Here's a long update with a lot of pix.
I've been working 70 hours a week on the project trying to get done in time to make it to Oshkosh. Might make it, might not. Since starting the first fabric work on May 19th I have the flaps, ailerons, stabs, elevators, rudder and gear legs all covered, stitched, and taped. Also, as of today, I have the first wing covered, stitched, and about half taped, along with the second wing almost finished covered and will be rib stitching on Saturday. If things go as hoped, I'll be ready to start spraying fill on the 24th. I'm using the Stewart System and so far I'm really liking it. Back in the 80's I used the Ceconite process on a set of T-Craft wings, and then in the 90's I did a Citabria in Stits. I'm using Ceconite fabric this time (Stewarts doesn't make fabric) and will be doing color in their EkoPoly.
Some of you might remember that my thread here started with questions about float fittings. Here's a pic of the Dakota Cub fittings that I welded on, and specifically the Super Fil that I added on either side of the weld to help smooth out the transition. My desire all along is to have the fitting look more like a part of the airplane under the fabric than they typically look. I think this will help a lot, but won't really know until it's all done.
Here's a close up looking down the leading edge tape on one of the ailerons. I find that the unique nature of the EkoBond glue makes it easy getting the tapes on really straight. Some of you might wonder about that pinked edge at the near end of the aileron... I like to finish off the ends with an end cap of fabric that gets cut around the radius and then folded over, but then I cover the fold-over with a tape near the edge so you don't see any fold-overs directly. This also allows me to run that last chord-wise tape in a straight line even if the end rib isn't quite true.
This is a close up of the rudder trailing edge where the fabric overlap glue joint is on the left side. I mixed up some Super Fil and applied a very thin layer with a crisp metal putty knife to help mask that overlap. I don't have a pic handy of the trailing edge tape, but I'm pretty sure once I spray fill on it you won't be able to see that overlap joint thru it.
The gear legs have the 1/2" square tube welded in for the 2,000# gross weight kit (centered on the front and rear tubes) so the inner surface isn't quite as funky shaped as a standard legs. I wanted a clean way for the brake line to exit so I made some aluminum 'washers' with a circle patch over them. Seems to have turned out pretty nice.
Here's a close up of a tape going over the stab stitches. I use flat rib lacing cord and the staggerwing knot. My research on the Stewarts process really pointed out that a key to making the finish process come out really nice is making sure that excess EkoBond is removed carefully and quickly from the top and edges of the tape. Of course I won't know until I start spraying, but it looks to me like the edges are really going to look nice. I also go over the pinked edges with an iron at about 250 degrees which really makes them look tidy.
I've watched the Stewart videos on youtube several times to pick up on the details, but I wasn't keen on using the blue paper shop towels for removing the excess EkoBond... so I thought I'd try the paper towels that we use in our home. They are cheap WalMart towels that are perfed at far less than full size (their term on the package is: 'sized 4 spills') - they sell the same towel full size so you have to look for 'sized 4 spilles'. They seem to be working fantastic. I fold them in half, and then again into quarters. That gives me 8 surfaces I can use to pick up EkoBond with by folding them as I use them. By having the towel nice and flat, the wipe is very smooth (compared to just using a towel in a wad) and I also get great mileage this way. I'm guessing I will wind up using about 6 rolls of these paper towels for the entire covering process... about $11 worth. I also don't have much trash since they are very flat once they've done their job.
I work alone and often their isn't even anyone around that could help me turn the wings over, so I came up with the idea of hanging them leading edge down for the entire process. I install the fabric, stitch, tape, and will spray fill and color without ever moving the wings. I have 3 different loops in the rope they hang with that allows me to change the height by moving the carabiner. And I can move them to a different height by myself. So far, the middle position is perfect for installing fabric, stitching, and taping. I will likely move them to the highest position when I spray the leading edges. This arrangement also makes good use of the 20' x 25' space that I'm doing all the work in.
I have a blue and a tan tarp on the floor anywhere that the fabric will touch. I installed heavyweight Ceconite 101 on the lower surface, running from the spar on the top of the leading edge and then around the flap and aileron well. Then the the upper surface, which is medium weigh Ceconite 102, is installed from the spar on the bottom of the leading edge (with a 3" glue joint) up an over the top of the wing to the flap and aileron well. This gives a full double layer of fabric on the leading edge, with the under layer being heavyweight. Best of all, no tapes will be in the radius of the leading edge. A 4" tape will cover the 3" glue joint on the bottom of the wing over the spar area.
The first wing as I make the 3" overlap seam on the lower surface. The bottom of the wing has the heavyweight fabric lightly shrunk, and the medium weight is hanging down to the floor as I make that glue joint. I then pull it up and spring clamp in a few places as I get it in position and glued at the trailing edge and tip.
Here are both layers installed on the first wing, with the 3" glue joint near the spar. The leading edges look fantastic with that double layer. I also made new skins anywhere there were dents (5 new sections total) so it looks like these leading edges are gonna look awesome.
It took me 12 hours of labor to stitch the first wing. Flat cord slows the process down a bit but I think it's totally worth it. I don't like having chalk line dust on the wing so I lay out the stitch locations with a 6 foot steel rule. I made a needle out of 3/32" welding rod with the slightly bent tip. Works great. I lay on the floor to run the needle from the top to the bottom side and then back to the front for the first 5 stitches, then I stand on a step ladder and reach over the trailing edge for the rest of the stitches. I think this is much nice than bending over for every stitch... especially now that I'm 56 years old!
Both wings last night just before giving up for the night. The near wing only has the bottom fabric glued, not yet shrunk.
Here's the second wing today with its lower fabric lightly shrunk and the upper fabric pulled up and over as I get ready to trim and glue it in place. The 3" overlap seem can be seen near the floor.
I've made a lot of progress in the last 4 weeks, and I have the fatigue to prove it! However, I'm feeling really good about the work and I'm hopeful I can keep the pace up and have the airplane in the air before long. I welcome comments but I will say that my priority is working on the airplane, so I might not be able to respond for a while.
Martt
1959 PA-18A
N9460D