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.

Estes Shark #1111, Build, Follow-up

Well, yesterday's post (shown below) ended up being posted on the wrong date, last week! Don't know how that happened. You can specify what days you want things to be posted. I must have hit "Set Date and Time" button and not the "Automatic" publish button.    

I got my BNC-50AR balsa nose cone from erockets.biz

The upper pic was the Alpha style "placeholder".

The lower picture shows the new, bare balsa cone.

How the rocket looked before:

Here's the build with the correct shape, original nose cone.

Sometimes a little change makes a much better design.

Estes Mini Arcas, #2441, Part 2, Tail Cone

Any rocket kit that has a tail cone only includes one cardstock shroud. If you've ever formed a cardstock shroud, you know the fit might be iffy. 

I won't be taking any chances with a single shroud.

I drew a 1" reference line above the printed kit shroud. The tail cone was scanned, the 1"reference span was double checked in Corel Draw. The shrouds were printed on 110 lb. cardstock.

Will I really need eight tail cones? No.

But, I can make a few and use the best fitting shroud.

Estes Mini Arcas, #2441, Part 1, Parts

Here's a newer one from Estes.

A larger BT-55 Arcas kit was produced by Estes from 1972-1973.

This "mini" motor version is BT-20 based with streamer recovery.

Parts are of good quality.

The streamer is 2" x 24" chrome Mylar.

To see the instructions: CLICK HERE

The balsa sheet is 1/16" thick.

The small laser cut pieces are the fin supports. They are tiny!

Only one cardstock shroud is supplied. 

More on that later - 

What Does This Have To Do With Rocketry?

It doesn't have much to do with rockets!

Still, a fascinating look at a pedal car restoration.

You think some rocket repairs are complicated?

Worth a watch - CLICK HERE

I'm Camping!

Sorry, no posts for the next three days - 

I'll be camping (with Dakota) at the Lake Manatee State Park in Bradenton, FL.

Posts should be back to normal this Saturday . . .

Estes Shark #1111, Build, Finished

Classic and clean, a favorite from my teen years.

No masking, just paint it gloss white.

The decals don't overpower the design.

Mentioned earlier,

The fin decals were borrowed from the Interceptor kit.

The mid section with the USAF logo decals.

The temporary nose cone - 

A BNC-50AR is on order through erockets.biz.

Note the tiny nozzle decals.

Estes Shark #1111, Build, Part 11, Tiny Thruster Decals

If you've ever tried to position those tiny camera targets in the Estes Saturn V kit, you'll wish they provided a few extras. These little decals magically disappear after you think they are in position. You'll find them sticking to a finger or in your lap!

This is one reason why I draw up and print more decals than I need. Some extras are used for "soak" time testing. Others are duplicated when I think there could be a problem.

There is two sets of four thruster ovals on the Shark decal PDF.

The instructions say to draw the thrusters with ink. I wanted a cleaner, consistent shape than what could be drawn by hand.

The thruster decals are small!

Use tweezers to hold them. Don't let the decals sink to the bottom of the soaking water. Float them on the surface as they soak.

After the decal set in and dries, 

apply some Future clear acrylic using a Q-tip.

I ended up using all eight decals to get four properly placed.

Estes Shark #1111, Build, Part 10, Low Position Decals

The red, white and blue fin decals go on both sides of one fin. Check the fin decal in relation to the tunnel positions in the instructions.

 

Trim the top and bottom of the fin decals close to the ink. You don't want clear border extending beyond the rounded fin edge.

The "ARMED" decals are set above the top of the fins. Do your best to visually center them between the fins.

The black roll pattern wrap is set above the upper ARMED decal. Wet the body tube before setting the decal down. You'll want a slippery surface to allow movement when lining up both ends of the decal.

Estes Shark #1111, Build, Part 9, Smooth Fillet Areas?

Occasionally I've been asked how I get smooth fillets. "Fine Sanding!" 

After the first white undercoats, closely examine the reflection of your fillet areas under a bright light.

   

Even though you've carefully smoothed a glue fillet, there will be streaks and lumps.

Wood glue actually sands pretty easily using 400 (or finer) grit. Try to sand just the raised glue. You'll end up with something like what is shown at the left.

The area between the tunnel and small forward fins was tight and difficult to smooth out with sandpaper.

Here's what that looked like after sanding the undercoat and glue lumps.

Another white undercoat follows.

Check under sunlight and the areas around the fillets should be smoother. You might need yet another undercoat and very light sanding before the final "wet" gloss coat.

On the left is a good example of smooth fillets.

The same area around the tunnel is much better.

No masking, just an overall gloss white.

Ready for decals!

Estes Shark #1111, Build, Part 8, Engine Mount & Fin Gluing

Set the engine mount and Kevlar line alongside the lower, longer tube.

The BT-20 engine tube is even with the bottom of the BT-50 main body.

This gives you an idea how long the Kevlar line should be, a little shorter than the top of the BT-50.

Tie a overhand loop knot (shown on the right) for the elastic shock cord attachment.

I used epoxy to glue the mount in, allowing me some positioning time.

Here's the BT-50 tube with the filler/primer scraped off where the fins will be glued. The scraping is a little shorter than the length of the leading edge.

The low fins are glued even with the end of the body tube.

On the forward fins and thrusters, I used a wrap of masking tape as an low alignment line at the corner of the trailing edges.

Estes Shark #1111, Build, Part 7, Fin Grain Fill

I first cut the thrusters from balsa -

Then I realized the would be a pain to fill and sand being so small. I cut a second set out of basswood.

Two step fill process:

1. The fins, tunnel. thrusters and launch lug got a brushed coat of CWF, then fine sanding with 400 grit.

2. After sanding down all the CWF, all were stuck down to some cardboard for a shot of filler/primer. 

The body tube seams and nose cone got the same two step fill.