We can glide and do, people use squirrel suits and do red bull activities for trophies and slim jims. As for the flying part, it’s just too heavy to power the complex motion of birb wings. They would have to be super big and light. Folks in science used some kind of turbo jet rocket boosters to make an iron man, maybe they can put them two ideas together in the future. I will wait and see.
It is, we just toyed around with the formula a bit since those crazy’s jumping off buildings at the turn of the century. Hang gliders are essentially what you’re describing, only it’s in a form factor that doesn’t outright kill you.
You totally could! You could absolutely attach bird wings to a person that they could fly or glide around in.
But unfortunately, humans are heavy. The wings would need to be at least maybe 22 feet across to work. But 22 foot wings that can keep a person aloft are really heavy to flap. You basically need to push your weight worth of air downwards, like a pushup except repeatedly. Human arms don’t have that.
The reason this scales so poorly is because of this idea called the “square-cube law.” The idea is that, when you scale an object up N times, the surface area of a thing gets N*N times bigger, but the volume of a thing gets N*N*N times bigger. Think about a cube that’s 1 foot across. The front of that cube is 1 foot by 1 foot, 1 square foot. Scale the cube up so every side is 2 feet across, and now the front is now 2 feet by 2 feet, which is 4 square feet. But the volume of the original cube went from 1*1*1=1 cubic foot to 2*2*2=8 cubic feet. Your weight comes from your volume. A wing’s ability to fly comes partly from its surface area. What’s that mean? Well, it means kaiju don’t really work, but it also means that if you scale up a small bird, it probably won’t be able to fly either.
But don’t let that bother you, we’re not limited by biology. We have science. You can strap bird-like attachable wings on today and glide around. That’s a hang glider.
With light weight carbon based materials, and advances in robotics, would it be naive to hope for a mechanically augmented human winged flight. You could have all of my money if anybody is working on this. I would be an angel investor!
One of the heaviest birds to have ever lived weighed as much as a human. It had a 6m wing span.
[https://en.wikipedia.org/wiki/Argentavis](https://en.wikipedia.org/wiki/Argentavis)
You would need an enormous amount of effort to flap 6m of even the best designed wings (and they would need to be very light and have an extreme amount of flexible movement and control – even accurate and ever-changing feather orientation is required to have a bird be able to fly properly).
“It has been estimated that the minimal velocity for the wing of A. magnificens is about 11 metres per second (36 ft/s) or 40 kilometres per hour (25 mph). Especially for takeoff, it would have depended on the wind. Although its legs were strong enough to provide it with a running or jumping start, the wings were simply too long to flap effectively until the bird was some height off the ground. However, skeletal evidence suggests that its breast muscles were not powerful enough for wing flapping for extended periods. Argentavis may have used mountain slopes and headwinds to take off.”
So if you can carry a 6m set of wings, had perfect and trained control over their movement, were able to flap and run up to 25mph and were prepared to jump off a cliff to start it, you might be able to glide like they probably spend most of their flight doing.
I wouldn’t recommend it, though, because weight-for-weight such a bird would have far, far, far stronger and faster muscles than you would have, even if it was the same weight as you, and spent its life from a tiny bird learning how to fly and not putting on weight (which would ground it immediately). They would have hollow bones, most likely, much of their weight would be accounted for by 6m of muscular wings (so we could chop your arms and half your legs off if you like, and then used the saved weight to give you a pair of wings, to keep the weights about even), and then you’d have to flap them JUST right, fast enough and hard enough to literally pull yourself off the ground against gravity.
I recommend you try it before you throw yourself off a cliff reliant on being able to fly your way out of danger. People did. For decades. Centuries even. Humans don’t really have the musculature to do it and the technique takes extreme amounts of energy and skill to do (it’s not just a case of flapping or gliding).
Pretty much, anyone who has ever tried has been unable to even get higher than they could have jumped without the wings, and never for longer than gravity takes to pull them back to earth.
The largest birds ever to have lived, with musculature far in excess of our own, wingspans that you literally couldn’t fit in most rooms (even with the wings dropped to the floor because you’re only going to be about 1.7-2m tall at most), with highly optimised and light bodies for their strength, all their strength in their wings and tiny, tiny thin and light legs and brains and bodies, weighing roughly what a human alone would weigh, throwing themselves off a cliff, with a lifetime of experience, getting up to 25mph (a near-fatal speed even in a car-pedestrian collision!) in order to be able to do some small piece of light flight for non-extended periods of time.
And even with all the modern tech a hang-glider can’t “flap” properly to increase height, the technology to do so would weigh more than the wing itself. All we can do is glide. And hang-gliders tend to have 10m wingspans or thereabouts in order to support the weight of a human and themselves in an upward draft of warm air.
If you got a kid, trained them from birth to bulk up their arms to become immensely strong (like gorilla-strong), never let them build up their legs or lungs or brain, kept them quite small and light in every respect, gave them a 6m wingspan, had a technological arrangement that you could modify the entire shape of the wing easily without any extra weight, got them to practice it every day from birth, you may be able to get them to lift off the ground for short periods.
“Am I a joke to you?” – hang gliders
First of all, birds aren’t real. They’re Surveillance robots engineered to fly. If you don’t believe that then you should know that birds are much less dense than humans. The majority of their weight is in their enormous breasts that power their wings. Humans are mostly water. Water is heavy. And our muscular system is designed to keep us upright while walking and manipulating objects with out hands. Even if we had giant wings, we don’t have the right muscles to power them. We do however have very big brains. And our big brains enabled us to conceptualize things like gravity and fluid dynamics and jet propulsion which inevitably lead to inventions and engineering marvels that allow humans to fly. And we fly faster and further than any bird. Take that birds. Losers.
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