Sunday, December 10, 2017

Riveting the right wing top skin

This week I finished the dimpling of the wing ribs, trimmed the corner where the two skins overlap, and started the process of riveting the skins to the ribs.  I know I've mentioned this before but all too often I come upon a step in the process that seems like it should be very quick.  Take this next step of riveting the top wing skin on.  If you look at the first picture below it looks like I'm ready to start riveting right?  Well, that's not really true.  First I have to load all the rivets in their respective by hand.  OK, sounds like a pretty simple, but time consuming process, but its not that simple because its not just a single size rivet...its several different sizes of rivets and they have specific holes they have to be in.  I suspect that it will take me about 2 hours just to load the rivets.  Then I have to place a small piece of scotch tape over each rivet to make sure it doesn't fall out of the hole before I am ready to smack it with the rivet gun.  That's probably another hour.  Then I'm ready to start riveting....but wait, I can't reach both sides of the wing myself so I will have to have some help riveting... enter Harry....again.  Harry is always there when somebody needs some help and even more often when that help is airplane related!  Harry came over on Saturday evening and helped me rivet the top skin.  It was pretty darn quick having two guys who know what they are doing.  We managed to do the entire wing in less than 4 hours!  I think each skin on my 9 took close to 8 hours.

One note I will make about these Van's kits... These pre-punched parts are awesome!  Before attaching the top skins to the spar/rib assembly I put a digital level on each end of the spar to measure for twist and found that there was as much as 1 degree of twist.  That concerned me so I clamped the spar down to the bench with the appropriate support so that it was perfectly strait before I started fastening the skins to the assembly.  After completing the process I measured the twist again without the clamps in place and there was no twist!  Now I have to make sure I keep it that way as I rivet the top skins in place.

Right wing ready to start loading rivets.
All rivets loaded and taped...except for the holes with cleco's of course.

I took this picture so I could show how I handled the skin overlap joint at the leading edge of main wing skin.  These two skins overlap each other and where they mate up at the spar will be double height if you don't do something.  Van's suggests that you grind down each to about half height and then rivet in place.  I tried that on my 9A wings and found that getting a good smooth transition was almost impossible.  This is my answer.  I trimmed the bottom skin back to just aft of the main spar (up in the photo).  Now the top skin lays flat on the spar and the lower skin is supported by the rib.  I did this on all 4 joints on my 9A wings and it worked out nicely so I decided to do the same on this wing.
Wing skins riveted on with the exception of the inner most row where all the nut-plates are.  I finished that up after the picture.

Outboard aileron hinge is the last step in this section and its done!  

I need a place to store the wings now that they are coming together.  This cart will allow me to store them both in the garage here and in the hangar when I am done with them.  As you can see the garage workshop is rapidly running out of room!