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rmancini
Newbie

Joined: 25/10/2009
Location: United States
Posts: 10

Posted: 10:17pm 01 Nov 2009

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Hello All-
This is my first attempt at a HAWT. The photos show a 3 blade mill - - I've since changed it to 6 blades at 24" long made from 8" sched 40 PVC.
So far there really hasn't been enough wind for a fair test but Ive measured 12.4 VDC during short gusts.
It's a direct drive config. A friend of mine is building a charge controller (since I'm "electronically challenged!")
So far, I've had a lot of fun building this thing. The cost has been minimal since I've machined just about all the components from stock on-hand.
Here in the PAC Northwest, the high winds should start any day nowso I'll be better able to gage what it's capable of.
Rich

Laissez les bons temps rouler

KarlJ

Guru

Joined: 19/05/2008
Location: Australia
Posts: 1178

Posted: 02:13am 02 Nov 2009

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interesting idea for the slip rings..
I like it but not sure how it will last.

Karl

Luck favours the well prepared

rmancini
Newbie

Joined: 25/10/2009
Location: United States
Posts: 10

Posted: 04:07am 02 Nov 2009

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Yeah Karl - I'm wondering that myself.
The rings were plasma cut from an old aluminum street sign, the spring loaded brushes were machined from 6061 aluminum so in theory, they should wear evenly.
I put a "Trail" of di-electric grease in the path of the brushes about 3 months ago and it's still there.
Conductivity is good - - Zero ohms resistance from the motor, through the rings and through about 30 feet of 10 gage wire.
I guess time will tell.
Rich

Laissez les bons temps rouler

Downwind

Guru

Joined: 09/09/2009
Location: Australia
Posts: 2333

Posted: 06:46am 02 Nov 2009

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Hi There,

From my understanding the more blades you have the torque goes up but the rpm goes down.
So with six blades you will have less than half the rpm of 3 blades but double the torque.
You might find your rpm in to low to get out of stall.
If i am wrong on this than someone please correct me.

Pete.

Sometimes it just works

rmancini
Newbie

Joined: 25/10/2009
Location: United States
Posts: 10

Posted: 12:32am 03 Nov 2009

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That's a good point.
When I had the 3 blade config, I couldn't get more that 7 volts due to slow rotation. I then went to the 6 blade but the blades are much shorter. My thoughts were that I effectively reduced the area by shortening the blades so I doubled the number of blades to gain some of that area back. In this config, I've measured 12V.
If I were to go to 3 blades BUT keep them short, will I get more RPMs?

Laissez les bons temps rouler

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