With the parts cured, I dimpled everything then started putting the skeleton together. The spar and the spar doublers went together much like they did on the vertical and horizontal stabilizers, but the rudder now has platenuts that will connect rod end bearings for attaching the rudder to the vertical stabilizer.
The platenuts only have two holes, and each had a small gap between it and the spar when only one cleco is installed. To keep the platenuts flush for riveting I used a spare bolt and nut to lightly tighten the platenut to the spar.
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| Much better! |
The rivets called out for use with the platenuts are AN470AD4-5, which are the same length as the rivets used to fasten the spar doublers to the spar. With the addition of the platenuts' thickness, these rivets didn't seem long enough to provide a thick enough shop head. These are critical components and I wanted to be 100% sure that they wouldn't fail, so I just used slightly longer -6 rivets instead. Looking ahead at the elevator diagrams, the platenuts for those are called out to be one length longer than the rivets used for the doublers. I used that as justification for using the longer rivets here.
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| The longer rivets were a good choice. The shop heads would have been pretty thin with the shorter rivets... |
The ribs needed to be dimpled before the can be attached to the spar. The aft end of the R-904 bottom rib is too narrow for the regular dimple dies to fit, so I had to get creative and use the close-quarters dimpling kit I got from Cleveland tools.
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| The female die is fixed to a piece of steel and screws into the table. I put the male die in a spare 2x4. |
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| With the 2x4 in place on top, all I have to do is put the rib between the dies and smack the board with a mallet. The clamps keep everything from going flying when the hammer comes down. It's crude, but it works. |
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| Success! |
The ribs got riveted onto the spar and I managed to get the horn brace and lower fairing attach strips on without much trouble. There way no way I was going to get the bottom four rivets with the squeezer or the bucking bar, so I used some LP4-3 pop rivets instead. Problem was, I only had three left. Not a big deal since I can order more once I place the order for some tank sealant. Oh yeah! That part's coming up soon!
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This part will be hidden by the bottom fairing, so trying to get solid rivets in these holes probably isn't worth the trouble.
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