Originally posted by Mad Rocketeer
I'd love to see a post on how to make good airfoils. Are there any jigs for that being sold? All I've seen are descriptions of doing it with a good eye, a steady hand, and lots of elbow grease. There ought'a be an easier way. Maybe a tool or a jig or something.
I reckon falling out of a window is easier than rolling downhill, but neither is very tough to do. We're talking balsa here. It takes no more elbow grease to airfoil a 3mm fin than it does to eat dinner.
4 to 8 push strokes of the fin across rough sandpaper laid on the table, for each side of each edge. For sharp airfoils, hold the fin at a steep angle to the sandpaper. For rounded, do it at a slightly different angle each time. For 4 big fins with 4 edges to round, such as a Big Bertha, it's a 15 minute job. This uses the same setup that you use to sand the fins all together at once to make sure all the edges are the same size. It's already there and ready to go.
If you want very consistent sharp angle airfoils, you can fold some cardboard into a wedge and use it to keep the fin at a constant angle to the paper.
Tip: always push the fin across the sandpaper with the grain. If you push them with the grain angled so as to dig into the sandpaper, it'll shred in tiny little fuzzies that'll have to be sanded off.
For very easy and quick airfoils on a small bird, I've even glued them on first, then took a small piece of rough sandpaper, pinched it between index finger and thumb, and run the fold down along the edges a few times. With each run, you pinch a little more, and it does different angles, producing a round edge.