Longeron Drilling

Time: 6 Hours

Well I finally got out to the Hangar for some more work on the fuselage after the thanksgiving holiday. It’s been a couple of weeks since I was able to get some work done. Today I started the process of positioning and drilling the longerons. The first ones to be drilled are the lower ones. The plans call for the extra caution needed to make sure that the drill bit stays square to the skin as you have several layers to drill through in several spots. For that I used a new tool I bought, called a drill cup. This will keep the bit square to the material being drilled.

IMG_4863.JPGSo with the drill cup I started working on the lover longeron working from the forward end aft.

IMG_4864.JPGThen I moved on to the middle “auxiliary” longerons. Before in installed these a while ago the plans had you draw a reference line for the rivet line. Since these kinda float as they sit right now being just held in by the sandwich of the skins and gear towers. You can move them up and down to get that reverence line centered in the line of holes. I was having a hard time getting the aft end down low enough to be centered. The reason was the angled gussets were binding a little. What I noticed was that I had clecko’d the top in the bottom spot and the bottom in the top. Down side to this was I drilled the lower ones already which opened the #40 holes to a #30 that was on the bottom longeron. The top needs #40 holes to match the skins, so I will order some replacements from Van’s.

IMG_4866.JPGWith the gussets removed I lined up the reference line in the holes and drilled away putting a clecko in as I went.

IMG_4865.JPGNow I hit the upper longeron where it met the engine mount on the forward end. I started with the skin side first and then the top side, making sure to stay square with the longeron as it sits at an angle.

IMG_4867.JPGFrom the top engine mount I worked aft along the top longeron drilling and cleckoing the forward skins. I used spring clamps to hold the skin tight to the longeron and to keep the edge of the skin even with the corner of the longeron.



IMG_4870.JPGThen I moved to the lower part of the gear towers. There are a number of holes that need to be enlarged to a #19 hole for #8 structural screws. I marked out the 17 holes with a red sharpie and drilled them with a #21 first and final drilled with the #19 bit.


IMG_4872.JPGOnce that was done I final reamed all the #30 & #40 holes in the forward skin that were not drilled with the longerons. Next I moved in to the mid fuselage skins and upper longeron drilling. I used the same clamps to make sure that the skin and corner of the longeron matched up. Once that was finished I match reamed all the remaining holes in the side skins.



IMG_4876.JPGI’m fighting a little bit of a cold and this day went slow but it felt great to be back to building! I cleaned up the hangar and called it a night. Next up will be the aft fuselage drilling and match reaming.

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