Wind turbine (part 2)

So I have been looking on ebay a lot for “permanent magnet motors” to try and find one for my turbine. There are lots on there, but it’s very hard to know whether what I am looking at will be any good for a turbine. This article answers that question:

You need 1 volt per 25 rpm, so just divide the voltage (in DC) by the top rpm and see if that’s 25 or less. If it’s not then it’s no good (unless you want to gear it, which I definitely don’t!).

Let the search continue…

Wind turbine part 1

Today I was walking home from work when I saw an old sailing mast that our hoarding neighbour wants to get rid of, and I had an idea. Why not build a wind turbine. The internet is going to show me how, but I thought I’d put my own process here in the hope that it might help someone else.

The best resource I found pretty quickly was this:

That seems like a good place to start, but first I have some questions. What is the difference between a horizontal and a vertical turbine, and which is better? The first page of this answers this question pretty categorically:

Vertical ones are less efficient. Easy. What next? How many blades should I have? Surely more is better right? Well no:

Ok cool. So I need 3 blades. Right lets go and find some scrap bits of drainpipe….