Working on the Elevator

Friends,

The last couple weeks have seen some progress. I was able to get the elevator skins bent properly (working on a video about those), and started drilling the skins. I like to pre-drill the skins so that I have pilot holes that allow me to see the center line of the ribs/spars underneath. This is similar to how Zenith used to ship their kits before they started CNC match-drilling everything. There are ways to drill the skins and ribs blind, but I prefer being able to visually ensure the ribs are in alignment. Plus, with the pilot holes drilled, I generally don't have to worry about the bits wandering.

However, if you use this method, you absolutely must ensure that you've measured your rib stations onto the skins properly. Somehow, I'd managed to locate a rivet line about 3/8" offset from one of the rivet stations. I think I accidentally had the tape measure hooked on something off the edge of the skin, but I don't know for sure. Maybe I just measured wrong. It was a duplicate measurement to the bottom side of the skin, and the exact same mirrored measurements for the co-pilot's side rear skin. It was just the top rivet line of the one side that I'd messed up. I'm going to re-make the skin and use it as a template to pilot hole the new one (without using the bad rivet line, of course). So it'll add an hour or so to the elevator (and scrap the original skin), but I'd rather take care of it now than just fill the holes with rivets.

Elevator Right and Left side Trailing Edge Skins:

Homemade gauge for checking the bend angle:

Elevator Nose Skins roll-formed manually with a 2x4:

 

Test layout of skins:

Center overlap of rear skins for strength:

Rear skins cleco'd to the spar and ribs:

Another thing to which you have to pay close attention is the rivet pitch and size specified in the plans. The overlapping skins in the center get drilled for A5 rivets at a pitch of 25. I missed that part on the plans, and accidentally drilled them to 40 pitch, which is what the rest of the elevator takes. I compensated by doubling the pitch to 20, with only results in an extra rivet on the front and rear rows, but it also means I have to remake the upper and lower control horns for the elevator to be able to use the existing rivet holes to mount the horns. With the 40 pitch, the rivets fall in slightly the wrong position, causing there not to be enough flange material on the horns. I'll remake the horns with longer flanges to solve that problem.