Mike Bullock's RV-7: Match Drilled skin, first part re-order

Build Time:
2236 Hours

Flying & Maintenance Time:
1636 Hours

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[January 2, 2006]

Today I got both the left and right skins of the rudder match drilled. Then I moved into trimming up the R-710 rudder brace. I didn't think that the trimming method was that precise because the instructions didn't state that the brace needed to be riveted to the skin/rib. I made a nice straight cut with my rotor-zip (with a 90 degree cut off wheel attachment, very nice tool!) right down the bottom of each of the pre-drilled holes. Smoothed everything out with the scotch brite wheel and match drilled the rib and spar attachments. Then it clicked - the brace needs to be drilled to the skin also. I looked online then and saw people warning about not making the cut too low. I proceeded to drill it anyways to see where I was and it was way too close - 4/32" to 2/32" from the hole to the edge. On the mightly RV, I read the following that might help someone in the future:


Lots of progress in the last three days. Got the rudder clecoed together, 
then trimmed and fitted the R710 rudder brace that goes between the rudder 
horn and the lower rib. The brace has holes punched in it to indicate where
material should be trimmed away for fitting, but the plans don't say
explicity to cut to the centerline of these holes as when trimming stiffeners.
I cut and trimmed to the hole centers, and found that I was a little short
on edge distance when match-drilling to the rib sides. I called 
Van's - again - and they said that due to the loading on this part, a 
little reduction in edge distance would be ok.

I know that my holes are way too close, so I will reorder this piece. Van's only wants $9.00 for the R-710, so I can deal with that. I also ordered some oops rivets, boelube, tank sealant for misc empennage stuff (like the trailing edge of the rudder) and a subscription to the RVator 2006.

Next I moved onto the R-918 bottom attach strips. I cut the pieces with the rotor zip and that worked very well. I am definitely going to start ditching the snips for thr rotor zip. The snips tend to bend the metal as they cut. The cut off wheel doesn't. I was going to get a die grinder, but a) I already had the rotor zip that can do 25,000 RPM and b) I don't have a large enough air compressor to handle the die grinders. They eat air like no other air tool.

I clecoed the attach strips to the bottom of the rudder and looked at how much they were offset. 18/32" is exactly the center of the strip, but it falls in the bend radius of the rib. I found that 19/32's worked pefect. Sufficient edge distance (6/32's from the edge of the #40 holes to the edge of the strip). As I was drilling, I caught that the holes on the rib-skin were not lined up. You can't put clecoes in the holes since you are clamping an undrilled piece. I quickly lined up the holes, reclamped and kept going. I am glad I caught this when I did so I didn't elongate any holes.

I have to say that this rudder is the most fun piece of the RV to build so far. A lot more fabrication is needed, and I really enjoy that. I doesn't seem as kit-like as the HS and VS. This slight break I need to take from the rudder for the brace is a good chance for me to start the stiffeners for the elevators. My goal is to prime the rudder ribs/spars with the elevator stiffeners.

The skin clecoed on, ready to be match drilled.

This is the R-710 brace. You can see my line goes perfectly on the outside of the circle in the middle. I was so happy that I was going to have a nice straight cut. Next time I may start above the circle and work myself down slowly.