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Old 04-02-2010, 09:59 PM   #11 (permalink)
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so it's creating a back pressure that the wind is pushing... interesting idea.

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Old 04-02-2010, 10:00 PM   #12 (permalink)
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Learn a little below.

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Old 04-02-2010, 10:08 PM   #13 (permalink)
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The physics of sailing

Quote:
How can boats sail faster than the wind? Lots of boats can---especially the eighteen footer skiffs on Sydney Harbour. Ask a sailor how, and he'll say "These boats are so fast that they make their own wind", which is actually true. Ask a physicist, and she'll say that it's just a question of vectors and relative velocities.

Downwind (diagram at left) is easy. If the wind is 10 kt, and the boat makes 6 kt in the same direction, then the crew feels a wind of 4 kt coming over the stern of the boat. The true wind vw equals the speed of the boat vb plus the relative wind vr (see vectors for more explanation). The equation vw = vb + vr tells us the problem: as the boat speed approaches the wind speed, the relative wind drops towards zero and so there is no force on the sail. So you can't go faster than the wind. When the wind is at an angle, we have to add the arrows representing these velocities (vector addition). Upwind (right), exactly the same equation holds: vw = vb + vr.

The faster that the boat goes, the greater the relative wind, the more force there is on the sails, so the greater the force dragging the boat forwards. So the boat accelerates until the drag from the water balances the forward component of the force from the sails.
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Old 04-02-2010, 10:19 PM   #14 (permalink)
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I thought I already had a post on here, wondering what theory this works on. It certainly is not featured on the huge blog, so until I see independent verification, instead of whining about somebody's official gearing rules, I'll assume somebody is using mundane magic on the video.
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Old 04-02-2010, 10:22 PM   #15 (permalink)
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Tack (sailing) - Wikipedia, the free encyclopedia

The blades are "tacking" all the time.

Another term used is apparent wind.
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Old 04-02-2010, 10:26 PM   #16 (permalink)
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Ryland: "so it's creating a back pressure that the wind is pushing... interesting idea." I had not that it like that - might a good way to think of it.

Bicycle Bob - are you saying you think this is a hoax and what they are claiming is not possible?
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Old 04-10-2010, 02:18 AM   #17 (permalink)
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Just check out BMW Oracle 2to2.5 X wind speed

http://en.wikipedia.org/wiki/USA_17_(yacht)
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Old 04-11-2010, 10:21 AM   #18 (permalink)
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I sure wasn't impressed by the blog or any video I've seen, but there seems to be some relevant theory posted at Sailing faster than the wind - Wikipedia, the free encyclopedia
The key seems to be to have the wheel acting as a brake, feeding power to the prop to let it pull. It is a mind-bender, all right. Even worse than sailing upwind, or building iron ships.
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Old 05-06-2010, 05:01 PM   #19 (permalink)
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visualization

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Old 05-06-2010, 05:15 PM   #20 (permalink)
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...ah, but there's a BIG difference between a "powered" wing and and "powering" wing.

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