Estes Mini Arcas, #2441, Part 10, Fin Gluing

 

The paper fin marking guide gave perfectly spaced fins. 

Part H (fin alignment and spacing tool) fit very well.

With the fin notches in line with the tail cone/body tube joint -

The trailing edges are about 3/32" from the end of the tail cone.

The fin support pieces should fit tightly into the root edge corners.

Go light with the glue fillets to allow a close fit of the support pieces to come.

Estes Mini Arcas, #2441, Part 9, Fin Supports

The fin supports were butted up against each other and shot with filler/primer. Sanding followed.

On the instruction sheet there is a full size cut template.

Setting the fin support over the template, my sanded pieces ended up a bit short. I was trying to be careful not to change the length, but they ended up short. 

I used a single edge razor blade to "score" the center break line.

Cut about half way through! Score a line.

Here's a support after bending and breaking at the cut line.

Great - another gap to fill.

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.