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Comment by CrimsonCape | Hacker News Reader

I grew up duck hunting and learned intimately how ducks use their wings and the variations of shapes at different velocities as they slow down to land on the water. I also grew up boating and swimming and have a likewise similar understanding of paddling, tracking a canoe straight, and using boat motor trim to "get on the plane".

I guess I struggle with articles like this because it's already so intuitive as a mix of air and fluid dynamics. In fact, fixed airfoils are so boring when you see what a duck can do.

https://www.youtube.com/watch?v=-3CVZYY8xS4

So for all the fancy physics talk, this duck is literally just paddling air with his wings. The same physiology I use to stay afloat when treading water while swimming.

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But when that fancy duck wants to get to Paris in a hurry, it still has to hop on a fixed-wing Concorde like everyone else.

Give it a strong selective pressure towards speed and a few million years and you will have your supersonic duck.

Intercontinental ballistic mallards? Just another trillion-dollar boondoggle from the military-ornithological complex.

Reverse dragooning by expelling fiery farts made of hypergolics fueled by fantastic fermentation?

Something like that is featured in Terry Pratchett's Discworld series of books. (Don't spoil the book it's in!)

GNU Terry Pratchett

There's also that Harry Potter spinoff movie in which he becomes a supersonic corpse with a farting jet-butt in order to visit some pretty redwood parks: https://www.inverse.com/article/17614-how-swiss-army-man-mad...

Something similar already happened in reality in another evolutionary chain:

https://en.wikipedia.org/wiki/Bombardier_beetle

(on a much smaller scale)

Hummingbirds go to mexico to vacation a lot more than I do. Imagine if humans had a manadatory 2000 mile trip and 6 month layover twice a year to survive.

Once you have technology that enables flapping type motion, it's opening up the applicable physics to like 6 degrees of freedom versus zero in current wing technology (fixed = 0 degree of freedom); much more complex and interesting to study.

How else will we move toward ornithopter style wings, or vehicles that can hover via wing movement.

Rotating wing aircraft have no problem hovering mid-air. All we need are a handful of breakthroughs in battery tech.

Rotating wing aircraft have problems with supersonic flight - and the wing (rotor) itself reaches supersonic much quicker than the aircraft itself, thats why helis are usually slow, compared to aircraft.

I guess “supersonic wing flapping” would have similar problems, but maybe there are more clever solutions than can be modeled, with so much degree of freedom?

And is “supersonic flapping” even possible?

The arctic tern flies from the north pole to the south pole.

I once ate duck in Paris.

That is a remarkable story...

> this duck is literally just paddling air with his wings

Grossly speaking, sure. But I feel like this simplifies away a lot of the interesting bits. It's not as simple as, say, someone on a canoe paddling. Why is the duck's wing shaped just so, and not another way? Why does it move its wings just so instead of another way?

I'm reminded of an analysis of fruit fly wings, showing how they re-capture energy from the air when flapping[1]. Maybe the duck is doing similar; I don't know.

Of course, these animals make it look easy, thanks to millions of years of evolution (:

https://www.nature.com/articles/s41598-021-86359-z

Fixed airfoil physics become really important at very high speeds.

Or if your Cessna isn’t equipped with a flapping system.

Amusingly, the flappy Cessnas were designed with the engine mounted right in front of the windshield.

Where else could it possibly go?

https://gallery.vtol.org/image/P2xYJ

I think you might be experiencing a bit of a dunning-kruger effect

Also, in my experience there’s a huge difference between having an intuition for something and having an understanding of something to the point where you could model it.

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