Matchdrilling work continues on the center fuselage. Now that all ribs are matchdrilled, time to position and drill the F623 corner ribs.
As it was not very clear to me how the skins butt against these flanges, I decided to go and have a look at my fellow builder Hugo's RV9.
The forward side skin actually only touches the flanges on the forward side (in the image below on the bottom right side, so where the cut at the end is the widest). That's where the skin will touch the corner rib. The other side (bottom left) is where the folded part of the skin willl pass but not touch the flange.
Also the long straight edge has no connection to any other part.
I shot the picture below to show you the fluting that is requred to get this part to sit straigt. The reason why I wanted to know where the skin touches is because you need to know where the prepunched skin holes will so that you can flute right between them.
I got the side skins out and temporarily hold them in place to make some sharpie marks on the flange of F623.
Once that was done, it was not that difficult to straighten the flanges to 90° and flute until the flanges laid flat on my workbench.
Next, I positioned and clamped the F623 corner rib to the bottom skin.
At this point, my visit to Hugo also paid off.It's good to know that the side skins lays next to the bottom skin. In other words the side skin lays next to the bottom skin. (NOT on top of the bottom skin). I used a strip of stock sheet and clamped it to the flange of the corner rib. This helps making sure the side skin will fit perfectly when installed.After some realigning I got it on the right spot.
This is a shot from the bottom where the corner rib almost touches the F705 bulkhead. A thin line between them. very good !
This is the end of the corner rib on the other side. I used my spacer part again to make sure I know where the F706 flange will end.
From the side, check that the side flange of the F705 bulkhead to the flange of the F623 corner rib has a nice transition.
Here you can see that the flange of the cornerrib will mate nicely against the side skin.
Then started by drilling #40 some of the holes, adding clecoes as I went on. This way, the corner rib is quickly demobilized and fixed into it's final position as you can then drill the rest in a more relaxed way.
And here it is, completely drilled.
That's how the holes look from the bottom side.
Finished the other side in the same way.