Lacing Lower Left Wing and Tips on Rib Lacing

The lower left wing is next to Rib Lace.  The stand was easier to attach to the fittings at the root end by just passing the dowel through the fitting holes, like it was done on the Cessna 140 wing.  I put some pieces of plastic tubing to keep the wing from sliding on the dowel while rotating.

The only real problem is that the 9 degree angle of the ribs makes rotating the wing a little weird, the stand pivot is not parallel to the wing centerline.  If you're not doing a lot of rotating it works well enough.  I should just make a new support piece that fits the wing fittings and with the 9 degree offset.

The reinforcing tapes are on and the stands work OK with the wing tipped like this.

We're ready to rib stitch.

I find it easier to do the stitching sitting in my tall work chair.  You're close to the knot while tying and can easily look under the wing to pass the needle through the holes.

I also find flat (braided) cord get tangled less than round (twisted) cord which wants to twist into a mess all the time, not so with the flat cord.

 We're lacing the fabric to the rib so every knot starts with a loop around the rib.  If you are right handed, like me and as shown in all these pictures, go down on the right side of the rib, around the bottom and back up on the left side.  You should be able to take all these pictures and mirror them left to right and see how to do this if you are left handed.  It works both ways and there is no requirement to do it right handed.

 For the starter knot Pull the needle through leaving about 8" of cord sticking out on the right side.  You need enough to get a good grip to pull the knot tight.  I also leave enough to pull the loose end back down through the wing, we'll get to that.  I've got the needle parked in a hole so I don't have to hold it.

You can start at the leading edge or the trailing edge as well as anywhere you run out of cord long enough to make it easy to pull knots tight.  The old method of knots on top of the wing included a splice knot.  With the hidden knot method just lock your last stitch with a half hitch and start a new piece of cord with a starter stitch.

 The starter stitch is a square knot with a half hitch on each side to lock it.  A square knot will slip without the half hitches.

The Poly-Fiber manual has a simple way to tie a square knot.

Make a "U" shaped loop by folding the free (needle) end back on itself.

Fold the loop over making 2 ears.

Fold the ears down, pass the short end through the ears, and pull it tight.

 If you want to see that this actually makes a square knot you can move the cord around to see it really works.

 Pull the knot almost tight to the rib leaving room to easily pass the ends back through to make half hitches on each side of the knot.  Don't pull them tight yet.

 Pull the square knot tight then tighten each half hitch making sure the knot is tight after tightening each hitch

 To get rid of the short end use another needle to pass the cord back down through the wing.

Pulling this end through the wing makes it easier to get the knot to slide just below the fabric while pulling the knot to the side of the rib with the free (needle) end of the cord.

Then trim off the excess sticking out the bottom.

 As I'm working I point the curved end of the needle in directions which make it easy to feed the needle from hole to hole.  When hiding the cord under the fabric, from knot to knot, I tip the end up so I can see where it touches the fabric and move the needle forward or aft to get the tip in the hole.

Pull the cord straight out and parallel to the wing surface.  Pulling the thread up or to the side can cause it to tear the fabric.  It's fixable just like any small cut but avoid tearing the fabric.

Some times as you are doing the lacing, the knot you just tied ends up setting on top of the cap strip rather than down through the hole.  Before I pull the cord tight to the next stitch hole I leave a loop big enough to grab easily.  Then pull the cord perpendicular to the rib to move the knot over to the hole.  You can pull to the side here because the knot holds the cord to the rib so it can't tear the fabric.  Then as you pull the cord tight to the next hole it's easy to push the knot down into the hole.

The needle goes back down the same hole it just came out so you can make the loop around the rib.  This time I point the needle tip toward the rib, the same when you come back up the hole on the other side of the rib.  This way the angle of the needle is more nearly vertical, fore and aft, and as the needle tip touches the rib it goes easily into the hole on the other surface of the wing.

While pushing the needle down and back up around the rib, hold onto the free cord, behind the needle, to naturally keep the fixed end of the cord on the far side of the needle and the free end on your side of the needle.

If you're holding the free end this way it's easy to be sure the needle comes back up with the cord forming a loop around the needle such that the end of the cord from the last stitch is on the side of the needle away from you and the free (needle) end of the cord is on the side toward you.

This makes what Carol, at Poly Fiber, calls an Island with the needle and cord forming her Palm Tree in the island. you can click on her name to link to her video and I have a video at the end of this posting.

You hold the free end of the cord with your hand and use your fingers to form the island into a triangular shape.

The needle goes under the side made by the free end going down into the hole.

The needle is moved forward so the needle can pass under the tight cord from the last stitch.

The needle then passes the palm tree cord on your side and crosses on top of the left side of the triangle.

All of this happens in almost a quick flip of the needle once you get into it.

Now pull on the palm tree cord to pull out all the slack.

As the knot tightens it looks like a figure 8 on it's side.

Once it's tight you see the X of the 8 on top of the needle letting you know it's tied correctly.

As the needle passes through the knot, swap hands to keep the palm tree cord tight as you pull it to the right to finish tightening the knot.

If as you finish tightening it you do it with a quick jerk to the right the knot will usually end up just under the fabric.

The video is about 7 minutes.  The blog software made it rather grainy looking.

I find it takes me about 2 minutes to thread the needle and make the starter stitch and knot.  After that each stitch takes 1 minute.  The last stitch gets locked with a half hitch but it only takes an extra couple seconds to do them.  Based on the stitch spacing, etc. on the Fly Baby I've got 79 Starter knots and 523 Modified Seine knots.  That's about 11 1/2 hours of lacing.

I also start a needle at each rib so when you get near the middle where you can't reach you just keep working your way around the wing pushing a needle through the wing or tying a knot.  With some light on the back side of the wing you can easily look through a knot hole to see where the hole is on the other side of the wing when passing the needle through.

The weather was warm today so I was able to get the first coat of Poly-Brush on the last wing panel and aileron.  I'll be able to finish lacing the wings.