02-17-2013: 2 hrs
In the past week, I didn't spend much time on building the airplane, but spent quite bit time to figure out what to do with the slight twist of the right wing. When the incidence angle of the right wing is set per Van's instruction with bubble centered at inboard rib, the 3" block needs raise about 0.06" to center the bubble at the most outboard rib, indicating about 0.15-deg twisting (positive washout). To get a better picture of this situation, I also measured the angle using bottom skins. Since the left wing incidence angle is set, I just use the left wing as a reference. Using the same method as measuring the angle on top skins, I first centered the bubble by adusting the length of the block (I clamped a ruler as the block). It turened out I will need 1" to center the bubble. Then I checked other locations. The bubble is centered for the entire left wing. I then used the same setup on the right wing. To my surprise, the bubble can be centered from root to tip, no twist observed. I don't know why is this, but it looks like the wing twist is not as bad as I thought. But before I get response from Van's, I will not drill the right rear spar.With that, I went ahead and drilled the left rear spar to 1/4". I will ream it to 0.311" when my reamer arrive. To make sure the hole is true and straight, I drilled 7/32" and 1/4" holes to a 1.5" long, .5"x0.5" hardwood block, and used the wood block as a guide.
I don't have long drill bit, so I have to remove the C clamp that I used to clamp the rear spar and the fork together. In order to keep the holes ceneter when drilling, I left the previous smaller sized drilled bit in the holes. When drilling the hole to a larger size, I just push the smaller drill bit out using larger drill bit. This worked out well. Now I just need wait for the 0.311" reamer I ordered a week ago from Averys tool to ream the hole to its final size for AN5 bolt.
Left rear spar drilled
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