20050312-allegro-04-microballoons:
Next, I used some 6ml of epoxy (1cc of hardener, 5cc's of resin) and a bunch of microballoons and some cabosil (probably in a 5-to-1 ratio) to make the fillet material. I probably used to much microballoons, as the substance didn't "flow" well, making it a little hard to form. When I tried to form it with a wooden coffee-stir, it didn't "smooth out" very well. Just use less microballoons. Drela recommends the cabosil to "prevent sagging". He also suggests adding flox "for toughness".
First, put some of the mix just fore of the bolt hole -- enough to covered the area just below and in front of the leading edge. This is where the bottom of the LE will meet. Then, place the wing on the fuselage and bolt it down. Then, slather the stuff on, and form it the best you can with a piece of scrap balsa. Feel free to "over do it" a little. Microballoons are easy to sand.
20050312-allegro-04-microballoons:
Next, I used some 6ml of epoxy (1cc of hardener, 5cc's of resin) and a bunch of microballoons and some cabosil (probably in a 5-to-1 ratio) to make the fillet material. I probably used to much microballoons, as the substance didn't "flow" well, making it a little hard to form. When I tried to form it with a wooden coffee-stir, it didn't "smooth out" very well. Just use less microballoons. Drela recommends the cabosil to "prevent sagging". He also suggests adding flox "for toughness".
First, put some of the mix just fore of the bolt hole -- enough to covered the area just below and in front of the leading edge. This is where the bottom of the LE will meet. Then, place the wing on the fuselage and bolt it down. Then, slather the stuff on, and form it the best you can with a piece of scrap balsa. Feel free to "over do it" a little. Microballoons are easy to sand.