RV-9A Construction Log for the RudderRudder
Here is what it looks like on paper. Included are some of the catalogs from the various suppliers that keep RV builders like me in tools and fastener hardware.
RV-9A Construction Log for the RudderRudder
Here is what it looks like on paper. Included are some of the catalogs from the various suppliers that keep RV builders like me in tools and fastener hardware.
..And here's what the rudder parts look like.
The stiffeners for the rudder skin start out as a stack of 1/2" angle aluminum with a bunch of guide marks punched in them for cutting. The long piece is how they come out of the box. Once cut in half you see the stack of 16 stiffeners ready for trimming.
Because the rudder is tapered all the stiffeners are different lengths so they are cut to size.
Now the tricky part. The rudder is like a really skinny wedge with the trailing edge the sharp side. This means the stiffeners have to be tapered down to the ends starting about 6 inches from the trailing edge. The tin snips shown in the picture just didn't do the job I wanted. The cut was irregular and hard to control and looked bad. What I wanted was a nice sheet metal shear but that was out. Some people had reported good luck with an industrial size paper cutter but Kinkos didn't like the idea of using theirs for aluminum. This thin aluminum can almost be cut with scissors..what to do...
AH-HA! Brain storm. Plain old garden shears or hedge clippers found hanging in the garage, arms length from the work bench. They were a bit old and rusty but cleaned up quick and sharp with a flat file.
This type of shear has an "anvil" blade and a "knife" blade. Lay the angle on the anvil blade with the guide mark for the taper just catching on the other blade. You want this way back in the shear so you can do this with one clean cut all the way to the end of the stiffener.
Take care to line up the cut and start slow.
Keep your fingers out of the way and keep the fingers. P-)
As the cut progresses to the tips of the shears it takes more push to finish it off. It's important to keep a good grip on the shears and maintain control of them so they don't flop over while pushing down on the handle.
Voila'! One slice and a perfect taper. 13 more to go..(yeah, I had a couple of "practice pieces")
This is what happens when you try to cut the taper from the end of the stiffener and not in the middle -- you get to add to the scrap pile. One more in the stack looks a little off.
The rest made it look like a production assembly line .. clean, straight and consistent.
Gently dimpling those .016 skins..
It's Sunday evening and time to call it a day. A little primer, a few rivets, and it's starts to look like airplane parts.
Back at it on Monday, using the hand seamers to straighten the flanges on a rib. (This particular one being the counterbalance rib.)
Rudder skeleton showing progress.
Looking like a rudder
One more trip to the paint booth for the final zinc-chromate treatment.
Final assembly begins with the spar and reinforcing plates, bottom rib and rudder control horn, and the counterbalance rib.
The counterbalance gets its skin..
..and its mass balance (chunk of lead).
Moving outside into the sunshine, the rudder gets its skin
Mixing up the glue (pro-seal fuel tank sealant) for the trailing edge and stiffner/spar junction.
I mixed WAY too much here. This is 10 ounces worth plus hardener. It was an old (expired) can so I had a lot to practice with..
Here is where I departed from the builder's manual. On my RV-4 and a few other planes I've looked at, the skins on the control surfaces (elevator and rudder) sometimes crack at the most forward rivet of the stiffners. I'm attempting to avoid that on this plane by applying a blob of pro-seal to the junction between the spar and stiffner to help tie them together and take some stess off of the skin.
Like I said..a blob.
A very scientifically engineered blob. P-)I will do the same to the elevator stiffners.
The rudder, now wearing rivets instead of clecos, is almost complete
..sorry, no pictures of riveting the trailing edge. It's done, won't win any beauty contests, but, it'll fly.
Every clamp in the house shown here squeezing the riveted trailing edge to flatten out the ripples caused by having the "glue" on too thick between the rivets.
Closing up the leading edge..
Here the rivets won't show because they are hidden by the vertical stabilizer. This is the hinge line between the rudder and VS.
..and once again we make it to another mile stone, the rudder is complete for now.
There are fiberglass caps that go on the top and bottom but those will come later.
