PMA mounting/offset, cont.

Discussion in 'Frame Construction' started by Prairiewind, Dec 21, 2013.

  1. So here are two photos of the furling mount with the HY Energy PMA mounted:



    In addition to the problem of the rotor tracking "left," it went into furl far too early (in the upper teens/low 20s mph) and stayed in furl far too long (when winds were dropping into the 14-16mph range).

    I'm certainly not trying to criticize WN or their excellent mount...I'm obviously doing something experimental on my own, and Josh was very helpful as I put the first construction together. But I sure would like to solve these problems if possible with the WN mount + HY Energy PMA/blades.

    As far as the troubleshooting I've done so far...I replaced the HY Energy 5-blade set with a set of 3 Windy Nation windgrabbers/hub. There is a significant difference in weight between these two blade sets, as well as their design. But even with the Windgrabbers, the turbine still oriented "left" as much as it did with the much heavier HY Energy blades/hub.

    I also a little over 2 lbs of weight out near the rear of the tail (mounted to the spline/rod, not the tail fin itself). That had no effect on furling or the "tracking left" problem.

    Then I added 5 lbs of weight to the tail like this:


    The winds haven't been strong enough to test the furling action of the tail, but this had no effect on the "tracking left" problem.

    So that's where I'm at. It's been suggested to me that what I should try next is 1. re-mounting the PMA to reduce the offset, and 2. building up more surface area on the tail.

    What do you think? Would this be a good mounting position as far as reducing the offset?


    (you can see the original position and mounting holes).

    'Any thoughts/advice greatly appreciated...
  2. TomT

    TomT WindyNation Engineer

    Photo's did not upload right. I can not see them. I do not know about others.
  3. Sorry Tom...are others having the same problem? This forum frustrates me as far as photos. Whenever I try to upload them directly, I always get the error message that the post is "too long"--even if it's just a single photo or screenshot and some text. And yes I'm resizing the photos so they shouldn't be too big. I never have this problem with other forums where I post similar things. So what I ended up having to do is embedding public links to the photos that are stored on a cloud server like Sugarsync or Dropbox. I'll e-mail you the photos directly Tom-

  4. UPDATE: In an effort to overcome the “left-leaning” problem of the “hybrid” build, I removed & remounted the HYE PMA closer to “centered” (reducing the offset; see pics below). The “old” offset was around 2-2.25”; the “new” offset is about ½ that. By the way, the Windy Nation PMA (ie what the WN furling mount was presumably designed around) is listed at 22lbs; the HY-1000 PMA I've mounted weighs in at around 30lbs. The HYE 5-blade/hub set is also considerably heavier than the stock WN 3-blade Windgrabber set. So that greater weight might have been the issue...the original offset might be fine with the lighter WN PMA + blades, but not with the heavier HYE PMA/blade/hub.

    I also replaced the stock WN tail with a “tail” fin consisting of large irrigation pivot sign. 'Not the sexiest build, but I'm just experimenting at this point. It is about twice as heavy as the original WN tail section and looks to be about twice the surface area.

    The result is a big improvement in the "tracking"--there is still maybe a slight "left-lean," but overall the "hybrid" is tracking pretty closely to center-mounted “stock” HY-1000 (videos here and here).

    (Original PMA offset)

    (New PMA offset


    (New PMA offset top view)

    (New "tail") (original WN tail on top for comparison)
  5. UPDATE: some decent output yesterday with pretty modest winds. Note that this 2 kWh is for BOTH turbines running, not just the new "hybrid." Each turbine is running to TWO x SunG 22-60v 1kw GTIs wired in parallel to split the load.

  6. Of course now the $64,000 question is whether I altered the offset/tail size/weight so much that I've thrown off the furling, which was of course the main reason behind this "experiment" in the first place...:confused:

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