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Showplanes Fastback Turtledeck advice

JDA_BTR

Well Known Member
I've tried a few things (lots of things) and need some advice. I've got the showplanes fastback top skin on across the three bulkhead tops supplied by Showplanes. I marked the approx hole location and fluted. Drew a line down the middle of the flange.

I'll be derned if I can get the middle of the flange in the hole center to drill it. The aft most bulkhead is the one I'm on; was going to move forward one at a time. To get a hand on it I put the skin on with the aftmost small bulkhead and aft deck on, then once the skin was on the longerons both sides I removed the aft bulkhead to get hand access to the first aftmost Showplanes bulkhead.

It is a slippery devil. Is this just a two-person job and I need to get a helper? Or is there a better way I haven't thought of yet? The goal is to start at the top and work down to the side each side.
 
I plan on doing the fastback mod too, so I'm curious as to how this goes. . Would some nylon ratchet straps at the bulkheads help hold down the skin tight?
 
When I was fitting/match drilling mine I had a helper use a wooden stick with a notch cut in the end so he could push or pull the bulkhead to reveal the thin blue sharpie line I had drawn on the flange.
 
Egg nog and a head scratch gave me the idea of tying a string to it. Might work to pull it aft while I drill.
 
Yes running a string thru the lightening hole worked great to pull the web back to center the flange. Hand for pushing forward to align subsequent holes. Easy.
 
Process

I'm assuming you already have holes in the longeron but no holes in the turtle deck skin?

If you already have holes in the top skin you can also cheat a bit by just marking a centre hole on the rib. Centre the skin exactly where it will end up on the rib (no need to even ratchet it down) and mark the hole on the rib with a sharpie. Remove skin and drill the marked hole in the rib. Clecoe skin on - at least this will get you started centering it

A bit different than my setup but if no holes at all I would:

1. Use threaded rod and nuts through the ribs the hold them parallel - just like good old days. Prob 3 rods required. Draw thin centreline on all bulkheads

2. Put skin on, use thin pieces of wood (I use household wood trim duct taped in place) and ratchet straps to pull it tight. Be careful not to dent skin by going too tight or allowing ratchet to contact fuselage

3. Crawl in fuselage with the sharpie and outline ribs. Also outline anywhere you don't want rivets to end up (like gaps in flanges)

4. Take skin off - drill #40 holes at spacing desired - prob 1" to 1 1/4" while flat on work bench

5. Put skin back on - tighten again - make sure it ends up in same place and you can see centreline through the holes

6. Drill bulkheads starting at top all way down

7. Have someone hold a hard piece of wood on outside of fuselage along longeron. Back drill through longeron and clecoe every hole.

8. Remove, debur, dimple, rivet

One thing to be very careful of is edge distance for top skin along longeron. Mine had very little slush.

Also don't rivet it in place until everything is back fuselage is complete - static ports, trim wiring, light wiring, ELT, autopilot, etc
 
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Stu that's really good advice.

Is it weird that as I read down through that, once I got close to the bottom and saw it was you, the reading voice in my head changed to your Canadian accent....?

Weird, anyways.... :D
 
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