Estes Skylab #001973, Build, Part 11, Fin Fairings

Before I get into the Fairings: 

They will fit - if you take the extra time to get the sides sanded and trimmed enough to fit just inside the ribs in the low wrap

TIP: Don't cut the sides off too close! The excess edges will crack off when sanding.

Leave a good 1/16" around the fairing sides.

NOTE: On this build I cut out the fin slot before sanding down the sides.

Next time, I would probably work on sanding the sides before cutting out the fin slot. With the slot intact the fairings seem stiffer making sanding down the sides easier.

Trace around the slot recess with a pencil before cutting. This makes the inside lines easier to see.

Some 220 grit sandpaper was taped around the widest, open part of the main body tube.

This is what takes the extra time.

Back and forth, back and forth over the sandpaper

Keep an eye on the sides and corners as they get thinner when sanding.

They will start to fold back.

When the plastic gets thin enough, you can bend it and remove the edges.

Add the reinforcement disks inside the bottom of the fairings before continuing sanding.

I did something similar on my Saturn V #1969 build. Those were simple 110 lb. card stock glued to the bottom face of the fairing.

These thick crescent disks are glued inside the fairing base. I used Fabri-Tac to adhere them.

Notice the inside edge overhangs the crescent disks. There is still more sanding and fitting to be done.