Friday, October 30, 2009

Another riveting tail (tale?)

Not so good, this one. But we'll get to that.

Building the rudder is eerily similar to building the vertical stab, starting with the preparation of the hinge brackets. Being as these are the brackets intended to attach to the vertical stab brackets, though, we are requested to test fit them. The brackets have to be attached to the vertical stab with bolts, which seems somewhat pedestrian after all of the cutting and riveting and other exotic machinations. The bolts needed to attach the hinge brackets to the stab are lumped into a brown paper bag with a collection of other bolts. As one bolt pretty much looks like the next, I had gotten into the lazy habit of identifying them by separating them into piles and determining their type by comparing the number in the pile to the number supposedly included in the bag. By doing so, I also accomplish an inventory of each bag. It was in the bag of bolts that I found my first inventory error:

It was the AN3-5A bolts that I was after, and it seems that I have one too many. That's all well and good, but the karmic balance was maintained through the exclusion of one AN3-4A bolt. I could pester Van's to send me one, but I'll just order one next time I buy other stuff and save them the hassle. They're not at all expensive. Even with the count disparity, I was able to determine which bolts were the AN3-5A and collect eight of them to attach the two hinge assemblies.

The top hinge assembly bolts into the nutplates that were installed early on in the building of the vertical stab. It was when I went to bolt on the bottom assembly that I realized there were no nutplates to bolt it into. My first reaction was to adopt the jaw-dropped look of utter confusion that I get when I try to use a self-checkout at Wal-mart; my second response was to look more closely at the manual. Oh, we tie it on with string or wire, and it will be permanently attached later. I remembered reading that, but hadn't full realized the import of it. Thought it could wait and all that. Luckily, I had some copper wire left over from the canoe debacle as was able to get a nice, tight temporary installation:

With that done, I needed to cleco the hinge brackets onto the spar that will be at the front edge of the rudder. The top hinge bracket is very similar to those on the vertical stab:

The bottom? Well, it's a bit different. It's powder-coated, welded steel. It needs to be far more robust because it also acts as the pair of control horns that the rudder control cables will attach to:

It was finally time to test fit the rudder spar to the vertical stab. This was again a matter of selecting bolts from the little brown bag and using them to attach the two parts. I can see already that this is going to be a real ugly chore when it comes time for the final assembly; it's tough to get the washers between the parts of the two assemblies. After finally getting the first of the bolts and its accompanying washers in, I realized that I had selected the wrong bolts. It was way too short. It seems that the counting and comparing method is not really the best strategy. After a bit of a search through the book that Van's thoughtfully included with the kit, I found a very helpful page printed in a very unhelpfully tiny little font:

After selecting the correct bolts, I repeated the process. The top bolt was even trickier than the bottom with regards to getting the washers in place and I had resort to using some of the left over copper wire to "fish" the washers into place:

Everything fit great. The manual offered the use of thinner washers wherever needed to improve the fit, but that option was not needed at all.

With the test fitting done, the next step was to start assembling all the little bits that will trail along behind the front rudder spar. The first of these is a rib. It gets riveted in through the spar and through the doublers used to strengthen the area where the upper hinge brackets will be. It gets riveted in with the same big, fat #4 rivets that were used to build the vertical stab hinge brackets. Remember how I said that I had read about people having problems squeezing those big rivets but that I had not had any real difficulty at all? You don't? Good! Because I got my comeuppance, good and hard.

The first rivet that I tried to squeeze in bent:

I drilled it out. Here's the head of it impaled on my drill bit:

That just leaves the shaft of the rivet in the hole:

With the thick parts I was working on before, it was a simple matter to just grab the remainder of the rivet with a pair of pliers and yank it out. It's not quite that simple with this thin aluminum. I had to disassemble all the parts and gently pull the remainder of the rivet out without bending or contorting the rib. That was such a hassle that I was extra careful to get the squeezer positioned correctly when I tried again. Well, the good news is that the shaft of the rivet squeezed straight. The bad news? Well....

The head is canted. Crooked. Not flush. Buggered. Lopsided. Sadly, it too needed to be drilled out.

I won't try to squeeze it again. Tomorrow I'll take it all over to the hangar and use my rivet gun to drive it (and the others) in. That will hopefully work better than trying to use the squeezer in the tight quarters of the inner flange of the rib.

1 comment:

Ted said...

Did you get a template for bolts? It is included in both my 9 and 10 kits. It is 4"x7" aluminum plate with a lot of holes. On one side there are four holes with different diameters, they are for #6 screw, #8 screw, #3 bolt, #4 bolt. You need to mark them yourself. Then there are holes for measuring the length of bolts. It is really handle for identifying bolts. I also wrote down the drill sizes and torque values on it. If you don't have one I will send you one of mine. You will have to wait since I am out of town for a week.

As for your AD4 rivet, make sure you are using the right length rivet. From the picture it looks too long. When a rivet is too length it bends! Squeezing AD4 rivet should not be a problem. Adjust your squeezer gap so when you are done squeezing the two handles are closed. The real fat rivets are those on the wing spar and fuse central spar. Mercifully, Van did it for us using hydrolic press.

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