I really enjoy the wing covering process as it impresses me just how much the fabric strengthen and stiffens the wing panels. Just like the fuselage, the first step is to sand the structure smooth and clean up any dust with a tack cloth. Make sure your work surface also is clean and get all your supplies ready. These include the Stits Lite fabric cut oversize for the wing panel, the Poly Tak adhesive, MEK solvent (Be sure to use Hand cream for protection from the chemicals), quality brushes and lots of #11 X-Acro blades for your hobby knife.
Sand all the wing ribs, spars, attachment plates, wing tips etc., smooth and then clean up any dust.
All of the Stits Lite and Poly Tone paint and sealers part of the Poly Fiber system used for full-size aircraft and are formulated to work together for both a mechanical as well as a chemical bond.
The big secret for a good looking covering job is to make straight and precise seams and overlaps. To do this you need to replace your X-Acto blade often as they dull quickly while cutting through the fabric.
Start by applying a coat of Poly Tak adhesive all around the outer edges of the wing panel and let dry. Now cut the fabric to the rough size for the part. I make it about an inch oversize all the way around. Be sure to have a clean work surface. I use drafting vellum as I have a large supply of it.
Center the fabric over the wing panel and then use cloth pins to clamp it in place. This prevents the fabric from moving and exposing an edge while working the cloth into place.
To seal the fabric into place, remove a cloth pin, fold the fabric over and apply another coat of glue to the edge. Then quickly pull the fabric into place and work it into the wet adhesive while pulling it tight to remove any wrinkles. Rub it down with your fingers until the glue has dried. Here you see the wing tip. You should work about 6 inches at a time and then when the fabric is bonded and smoothed into place, move to the opposite end of the panel and repeat the process. Then glue don the fabric along the edges a section at a time, all the while pulling the fabric free of wrinkles. Work your way all around the wing panel until all the edges are glued down.
Here you see the wing panel with all the edges bonded down. For a neat appearance I apply another coat of glue to underside of the fabric along the edges and then trim the access away. I then press the fabric down while the glue is still wet to seal it down. Straight neat edges give the model a professional neat appearance.
Here is a close up of the edge along the aileron cutout area. Before covering the underside of the panel, I use the covering iron set at 225 Degrees F. to seal and press the edges down completely. Then the whole process is repeated for the second side.
Here is the hatch opening for the aileron servo. It too must be sealed down tightly before cutting the area open. A trick here is to brush MEK through the fabric (after it has been shrunk tight), to reactivate the adhesive around the opening. Then use your fingers to smooth the fabric down into place until the gue dries again.
Here is the underside of the wing tip. Note there are no wrinkles and the fabric has been sealed down and smoothed into place along the outer edge. No heat has been applied yet.
Here’s the completed wing panel. Note there are no wrinkles. You have to remove all the wrinkles before shrinking the fabric tight with your covering iron. If you try to remove wrinkles with heat, the fabric will loosen after it has been painted and finished.
That’s it. Now repeat the process for the rest of your wing panels and it will be time to add rib stitching and tapes and then sealing the fabric making it ready for paint and finish.