rear wing channel work and nose rib symmetry

Yet another delayed update on my blog.  December was real busy with work (back on temporary assignment in the tech side, Monday to Friday) and the Christmas season.  I didn't get the chance to post any updates - but things are coming along nicely.

I clecoed the main wing ribs to the spar, in preparation for mounting the rear wing channel.

Finger clamped the rear channel into place - very pleased with how it fits on the ribs.  The ribs do have slight upward taper towards the rear, so I propped up the rear channel on shims and made sure everything was perfectly level and square.

I didn't get a bunch of pictures of the rear channel root doubler.  It's made from 0.125 aluminum plate and sits inside the rear channel at the wing root end.  The root rib (on the right) actually attaches to the channel slightly outboard from the inboard end of the channel and on top of the doubler.  I had a real hard time getting the rear channel to line up perpendicular with the main wing spar and ribs working outboard to the tip.  Turns out the rear flange of the first full rib (shown on the left) mounts to the rear channel between the doubler and channel.  It doesn't sound like much, but makes a huge difference the further outboard you go.  The angled root rib allows for the difference in thickness of the doubler.

Brenda invested in a CriCut Maker machine for herself for Christmas.  The machine is a plotter/cutter for home crafters/makers.  It's really cool; it prints, it cuts, it can emboss.  Check it out here:

https://cricut.com/en_us/cricut-maker​

I got my first lesson in how to use it.  Essentially you upload .SVG (simple vector graphics) to the proprietary software, modify as you wish and let the Maker machine create your items.  It's real simple.

I chose some public domain SVG files of some logos for Ron's airplane and used the Maker to cut them out of basic construction paper.  I was amazed at how well it cut them out.  It can cut adhesive backed vinyl too among many other materials.  This will be AMAZING for doing custom graphics and registration letters for our airplanes!  I already have some ideas about other uses to, including cockpit panel overlays - carbon fibre vinyl anyone?  So cool :)

Sometimes, I'm like a kid in a candy store.  Anyhow, back to the build (focus Jason... focus)...

I noticed a discrepancy in my plans.  The overall picture of the wing skin rivets show A5 rivets along the rear channel from root to tip (top of red arrows), but the side view shows A4 in the rear channel (bottom of red arrows).  A head scratcher....

Here is where the internet is handy.  I posted the question to the Zenith Builders Group on Facebook and with a few minutes had a better idea what should be happening here (thanks Skip Rudy for the picture below).  I further clarified this with Roger at Zenith, he advised me A5 to station 2040, then A4 out to the tip, or just A5 all the way out.

With the rear channel and rib attachment points pilot drilled to A3 hole size, I took the rear channel back off the wing assembly and drilled the top holes along the length.  I was so pleased with my progress.... until....

....I remembered that I should have left the top holes at A3.  In my mind I had the answer, these are supposed to be A5.... eventually :(  This will make drilling the holes in the skin more time consuming, but not a huge deal.    At least I know they are correct.

Next task is to start adding the nose ribs to the spar.  This is done by back drilling from the rear of the spar into the nose rib using the pilot holes drilled for the main ribs.  When brought up to A5 size, these holes will be the connection between the nose rib and main rib, with the spar web in between.

All the nose ribs in position on the spar, perfectly level with the top and bottom spar caps.

Had to make some small adjustments on nose rib number 5 in order to be clear from the forward facing spar web doubler flange.  This doesn't affect any structure, but make the nose rib fit proper (picture just after the cut was made to the flange, prior to debur): 

Nose rib 5 now fits where it should:

With the nose ribs in place on the pilot holes, it's time to make the slat attachment skin support angles.  It starts with a piece of standard L.  Five points are measured out according to the build instructions, then drilled out to A5 size:

Notches are cut to the edges of the holes with snips, then everything is deburred with sandpaper and small round files.  This angle can now be bent to form a rounded support for the nose skin.

Slat attach brackets are next.  I scribed some Sharpie lines 10mm from the edges.  Where they intersect is the attach holes where the slats will attach.

I stacked all four needed for the right wing, clamped them together and pilot dilled them to A3.  Final holes will be drilled when the slats are attached to the wings.

I didn't capture in pictures how I got the slat attach bracket and skin support angle positioned on the first nose rib, but I used the same thinking as I did with the slats, seen on a previous blog post here​ 

It turned out very well.  This should go a long way to making the slats equal, straight and easy to install when the time comes.

Attachment in place, waiting on others to be completed (I'll likely use this one as the template for the rest).  Will need to come off for debur and prime before final rivets.  I might leave the rivets until the nose skins are cut and fit.

It's really starting to look like a wing with each passing shop session.

I've placed an order for more 020 aluminum as I am just about ready to skin this wing.  Also need to order some Tefzel wire for the nav/strobe/landing lights and some plumbing pieces for the fuel system. So much to think of!

When a build like this all seems overwhelming (and it sometimes does - trust me), it pays to stop and admire the work being done.  I sat on a stool for a quick drink of water and couldn't help notice the symmetry of the lightning holes in the nose ribs when looking in from the tip to the root.  I can't believe it was over 3 years ago that I cut these rear and nose ribs out and debured the blanks.  Unreal!

Thanks for continuing to follow along on my journey.  Your support means a lot to me.​