Last night I had a few beers with Mike Bullock of RVPlane.com fame. Mike asked me what the favorite part of his builder’s log was, and I answered “the photographs!” But there is more to Mike’s site than just great photos. He also does an excellent job of chronicling each session in the shop. This got me thinking. What can I do to improve my posts? I decided to do two things. First, I’d endeavor to take more photos throughout each session. Second, I would use my trusty digital sidekick, Siri, to periodically take notes (via the excellent WordPress app). In this way when I finally get around to publishing my post, I’m not forced to rely solely on my poor memory. Today’s post is the result of my new technique. Hopefully it is an improvement, and one that I will have the discipline maintain.
Today’s primary project was to fit the fuel tanks on to the spars and complete the scarf joints. The first step was to fit the fuel tanks to the wing. The idea was to put the tanks on temporarily in order finish the scarf joints. With the scarf joints complete, I will be able to dimple the skins and rivet the top skins on. Then the project can be moved easily and safely to my hangar.
Next I installed the screws near each scarf joint. I only installed enough screws to overlap the scarf joint location. Upon installation of some of the screws I discovered I have a few alignment issues that I’ll need to fix. First, the corners slightly bow out by virtue of putting the dimples in. I took care of the very first one on the top of the right wing. But there are a few other corners that will still need fixed. Here is a blurry picture, but it should be sufficient to display the corners I’m speaking of. Additionally I have one area where it seems the right leading edge is slightly pushed and leading to a misalignment. All should be easily fixed.The scarf joint shown below is the one that I have previously worked on. It is about 90% complete. You can notice that there is only a slight misalignment to the far right of the joint.Pictured here is the overlap between the inboard and outboard skins prior to any work on the scarf joint. You can clearly see the misalignment. BEFOREBefore I began working on the scarf joints, I temporarily hung each skin in position. This way I could remove one skin, work on the scarf joint, and the replace it to check my progress. I used an pneumatic angle grinder from Harbor Freight with a small sanding disc to make each scarf joint. I also have small scotchbrite disc (similar to the maroon scotchbrite pads) for the angle grinder that I finished each corner with. Here is a scarf joint in progress. Completed product. This is the same joint that is shown above as the “before” photo. AFTERAfter completing all four scarf joints I’ve decided to prime the overlap as well as the areas of the scarf joint. To achieve this I’m going to use a little blue painter’s tape. I applied the tape before removing the skins to ensure I had perfect overlap alignment. Next I used a scotchbrite pad to lightly scuff each overlap area and then I cleaned each with acetone and cheesecloth. Here are all 8 skins. On the left are all the inboard skins with their overlaps, and the four outer skins with the scarf joint corners exposed. After priming.Here are the completed overlaps after priming and removing the tape.