Mon Apr 30 2007

Spar flange problems

After a talking with Scott at Van's, I learned that the spar flange angles are:

Top flange 88.5 +/-.5 degrees. Bottom flange 89 +/-.5 degrees

Measured between flange and web (in the corner where the main ribs sit)

My spar flanges were definitely out of spec. Scott indicated that they have had several spars with this problem. Apparently the spar channel is OK until it is assembled with the top and bottom bars. This causes the flanges to open up a bit.

Scott recommended the same fix they use at Van's when they encounter this problem...cut a slot in a 2x4 and use that as a lever to tweak the flanges into positon.

So I began the painstaking process of drilling out all the rivets which my friend, Scott, and I had put in a few days before.

A couple hours later, the left spar was once again free of main ribs. What a mess.

I cut a little angle checking gauge from a piece of oak. The cutouts in the bottom are clearance for the main spar rivets.

I tried bending the spar flanges with several pieces of wood and composite material...all of which broke on the first try.