old wisper 1000 revived

Discussion in 'Post Your Photos' started by fixitguy, Feb 28, 2011.

  1. fixitguy

    fixitguy WindyNation Engineer

    sorry Timber but im not grasping what your saying.yes the tail boom is directly inline with yaw bearings.looking at the picrure view your saying move the tail pivot off center twards the the PMA? please explain.
     
  2. timber

    timber WindyNation Engineer

    It's a tough one to explain but the following sketch by one of the guys at Otherpower might help.

    [attachment=0:2iwgvwbi]Otherpower.jpg[/attachment:2iwgvwbi]

    This sketch shows the turbine in full furl position but remember, it's the turbine that furls, not the tail.
    The tail tends to remain in the direction that the wind is going, in high wind, the turbine rotates around the yaw toward the tail.

    Note how the tail pivot axis is skewed 5 degrees to counteract some the rotation of the turbine around the yaw.
    The skew helps keep the turbine facing directly into the wind during normal operation (while not furling).

    In other words, if you didn't have a tail, the turbine would tend to rotate counter-clockwise around the yaw bearing until the blades were parallel with the wind direction.
    Adding a tail straight back will help but the turbine will still always tend to rotate some in a counter-clockwise direction due to the yaw being offset.
    By making the tail skew 5 degrees of so to the opposite side from the yaw bearing you get a balance to the tendency of the turbine to rotate counter-clockwise.

    Hope this helps,

    Dave
     

    Attached Files:

  3. timber

    timber WindyNation Engineer

    Actually, the pic shows a 10 degree offset during normal operation (sketch on left).
    I said 5 degrees above but meant 10.
    The actual number of degrees will vary, depending on how far the yaw is offset from the turbine.
    Small yaw offset, less degrees of skew, large yaw offset more degrees of skew.
    Your offset looks to a few inches, I would guess a 5-8 degree skew might work best to keep your turbine directly into the wind during normal operation.

    Dave
     
  4. timber

    timber WindyNation Engineer

    My thought is that skewing the tail will help prevent premature furling as well as keep the blades directly into the wind to get the best turbine output during normal operation. Sorry for so many posts here, just trying to explain why I would suggest this.

    I think if you look at the turbine from a bird's eye view, you can see why a skewed tail will help.

    Dave
     
  5. fixitguy

    fixitguy WindyNation Engineer

    now i see the big picture thanks Dave.i almost put the new weldment in the scrapbin and was gonna make a new one with an adjustable tailboom.but then i thought why not just put a bend in the tailboom instead to make the offset.:) got it flying today using the weldment with the slipring and no problems so far.except for the baby breath wind today.sunday's wind is sapossed to gust to 25MPH.i'll know more then.
     
  6. timber

    timber WindyNation Engineer

    Bending, good plan!
     
  7. fixitguy

    fixitguy WindyNation Engineer

    seems to be tracking perfect in 6MPH winds.
    [attachment=1:2g77m2tg]slipring.jpg[/attachment:2g77m2tg]
    [attachment=0:2g77m2tg]5.8mph.jpg[/attachment:2g77m2tg]
     

    Attached Files:

  8. timber

    timber WindyNation Engineer

    Good job Fixitguy, let us know how it does in higher winds and furl when that happens.
    Looks like even in low winds you get some current.

    Dave
     
  9. fixitguy

    fixitguy WindyNation Engineer

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