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  • BEN AARON: In the 1800s, as engineers searched for cost

  • effective alternatives to horses and steam

  • for powering public transport, wind,

  • in the form of large kites, were seriously considered.

  • But now after two centuries of development,

  • we still don't have kite powered buses.

  • But we can do this.

  • The board flip.

  • Yes, the butter slide.

  • A nice fence for a grind.

  • Watch out for my post turn.

  • And then there's this.

  • The roll.

  • An airborne inverted spin.

  • Nice work.

  • See you next time.

  • That was an advanced version of a role.

  • A core kite surfing trick with plenty of variations.

  • Kite surfers can front roll, back roll, roll, and nose grab.

  • There are all sorts of ways of mixing it up.

  • And that wasn't one of them.

  • To perfect the right kind of airborne rotation for a kite

  • surfing role requires a mastery of angular momentum and lift

  • force.

  • Here's the roll 101.

  • As wind flows over a kite's wing-like shape,

  • it generates lift force, pulling him across the water.

  • On launch, he throws his body backwards,

  • generating just enough angular momentum

  • for a complete rotation.

  • To land, he steers his kite downwards and ahead of him.

  • This increases lift force in the direction of travel,

  • so he avoids sinking.

  • It is complicated stuff to deal with all at once,

  • so first, let's just practice using lift

  • force to get a little air.

  • OK, We've got that covered.

  • Now let's add some angular momentum for the roll.

  • I said, some.

  • I mean, he did get enough angular

  • momentum for one rotation.

  • But he didn't have time for two.

  • OK.

  • Let's work on the landing.

  • Now, can you remember which direction

  • we need to send that kite?

  • No, quite the opposite.

  • He actually aced the angular momentum,

  • But if you want to go in this direction,

  • like your board, and your kite is

  • steered down in this direction,

  • It's not going to happen.

  • OK.

  • Last chance.

  • Arguably worse.

  • Lift force in wrong direction,

  • Too much angular momentum.

  • Very sinky landing.

BEN AARON: In the 1800s, as engineers searched for cost

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B2 kite angular momentum angular momentum lift roll

The Dangers of Kite Surfing | Science of Stupid: Ridiculous Fails

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    林宜悉 posted on 2020/11/13
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