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question on wing rib count-----

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  • #1

    question on wing rib count-----

    This is going to be a stupid question ( advanced warning of impending blonde moment---)

    The plans say in the text paragraph--- that there are 5 center (the long ones) inner ribs that are .032 and are not flanged. (I have made 10 total so far-)

    In the drawing it shows two riveted back to back as the root rib, then rib #1, then center ribs 2 and 3 are superimposed on the space for the fuel tank---, then 1 or 2 more outboard of the tank space. So---- what happens to the center ribs that show going through the tank space ? Do I build those ribs
    and later be cutting the bottom of them out ? or are they even installed ????

    The text blurb seems to indicate I need 5 thick inboard center ribs on each wing. but on the drawing---- shows that there are 2 at the root, next one forms the inboard tank space, next two appears that you only use part of the rear section between the tank bay and rear spar (???????) -- then moving outboard---another one forms the outboard tank space wall, (that one is labeled #5 ) So If I count those and include the 2 in the tank space I get 6 per side. (12 total) (if I only use the rear portion of ribs 3 and 4 cut from the whole rib )

    The plans never mention where the 2 pieces behind the tank bay come from----- (that run between the rear and false spar)

    There is mention of stiffeners that go on the underside of the top skin in the tank bay--- implying that there is no rib there to shape the skin---

    Can some kind person give me an idea here where I should be going ?

    Thanks
    Tim B.

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  • #2
    Pretty sure you are looking at the skin stiffeners on the underside of the top skin in the fuel tank bays (they are hat-sectioned formers that maintain the upper surface shape) and the stub center ribs behind the false spar that closes the back of that bay.

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    • #3
      You don't say which model, if 4-place, there are hat section stiffeners both on the top skin and on the fuel tank cover, I would think that is true for the other models as well.

      Comment

      • #4
        Yes--- this is a 4 place model B. I looked at the pictures on the web page where they do a factory tour. No center ribs in the tank bay--- as I thought it had to be. But the 2 questions remain---- do they intend you make the little rear stubs out of whole ribs ?

        So----- it looks like if i dont count those 2 "stubs" as ribs---- then I get 5 thick center ribs per wing. 2 at root, one either side of fuel bay and 1 more between bay and root ===== 5 total. Perhaps I answered my own question------ :-) told you it was a blonde question.......
        I am just digging back into resuming work after a year off to move from FL. to TN. My mind is rusty------

        Thank you guys !

        Tim

        Comment

        • #5
          Tim,

          I can't comment on the Model B but the Patrol has a dedicated detail for the short ribs that go behind the fuel tank bay. These short ribs are part of the 5.

          The note for the Patrol ribs states "Total of 24 center ribs, plus 4 short ribs between the false & rear spar, are needed. Ribs 1, 2, 3, 4, 5 are .032...Two .032 ribs with opposing flanges are used to make up root rib"

          So on the Patrol, the first five ribs are thus:

          Rib 1: two .032 ribs back to back
          Rib 2: .032 full length (this is the inboard rib of the tank bay)
          Ribs 3, 4: .032 short ribs
          Rib 5: .032 full length (this is the outboard rib of the tank bay)

          Can you post a photo of the note you're referring to?
          Mark
          Scratch building Patrol #275
          Hood River, OR

          Comment

          • #6
            Originally posted by fairchild1934 View Post
            Yes--- this is a 4 place model B. I looked at the pictures on the web page where they do a factory tour. No center ribs in the tank bay--- as I thought it had to be. But the 2 questions remain---- do they intend you make the little rear stubs out of whole ribs ?

            So----- it looks like if i dont count those 2 "stubs" as ribs---- then I get 5 thick center ribs per wing. 2 at root, one either side of fuel bay and 1 more between bay and root ===== 5 total. Perhaps I answered my own question------ :-) told you it was a blonde question.......
            I am just digging back into resuming work after a year off to move from FL. to TN. My mind is rusty------

            Thank you guys !

            Tim
            I’ve made a separate template for the short ribs. I would assume you could use a whole rib and cut it down but that’s a lot of waste. It’s on drawing drawing #3.

            Comment

            • #7
              Thanks Mark, Scags, Rod and spruce.

              OK --- I see the drawing for the short rib (#3 and #4) I seem to have mistakenly made 5 big center ribs in stead of 4. No harm done. Never know--
              the rivet gun may slip later on :-)---- might need a spare. I see I was just confused that the plans are referring to the short ribs the same as the long ones
              in the text blurb. May have to add an extra steel bushed locating hole in my MDF tooling to be able to locate the baby ribs on the tool. That shouldnt be a problem---
              Thanks for the help---- im probably not good at finding details in these plans---- :-)

              Tim

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