Building, testing and operating an experimental aircraft

Rudder Progress

01 Jul 2010

After several weeks of (real) work for me, and lots of great (airplane) prep work by Dad, we returned to the Big Project. When we last left the horizontal and vertical stabs, we had several un-riveted holes that we weren’t able to reach, most notably the ones closest to the leading edges.

No-Hole Yoke No-Hole Yoke

So, we picked up a 4” no-hole yoke from Avery Tools, and with this we were able to squeeze those tight-quarters rivet placements. And if the photo below were at all legible, and/or there wasn’t a bookshelf in the way, you’d see that, yes, we do in fact have a set of completed tail feathers.

Tail Feathers Tail Feathers

We then jumped right into riveting the stiffeners to the rudder skin, since Dad had spent the last several weeks doing the trimming, drilling, dimpling, deburring of the rudder components. We used the C-frame backriveting technique for most of this job, but found that is was not quite as foolproof as we would have liked – we still ended up with some clubbed rivets.

Backriveting Rudder Stiffeners Backriveting Rudder Stiffeners

We’ve since decided that the thin skins of the moveable surfaces, coupled with #40 holes and dimples, cause the rivets to move around a little too much in their holes, resulting in some of them bending over while driving. We might try a slightly smaller drill bit (#41?) next time.

Rudder Trailing Edge Dowel Rudder Trailing Edge Dowel

We then moved on to bending the rudder trailing edge with the great 2x8 press brake that Dad fabricated (I’ll get some pictures of that process when we do the elevators), and we were pleasantly surprised with the results. Following the advice of several other builders, we taped a wooden dowel to the inside of the trailing edge to ensure that we got the proper bend radius.

Rudder Assembly Rudder Assembly

Finally, we assembled and drilled the rudder understructure, and prepped the parts for priming.

R-710 Edge Distance R-710 Edge Distance

Of course, no airplane work session can be without its pitfalls and heartbreak, and this one was no different. While match drilling the rudder understructure, we noticed that we’d over-trimmed the R-710 rudder horn brace, pictured above. This caused our drilled holes to be too close to the top edge (the bottom edge in the picture) to meet minimum edge distance requirements for a 3/32 rivet.

After much debate and hand-wringing, we decided to order a replacement part, and we moved on to priming and riveting what we could of the rudder skeleton.

Brian Doing Something Brian Doing Something

Oh yeah, and last but not least, here’s a picture of me, doing … something.

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