Rudder skin deburring

Posted on by Neal

Tonight I finished deburring the other rudder skin, and then took apart the rudder frame which was clecoed together. I made a mistake at one point, as I was deburring a hole in the skin with a counter sink in a hand tool, the tool slipped out of my hand and fell sideways while the countersink pilot was in the hole. This levered up and bent the skin, so I ended up with a bend up on one side of the hole and a bend down on the other. Luckily the skin didn’t crack, but it was very frustrating. Then I started the dimpling process by dimpling both of the skins. It was a long process, as I went slow and tried to avoid any scratches or mistakes. I started with the hole where I had bent the skin while deburring. As I hoped, putting a dimple in the hole straightened out all the damage, leaving no trace of an issue.

Next steps on the rudder will be:

– dimpling the stiffeners, ribs and spar – Monday

– counter sinking the trailing edge wedge – Tuesday

– back-riveting the stiffeners to the skins – Wednesday

– riveting the shear clips to the spar – Thursday

– pop riveting the skin stiffeners (with skins attached) to the shear clips – for this step I will need help; maybe Friday night

– riveting top and bottom ribs – Friday

– riveting the trailing edge – Saturday

– rolling the leading edges and pop riveting them together – Sunday

If all has gone well, it will be finished!

Rudder final drilling

Posted on by Neal

I rigged up a better solution for my air hoses today, then final drilled the few holes that need it in the rudder. Most of the rudder parts are pre-punched to final size, and just need a little deburring. Then I debuted the skins, getting ready for dimpling, then assembly.

Here is what I ended up with for air hoses:

It’s much better with the hose coming down from the ceiling than to be dragging it around on the floor. The coiled hoses are very light weight, and are only rated to 120 PSI, which is well above anything I’ll be using them for.

I made up a little template to assist with the trailing edge drilling. The holes need to be drilled perpendicular to the chord line of the trailing edge wedge, which turns out to be 6 degrees forward of square with the skin. I found that the drill naturally hits that angle because the trailing edge wedge is already drilled to that angle, and the skins are so thin, it’s easy to get it pretty close. On a couple of holes the drill caught the upper (left) skin, and ended up enlarging the hole slightly. Once dimpled, will see if I need to do anything about it.

I final drilled all the holes in the top ribs, and matched drilled one on the front, but didn’t get a picture.

Then it was onto deburring, which is very carefully done given how thin the skins are. I made up a practice piece to see how excessive debuting affects the hole, after dimpling. It’s amazing how a few spins with the deburring tool remove enough material to really expand the hole diameter once dimpled. I got all of the left skin done, and partly through the left one, but I’m so tired I need to go to bed now. Will tackle some more tomorrow.

Rudder assembly

Posted on by Neal

Tonight I clecoed together the rudder in preparation for final drilling the trailing edge and ribs (counterweight support and tip rib). It’s interesting how some parts are punched to final size, while others are not and require final drilling. At least all the stiffeners and corresponding skin holes are final size, that will save me drilling and debuting several hundred holes.

First I clecoed the ribs and stiffeners to the spar:

Then measured and cut the trailing edge wedge to length, and marked the skin where I’ll scuff with scotchbrite for extra adherence of the tape that will hold the wedge and the skin together while it’s riveted.

Then it was time to cleco the skins onto the frame. Here’s a picture of the whole structure clecoed together:

The next step will be to final drill the trailing edge holes in the skins and the trailing edge wedge. You can see the end of the wedge in the picture:

Drilling the trailing edge is tricky because the hole must be perpendicular to the chord line of the wedge, which means it intersects the skin at around 84 degrees instead of 90 degrees. Getting it wrong leads to a cascade of problems culminating in a wavy or curved trailing edge. I really want to get this step right the first time!

Riveted rudder frame

Posted on by Neal

Tonight I riveted together the pieces I had clecoed to the rudder spar. This took a little longer than I had planned, as I needed to test my squeezer on a few of the longer length rivets. I also took the chance to review plans and decided I should dimple in a couple of spots that would be hard to reach later.

I was able to squeeze all of the rivets except for one where I needed a double offset piece and my heaviest bucking bar. After a few runs at it, I had a good looking rivet. Somehow I ended up with a little smily face, but I was just happy to set it set correctly. These are seriously long rivets, 9/16 of an inch long, and 10/16th for the nutplate rivets. You can’t tell from the pictures below, but there are 4 layers of aluminum that these rivets are holding together, including the rudder horn which is around 3/16 thick.

