<September 18, 2005>
Riveted the Left Elevator
Today was actually two building sessions. The first between the hours of midnight and 2am, the other Sunday afternoon. Technically both were on the 18th, so I am logging them as such. In the late night hours, I riveted the elevator skeleton, and then the next afternoon I worked on the elevator tab and skin.
Update… Read my comments on Trim Tab bending posted in the Van's Air Force forums.
Here is the skeleton all riveted together, no problems this time! ;-)
I started working on the skin by placing a gob (technical term) of blue (sensor-safe) RTV between the aft rivets of the stiffeners. From what I hear, this helps with vibration (and cracking).
To bend the elevator tab, I started by drawing a line perpendicular to the edge of the trim tab cut-out in the skin. If I had to do this again, I would have drawn the line about 1/32" further inboard... read on...
I fabricated some wooded blocks, and using double sided tape to assist in holding them in place, I clamped everything to the edge of the workbench. What you can see is the other clamp off to the left, keeping the skin from rotating. I then started by bending the lower tab down (the elevator in upside down) by using a scrap piece of wood. This worked pretty well, but it really wasn't very close to 90-degrees.
I then followed with my rivet gun (set at about 20psi) and my flush set. This completed the bend quite nicely, making it almost perfectly flush with the wooded jig.
I then bent the upper tab up (sound strange but true), first with the scrap wood, then with the rivet gun and flush set.
The finised tabs. Unfortunately, even with the rivet gun turned way down and the trigger only slightly depressed, the flush set still does a number on these skins. If you look closely you can see a few of the dings and dents. They are very shallow (approx 1/64") but they are there. If I had to do it again, I would have place a this piece of wood between the tab and the set to absorb some of the direct shock and to spread out the pressure. Oh well, it is very minor, and a very small amount of will even it out.
While in general, I am happy with the way this turned out, I think I might end up with a large gap than I want between the elevator and trim tab. I drew the line and set the wooden form into place thinking the bends would be more gradual. Nope, after using the rivet gun, they are curved but tight. I think offsetting the line and form inboard 1/32" to 1/16" might have helped. We will just have to see what happens when the trim tab is bent.
After the tabs were bent, I riveted the left elevator shut. No major problems here, other than a few holes that didn't perfectly line up and had to be reamed again. I used MK-319-BS pop/blind rivets in a few places here, but I ran out before I finised the job. I borrowed the needed rivets from another builder, but this is now the 2nd time I have been short rivets. Van's needs to throw a few more into the kits.