June 30, 2007

Finished the Rear Spars! - 3.5 hrs.

Today was the perfect, beautiful day I've been hoping for to prime all the parts for the rear spars. So after a new layer of plastic was put down over my old picnic table, I dragged out the chicken-wire priming frame I made a few months ago and laid out all the parts. As you see them here, they have all been scrubbed with naphtha and scotchbrite pads, wiped clean with a naphtha-dampened cloth, and laid out to dry (which only takes a few moments).

The priming itself was straightforward and went quickly. I love this SEM primer. It sprays well, dries quickly, and leaves a nice smooth finish. I was able to turn the parts over almost immediately and spray the other side. Here you see them, all done!

Another shot of the finished parts. By the time I cleaned up and put the sprayer and paint and all the stuff away, these were dry. Time to drive some rivets!

Back in the shop, I started on the outboard ends of the rear spars. Most of the holes are actually left open at this point because later on, the aileron hinge brackets, and the furthermost outboard rib will get riveted to these spars. So you have to pay attention and tape or mark the ones left open. If you rivet these holes now, you will just end up drilling them out later.

Then you move on to the center of the rear spars. Cleco the stiffeners on and rivet. Again, quite a few of the holes are left open at this point.

Finally, I finished with the inboard ends of the rear spars. The two stiffeners are clecoed on, and the holes that are left open are marked or taped. My rivet squeezer and longeron yoke made quick work of this operation. Above, you can see the forward side of the right spar, and the aft side of the left spar.

A close-up shot of the finished rivets, front and back sides. Beautiful! I'm so pleased with how this has turned out. You may also notice that some of the holes in the spar flange have been dimpled already. This is done before riveting the stiffener on, because the thickness of the stiffener and its rivets sticking up would make dimpling very difficult, if not impossible. Trying to fit a dimpling die in there just isn't possible with all that metal in the way, so they are dimpled first. Following the plans carefully and reading ahead helps you avoid any mistakes here.

I couldn't help but stare at this for a while. The rear spars are assembled and finished... ready for ribs!

Speaking of which... there is now a huge pile of ribs waiting for me. I'm not looking forward to the long boring task of deburring, fluting, straightening, and preparing the ribs for assembly. But that's the task next on the list, and you have to just bite the bullet and dive in and get this stuff done. I'll tackle it soon, a few ribs at a time as time permits. July will be a very busy month for me, but I'm still trying to get at least a little bit of time in each day.

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