July 23rd, 2011

Pretty much finished up the right elevator this week. The only thing left at the end of the week was to let the proseal on the trailing edge cure for a couple of days so I could rivet it. Actually did that late Sunday night since it cured more quickly than I thought it would.

Here's a shot of the plans from Van's. We use this and a written description as a guide during building.

From Dale's RV Project - Elevator

Counterbalance ribs and skin going together.

From Dale's RV Project - Elevator

Fitting the elevator horn to the spar and making sure it lines up with the whole elevator assembly.

From Dale's RV Project - Elevator

Here's what it looked like once it was all riveted.

From Dale's RV Project - Elevator

Getting ready to back rivet the stiffeners in place. On the far end you can see lines of orange rivet tape. The big steel plate in the table is a back riveting plate.

From Dale's RV Project - Elevator

Back Riveting - thought I'd include a description since most folks won't know what back riveting is.

Normally when you rivet, you put the rivet gun against what is called the factory head, and a tool called a bucking bar against the unfinished side (called the shop head). When the trigger on the rivet gun is pulled, it basically very rapidly hammers the end of the rivet, striking the bucking bar, flattening out the shaft and making what is called a shop head.

Close up of the shop head side of a rivet after it has been riveted.

From Dale's RV Project - Elevator

Back riveting reverses the process. The back riveting plate takes the place of the bucking bar, and is installed in a recess in a table. The factory head of the rivet is placed down against the back riveting plate, and a special rivet set (are you ready - a "back rivet set") is used in the rivet gun and drives the shop head. It makes for an extremely smooth finish. Honestly pretty much anything than can be back riveted a builder will, because the finish is so smooth. It's used a lot on the thin skins of the elevator and rudder to prevent deforming them.

Back rivet plate:

From Dale's RV Project - Elevator

Rivets taped in place. This view is from the inside of the skin.

From Dale's RV Project - Elevator

Stiffener in place and ready to back rivet.

From Dale's RV Project - Elevator

Back rivet set in action.

From Dale's RV Project - Elevator

Riveting the skin to the spar. The wood is holding it vertical so I can get to both sides.

From Dale's RV Project - Elevator

View from the other side. You have to work your hand down in that lower gap, hold the bucking bar against the rivet (which you can't see) then rivet from the far side. Very tight fit, and everything has to be done by feel.

From Dale's RV Project - Elevator

Back riveting the bottom skin stiffeners. The cleco buckets help prop the skin up so I can get in to rivet.

From Dale's RV Project - Elevator

Pretty much everything has been riveted at this point. All I have to do is the trailing edge.

From Dale's RV Project - Elevator

Working on the trailing edge. There is a thin (3/16" by about 1/2" wide) wedge shaped piece of aluminum called an AEX wedge that goes in the back of the trailing edge to make a nice clean line. The wedge is put in position and both the wedge and bottom skin are match drilled to the pre-punched holes in the top skin.

From Dale's RV Project - Elevator

Match drilling the AEX wedge. There is a 2x2 1/8" thick aluminum angle on the back to hold it dead straight. Drill through the skin, wedge, bottom skin, angle *and* the table and cleco the entire thing (including table) together. Want this dude absolutely straight. Any irregularity will affect the flying quality of the plane.

From Dale's RV Project - Elevator

Countersinking the AEX wedge which is used for the elevator trailing edge. The piece of hinge in front is just being used to keep the wedge level. The AEX wedge is about a 12 degree wedge of aluminum about 1/2" wide.

From Dale's RV Project - Elevator

I realized I haven't described machine countersinking, so since I just showed the result I'll show a picture of how that happens (yet another cool tool).

This is the business end of a microstop countersink tool. Basically a tiny drill press, but this has a countersink tool in it instead of a drill bit. The barrel is finely threaded so this can be adjusted to within a few thousandths of an inch. Very precise. Used to make a countersink in aluminum so the rivet will fit exactly flush with the surface.

From Dale's RV Project - Elevator

Microstop countersink in action. The center piece is spring loaded. To use you chuck this in a drill, get it adjusted, then put it in the hole you want to countersink and press down.

