I spent a couple of hours making riblets for my trim tab today. had already folded the trim tab closed and clecoed it to the trim tab spar. I then placed the end onto a piece of paper to make a pattern. I then transfered the pattern to a piece of oak and cut it out using my band saw. I then cutout a piece of AL from scarp that had the right shape for the web and flange. I lined that up on the oak block, clamped it in place, drilled holes for some clecos. I then used a wood block to bend the flange down and finished it off with the flush rivet set, just like the way the trim tab would normaly be closed. It took a couple of tries to get this right, I couldn't do it with MDF or pine the edges just mushed over rather then bending. Now that I had the riblets I moved onto the rest of the trim tab so I could figure out where to make holes in the riblet for the trim tab horn rivets.
This wasn't my design I followed the example of others(http://www.rv7blog.com/category/empennage/trim-tab/)
