Author Topic: What tail size should I use? How much should it weigh?  (Read 11386 times)

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WindJuggler

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What tail size should I use? How much should it weigh?
« on: June 12, 2010, 04:17:16 PM »
The size of the tail on the windmill determines how fast the windmill seeks the wind direction.

A general rule of thumb for the length of the tail boom is 60% of the length of the windmill diameter.
The weight of the tail determines the cutout or furling speed of the windmill. The more weight, the longer it will stay in the wind.

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« Last Edit: June 21, 2010, 08:07:18 PM by wooferhound »
Wim

coldspot

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Re: What tail size should I use? How much should it weigh?
« Reply #1 on: June 19, 2010, 02:41:18 PM »
Size ?
General rule of thumb-
20% of the rotor size
$0.02

windy

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Re: What tail size should I use? How much should it weigh?
« Reply #2 on: June 20, 2010, 02:14:42 PM »
Is 20% the correct figure? For my 16 foot diameter blade, that only comes up to 3.4 square feet. That seems quite small. Any comments?

windy

DanG

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Re: What tail size should I use? How much should it weigh?
« Reply #3 on: June 20, 2010, 03:52:49 PM »
check your math - 16' diameter = 201.06193 square feet area....

windy

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Re: What tail size should I use? How much should it weigh?
« Reply #4 on: June 20, 2010, 08:43:32 PM »
 I was taking rotor size as the diameter.  I tried 20% of the 16 foot rotor sweep area which comes out to 40 square feet but that seems quite large. That would be a 4'x10' sheet. I looked at Dan B's book, Homebrew Wind Power and he states that "The tail vane should cover at least 5 percent of the swept area of the blade for this design". That was for a 10 foot diameter blade. Five percent of the 16 foot sweep area is 10 square feet. Correct me if I am wrong.

windy

DanG

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Re: What tail size should I use? How much should it weigh?
« Reply #5 on: June 20, 2010, 09:37:58 PM »
I'm with you 100%, mixed terminology injected in postings, just asking everyone to check their math...

My 10' Dans built swept area is 77sqft with 5.85sqft vane for 7.75%.

SparWeb

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Re: What tail size should I use? How much should it weigh?
« Reply #6 on: June 21, 2010, 12:32:19 PM »
8-foot rotor makes 50 square feet swept area.  The tail has 3 square feet of area, so the ratio is 6%.  Furls okay.
Note that the offset of the rotor axis from the tower axis is 8 inches, which is proportionally more than normal.
Tail size is worthy of a FAQ, but a worthy answer would be one that is simple to apply and works 99% of the time (90%?). 
That answer isn't out there at the moment, and I don't have one to offer, either.  Goodness, I've tried.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

System spec: 135w BP multicrystalline panels, regulated by Xantrex C40, DIY 8ft diameter wind turbine, regulated by Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024