Finally in the air! What a relief to have the windmill back together and running "on schedule".
Here's my data-logger screen (PICLOG: www.thebackshed.com) showing a 20kph wind giving me about 200 watts. The wind picked up Saturday afternoon and I had it logging for 2 hours when I took the photo. For the two hours you can seen 450 W-hr collected. Not bad but it could have been more. The tail was too light, and furling in the 30 kph gusts! I lowered the tower again on Sunday, added weight, and sent it back up. That was also an opportunity to add protective tape to the leading edges of the blades (oops forgot).
This wind turbine replaces the one destroyed in an accident in April. I'd already collected this 3-phase motor for another conversion, but it was supposed to be in addition to the old GE motor conversion, my first wind turbine. With the destruction of the GE, I had to get started on this motor conversion as a replacement .
The conversion process required scavenging the magnets from the GE. There is enough room on the rotor of this one to use the same number of mags. That offered the promise that this conversion would produce roughly the same amount of power as the GE, too. Some simple bench tests showed that this was likely to be so.
The blades were damaged in the crash, too, and I decided to make new ones using the one survivor as a template instead of trying to start a new design all over again. After laminating together a set of boards, I carved two down using the old third as a guide. There was one drawback to doing this. The old blades ended up weighing less than the 2 new ones, due to its age and dryness. Balancing the blades became a tricky question because I would either need a pound of steel counterbalance or have to "tweak" the heavy ones. In the end I discovered a way to adjust the heavy blades and just get them into balance. I did so by weighing each blade and finding its center of gravity. For the blades with more weight near the tip, I shaved them just a little at the tip to remove that weight. It took a lot of repeated shave-check-shave-again to get it right. Now I have a well balanced set of blades with no counterweight to cause dynamic imbalance. Now that it's up and turning, I can see the benefit already. There is less vibration to feel when I hold on to the tower.
Fortunately, much of the tower and parts from the old wind turbine mount survived the accident. I didn't have to build a new generator mount or tail arm. To bring the tower back into service, I installed a winch for raising and lowering it. Using the winch makes the process of raising slower, but it affords more opportunity to stop, check on things, and to notice tangled cables. This happened during one raising with the winch already, so it's already proven its worth. The winch itself is a worm-gear winch, and it holds the tower in any position with no little pawls or free-spooling levers to get bumped. Instead of hand-cranking the winch, I have an eye-bolt that I chuck into the power drill, and use the drill to turn the winch much faster than I can by hand.
