Wing skin overlaps

Afternoon all-
Would anyone happen to have a good picture of how their wing skin overlaps turned out? I'm in the process of "beveling" the inboard / outboard skin joints. I dont want to thin the skin too much but I still want a nice looking overlap. I'm trying to get a realistic ides of how these should look. My OCD / perfectionistic side wants to get a perfect joint but overlaping .032 & .025 skins leaves a bit of a bump at the spars. Thanks All!

Daniel,

I don't have any pics yet, but I do have a word of caution. I used a vixen file and found that it works well, maybe a little too well at removing material. I was trying to measure the material thickness on the beveled portion for the perfect joint. On the inboard skin I caught the corner and messed up the corner a little bit. I ended up camferring the corner a little bit to fix it. I'm not too worried since it is on the bottom, but I'm be more careful with the next one.

You are going to see the joint no matter what since you are only scarfing the last couple of inches. I'll take less off next time and live with a slight bump.

I did the alternative method where you just remove about 1.5" of the skin on the bottom. Looks great and is very easy.



Several RV's been done like this around our area.

Good timing, as I just finished this up yesterday. I started bottom side of the left wing with a vixen file, and found it to be way too agressive; it leaves scratches too deep to sand out. I ended up using a piece of a worn 80-grit sanding belt on a sanding block, and a LOTof elbow grease. Starting with fresh 80-grit paper would have been easier, then move up in grit to take out those scratches. I also clecoed the corner of the skin to a strip of plywood for support while sanding. See my log entry for 11-28-12.



Remember that only the upper few inches of the overlap needs to be scarfed, not the whole width of the panels. The photo above shows only a triangular section scarfed, but scarfing the whole width of the area toward the forward edge allowed for a better fit. Also, before I started, while both skins are clecoed to the skeleton, I careully masked off the inboard skin right at the edge of the outboard skin, so the scarf wouldn't protrude out into a visible area. I still haven't given up on the possibility of at least partially polishing the airplane, but still wanted to scuff and prime the overlapped secton of the inboard skins.

One other thing I did was to slightly "break" or bend the forward edge of the skin. Do this AFTER scarfing, otherwise you won't be able to scarf inside the bend.

Here's an intermediate result on the top of the right wing. This one is still a bit proud, and took about 15 minutes more work to fit:

Brantel said:

I did the alternative method where you just remove about 1.5" of the skin on the bottom. Looks great and is very easy.

Several RV's been done like this around our area.

Click to expand...

You really need to do it this way anyway and is what used to be called out in the plans. You should bevel where the two skins overlap along the entire joint unless they changed the instructions. I think that is what he is talking about, not the portion aft of the rear spar which gets cut out.
I used a vixen file and took care in how much material I took off.

I used a roloc scotchbrite disc in an angle grinder to scarf the skins. Was relatively fast and easy, and they came out looking quite good.

Make sure you prime the areas where you scarf; alclad sheet is alclad because 2024 is corrosion-prone. When you scarf it, you're burning through the alclad layer, and exposing the 2024 underneath.

JonJay said:

You really need to do it this way anyway and is what used to be called out in the plans. You should bevel where the two skins overlap along the entire joint unless they changed the instructions. I think that is what he is talking about, not the portion aft of the rear spar which gets cut out.
I used a vixen file and took care in how much material I took off.

Click to expand...

The 7 already has the area aft of the rear spar cut out. This method in the pic is the area where the two skins overlap and mate to the front spar.

The directions tell you to scarf the corner of the two skins so they will lay flat behind the leading edge skins.

I am pretty sure the directions here have changed over the years. I don't remember seeing anything telling you to scarf the entire length of the overlap.

The method in the pic eliminates any scarfing....

Brantel said:

The 7 already has the area aft of the rear spar cut out. This method in the pic is the area where the two skins overlap and mate to the front spar.

The directions tell you to scarf the corner of the two skins so they will lay flat behind the leading edge skins.

I am pretty sure the directions here have changed over the years. I don't remember seeing anything telling you to scarf the entire length of the overlap.

The method in the pic eliminates any scarfing....

Click to expand...

Got it. That is different than earlier kits for sure.

On mine I didn`t do a scarf as such. I only beveled the edge of the bottom sheet forward of the main spar rivet line and broke the edge of the top sheet to sit down over it and tuck behind the leading edge skin.
Minimum material removed and the rivets pick up full sheet thicknesses to the spar.