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Empennage

Rudder ready for priming

I’ve managed to get a few hours clocked up in the shed during the week. Most of it has been deburring the rudder. I spent about 8 hours over 2 days breaking edges and deburring holes. Nothing too exciting so I didn’t take any photos of me working on the ribs, spars or skins. Here is a shot of most of the parts deburred and ready for priming.

The unique thing was the trailing edge strip which had to be countersunk on both sides. I used my ali box tube to set the countersinking tool to the right depth. I tried a few different depths and tested each with my dimple test piece to check for fit.

I found that if I set the depth shallow enough to avoid a knife edge between the two countersinks, the test piece did not sit flush (i.e. the countersink is too shallow).

If I set the countersink deep enough for the test piece to sit flush it looked deep enough to create a knife edge and slight hole enlargement on the wedge as it is pretty thin.

I thought about this a bit and decided to go with the deeper option and have the skin being able to sit flush against the wedge. I figured there are HEAPS of rivets on this trailing edge, it will also be fully bonded along the entire length, and it is more important aerodynamically for a straight, sharp trailing edge. With that decided, I countersunk both sides of the trailing edge wedge.

The other issue of note was trying to dimple the rib flanges at the narrow ends. I couldn’t dimple the last 3 or 4 holes using my DRDT2 or squeezer. I ended up using my hand seamer and bending the flanges outwards enough so I could use my DRDT2, then I bent them back into position. I later discovered an alternative method using pop rivets which can be found on the EEA website. I think the pop rivet method is probably better and will give this a go next time.

I then spent 2 hours using PreKote to clean and prepare the rudder parts for priming. Nothing too exciting but here is a photo of the cleaned parts anyway.

Total build time over the past few days – 10 hrs.

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About gstrack

Husband and father of 2. Control & Instrumentation Engineer. Flying nut. Gadget geek.

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