Estes Mini Arcas, #2441, Part 8, Fin Primer & Sand

A strip of tape was set down the root edge to prevent the primer/filler from soaking in.

The tape strip was needed because the root edges weren't  straight. 

The fins were set on scrap cardboard for the filler/primer spray.

Here's the before and after sanding the fins and short launch lugs.

The filler/primer soaks in a bit and helps seal the surfaces.

For me - Balsa grain filling and tube spirals filling is a two-step process - 

STEP 1: After applying and sanding the Carpenter's Wood Filler (CWF) 

STEP 2: The sprayed and sanded filler/primer fills in any remaining grain.

Everybody has their best methods.

Estes Mini Arcas, #2441, Part 7, Fin Fill

When applying the CWF, clear that small notch above the root edge round cut out.

After sanding the dry CWF, round out the root edge cut out with a small rat tail file.

Here's the before and after CWF sand.

The small notch above the cut out aligns with the boat tail / body tube seam.

The fit of the fin root edge was very good.

The original ARCAS fins had a diamond taper. This smaller version just has a rounded leading edge. It would be very difficult to sand a diamond taper in 1/16" thick balsa.

Estes Mini Arcas, #2441, Part 6, Fin Supports

The basswood strips were sanded down to 1/16" square.

About 12 lengths were cut. I'll only need 8, I'll pick the best shaped for the build.

The originals were left on the balsa sheet. Angled pencil lines were drawn for a cutting guide.

I used a single edge razor blade to cut the sides. 

Draw pencil lines on the top and bottom apex for a sanding reference.

Shade the sides for a visual contrast when tapering the ends.

On the right - 

The ends are tapered using the pencil lines and shading. Without the pencil markings it is difficult to see how much you are sanding off. Use 400 grit on a sanding block.

Round off the length of the support and the tips.

The pic on the right shows the underside, still square.

Estes Mini Arcas, #2441, Part 6, Fin Supports?

Here's one reason why this kit has an "Advanced" skill level.

These fin supports were tough to shape when the original Arcas was a larger BT-55 size.

Check out the original K-26 kit instructions: CLICK HERE

"Sand a 14 degree angle after cutting the support in two?"

What makes it even harder - forming the smaller supports out of balsa!

The laser cut balsa supports are only 3/4" long by 1/16" thick. 

I made a special trip to an actual hobby store to find some strip basswood. I'll be cutting these out by hand. Basswood doesn't have grain pores to fill like balsa wood does.

The picture on the right shows an attempt at forming the first support. I can't imagine trying to shape and fill seven more of these from balsa!

Estes Mini Arcas, #2441, Part 5, Tail Cone Fix

Next time you make a tail cone, try placing the glue inside the end, opposite the glue tab.

I decided to make a double layer "super shroud". This makes a much stronger piece.

For more detail, I wrote an article for the Apogee Peak Of Flight newsletter: CLICK HERE

Notice the lower step inside the cone in the right side pic.

Glue one cone inside other.

Let dry with a coupler inside (don't glue the coupler in) to maintain the round shape.

After all is dry,

Cut off the upper overhang using the ridge as a guide for a razor blade.

Sand the upper side square using a sanding block with 400 grit.

Estes Mini Arcas, #2441, Part 4, Tail Cone Fix - Gotcha!

After forming too many shrouds printed from the scanned kit tail cone,

I thought I'd try the provided kit shroud.

GOTCHA: The kit shroud fit like my scanned cardstock ones did - 

It fits the BT-5 but was small on the BT-20 top end.

So - off to payloadbay.com and their transitions tool.

Four more were printed and cut out.

Notice the picture on the left - 

Run a fingertip over the curved sides, you'll feel some very subtle raised areas. With 400 grit, sand and round them down. This removes the high spots and makes a better fit at the base of the BT-20.

Four cardstock tail cones were formed with a clean dowel in the heel of my left hand. Check the last post picture.

Estes Mini Arcas, #2441, Part 3, Tail Cone Problems

Cut the flat sides with a ruler and sharp knife. 

Cut the curves with scissors.

I make a smooth curve by rolling a dowel in an arc pressed against the soft heel of your hand. 

It take very little glue to join the ends.

With the printed edge lines lined up, I held the shroud closed using smooth faced tweezers.

 

Here's where I ran into problems.

The bottom fits the BT-5, but the wider end doesn't match the diameter of the BT-20!

I made another tail cone with a slightly wider top. 

It was still too small!

These two shown above aren't the kit supplied tail cone. The kit shroud was scanned and some extras were printed up on 110 lb. stock. There doesn't seem to be any difference in size between the kit shroud and what I printed. I was saving the kit tail cone for a final try. It's a bit thicker and has a smooth side.