#9 Covering & Sealing With The New Material

Got the new material (now thought to be the right stuff which turns out to be a bad assumption) and re-started the covering process. The leading edge glue line I had penciled in on the first attempt was still visible so we used that to glue this bottom piece to. The bottom “blanket” of fabric was then rough cut to span length adding 6 inches of extra cloth off the tip and the root struts. The factory edge was very smooth so we just glued it on beginning at the middle and moving out toward the tip and then out to the root end. We wet glued this leading edge line meaning we applied wet glue and then immediately set the fabric in it. You can also pre-glue full strength and then come back and use 50/50 MEK/glue and set the fabric that way which I believe is what the plans spelled out. It's a real guess as to how much spanwise tension to apply. Even the moderate amount we applied created a spanwise sweep about 3 inches beginning at that internal strut. There just isn't anything in the frame to keep that from happening. After gluing the leading edge of the bottom blanket, we applied glue to the bottom rib cap strips and then came back and mashed the cloth into the half dried glue with 50/50 glue/MEK mix. Massaging this in gave fairly thorough and consistent cloth penetration with no pull up or separation. The tip and root ribs were wet glued since it was much easier to handle the cloth over wet glue at the ends of the panel. There was some detailed trimming to do at the root strut where the cloth has to be terminated. This was done with the soldering gun blade tip and basically followed the outer edge of the root gusset plate where the chafing tape stopped. Here's a shot of the finished panel prior to detailing with the iron. Most of the large area shrinking has already been done and you can see the inter-rib sag that occurred as a result.

The sag measured nearly an inch in the worst bays. I released the leading edge seam on the worst bays and relaxed it back to where there was only about ½ inch overlap left and gained back a lot of the airfoil.

 At this point I am getting the feeling that there is just too much frame distortion to expect the panels to fit together well enough to set up or fold down not to mention the inter-rib sag which looks severe to me but I continue with the sealing step anyway.  You can easily see the dog leg sweep on the leading edge caused by the fabric tension.  It starts right where you'd expect it to....at the internal diagonal rib and out to the tip.  I took the time to do some detail work most would skip such as these patches over the gusset holes. Even though I did a fair job of cutting the gusset slits, these patches really clean up each gusset position.  I drew the pattern out using a drafting compass and cut it out using a pinking shears.

Starting the sealant coat (Poly Brush in this case).

The gusset patch after sealing. It really did look better with the patch than without.

A shot of the bottom of the panel with the first coat of sealant complete.

Top of the same panel at the same state. I could have used clear Poly Brush but felt being able to see where I had been was more important which is why it is rust colored (their standard sealant color). I planned to paint the wing so this would all be under a couple coats of paint when I'm finished.

After all this, I finally verify that the original plans and kit for this glider involved applying pre-shrunk polyester dress lining material using standard aircraft fabric cement (Super Seam) and nitrate dope referred to now days as the Ceconite process (except for the fabric of course). All my effort and hours of detailing the spars using the small iron was just practice. I stripped the airframe and place an order for pre-shrunk polyester for the material used up during the first attempt at covering. I won't get back to working on recovering until September most likely. The next post will cover some of the things I'm working on this summer that are directly related to the project including reconfiguring the trailer, inspecting an old Icarus cover job and inheriting a completely finished and flyable Easy Riser during my annual trip to fly at Fort Funston near San Francisco.