From Dale's RV Project - Elevator

Once the trailing edge is dimpled and the wedge countersunk, it gets scuffed, cleaned with acetone, then glued together using proseal.

Proseal. Has an evil reputation for being unbelievably messy. It's like very thick nutella. Not as bad as I feared, and sticks like mad to anything.

This stuff is also used to seal the fuel tanks (that is actually it's real purpose, but Van's like to use it for other things since it is a good adhesive and not horribly expensive).

From Dale's RV Project - Elevator

And this is the final result of all the work on the trailing edge. Let this cure about 48 hours, take out the clecos, then *very carefully* back rivet the whole thing making sure to keep it dead straight.

From Dale's RV Project - Elevator

By the way, the adhesive has nothing to do with the structure of the airplane. It's just there to hold everything straight so it can be riveted. The rivets do all the work structurally.

Jeff Moreau suggested I use some proseal to fill a tiny gap I had in the trailing edge of the rudder that I didn't like. Since I had some proseal left over, and it will not keep, I did exactly that. Good idea Jeff. Thanks!.

Trailing edge of the rudder with some proseal in it. I'll trim it flush once it's cured.

From Dale's RV Project - Elevator

July 16th, 2011

Still working on the right elevator. This week I mostly finished the prep work (cleco together, match drill, take apart, deburr, remove all the stress risers and tool marks from the parts, scuff and prime).

Making an airplane consists of putting things together and taking them apart a bunch of times. For the elevator, I probably put the whole thing together 4 or 5 times, fitting, drilling, dimpling, etc. The actual assembly and riveting goes very fast.

It's a *lot* like painting. I've heard painting described as 90% prep work and 10% painting. This is pretty much the same. You don't have anything but a pile of parts until the very last, and then it goes together very quickly.

Match drilling the right elevator skin. Under each line of clecos (silver things that look like bullets) is a stiffener. There are some stiffeners on the bench to the right of the photo. Once they are all in place I drill through the skin and stiffener to ensure the hole is correctly sized for the rivet and that the holes exactly match the part that will be installed.

From Dale's RV Project - Empennage

This is the right elevator spar. The two square plates are reinforcement plates, and the dark grey part riveted to it is called a nut plate. The nut plate is threaded and allows us to put threaded parts into places we could not get a wrench into. Think of it as a way of permanently attaching a nut to a part we need to bolt. The rod end bearings for the elevator hinge thread into these from the other side. The hinge points are the square slots cut in the front of the elevator skin.

From Dale's RV Project - Elevator

July 9th, 2011

Worked on the right elevator all week. Basically the process is to trim all the stiffeners to length (I used my $25 garage sale band saw), then clean up the cut edges until they are nice and smooth.

From Dale's RV Project - Elevator

Also went back and riveted some tight spots on the rudder and vertical stab. My squeezer yoke wouldn't fit and had to wait for the thin nose yoke to arrive.

From Dale's RV Project - Empennage

Here's the pneumatic squeezer with the thin nose yoke. Won't go everywhere, but it comes close.

From Dale's RV Project - Elevator

Cleaning up the cut edges of a stiffener with a scotch brite pad in the bench grinder.

From Dale's RV Project - Elevator

( stiffeners are used on the thin skins of the rudder and elevator to lend strength and stiffness without adding a lot of weight)

Here's what they look like all cleaned up; primed, dimpled and ready to install.

From Dale's RV Project - Elevator

Counterbalance ribs being match drilled. Lead weights will go in the 3 open holes on the squared off end to balance the elevator. They had to be trimmed down (easy to do on the band saw) and won't be final balanced the tips are installed and final painting is complete. They can be adjusted by drilling additional lightening holes in them.

From Dale's RV Project - Elevator

Once everything is match drilled, the skins, ribs and spar are dimpled.

From Dale's RV Project - Elevator

July 23rd

Working on the right elevator the last week or so.

The elevators are built

July 16th, 2011

Had a lot of interruptions (and a visit to Busch today to go coaster riding with Becca :) so progress on the right elevator has been a bit slower than the usual pace.

I've been doing the cleco, match drill, deburr, dimple dance with right elevator parts for the last week or so.

Also got to go