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Author Topic: Blade offset  (Read 1052 times)

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VW cat

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Blade offset
« on: January 10, 2005, 12:39:09 PM »
What is the rule of thumb for offsetting the blade to get it to furl? I'm thinking of using the 10'laminated 4 blade design shown recently in my first attempt. Maybe this type of blade will never overspeed anyway?? Thanks in advance.
« Last Edit: January 10, 2005, 12:39:09 PM by (unknown) »
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Flux

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Re: Blade offset
« Reply #1 on: January 10, 2005, 11:50:12 AM »
Normally about 4% of rotor diameter.  I am not sure what your blade is, if it is higher solidity you may get away with a bit less, but stick to 4% and be safe even if it needs a bigger tail.


Flux

« Last Edit: January 10, 2005, 11:50:12 AM by Flux »
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picmacmillan

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Re: Blade offset
« Reply #2 on: January 10, 2005, 12:50:30 PM »
question for vwcat, with 4-blades on your first genny, did you get good power or no?...i was told 4 blades may not work well for various reasons , just wondering?....pickster
« Last Edit: January 10, 2005, 12:50:30 PM by picmacmillan »
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VW cat

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Re: Blade offset
« Reply #3 on: January 10, 2005, 01:08:36 PM »
Does it matter which side is offset compared to blade rotation?


I can't seem to find it on a search. I'm like to build a blade using 7 spruce 1"x4",actually 14 in this case, because it looked interesting and I wanted something that would catch a slow wind. Not sure if the knots are a bad thing..  

« Last Edit: January 10, 2005, 01:08:36 PM by VW cat »
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Flux

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Re: Blade offset
« Reply #4 on: January 10, 2005, 02:07:38 PM »
Doesn't really matter which side you offset it.


There may be some case for choosing the direction so that when it furls the gyroscopic force brings the bottom of the blade forward so there is less chance of a tower strike, but it is not a good idea to have so little clearance that this becomes an issue.


Flux

« Last Edit: January 10, 2005, 02:07:38 PM by Flux »
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VW cat

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Re: Blade offset
« Reply #5 on: January 10, 2005, 06:10:06 PM »
This is my first attempt at a windmill. I read the July 29 e-mail in this section and want to try making that 4-blade unit that was used in Finland.I know so little about blades that were having trouble figuring out which way it is supposed to turn. That's  not to good. But I spent 4 months making an interesting tower, I will post a pic if anyone's curious. Having fun.  
« Last Edit: January 10, 2005, 06:10:06 PM by VW cat »
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Walt

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Re: Blade offset
« Reply #6 on: January 10, 2005, 09:02:20 PM »
VA


Never any need to ask if we would like to see pictures, we all like to see what others are doing.


Walt

« Last Edit: January 10, 2005, 09:02:20 PM by Walt »
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