Another day of work is in the bag, literally. Today was spent making a long board sanding spline, and then contouring the lower surface of the wings and strikes. A days worth of contouring, and this is what I have to show for it, half a bag of dust. Incidentally, I was shocked how much weight was in that bag, and most importantly, not on my airplane.
Looks a lot like what comes in the bag of micro from the supplier, huh? A full day of sanding seems like a long and tedious process to end up with what I started with.
All kidding aside, I’m pretty happy with today’s progress. There is something about the ugly, multi colored epoxy structure being covered In a uniform, white filler that makes it seem closer to being an airplane. Then when contour sanding, out of an ugly unevenly frosted shape emerges a beautiful, almost airworthy airfoil. It is quite a transformation. Or maybe I have been spending too much time with epoxy fumes!
There is still much work to do, I am not even seeing hints of the underlying structure yet to tell me I am getting close to an accurate contour. But I am happy to report that so far I only have a few localized low spots, and many of those may go away as I get down to contour. Of course I also have a few air bubbles that revealed themselves, nothing a small amount of fill wont handle.
I did notice a few very small peculiar dark areas in the micro. I thought maybe there was an underlying air bubble, and that I could chip it away. Upon inspection, it was uncured micro. Everywhere else had cured properly.
After some thought, I think it was a bit of resin that was improperly mixed. Remember that it is very important to scrape the sides of your mixing cups to ensure that there isn’t any stray resin on the sides of the cup. All resin has to be thoroughly incorporated into the mix before adding the micro. Once the micro is added, you cannot ensure that the resin will be able to find the harder it needs. Here is a photo showing the dark, uncured area. As a size reference, the streak on the right is about 2″ long by less than a quarter inch.
Tomorrow has more contouring in store for me. Also I would like to try to prep the right wing/strake underside. Here are a few photos from today.