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This is a really good explanation I saw a while back of the phenomenon. This debunker (a PhD @ Google) originally said it was impossible - and then realized he

by smanek 16y ago

This is a really good explanation I saw a while back of the phenomenon. This debunker (a PhD @ Google) originally said it was impossible - and then realized he was wrong. Initial claim of impossibility: http://scienceblogs.com/goodmath/2008/12/windpowered_perpetual_motion.php http://scienceblogs.com/goodmath/2008/12/windpowered_perpetu... Recognition of truth ;-): http://scienceblogs.com/goodmath/2008/12/the_real_bozo_attempts_to_aton.php http://scienceblogs.com/goodmath/2008/12/the_real_bozo_attem...

stygianguest 16y ago
Thanks! That was far more readable than the original article. I had dismissed the idea for exactly the same reasons as the author, and now understand how I was wrong about it. Glad to have learned something today.
nl 16y ago
Thanks. That's the best explanation I've seen. It took me a long time to persuade myself that it wasn't a hoax, and when I submitted it here I was half expecting someone to point out some flaw.
Marticus 16y ago
What makes me really happy is that when me and my roommate discussed how this worked months ago, we eventually explained it exactly as he did in less-equation-y form. Moral of the story: I don't fail completely at fluid dynamics.
jedbrown 16y ago
I prefer Terry Tao's explanation (http://terrytao.wordpress.com/2009/03/23/sailing-into-the-wind-or-faster-than-the-wind/ http://terrytao.wordpress.com/2009/03/23/sailing-into-the-wi...), carry the result over to land by replacing the "keel" with gears.
- Jun8 16y ago
  As always, Tao's explanation is crystal clear, takes you from the absolute basic layman level to as deep as you want to go.
dspeyer 16y ago
Thank you! That link is much clearer than the article. One thing wasn't in it that I found cleared this up a lot, though: with a normal sail, wind that gets caught still moves forward relative to the ground, just slower. With this thing, it winds up going backwards. That supplies the extra needed momentum.

by smanek 16y ago

stygianguest 16y ago

Thanks! That was far more readable than the original article. I had dismissed the idea for exactly the same reasons as the author, and now understand how I was wrong about it. Glad to have learned something today.

nl 16y ago

Thanks. That's the best explanation I've seen. It took me a long time to persuade myself that it wasn't a hoax, and when I submitted it here I was half expecting someone to point out some flaw.

Marticus 16y ago

What makes me really happy is that when me and my roommate discussed how this worked months ago, we eventually explained it exactly as he did in less-equation-y form. Moral of the story: I don't fail completely at fluid dynamics.

jedbrown 16y ago

I prefer Terry Tao's explanation (http://terrytao.wordpress.com/2009/03/23/sailing-into-the-wind-or-faster-than-the-wind/ http://terrytao.wordpress.com/2009/03/23/sailing-into-the-wi...), carry the result over to land by replacing the "keel" with gears.

Jun8 16y ago
As always, Tao's explanation is crystal clear, takes you from the absolute basic layman level to as deep as you want to go.

dspeyer 16y ago

Thank you! That link is much clearer than the article. One thing wasn't in it that I found cleared this up a lot, though: with a normal sail, wind that gets caught still moves forward relative to the ground, just slower. With this thing, it winds up going backwards. That supplies the extra needed momentum.