Countersink trailing edge wedge

Posted on by Neal

Tonight I counter-sunk the rudder trailing edge wedge. I used the Cleveland tool jig and counter sink, and was happy with the results.

Because of the shape of the wedge, and the fact that the hole is perpendicular to the wedge chord line while the counter sink is perpendicular to the face of the wedge, the holes ended up slightly oval looking, with a knife edge on the trailing edge side. From researching ahead of time, I think this is normal and not an issue. The wedge’s job is to hold the skins at the correct angle, while the rivets pass straight through with the heads gripping the skins, not the wedge.

Here are the completed rudder parts, ready for final assembly:

Over the last few days I did a couple of odd jobs, including dialing in the counter sink and practicing with wedge scrap.

I bought some side cutters and ground the face flat, then fixed the pop rivets with the broken mandrel.

I also made a start on the Horizontal Stabilizer by straightening out a couple of the doublers that were bent from the press.

Rudder shear clips

Posted on by Neal

I finished back riveting the stiffeners to the left skin, then moved on to riveting the bottom rib to the right skin. With that done, I pop riveted the shear clips onto the left skin stiffeners.

Everything went well, except for a pop rivet where the shank broke off in the wrong place. I will need to pick up some side cutters and cut it off. Not sure why it broke there, perhaps I twisted or flexed the hand tool as I was giving it the final squeeze.

My countersink for the trailing edge wedge won’t arrive until Monday, so I’m blocked on the rudder now until that arrives and I can get that done. I started reading ahead on the Horizontal Stabilizer to see what I can get done over the weekend. Looks like plenty of deburring to keep me busy for a while.

I also looked at the timing for Vans to ship the next few kits. I need to make a decision in the next couple of weeks as to whether I want to go the quick-build route, or slow build. The slow-build kits have a 10 week lead time, and the quick build kits are 5-6 months. If going the quick build route, Vans recommend ordering the fuselage and wings together, or risk a longer delay. While I’m not in a hurry to finish, the idea of saving a year or more of work is certainly appealing. On the other hand, the idea of knowing every piece of the airplane, every rivet, bolt, nut, fitting, wiring run etc, is appealing.

Back riveted skins

Posted on by Neal

After a little practice on some scrap aluminum, I back riveted the stiffeners onto the right rudder skin tonight. It was getting late by the time I finished, so I didn’t try to tackle the left skin. Riveting at midnight isn’t ideal with young kids sleeping in the house. It was a little slow at first as I measured each rivet with digital calipers to calibrate my technique. In the end I was moving quickly and getting a consistent head on each rivet. A couple of rivets ended up driven slightly more than I was aiming for, but are still within tolerance.

This was my setup, with a practice piece on the back riveting plate.

I started with this stiffener, and was happy with the results. I later increased the PSI from 20 to around 22, and the difference was noticeable; fewer hits needed to form the shop head. I’m using a 3x gun, which has a lot of power.

Here are all the stiffeners fastened to the skin:

I realized yesterday that I don’t have a #40 countersink that will work on the trailing edge wedge. Because the countersink is flush with the side of the wedge, but the hole isn’t (it’s perpendicular to the chord of the wedge), I need a countersink with a short and/or tapered pilot. I could probably grind one down, but I only have one. So I went ahead and ordered the special part from Cleveland tools. $20, and will arrive on Monday. That means I can’t finish the rudder until next week, but what’s the rush? I can always start on the Horizontal Stabilizer.

Dimpling rudder spar and stiffeners

Posted on by Neal

I finished dimpling all of the rudder frame components tonight. It was a straightforward process, except for a couple of spots on the spar where the shop head interfered with the squeezer. If I had oriented the rivets so that the manufactured head was on the forward side, it wouldn’t have been an issue. At the time I set these rivets, I was thinking about putting the manufactured head on the side with the thickest material, but in hindsight I would have set these the other way around, since the shop head is a fraction of on inch too high to get the dimple dies to sit square to the hole. Not a big deal, I was able to use a hand tool to get a reasonable dimple on them.

Rudder skin deburring

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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 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

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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.

Rudder counter weight

Posted on by Neal

Tonight I covered just a couple of steps in the plans, fitting the rudder counterweight into the rib that will hold the weight. This was a quick process of final and match drilling a couple of #12 holes (drill size), deburring, dimpling (for a #10 screw), then counter sinking the lead weight to fit. I used the drill press to get nice straight holes, and it came out perfectly.

My adjustable set for my pneumatic squeezer should arrive on Thursday, which will allow me to finish the Vertical Stabilizer. I’m also about ready to prime the rudder components, as I have done as much as I can before I need to start assembling parts.