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Flap Nose Skin

JDBoston

Well Known Member
Each new section seems to introduce a structure I am unfamiliar with, so I will ask this basic question:

When assembling the flap should I expect a bit of "preload" or force needed in order to make the top part of the nose skin line up with the nose ribs (and top of the spar) and cleco the assembly together? The rest of the structure seems to come together pretty well however once you slide the nose skin on from the bottom, you then need to push quite a bit in order to get the holes lined up with the top portion. It also seems like there is a little bit of a gap between the skin and the rib below as you need to drill holes into the rib using the skin as a guide.

Hopefully that was clear. Anyone else have this issue?

I am also a bit paranoid about twist, and how to identify it and prevent it as I assemble.

Thanks
 
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Flap nose skin

Jeff. I built the ugliest aileron known to man! On my 9a.
I had to chuck it and build another one. The upward force
Of the pre-bent nose skin unclamped before riveting to the spar,
created upward force and tweeked and twisted the trailing edge in the worst way. When you bend the leading edge down to the spar, put a board the full length and clamp it down. Clamp the trailing edge down to a flat surface and glue with 3m 5200 quick cure purchased from HOme Depot. 5200 is an amazingly strong marine sealant. Use gloves! It's equally bad as pro seal to deal with. The trailing edge ends up straight as an arrow. My recommendation is glue
The trailing edge before riveting.
 
Thanks Al. Hope all is well.

It is my first time dealing with a nose skin as most of the other surfaces so far are nose/large skins where there is not much preload at all.

I took it apart again as some of my problem was the clecos holding together some of the rib assemblies getting in the way. On the second time assembling there was less force needed although more than I would have expected. I think I am all set now though.
 
On my RV-3B, this is how I prevent twist in the surfaces - I made a jig:

1072qg0.jpg


The jig is simply two pieces of plywood with vee cuts to match the surface, mounted on a piece of plywood that I could shim to get the vees aligned.

Dave
 
Flap nose skin

When assembling the flap nose skin to the flap (with top & bottom flap skins clecoed in place), cleco the bottom nose skin to the bottom flap spar and try using a couple of ratchet straps around the nose skin & flap to help pre-load the nose skin to the top spar in order to make the top part of the nose skin line up with the spar and cleco together.
 
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