I'm currently flying my fourth generation of blades in my evolution of trial and error. The conditions I'm working in get low to moderate winds with plenty of turbulence and neighbors who are, thankfully, more curious than they are annoyed. I've got a fifth set still in my head that won't be realized until my current motor conversion project is complete. So many projects, so little time.
The first set of blades I made were thrown together to get something mounted on the pole with a newly acquired DC forklift steer motor. I used four 48"x4" flat blades cut from scrap polycarbonate plastic. The blades actually worked fairly well. They started in low winds and didn't flex as bad as I thought they would. The problem was they reflected the sunlight and bounced it all over the neighborhood! A coat of matte paint could have solved that problem, but they were meant to be a temporary set while I worked on my next set of blades so they came down fairly soon.
My next set was an 8' diameter PVC rotor based off of ideas on the board. I think Zubbly put together the plans I ended up using. They worked fine, about as well as my first set but they just didn't "look" right. Once those blades were up I started crafting my next generator.
After my first motor conversion was mounted I went back to the drawing board for my third set of blades - taken straight from Hugh Piggott's turbine handbook. I was a little intimidated starting those blades because he makes it look like a lot of hard work, especially with all the handtools he's known for! His layout is very precise, which is good, but it didn't seem to leave any room for error. Then I happened to find an abrasive wheel for my hand grinder that chewed up wood like a beaver on steroids. I decided to just jump in and learn whatever I could in the process. I could always make another set if I screw it up, right?
All it took was maybe two evenings to complete that set of blades and they were ready to fly the next weekend. All I had to do was wait for the wind. Then I had to wait for more wind. Then just a little more. It didn't take long to realize these blades weren't going to work with what little wind I get in my conditions. Carved from 4 foot lengths of 2x6's, they looked huge on my little 16' tower. I'm sure they'd look less massive perched upon a decent sized tower alone in the breeze with good clearance all around - just like in the pictures. But then again I barely have 15' clearance from the nearest utility pole. I suppose Hugh didn't design these blades for my backyard. They would spin great at a steady 20 mph but I don't often see that much clean wind through all the trees so I knew I had to try something different.
I had plenty of time to think of a new design while I waited for enough wind to turn those monster blades. Time for a break. I'll give a description of my current setup with some details to build from when I return.
