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  • Short rib questions

    Hello all, I recently finished my master rib form. Thank you to all who have asked questions, answered and provided videos, tips and tooling info. It is already a life saver. I have a quick couple questions that may have already been answered regarding the short ribs for aft of the fuel tank before I make the rest of my cutting and forming blocks. I didn't initially see a flange dimension but assume the note for all rib flanges being 9/16" would be the same for the short ribs? Furthermore, there appears to be an additional hole, looks like it should be about 7/8", below the oblong lightening hole. Is that only in the short rib, or should that exist at the tail end of all center ribs?

    Happy holidays,
    Erik

  • #2
    I will have to look at the plans when I get home to confirm, but if memory serves, the hole in the short ribs is for the flap torque tube and only one of the full size center ribs requires it. Without the plans in front of me, I'd be guessing at the flange size.
    Todd Weld
    Plans #1515B
    www.facebook.com/N729TW/

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    • #3
      The patrol shows similar callouts as you describe. Ribs 1-5, which include the short ribs but also the full size ribs inboard of the flap drive. So for the patrol (be sure to verify for 4 place...)
      -9/16" flange is correct
      -One hole towards the rear bottom portion to accommodate the flap torque tube.
      -Modified lightening hole D for these ribs which have the torque tube pass thru.
      -One hole towards the rear top to accommodate the aileron cable.

      There's a lot of detail to keep track of!
      Mark
      Scratch building Patrol #275
      Hood River, OR

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      • #4
        I can verify that it’s through ribs 1-5. You can see on drawing 2B that the flap tube goes through those. I believe the aileron cable angled down, so you do only have that through the .032 ribs, then it travels through lightening holes, but I could be off and that’s need to be verified (I’ve seen other wings that had it that way, but that doesn’t mean that was right...). Hopefully that helps!
        John Wiltberger
        Model B - #1544B
        Maricopa, AZ

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        • #5
          I see where I misinterpreted the plans there. There are three separate drawings. The short rib, the aileron tube inner ribs and the rest outboard of that. I was thinking I only saw two for some reason. Thanks for the clarifications. If I might ask another question, rib spacing and how to properly read the plans. Are most folks measuring the plans add multiplying by the scale factor for rib placement? (Looking at the flap and aileron drawings). And do the lines represent the rivet line or the placement of the rib web?

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          • #6
            The ribs are spaced 12.25 typ. Which means unless otherwise noted that is the spacing. There is a dimension for a couple of the ribs and then you can go from there.

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            • #7
              Thank you. I'm probably rushing my thought process and missing some of these basic details that are right in front of me. I have about two weeks until I deploy for half a year and am really trying to get some work done on that short time. Thank you all for the tips and assistance.

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              • #8
                I’ve found putting this together in SolidWorks makes it easier to work out all the details and seeing where research may be needed. We get the educational version for free with an EAA membership and they have some decent tutorials to learn the basics. Might be outside the wheelhouse for some, but definitely helpful if you can take the time
                John Wiltberger
                Model B - #1544B
                Maricopa, AZ

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