Wool sticks on Velcro.

They don't stick by Velcro or suction or glue.

What paper went into that flap?

How would you make a single flap?

We're going to learn how to make one flap.

Well, there are other ways of making a flap.

I didn't have to try to flap my wings.

Do they do it by interlocking? That's kind of a like a Velcro like thing.

So that's the flap, and all the rest of the paper's left over.

It's very complicated, but it turns out they flap their wings very quickly.

And if I make the flap from the middle, it uses a full circle.

And they don't stick by glue, or they don't work like Velcro, or they don't work with suction.

If I put the flap on the edge, it uses a half circle of paper.

And you can see there, it needs a quarter circle of paper to make a flap.

This is strips of Velcro, this is my drawing slate, and this is my drawing pen, which is basically a film box.

So, no matter how I make a flap, it needs some part of a circular region of paper.

If I make the flap as skinny as possible, I get to the limit of the minimum amount of paper needed.

The U.N. you know, they took 20 years just to add a flap to a tent, but I think we have some more exciting things.

George de Mestral this is not bugs all over a Birkenstock was walking his dog in a field and got covered in burrs, sort of little prickly things, and from that came Velcro.

And from that stick figure, I somehow have to get to a folded shape that has a part for every bit of the subject, a flap for every leg.

And we tackle this problem by building giant, dynamically scaled model robot insects that would flap in giant pools of mineral oil where we could study the aerodynamic forces.

Well, if I unfold it and go back to the crease pattern, you can see that the upper left corner of that shape is the paper that went into the flap.

And I had these legs that were made of a wood and plastic compound, attached with Velcro straps big, thick, five ply wool socks on you know, not the most comfortable things, but all I'd ever known.

Take a square. Fold it in half, fold it in half, fold it again, until it gets long and narrow, and then we'll say at the end of that, that's a flap.

He snips it, throws the tip over his shoulder, and then grabs the scrotum and pushes it upward, and then his head dips down, obscuring my view, but what I hear is a slurping sound, and a noise that sounds like Velcro being yanked off a sticky wall and I am not even kidding.

And it turns out that the insects flap their wings in a very clever way, at a very high angle of attack that creates a structure at the leading edge of the wing, a little tornado like structure called a leading edge vortex, and it's that vortex that actually enables the wings to make enough force for the animal to stay in the air.

PRINCETON Forty years ago, I stood with a few other students in a busy Oxford street handing out leaflets protesting the use of battery cages to hold hens. Most of those who took the leaflets did not know that their eggs came from hens kept in cages so small that even one bird the cages normally housed four would be unable to fully stretch and flap her wings.