Wing covering, Part 1

Whelp, it took amazing weather, (effectively) weeks of making sure I'd cleared all the to-do items, and a job change for me to make time to tackle covering the wing.  But here we are with the right wing completely covered and preparations for the left wing underway.

This isn't going to be a comprehensive how-to post for covering.  I just shot images of the highlights, mostly for my own recollection if (when!) I do this again, and enough shots of what is now going to be really difficult to inspect.

I ended up adding foam spacers to the compression ribs, as a way to support the lower surface covering.  This trick was not on the drawings (that I saw), but was done by Alan of the Yando Goat (IIRC).  Making these foam spacers is easy enough by hand, though I knocked them out on the CNC router.  The outer surface that touches covering has a layer of fiberglass tape and has all edges sanded smooth.  The spacer height roughly matches the bolt brackets or leading/trailing edge tubes as appropriate.  Here is a close-up:

Starting the covering with the first drape looks fairly sad and wrinkly.  This first pull showed the areas where I'd need to trim for eyebolts or brackets to pass through.  The root was quickly identifiable as a tough area.

Using the Stewart Systems process, I worked around the leading and trailing edges.  The root area definitely was the toughest.  I wrapped the covering around from the bottom (no extra spacer rib) to the upper tube of the root rib.  This gives continuity, but means the wing attachment brackets are a massive pain.  Instead of going over those, I ended up trimming the corner on the bottom and leaving those brackets exposed.  This photo is also before I poked holes for the aileron cables, or trimmed the trailing edge fabric.

After a few hours, I had the lower surface ready for shrinking.  It wasn't that terrible if I'm being honest.

And the lower surface after the initial shrink to 250F was looking really good!

I put in several inspection rings, including in places I don't plan to cut open, but now have as an option (e.g. for cable tensioning).  As noted in the Stewart Systems instructional videos, these ring locations are MUCH easier to mark from the inside of the wing after the bottom covering is on, but before the top fabric goes on.

This is a medium shot showing the inspection ring located below the aft aileron cable pulley.  This location should allow me to inspect the pulley and re-tie the cable knot if that is ever needed.

The bottom covering also had some challenging covering areas, such as around the tip handles.  Following someone else's process (Brady Butterfield??), I removed the tip handles, added two slits to the covering, added reinforcement patches, and reinstalled the handles after covering.  This worked rather well, and leaves the whole area with a continuous fabric.

Next up was covering the top of the wing, which was a bit trickier with respect to the curvature, but was overall easier due to fewer protuberances such as bolt heads.  Here is a shot after going around the perimeter for the first time, with only basic wrinkles pulled out.

With further cleanup of the perimeter, the upper surface was ready for the initial tensioning to 250F.  As every online instruction suggested, I started in the middle, and worked to bisect the remaining sections, moving back-and-forth to stay balanced.  Shrinking took maybe 15 minutes and was very satisfying!

Here we are after tensioning!  The lighting and wide-lens makes the sagging between ribs look worse than it actually is.

Finally, I added the reinforcing tapes.  The roll of Ceconite tape was a much heavier cloth, so I ended up cutting four strips of 2 inch wide fabric from the trailing edge cutoff (sooo much cutting with pinking shears).  This reinforcement on the leading edge puts the upper surface fabric in double shear, in addition to its overlap to the lower fabric of three inches.  I thought about doing the same tape job on the trailing edge (I think this is typical), but the fabric overlap is already over three inches there, despite only needing to be overlapped by one inch.

That's where she stands right now --- I'm actually partly through the other wing half already, and will most certainly do an assembly in the back yard once both are completed.

One random note: the wing panels are much more difficult to handle once the covering is on.  I was used to picking up the panel by myself by holding onto the internal structure.  Now, instead, I have to pick it up differently, and that makes the panel seem much heavier and/or more awkward.  It sure seems like this will be a two-person assembly process.

If anyone sees anything questionable about my process or of the structure itself, please, please leave a comment.  Your five minutes of typing just might save my life, or maybe saves me hours of repair work later.