Monday, July 14, 2008

Vertical Axis Windmil - Materials problems

I've been trying to do preliminary design work on a windmill as a for-fun project. That is, besides the fact that I've got a lot going on around the house fixup-wise, I thought it would be a fun build.

So, basic decision #1:
Question: propeller or vertical axis wind turbine?
Answer: Unequivocally, I'm going with VAWT:
- very tight suburban location with high trees nearby
- aesthetics important;
- chaotic winds are typical
- simple build is better, this is practice.

Decision #2: Surface area available to wind?
Answer: Probably maximum of 1 to 3 square meters.

Decision #3: Type of turbine?
no answer yet. I found it's very hard to buy squirrel cage / blower fans as a one-off. Everyone wants to sell me 500 of them at once, for lots of money.

I called a company in Canada and found they were already going to be making some for another customer and would just extend the production run for me. The price was about $120 for a crossflow blower fan, which is a cylinder 30 inches tall by 8 inches diameter with the outside serrated and each tab bent at an angle (google 'crossflow blower' to find an example).

That's 240 square inches of wind-face for $120 = about $0.50 per square inch. This might be a great solution for someone, but I'm too cheap for this. This is a for-fun project and I'm budgeting about $200 for the whole thing. Since I'd need about 10 of them to get my surface area, I'd be 5x my budget and still without any other major components. Plus, I'd have to wait a couple of months since I'm tacked onto another order, but I understood that.

The lady at this company was very nice, though, and kind to speak with me given I'm a random person to call her and ask such a wierd question. If you're interested, the company name is

I'll have to think more about how to do this more inexpensively. I'm thinking I'd like something like a savonius rotor, since it's cheap to make. I just put out the call to my mother and her church group to start collecting a bunch of extra-large V-8 juice or grapefruit juice cans (the 6-inch diameter fans). I know that'll be cheaper, but it's going to be a more complex build, and I'm going to be fighting complexity this whole time.
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