This post covers the past 2 weekends. Last week, I drilled the skin to rib holes to the correct size, drilled the skin spar attach holes to #19 size, and countersunk the spanwise holes on the tank skin on one side that join to the baffle plate. There wasn’t anything really exciting or different to doing this on the left tank so I didn’t bother taking any photos.
Today I countersunk the spanwise holes on the other side then disassembled the right tank.
I then marked out the angle I had half-finished when I did the left tank. I used the rib as a guide to mark the trim line, then used a hack saw to cut away most of the unwanted metal. I finished shaping the angle using the Vixen file to get most of the metal off, then finished off with a normal file to get a smooth finish. Here is a photo with half the metal cut away.
I “filed and checked” the angle to the tank rib a few times before I was happy with the fit, then it was time to mark the holes to be drilled. I remembered that the plans don’t give any measurements for the locations of these holes and I didn’t want to bother trying to measure then off the scaled drawing again, so I clamped the left and right angles back-to-back and match drilled the right tank angle using the left angle as a guide.
I then picked put the rib reinforcement plate and cleaned it up on the Scotchbrite wheel. Using a clamp, I sandwiched the rib betweend the plate and angle and carefully drilled the first hole. After putting a cleco into the hole, I then carefully drilled a hole on the other side and put another cleco in it. This held everything together pretty well so I was able to remove the clamp and drill the rest of the holes.
I then cleaned up the angle on the Scotchbrite wheel and deburred all the holes. The right tank is now at the same stage as the left tank.
I need to figure out how I am going to cut out a circular 5.25″ hole in both inboard tank ribs. I haven’t been able to source a flycutter locally so I’ll need to have a look at other options.
Build time 3.5 hours.