The one remaining hole is to secure a cable tie attach point, which I’ll pop rivet on tomorrow.

Here’s the whole piece as it currently stands. This really is a big rudder!

Finished Vertical Stabilizer

Posted on by Neal

I set the last few rivets in the Vertical Stabilizer tonight, then clecoed together the rudder spar, plates, shims, and a couple of ribs. They are ready to be riveted next.

I ended up bucking most of the rivets in the trailing edge of the VS, and they all came out ok. A couple of the shop heads are right at the max allowable dimensions. I contemplated drilling them out and redoing, but the reality is that the removal process will likely cause more harm than good. Since they are still acceptable by my measurements, they are staying as-is.

The last 3 rivets are pop-rivets since the back side of the rivet is completely enclosed. I practiced a couple of pop rivets then set these without any issues. Here is the final rivet before being set:

Here’s the finished product:

I picked up some more tools from Cleveland Aircraft:

I think the trailing edge tool will be a huge help in the near future as I get to forming the trailing edge of the rudder.

I clecoed together the rudder spar and the various pieces that are called out in the plans.

After this is riveted, some brackets are attached, the stiffeners are back-riveted onto the skins, the trailing edge is shaped, then the whole thing is riveted together.

Primed Rudder Parts

Posted on by Neal

I primed all of the rudder components today, starting with cleaning, then etching, then priming. Because it takes a while, and parts of it are time sensitive, it’s easier to do on a weekend day than in the late evening during the week. The job was much easier the second time through, and I was really happy with the end result. I have a nice light but complete coating on all parts except the skins. I decided not to paint the skins, because every part that touches the skins will be primed. If I end up scratching the skins, I may prime parts of them later. I am clear to start construction of the rudder frame now.

With the painting done, I squeezed a couple more rivets in the Vertical Stabilizer. Unfortunately one ended up sitting a bit proud of the skin, so I had to drill it out. It turned out to be a real pain, but eventually I got it out, without enlarging the hole.

I going to have to buck the last remaining rivets in the back of the Vertical Stabilizer skin, as I just can’t get a squeezer in to a few spots due the universal head rivets that hold the doubler to the spar.

Vertical Stabilizer Skin

Posted on by Neal

Today I riveted the vertical stabilizer skin to the forward spar and ribs, clecoed on the rear spar, and started riveting the skin to the rear spar. It was getting late and I was tired, so I decided to stop before I started making mistakes.

First, each family member signed one of the inside skins, leaving a few secret messages.

Then I started with some more experimenting with my adjustable squeezer set, and with some practice parts to get my rivet bucking skills somewhat current. I set up a cradle of cardboard and clean rags to keep the VS on it’s edge, which seemed like the best approach for bucking rivets.

Overall, I was happy with the way everything turned out. I had to drill out two rivets, both times the bucking bar slipped off the rivet. I was able to remove both without enlarging the hole, so replaced with the same sized rivet. The second rivet was annoying, as I somehow put a minor dent in the rib and skin when the bar slipped. I’m not sure how it happened, but the result is a slight bump in the skin near the rivet. The main thing is that the rivet set well the second time. You can see how the light is slightly distorted around the middle rivet in the picture below.

I was able to squeeze rivets along the edges of the skins, even the most forward holes on the top rib.

I can see why the plans recommend setting the manufactured heads aft on the rear spar. There is very little room to get at the skins rivets along the rear spar. I did the easy rivets with the squeezer, but I didn’t want to tackle those with less clearance tonight. I’ll try to finish up the remaining rivets on this piece tomorrow.

Squeezed Vertical Stabilizer rivets

Posted on by Neal

Tonight I received my adjustable set for the pneumatic squeezer, along with some scrap aluminum. I spent an hour drilling, counter-sinking and riveting some practice pieces, and documenting the settings needed for each length rivet. Then I re-squeezed all of the rivets on the VS spars and ribs, and they all came out great. The hardest three rivets are where the root ribs meet the front spar. There isn’t much room, and the ribs aren’t square to the spar. I had to switch to my rivet gun with a double offset piece to finally get those done.

With the rivets done, I can finally complete the Vertical Stabilizer. I clecoed the frame to one side of the skin in preparation for riveting. But it’s a bit late in the evening now to start riveting. I’ll try to knock it out tomorrow.