1.5 Hours -
My fretting over fluting was overblown. I found a couple of good tutorials on the web which made the process fairly clear. Basically, you just lay the rib on your work table, see where it is bowed, and then flute the flange above the bow. Repeat this until the rib lays flat. Then, check to make sure the flanges are perpendicular to the rib web. If they are not perpendicular, bend them and then check to see that the rib still lays flat. Repeat as necessary. It may sound complex, but it took me only a couple minutes per rib (after the first one was out of the way).
It's difficult to see in this picture, but the rib bows slightly upwards.
Nice and flat!
On to the next step and even more confusion. The plans tell you to mark the locations of four holes on forward side of the forward flange of the HS-405 ribs. The plans also say that all the measurements are nicely laid out in SEC D-D of the drawings. This is a bunch of BS!! The plans tell you to measure based on the locations of the splice angles, but they don’t tell you where the rib is supposed to attach to the front spar assembly!
Not wanting to screw this up, I did a quick search of vansairforce.net and a couple builder’s sites. It seems a lot of people mess up here and have to order replacement parts. The consensus is to skip this step until the skin is on the assembly. With the skin on, you can clamp the HS-404 and HS-405 ribs in place and mark the exact locations where they will be joined to the front spar. Since the skin is pre-punched, it aligns the pieces for you. I’m sure Van’s has a reason for doing it the way they write it, but it sure seems like this method is much more simple and accurate.
I quickly put all the ribs in place and marked all the pieces of the HS skeleton so that I would know their orientation. Then, I disassembled the right half and left the left half intact. The next step will be to put the skin on the left side and match drill it to the ribs.
It actually looks like an airplane component!
