Human Flight: from small working model in footage to life size model?
March 21, 2012 8:21 AM   Subscribe

After seeing the Human Bird Wings video (doesn't matter if it's real or not), I thought about this TED Talk again. Are there any 3D programs/motion-capturing software that can map out that bird and its motion from the talk and convert a 3D model out of it? Then all you would have to do is scale it to human size and build it offline right?
posted by querty to Technology (4 answers total) 1 user marked this as a favorite
The real world is not scale invariant. You can't just take an arbitrary design, build it 10 times bigger and expect it to work. The problem is often the strength of materials.

Just like a roof would collapse if you made a building ten times bigger without changing the design, wings with ten times the surface area but no more strength would break up under the increased forces. If you reinforced them sufficiently, they would be to heavy to lift themselves by flapping.

Hence engines and fixed wings.
posted by caek at 8:29 AM on March 21, 2012

The problem is that mass scales with volume (r^3) but the lift force provided by the wings scales roughly with area (r^2) I believe.

So to scale a bird up to human size, you'd need to make it a whole lot lighter or make the wings a whole lot bigger. Both of those "solutions" would only cause more problems to deal with.

There's a legend that says that the architect commissioned to build the Colossus of Rhodes was bankrupted when he decided to double the height of the statue but didn't realize he would need 8 times as much material to do so. Scale matters.
posted by no regrets, coyote at 8:53 AM on March 21, 2012 [1 favorite]

Also note that birds have adaptations that allow them to fly -- that is, going the other way around, a bird sized human may still not be able to fly.

Due to their high metabolic rate required for flight, birds have a high oxygen demand. Development of an efficient respiratory system enabled the evolution of flight in birds. Birds ventilate their lungs by means of air sacs.

The bird skeleton is highly adapted for flight. It is extremely lightweight but strong enough to withstand the stresses of taking off, flying, and landing. One key adaptation is the fusing of bones into single ossifications, such as the pygostyle. Because of this, birds usually have a smaller number of bones than other terrestrial vertebrates. Birds also lack teeth or even a true jaw, instead having evolved a beak, which is far more lightweight. The beaks of many baby birds have a projection called an egg tooth, which facilitates their exit from the amniotic egg.
posted by Comrade_robot at 9:03 AM on March 21, 2012

There are other problems. Birds have feathers; upscaled ornithopter wings humans invent don't (AFAIK, none have). The feathers rotate slightly as the wing goes up/down, opening/closing like vents, reducing/increasing the drag on the air - so more force goes into moving air down and less is required to pull the wing up again.

But, yeah: the 3D-weight vs 2D-surface area issue is the big one.
posted by IAmBroom at 11:53 AM on March 21, 2012

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