Zipping up the Aileron/Trim Tab

2-16-18 – 7 hours spent

So today’s goal was to close the dimpled aileron.  This was a lot of work, because 1) I don’t like pulled rivets, and 2) the internal structure that was added to this aileron to strength it for the trim tab did not lend itself well to using solid rivets.  Still, whats building an airplane for if you don’t like 3D puzzles?

So here is the skeleton clecoed together.  I started with the squeezer, and I wanted the rivet heads (factory) to be facing outward if I ever needed to drill them off and open the rivet.

Unfortunately, the squeezer wouldn’t fit all the locations, so the long #4 rivet set comes out and into play.  And I got out the first bucking bar for the day.

Now its time to drive the skin rivets into the top of the aileron.  This is a relatively simple operation, as the way the skin wraps around the bottom of the aileron, the top rivets are pretty easy to reach.  Other than the need to use LOTS of clecos to keep the dimples nested, it should be pretty straightforward.  And the rivets go in one by one until

Uh Oh!  Somebody (me) screwed up the dimpling.  Here you see the pretty dimple on the skin – but you will notice it isn’t lying flat.  That’s because I didn’t dimple the hole underneath it.

I was going to countersink this hole, because the dimple die doesn’t fit due to the nutplate that is in the way.  There is no way the dimple die would fit before – but now I am up a creek without a paddle.  There is no way I’m drilling out all those rivets and countersinking the hole, and I can’t countersink the hole with the skin over it.  I built that rivet gun dimple adapter yesterday, but that won’t work without a low profile female dimpler.

So its time to modify another bucking bar.  The foot of the standard bucking bar makes a great female dimple die.

And its hard to see in the pic, but now I have ALL the holes dimpled, and the rest of the rivets in the top went in smoothly.

When I say smoothly, that may be a bit of a stretch.  You can see the tools and the coffee mug.  One rivet at a time.

And here is the results on my hand.  Lots stress and one bandaid…

Before zipping up the back, I think that I’d better zip up the trim tab.  It’s going to be a difficult process.

And so I’m motivating by looking at the top surface of the aileron.  I’m pretty happy.

Although if you catch the light right, it isn’t perfect.  Still, it beats a lot of production aircraft…

So before closing the trim tab, I need to add a control horn.  I’m going to put it near the center.  It would be so easy to just make an angle and rivet it on the outside, but I need better than that.  After all, this is probably the only RV6 I’m going to make…

Here is a first try to sketch a control horn that works.  But I really want to catch the front spar and the center rib.  Probably overkill, but I want to make sure that there is no way that fatigue can crack that skin.

So here is the trim tab control horn sitting on the end of the tab.  Of course it needs to be mounted in the middle.

And its going to need a slot cut in the skin.  The most important measurement for this is the alignment with the side of the rib.

Clearing out the slot with 1/8 drill bit.  Then a set of needle files to finish it up.

Here is the control horn sticking out of the slot.  Now I need to ensure that the horn is appropriately situated inside when I drill the holes.  I held the horn against the spar and the rib at the same time, and drilled the angle to the spar.

And here is the horn.  I got the three holes drilled into the spar and the control horn.  I also drilled the back of the control horn, but I have not drilled the rib.  I can do that last – after that aileron is skinned.

Now I have to zinc chromate the control horn.  Back to closing the aileron while I wait until the chromate dries…

Its going to need to be done in the exact right order or there will be no way to git-er-done without those unfortunate “pulled” rivets.  (Spits on floor.)  The good news is that I found the perfect bucking bar.  This little beauty fits exactly in the spot it needs to.

So here goes.  First the underside of the two nose ribs – one faces each direction (outboard).  After I got those three rivets on each nose rib, I had to tuck the rear skin under the front skin.

After tucking the skin in, I used a LOT of clecoes to make sure the dimples align.  Luckily, the trim tab cutout lets me get in there with a long bucking bar.

And here is one side of the aileron closed.  The other side will be a little easier IF I remove the rear rib from the other side, I use my long bucking bar.  But I’m out of time for the day, and its time to quit.

Before I put everything away for the night, I did want to take a picture of all the bucking bars I used today.  So glad that I have a lot of options on the shelf.  There is no way I could do this without pulled rivets if I didn’t have the tools…

Leave a Reply

Your email address will not be published. Required fields are marked *