The Mystery Fin

Last November, my Sister finally brought my comic books from California. When I was going through the books, I came across this fin.

It looks to be 1/32" plywood. It is airfoiled. I think it came off a Streamer Duration model I flew at NARAM 17.

If you are curious, the comics were from the mid to late 1960s. 

The box of comics sold for $700!

Estes Mini Bertha Clone, #TK-3, Part 12, Finished

This was a fun little build. My original 1970s fleet had quite a few Mini-Brutes and this was a favorite.

The double layer decals got me close to the full black color density on the nose cone.

I tried to clean up the "bug" decal. In the original art the lettering was thicker and a bit hard to read.

This one represents the 1970s Estes décor. Many catalog  rockets then were only two colors, one fin and the nosecone the same color.

Estes Mini Bertha Clone, #TK-3, Part 11, Two-Layer Decals

This was one of those home print decals that didn't give a good opaque coverage. With the nose cone in place you can really tell the difference between the two blacks.

On the left is a single layer decal, on the right is a two layer. There is a big difference. Sometimes home print decals don't cover over white paint.

Lay down the first decal and let fully dry overnight.

To apply the second decal - 

Soak the decal, wet the first decal already set on the tube. The surface is wetted down so the second overlay decal can easily slide into position.

As you are positioning the second overlay decal, simply line up the ink lines on the decal underneath. It's easier than it sounds.

I only had to double the two wrap around decals. The two Mini-Brute bugs looked fine.

Here's the shock cord ties.

The nose cone screw eye got the Duncan Uni-Knot.

The Kevlar / Elastic shock cord got interlocking overhand knots.

There was some clear decal overhanging the top of the body tube. When the decal is completely dry, you can shave off the edge with a razor blade.

Use a "sawing" back and forth motion when cutting off the clear overhang.

Apply some clear acrylic Future on the exposed edge so it won't peel back. I don't overall clear coat models, just decal edges like this. 

The tube edge got some Sharpie to blacken up the white paint.

 

Estes Mini Bertha Clone, #TK-3, Part 10, Black Fin & Nose Cone

The single black fin was spray painted black.

The nose cone was painted black separately, off the model.

Note the masking tape doesn't completely cover the shoulder. The edge of the tape is a little below the shoulder lip. The gives you a little paint below the joint. You won't see balsa peeking out if the nose cone isn't completely seated into the body tube.

I drew up some decals based on the old catalog page graphics.

These were home printed on clear decal paper.

PATREON - The Mini Bertha decal PDF is only available to Patreon supporters. Email me at oddlrockets@bellsouth.net and ask for the Mini Bertha PDF.

The fit was good, the decal start and stop overlap was set in line with the launch lug.

The Mini-Brute "bugs" were set on the body tube and both sides of one white fin.

Estes Mini Bertha Clone, #TK-3, Part 7, Gluing On The Fins With No Wobble!

Well, I did it again! This is a missing, out of order post, 

It's an important one, showing how to get rid of standing wobble of four finned models. 

Here's post #7. I'll put them into correct order in a few days.

 

Extend the fin position lines under and onto the centering ring.

I also mark the intersection of the root edge and trailing edge on the fin itself. It gives me another alignment point.

I've scraped the glue lines for the four fins and the launch lug.

After scraping the pencil alignment lines are redrawn.

TIP: Four fin rockets can wobble when standing up on the fin tips. To fix this - 

Glue on three fins. The model might stand up by itself now, but can tip over.

Apply glue onto the root edge of the fourth fin.

Set the root edge on the pencil line.

While the fourth fin glue is still wet - You can slide the fourth fin up or down. 

Set the fin and check by standing the model on a tabletop. 

Pay attention to the last glued, fourth fin position. By making slight up and down movement on the fin down the alignment line you should find the spot where the model will stand on all four fins without wobbling.

Estes Mini Bertha Clone, #TK-3, Part 9, White Paint & Masking

Here's the model after the first white coat.

This is an easy mask, the body is white, the nose cone and one fin are black.

There are always glue fillet ridges.

Here's the same fillet area after sanding.

The single fin is painted black.

This shows the Scotch tape masks.

These are followed with brown masking tape covering the larger areas. A plastic bag covered the upper tube.

Before spraying the black, the edges are soft burnished with a Q-tip.

Estes Mini Bertha Clone, #TK-3, Part 8, Prep For Paint

Here's an old school idea:

TIP: On a four fin model, look across the trailing edges to check the fin alignment. 

While they didn't wobble,

The trailing edge tips weren't perfectly flat. It took very little 400 grit sanding to square them up.

If I had sanded through into the raw balsa, sometimes you can rub some wood glue into the small trailing edge to reseal it. Keep the glue only on the trailing edge.

You can only use this glue seal on small areas like the tip of this fin. Follow with some light sanding.

 

The model is ready for white paint.

Look close to see the masking tape pieces out the back of the engine mount tube, sticky side out. This keeps the paint out. A dowel was slipped in for a painting wand.

To get full paint coverage, the nose cone is pulled out about 1/16". This puts paint over the shoulder lip so you won't see a white line if the nose cone isn't fully seated in the tube.