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Why are wind turbine blades long and skinny instead of short and fat? - Page 2

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Posted by Gene S. Berkowitz on April 11, 2010, 10:03 pm

The size and shape of the blades is not determined by solely by

*  Wide, fat blades increase the wind load that the tower has to
withstand.  You can't put guy wires on a large wind machine, so
the monopole tower is a trade-off between cost and strength.

* Nobody wants to look at giant lollipop disks on the horizon.  
Wind machine aesthetics has a lot to do with reducing opposition
to them.

* Big disks cast big shadows.  Thin blades cast thin shadows.


Posted by Bob F on April 12, 2010, 12:50 am

Gene S. Berkowitz wrote:

And the concept that wide fat blades are more efficient than narrow blades
because wide fat blades are used in cheapo house fans is ludicrous. Larger
commercial pesestal fans, for instance often use a much narrower blade than the
cheap residential fans.

It is an interesting way to arrive at a conclusion, but hardly a sensible one.

Posted by Energy Guy on April 12, 2010, 3:49 am

Bob F wrote:

You mean like these:






It's a fact that any fan you can find (industrial, commercial, farm,
etc) will have a larger blade-area to swept-area ratio than the large
3-blade wind power plants.

Posted by Daniel who wants to know on April 12, 2010, 4:48 am

Do a Google image search for "drum fan" and look at the blades. Most have 3
long and skinny blades.
http://images.google.com/images?q=drum+fan   BTW only links 1,2, and 4 have
commercial pedestal fans. The other 2 links are fancy residential models.
Drum fans are industrial/commercial.

Posted by Energy Guy on April 12, 2010, 3:39 am

"Gene S. Berkowitz" wrote:

But your premise in that case is that you take an existing tower, with
it's 3 long, skinny blades, and replace them with 3 fat blades.  That
wouldn't really happen.  You scale down the 3 fat blades (they wouldn't
be as long as the typical long, thin blade) and the tower wouldn't need
to be so tall either.

And as mentioned above, the new tower (with it's 3 fat blades) isin't
going to be as tall, so it wouldn't be as visible from a distance.

I would even argue that 3 fat blades turning in the distance wouldn't be
as visually noticable (from a motion or movement pov) as 3 long and thin

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