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prkaye

Well Known Member
I ran into a pretty serious problem with my ailerons today, but I'm at a loss to explain what's gone wrong. I drilled and put together the spar, ribs and counterweight as directed. I put the stiffeners on the skins. Then I temporarily riveted the bottom skin to the ribs as directed. Then flipped it over and put it on my (very flat) table and clecoed the top skin to the ribs as directed. Then I put clecoed the leading edge skin to the spar, as directed. This was very difficult - I had to pry with a hole-punch to get the holes to pull together. When I finally got it on, it caused a severe buckling and significant wave in the upper and lower main skins, which cannot be flattened out with weights. Is as though the leading edge skin is pulling the spar out of line, so that it's making hte main skins buckle.
What to do??? Photo attached shows the situtation (two photos together):

 
more weight

Hi Phil - I'm just past you (or at least I was...). I think you need more weight. I had the same waves. I used (2) 2x8's with 3 full buckets of clecos. It was nice and flat.

If you haven't already, be careful when you countersink the spar and nose ribs. I went too deep on both and now I need new parts.
 
wavy add more weight

Phil,

Iowa dreamer is right. Use more weight and rivet that sucker. I used three 25 pound bags of lead shot laid on top of a flat board and they came out straight and no twist.

Using an awl or ice pick works great to align holes. Wait until you build your fuel tanks.

Mike
 
re-assembled

I took it apart and re-assembled it with the weight on it (last time, I had assembled without weight, and put the weight on after... in that case the weight did not eliminate the buckling). This time, the weight (1x4 laid along length of it, with bricks on top) is holding the thing flat. If I take the weights off, a wave appears. By drilling and riveting with the weights on, will this result in the aileron being locked-flat, so the wave won't reappear? I can't fly with bricks on my aileron ;)
 
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Phil,

I drilled and riveted mine with sandbags on the ailerons and they came out flat. I did the same thing on the flaps, too.
 
I did my flaps, and they came out great. But the difference with the flaps is you have all those ribs to pull everything into alignment. These ailerons, with only one rib at each end... not as much to pull the skins together and eliminate the buckling and waving. Maybe the TE will help. I'll just move ahead and hope for the best. With the weights on it right now, on the table, it's fine.
 
Phil - same thing happened to me and others whose builder sites I peruse. Scares us all at first. You need to have enough weight to hold flat (I used 2X4's planed flat on one side and 4-5 bricks, 8 for the flap). The TE will be flat then, and will stay that way when you drill into it (perpendicular to the chord!) and cleco into the table. When you do final riveting, it should be nice and flat.
 
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