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antipaganda | 15 years ago
For those who still feel like idiots, here's the post on Autopia that made me a believer:
"Let me get this straight. It is common knowledge that a sailboat can tack at an angle to the wind sufficiently fast to reach a directly downwind point faster than the wind itself. Yes? And yet people actually thought that merely doing this in a straight line would be “impossible”?
Assuming the former is true and commonly accepted, all you have to do is imagine an arbitrarily small (narrow) “zig zag” tacking pattern — which is roughly the equivalent of your “cylinder earth” thought experiment. If the zig-zag is small enough to be contained with in the width of your “boat”, that’s all you need, in principle.
The rest is just engineering (and using a propeller is much better than a zig-zagging mechanical device of some kind). I had never heard of this controversy, and halfway through the article I’m thinking “this is just obvious.”"
http://www.wired.com/autopia/2010/08/ddwfttw/2/
Tacking within the width of the boat is the key, right? Now, think about changing the angle of the sail not by swinging it horizontally back and forth, but by TURNING THE SAIL UPSIDE DOWN. In other words, constantly spin the sail at the correct rate, and it's the same as tacking back and forth; and we already know that you can beat the wind that way.
cma|15 years ago