"You never really finish the contouring process. You just decide to quit at some point."......Anonymous Builder
Okay, it's time to turn this rough, ungainly fiberglass airframe into a work of art. Time for the ugly duckling to become the swan! I'm using the basic process outlined in Chapter 25 plans. But I've incorporated a few techniques, tips, and tricks that make the job easier. I adopted them from builders whom I consider to be experts on the contouring process.
Step 1: Inspections and Repairs -- inspect the structure and make all necessary repairs.
Step 2: The Prefill -- fill the low spots first and bring them up to contour with the surrounding surfaces.
Step 3: The Big Fill -- cover the entire part with a layer of dry micro that is thicker than the highest high spots.
Step 4: Sanding to Contour -- use an alternating, 45-degree sanding motion to shape the part into contour.
Step 5: Filling Pinholes and Scratches -- skim coat the surface with pure epoxy to fill scratches and pinholes BEFORE applying the primer.
Step 6: High Build Primer -- Apply high build primer and sand it down to perfectly finesse the shape and surface finish.
Step 7: Painting -- Apply the top coat finishing paint. Go flying!
"Finishing a Composite Airplane" is one of the best how-to articles I've found. Written by George Sychrovsky, it is filled with techniques, tricks, what-to-do's, and what-not-to-do's. George preaches the Prime Directive, which is to apply the big fill ONCE and sand it off ONCE. I've also become a disciple of the raw epoxy finishing technique -- i.e., "skim coating" that Cory Bird used on Symmetry, the 2004 Oshkosh Grand Champion. After rough contouring, he uses pure epoxy to fill pinholes and scratches before moving on to the high build primer. I also pay a lot of attention to what Dennis Oelmann, Ken Miller, Nick Ugolini, Carl Denk, Jeff Russell, and Jack Morrison have to say. They are canard builders and flyers who have fabulously-finished aircraft. They are always forthcoming with tricks and techniques that they've learned over the years. I'm truly standing on the shoulders of giants!
With that, let's get dusty!