35 inch Windgrabbers

Discussion in 'General Questions' started by SL Mauk, Jan 5, 2012.

  1. I have recently rebuilt my home-made wind generator, and I am looking for some advice. I am using a set of the 35 inch windgrabber blades, ( and I am very pleased with them!). I had some fairly high wind for this area a few days ago, 30 mph with gusts to 45, and the system furled properly, like I wanted. Tonight the winds are 8-10 mph, the system is making a little power, but I went out there with a spotlight, and in comparing the direction of the wind generator with the weather station I have on the tower, I can see that I am running app 10-15 degrees out of the wind. The tail is not folding up at this speed, the unit is just not tracking as it should. Would you suggest more area to the tail, or extend the length of the tail? My rotor area is about 30 sq ft, the tail is 40 inches long and the area of the tail is 2.75 sq ft
    Thanks for any suggestions
  2. windyguru

    windyguru WindyNation Expert

    First try some simple things:

    1. Make sure your tower is vertical using a level.

    2. Make sure the center of mass of your wind turbine is close to where the wind turbine attaches to the tower. If the center of mass is off too much, it will prevent the wind turbine from properly tracking.

    3. If both those (1) and (2) are good, try putting two bushings (two flat circular discs) of UHMW in between the top of the tower and the base of the wind turbine. The rotation point will be between the two UHMW discs. This will reduce the coefficient of friction which will allow the wind turbine to track the wind more easily.

    4. Or, put a bolt flange bearing with a locking collar on the base of your wind turbine.

    https://www.surpluscenter.com/sort.asp?search=bolt flange bearing&PAGELEN=20&PageNo=4

    If you follow these steps I think you can fix your tracking problem without having too much work.
  3. I have the tower level, I double-checked it, and the generator sits on a bearing. When I built it I set it up on a stand in my shop and made sure that the weight was reasonably balanced over the pivot point. I climbed the tower, and it seems to swing freely, I am thinking that I just made the tail length a little too short. As soon as the wind gets to about 8MPH, I can see that it is start to furl slightly, and as the breeze increases, the amount of furling increases.
  4. TomT

    TomT WindyNation Engineer

    Could you post a picture of your turbine here?
  5. windyguru

    windyguru WindyNation Expert

    Hi Sam,

    I am confused. In your first post you said that the wind turbine was not tracking the wind properly and that it is pointing approximately 10-15 degrees off target.

    In your second post you said that "As soon as the wind gets to about 8MPH, I can see that it is start to furl slightly, and as the breeze increases, the amount of furling increases." Which one is it: Does the turbine (1) not track the wind properly or (2) is it starting furling in too low of wind speeds?
    Please let me know. Thanks.
  6. Probaly my poor choice of words to describe what is going on. The way I should have described it perhaps is that it is starting to turn out of the wind at wind speeds way lower than it should. Somewhere around the 8-10 mph range it is starting to swing to the side, although the tail section doesn't start to fold up until winds are considerbly higher. I want it to be able to make power, but of course, still protect itself at high winds. And as far as a picture, it would have to wait until the weekend. It is dark by the time I get home nights.
  7. windyguru

    windyguru WindyNation Expert

    OK, got it. I think the fix probably lies in increasing the surface area of the tail. I think the rotational inertia of the blades spinning is overcoming the normal force of the wind pushing on the tail. I recommend somehow doing this test by mounting your turbine on a truck (your friends truck if you do not have one :)). This will allow you to optimize the size and length of the tail for wind tracking and furling in 1-2 hrs instead of taking your turbine on and off the tower multiple times over several weeks.

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