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I was watching a YouTube about installing the turtle deck and he actually attached the formers to the skin at the splice channel prior to setting it on the fuselage. I'm not sure if he drilled the pilot holes into the formers at all at that point. They were kinda dangling but he didn't appear to have done anything with the floor yet. I clecoed my floor in very accurately to make certain that the fuselage was square and I've measured diagonally in several different locations and it's on the money. Obviously I have to remove the floor to get inside for the turtle deck. My concern is that I'll jostle it around and it will get out of alignment and I'll have it anchored in that position with the turtle deck and then when I reinstall the floor it won't match the holes in the longerons underneath. Am I overthinking this?
I thought maybe I could tuck the turtle deck skin behind the side skins and go ahead and drill and cleco the formers then reinstall the floor to make sure the fuselage is square then drill the turtle deck to the sides and reposition it on the outside of the lower skins. I don't have the plans with me but I'm pretty sure I was supposed to fit the bottom skin when I did but not rivet it until later.

Don't rivet the bottom skin until the day before your inspection! Clecos are fine. Believe me, you will need to get in there hundreds of times until then. These are pictures of my bottom skin going on the day before my DAR inspection.
http://www.mykitlog.com/users/display_l ... 0851&row=2
http://www.mykitlog.com/users/display_l ... 0899&row=1

As John Monnett likes to say, you're not building a Swiss watch, so don't over think it.

Have you checked out other Sonex build sites? Usually the turtledeck skin is joined with the channel that runs down the spine, and then installed before any formers are installed. The formers get installed after the skin, not before.

http://www.mykitlog.com/users/display_l ... 97&row=111
http://www.mykitlog.com/users/display_l ... 67&row=109
http://www.mykitlog.com/users/display_l ... 88&row=108
http://www.mykitlog.com/users/display_l ... 64&row=105

Unless the Bs are different, the turtledeck skin is supposed to go between the longeron and lower skin. Not on the outside.

I haven't paid close enough attention to the skin overlap yet other than the assembly order mentioned a 1" overlap. I guess the rules in building construction don't necessarily apply to airplanes. I just assumed the lower skin was under the upper skin to make it more water resistant.
I'm mostly concerned that when I remove the belly skin to work on the turtle deck that there's nothing to keep the fuselage square and it'll get jostled around and once the turtle deck is locked in place the belly skin won't line up with the holes. Even if I can shift it around enough to get the holes to line up again, would that throw a wrinkle into the turtle deck?
I have a partial sheet of 3/16" plywood in my shop. Maybe I'll cut a piece large enough to cover the underside of the 2 forward bay's and use the belly skin to drill holes in it and cleco it in place to keep everything stationary and work from the back to the front. I can probably work the 2 forward formers from the front opening without having to remove the plywood. I could probably get away with leaving the belly skin off and just pop the plywood off and on when necessary. Thanks for the feedback.

You are over thinking this. Forever forward!

For what it's worth, I took off my lower aft skin after updrilling and set it in the corner of my basement (and then the corner of my hangar) for 3 years/1200 build hours. The only time it went back on the plane was when I joined the forward/aft fuselage together to up-drill rivet holes to the fwd fuselage floor, after which I took it right back off. I did my turtledeck, put the plane on wheels, hung the engine, rigged the wings, installed/rigged my stabilators/rudder/flight controls, moved the plane to the hangar etc etc all with the aft fuselage floor off, and when it came time to finally attach it at the end of the build it fit just like it did 3 years earlier.

I wouldn't worry too much about losing your "square" aft fuselage by removing the floor as long as the rest of the tail cone box is riveted up.

Here's the process I used installing my turtledeck, which I believe is the same way it's called for in the plans with the exception being that I didn't rivet the "spine" until the very end, instead using an absurd amount of clecoes. My idea was that I wanted all of the rivet holes fully drilled (including the formers) before disassembling the skins and polishing them. In hindsight this didn't really make things any easier and I'd probably just follow the plans (fully rivet the spine before doing the formers) if I did it again. I ran a high risk of bending up the skins at the spine if I didn't use enough clecoes which thankfully didn't happen.

http://www.rynoth.com/wordpress/waiex/2 ... eck-cleco/

Another thing I notice looking back at those old photos is I had the bottom of the aft fuselage supported directly on a piece of wood with no padding, which is probably a bad idea since the side panel skins (by design) protrude slightly beyond the lower longerons, meaning the edge of the skin is what was touching the wood rather than the longeron. Again, something that could have bitten me but ended up being OK.

wingnut wrote:I haven't paid close enough attention to the skin overlap yet other than the assembly order mentioned a 1" overlap. I guess the rules in building construction don't necessarily apply to airplanes. I just assumed the lower skin was under the upper skin to make it more water resistant.

The turtle deck definitely goes below the side skin. You'll see when you put it on, but you'll need the force of the outer skin sandwiching the turtle deck skin against the longerons to keep the bottom edge of the turtle deck nice and flat. If the turtle deck was on the outside, the bottom edge of it would bulge outward. I think it will make sense when you do it!

As far as water, I can't imagine much would leak through that seam, and even if some did it would probably just leak back out the bottom floor anyway.

Funny story that has probably been told before. I visited the Sonex factory in 2006 when I was thinking about building my first Waiex. I asked John about that turtledeck fitting under the fuselage side skin. I thought if it was outside the water would not get in as much. His answer to me was "Water gets in everywhere, it also gets out everywhere". So... do it the way the plans say and don't think too much!

I had the same fears of the whole shebang getting out of alignment while doing the work on the turtledeck/formers, so I never did completely remove the bottom skin. Un-clecoed whichever end I was working on, and rolled that half under the fuselage.