Saturday, August 7, 2010

Aug 1-7 -- Rudder Stiffeners

Have been plugging away at this each evening this week. Well, not quite... The pain from the ruptured discs continues, and between medication, not feeling well, and lots of "real work", time spent on the RV was not a lot. And now I have to go in for back surgery on Wednesday, so there will be close to five weeks of no progress coming up.

You can see in the photos that I primed parts, dimpled everything related to the stiffening ribs, and even riveted them to one skin. The other skin is hopefully tomorrow's project.

There are many reports that cracks appear once the plane is in service. These cracks are always around the end of the stiffener closest to the trailing edge, and common wisdom is that ProSeal will help dampen vibration, and therefore reduce flexing that causes cracks. I almost traced the parts onto 0.020 aluminum, instead of using the standard 0.016 skins, because others have also reported that thicker metal solves the problem.

I decided on the ProSeal approach. Purchased an ounce from Van's and put it under each stiffener -- paying particular attention to the ends. For this part of the assembly I tried to be a neatnik, so I used masking tape to mask off areas where I don't want Proseal to find its way onto the skin. I mixed half the Proseal in the bottom of a yogurt cup, then worked as fast as possible in order that the Proseal would not set up before I finished.

As I assemble the skins to the trailing edge, I plan to add additional generous quantities to the skins in order to dampen vibrations. But for now it's only under the stiffeners.

This was the first run at back riveting, too. In one of the photos you can see the cool tape that holds lines of rivets in place. Sure beats picking off the remains of masking tape! I used a flat steel plate underneath the skin, but first I wrapped the edges in tape to prevent scratches. Still managed to rivet one spot with out the plate under it. Fortunately the damage was easy to repair.

I also continued priming everything with NAPA MS 7220 grey. Others pooh-pooh primer; however as the owner of a Luscombe that was built in 1947 without internal primer paint, I am convinced that (a) you need primer for a long-lasting plane, and (b) airplanes stay in service much longer than anyone expects. So I want mine preserved for the first Klingons that visit Earth.

Total time this week: 8 hours.

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