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Thread: Laying out rib stitching (top verses bottom of wing)

  1. #1
    Senior Member LSaupe's Avatar
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    Default Laying out rib stitching (top verses bottom of wing)

    Getting ready to rib stitch and see that I just cant lay out the same distances on the top vice the bottom (as I had hoped), due to the significant differences in arc length. How do you guys typically hadle this? At first pass I am thinking about laying out the bottom and them thansferring the top holes by putting a pointer through the bottom holes with a device to keep the pointer normal to the bottom surface.

    How is this typically accomplished?

  2. #2
    Super Moderator Av8r3400's Avatar
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    Default Re: Laying out rib stitching (top verses bottom of wing)

    My method: from the butt rib face mark your top surface (important one) use a vertical level (wing flat) or horizontal level (wing vertical) and mark bottom surface. Then measure bottom surface marks from trailing edge and transfer to tip end of wing. Snap chalk lines. Done.

    Learned this from a Poly Fiber seminar.
    Av8r3400
    Kitfox Model IV
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  3. #3
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    Default Re: Laying out rib stitching (top verses bottom of wing)

    good tip.

    I am wondering if it matters whether the lacing goes vertically through the wing. Would an angled lacing hurt anything?

  4. #4

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    Default Re: Laying out rib stitching (top verses bottom of wing)

    see pages 33 and 34 of the Poly-Fiber manual " how to cover an aircraft".
    In essence you make a cardboard pattern of the shape of the wing, lay out
    the stitches on the bottom, and transfer them to the top perpendicular to the cord, and use the pattern to mark top and bottom on each end of wing, then snap chalk lines. Kitfox sells the manuals at a very competitive price.

  5. #5
    Senior Member ken nougaret's Avatar
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    Default Re: Laying out rib stitching (top verses bottom of wing)

    Like Neville said, make cardboard template of rib, mark your parellel vertical lines on it, transfer marks to each end of wing, snap chalk line.

  6. #6
    Senior Member jiott's Avatar
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    Default Re: Laying out rib stitching (top verses bottom of wing)

    My method: Essentially the same as Av8tr3400 but I transferred the marks from the butt rib to two (for top & bottom) 1" wide strips of flexible fiberglass trimmed from the wingtips, flush with the trailing edge. Then transferred the marks from these strips to each rib-eliminated the need to snap chalk lines. One caution-when you first lay out the spacing marks you must check that your stitching will miss all internal structure, cross bracing, etc. It takes some fudging and adjusting of the spacing, but it is possible to find a layout that works for all ribs.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  7. #7
    Senior Member LSaupe's Avatar
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    Default Re: Laying out rib stitching (top verses bottom of wing)

    Perfect. Many thanks guys.

  8. #8
    kitfoxnick's Avatar
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    Default Re: Laying out rib stitching (top verses bottom of wing)

    I use a piece of elastic that you get from a fabric store. Cut it to the bottom cord then stretch it for the top.
    Nick W
    IV 1200
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  9. #9
    BobRS's Avatar
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    Default Re: Laying out rib stitching (top verses bottom of wing)

    Make a cardboard template and draw vertical lines at the recommended front to back spacing. If you cut out the spar holes you just need one and place it on each end of the wing and make pencil marks (top and bottom). Use a chalk line across the wing top and bottom.
    http://www.teamkitfox.com/Forums/att...1&d=1425628077

    http://www.teamkitfox.com/Forums/att...1&d=1425628077


    This is what the rib stitching will look like when you're done. Buy the poly fiber movie if you haven't, and run it in slow motion to see how to stitch. It's really fun after the 1st 20 or so knots, but your fingers get cut with the waxed nylon when tightening the twine.

    BobRS, Albuquerque NM
    SS7, Rotax 914, almost done!
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    Senior Member HighWing's Avatar
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    Default Re: Laying out rib stitching (top verses bottom of wing)

    Just curious, There is a recommended riblace spacing depending on typical airspeeds and whether or not the fabric is in the prop wash. My understanding is that the tendency to lift off the rib is greater on top where the higher speed air creates the lift. I wonder why the beginning spacing is done on the bottom which would increase the spacing a tad bit on the top. Wouldn't it be preferable to do the layout spacing on top and then make the adjustment on the bottom spacing?
    Lowell Fitt
    Goodyear, AZ


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