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Right Horizontal stabilizer is drooping down

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  • Right Horizontal stabilizer is drooping down

    While checking the tightness of the tailwires before first flight I just noticed that the right horizontal stabilizer is drooping down by about 2.5 degrees. Even if I loosen the tail wires and remove the front support strut and try to push it up manually, the maximum I am able to get it to is to 2.5 degrees off. Wondering if this is going to be a big issue? any comments please?

    Thanks
    Hari

  • #2
    Measured from what datum? Are the wings level first?

    Maybe one strut was made slightly longer to fit your particular stab/fusalage combo. Measure both of them? Swap them side to side? Washer(s) under one strut at the stab?

    Comment


    • haribole
      haribole commented
      Editing a comment
      Measured with the fuselage level perpendicular to the longerons. Measured at the aft tube of the stabilizer where the elevators are attached. I removed the strut and tested by even pulling up the end of the stabilizer to the max. Didn't think of swapping them. can they be?

    • svyolo
      svyolo commented
      Editing a comment
      The kit parts, including the welded steel stuff seems to fit really well. I doubt they could do that completely in a jig. Some of them seem to be individually fit. I think I would try measuring or just swapping the two struts side to side and see ow it comes out.

  • #3
    There are a left and right elevator, and it matters a lot, and you'd never know it looking at the plans. Could be with the horizontal as well, though I can't think of how.

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    • #4
      There are a left and right elevator, and it matters a lot, and you'd never know it looking at the plans.
      What is the consequence of getting them the wrong way around? One thing I found was that the trim tab hinges appear to have been welded in position, and the hinges are not quite symmetrical. So each has a very good fit on its “correct” elevator, but was off-center if placed on the other elevator (i.e. the tab would bind against the elevator), dictating which elevator was which but not very obvious at all. The bell-cranks didn’t seem to have a perfect match either way.
      Nev Bailey
      Christchurch, NZ
      Builders-log
      YouTube

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      • davzLSA
        davzLSA commented
        Editing a comment
        Elevator control horns would be up side down if you swapped the elevators

    • #5
      Originally posted by Nev View Post

      What is the consequence of getting them the wrong way around? One thing I found was that the trim tab hinges appear to have been welded in position, and the hinges are not quite symmetrical. So each has a very good fit on its “correct” elevator, but was off-center if placed on the other elevator (i.e. the tab would bind against the elevator), dictating which elevator was which but not very obvious at all. The bell-cranks didn’t seem to have a perfect match either way.
      The bell crank is not 90 degrees(it's like 96/84 or something) to the elevator and if you put them on backwards, the bellcrank will hit the empennage tube that acts as a travel limit too soon and you'll have half the deflection you need in pitch up and twice what you need in down. This results in running out of elevator for flare at slow airspeeds, especially with much of any flaps in or a forward cg. If you measure the deflection before you go fly you'll catch it if it's wrong.

      The plans don't seem to call for this slight offset, but my kit is that way, as are a couple other kits I had measured when I ran into this issue.
      Last edited by zkelley2; 11-26-2020, 03:31 AM.

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      • #6
        I can’t think of why the H-stab would hang down other than the strut being adjusted too short, the bottom tail wire being adjusted too short, or the stab front attach tube being installed crooked.

        My factory elevators have the hinge lubrication holes facing up. I wanted the holes facing down but ran into the same thing Zack described above plus the elevators just didn’t fit very well.
        Scratch Built 4-place Bearhawk. Continental IO-360, 88” C203 McCauley prop.

        Comment


        • #7
          Originally posted by whee View Post
          I can’t think of why the H-stab would hang down other than the strut being adjusted too short, the bottom tail wire being adjusted too short, or the stab front attach tube being installed crooked.
          Agree - I can't understand the problem.

          Do you mean one elevator is hanging down??? Because yeah I can tell you about that problem

          Comment


          • #8
            Thanks everyone, I was able to get the stabilizer aligned perfectly. Had to loosen the bolt attaching the stabilizer to the cross tube in the fuselage and readjust the bottom and top tailwire to get it to be horizontal.

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