I was watching mythbustrers last night and they were attempting to debunk the old cartoon myth about blowing your own sail via fan. While watching them try to prove this myth I felt confident that they would never move. Any sailor knows a little about physics and the law that states for every action there is an equal and opposite reaction. However with a large enough fan and sail they were able to propel a flat bottom boat forward.
Their conclusion was that with a large enough sail area and enogh air movement form the fan the sail would not catch all of the air and force some of the air back, which would in turn propel the boat forward.
I don't think they defied the laws of physics, but created a scenario that allowed for the sail to propel the boat. MAssive fan/sail for the boat size.
Did anyone see this or have any other thoughts on the topic?
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Griff
Hobie 16
Tuscaloosa, Alabama
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Mythbusters blew their own sail
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Posted: May 12, 2011 - 10:07 AM
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Posted: May 12, 2011 - 11:54 AM
Way too much time on your hands! Pete
Edited by pbegle on May 12, 2011 - 11:55 AM. -
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Posted: May 12, 2011 - 12:15 PM
Pete
Who are you telling! I know I know! Good excuse though, I just graduated and am on the job search so I gotta occupy myself somehow.
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Griff
Hobie 16
Tuscaloosa, Alabama
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Posted: May 12, 2011 - 12:25 PM
I watched it with the same smug assurance that they were wasting an episode of my favorite show. I hate it when they spend time on something that is just plain stupid and anyone who can think should know better. (Prime example is the "theory" that an airplane wouldn't be able to take off from a treadmill)
This one was a surprise but the result was obvious once it was done. By using a really big fan against a curved surface (square sail) they simply produced a really inefficient ducted fan which produced enough thrust in the right direction to propel their boat at 3 mph.
Loved being surprised.
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Damon Linkous
1992 Hobie 18
Memphis, TN
How To Create Your Signature
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Posted: May 12, 2011 - 12:36 PM
Isn't the prop on a plane a 'really big fan'? And aren't the wings, sails? Seems to me if a plane can take off from a treadmill then a sailboat can blow itself. Although I think it would be much more fun to have someone else do the blowing.
Edited by Wolfman on May 12, 2011 - 12:37 PM.
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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Posted: May 12, 2011 - 01:23 PM
Why wouldn't it have worked. You guys think way too much. If you put enough typewriters in a room full of monkeys one of them is bound to spell King Lear.
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Nacra 5.2
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Posted: May 12, 2011 - 05:58 PM
I missed that one but liked the episode where they made a complete sailboat from duct tape! Pretty sweet -
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Posted: May 13, 2011 - 01:15 AM
Golfdad, I agree, but that would be statistically irrelevant compared to all the four letter words they would produce
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Posted: May 13, 2011 - 06:49 AM
When I figure out what that means I will come up with a crushing reply.
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