Work Session 10/12/2011 - Rib Stitching Workshop

Due to a few small, but critical flaws in the covering of the airplane's left wing last weekend, it will need to be recovered. This was the conclusion of our Technical Counselors, Jack Phillips and Terry Gardner, with confirming input from the PolyFiber expert, Jerry Stadtmiller of BIPE Inc. in Andrews, NC. Fortunately, we have plenty of material to do this. The good news is, this provides us with an ideal means to learn how to rib stitch.

We held our first such session on 10/12/2011, which saw a number of BCAC members mastering the starter knot, the modified seine knot and the finishing knot. The images below show the steps taken. Note that in the actual rib stitching of our wings, the fabric will have first received coats of PolyBrush (pink stuff) and rib tapes will be affixed over the ribs prior to stitching. The next rib-stitching workshop will be held this coming Saturday afternoon. Anyone interested is invited. NOTE - If you have one of our four copies of the PolyFiber guidebook, please bring it back to the shop.

In preparation, please read the PolyFiber handbook (if you have a copy) and study these three short videos from PolyFiber:

http://www.eaavideo.org/video.aspx?v=22167622001
http://www.eaavideo.org/video.aspx?v=22430488001
http://www.eaavideo.org/video.aspx?v=23753223001

You'll see some other videos on fabric covering at this link, see all pages of videos as they are mixed with tube-related videos.
http://www.eaavideo.org/channel.aspx?ch=ch_hints_tubefabric

First, a rib template was made from cardboard, using the steel template that had served to cut the wing ribs. We chose a 2" distance between stitches. These are marked along the upper edge of the template, then straight lines are drawn to the somewhat closer marks along the lower surface of the template.


















Here, Terry transfers the cardboard markings onto the front and back of our flexible aluminum spline. These are used to mark the inboard and outboard ends of chalk lines for the upper and lower wing surfaces.














Joel, Nathan, Mike and Terry discuss the next steps, snapping chalk lines down the span of the wing's upper and lower surfaces at each stitch mark.














The under surface of the wing with snapped chalk lines. We then used the sharp end of the needles to pre-punch a hole on either side of each rib where a chalk line crossed. Special thought was given to internal obstructions, especially the two spars.














Martha and Mike had practiced at home and became tutors for others, along with the step-by-step procedures in the PolyFiber guidebook.


















When followed closely, after a few tries the directions in the PolyFiber manuals make sense.














While Mike pre-punches the holes, Joel drills through the outboard rib reinforcement which would otherwise block the rib stitching.


















Nathan was a quick study. The lamp under the wing really helped in finding the right place to penetrate the fabric.














Here, late-comer Konrad is aided by quick-study Nathan.


















Above and below: With practice done for the evening, we gave some thought to the placement of the new panel using the old one as an example.