These pages will describe the build process.
Since the last update, I've finished the tail hinge and welded it to the wind turbine body. It's welded on at an angle of 45 deg to the rotor plane. The hinge it's self incorporates an angle of 20 deg from vertical to allow the furling mechanism to operate. A basic tail boom has also been fabricated for the test. A tail (piece of plywood) was held on with some molegrips.
I couldn't resist the temptation of seeing the wind turbine doing it's thing in the wind. There's no alternator on there yet. So no output figures. At this stage it's just a bit of fun. I did however fit a cycle computer to the hub, so that I could take some RPM readings. The blades were made by my dad. He was eager to see some turbine action too. They are 900mm long, each. They have no twist and are set at an angle of 5 degrees for the full length. They actually seem to work pretty well considering their basic design. They do seem slow to start though.
Although it's a fairly windy day, the turbine is only about 7 feet from the ground, and the garden is surrounded by a tall hedge and lots of trees. The wind was not a good constant wind, but quite gusty. The wind turbine managed to pick up a couple of decent gusts. The highest RPM count was 380. Not bad considering the wind obstructions and the basic blade design. The turbine should hopefully catch much more wind once it's up on the roof. For now... It's waiting for the magnets to arrive and a bit of paint to put on the tail hinge....
A few days later.............
The magnets have arrived, YAY.... And I've painted the tail hinge. I cut a new spacing jig to accomodate the new larger magnets. I had decided a while back to make the alternator, 8 poles (16 magnets) and 6 coils, but have since changed my mind again, back to the original plan of 12 poles and 9 coils. I figured the more magnets in there the better. It will produce more power than the 8 pole setup, but not as much as the 50% increase in magnets would suggest. So efficiency is lower, but overall output will be higher, and output is what we are interested in.
Before I get into building and testing the alternator, I want to make the yaw bearing, so that the wind turbine would sit nice and straight on it's pole and turn freely to face the wind. I got lucky and found a thrust bearing that exactly fitted the pole diameter that the machine will sit on, so I machined up a clamp on the CNC router for the bearing to sit on, and also a bushing ring to make the mounting pole and inner strut tube diameter a nice close fit. You should get the idea from the pictures on the right. There is a second bushing ring, not shown in the pictures, that fits up inside the top of the strut tube. This does the same job as the bottom ring, but at the top. The bearing and bushing rings will all be covered with grease before final installation. So that's the yaw bearing done. The next page is the start of the alternator building and testing.