Estes Mini Bomarc Clone, Kit #TK-5, Part 6, Nose Weights

I needed two Estes NCW-1 nose cone weights. I found an single original lead weight in my spare parts drawer.

The older Estes catalogs say one lead washer weighs 0.12 oz. Two would weigh 0.24 oz.

Deep in the spare parts drawer was a few older Semroc NCW-1 weights. One weighs 0.15 oz. There is no center hole for the screw eye.

The Semroc weight is larger in diameter and won't slide into the BT-20 main body tube.

I used a wire cutter to reduce the diameter. 

The lead disk was rounded on some 220 grit sandpaper.

A diamond rat tail file started a hole for the screw eye.

After drilling and shaping, the disk now weighs 0.30 oz. I did some more sizing and got the two lead disks down to 0.25 oz.

The nose cone was from Balsa Machining Service (BMS).

BMS drills out their nose cones for a hardwood dowel. The screw eye is turned into a small hole in the dowel center. This attachment is much stronger than balsa alone.

The fit of the dowel was tight. I sanded the sides a bit, but it wasn't enough.

When pressed into the hole, the nose cone started to split! Some CA glue was run into the split and the gap filled.

Estes Mini Bomarc Clone, Kit #TK-5, Part 6, Downsizing A Parachute

The original Mini Bomarc kit had a 10" parachute. Estes makes a 9" chute, but I didn't want to spend the $4.49 price.

I have a lot of Odd'l Rockets parachutes. I'll cut a 10 chute from one of these.

Mark the center of the chute material. Then, simply mark 5" on either side of the center. Repeat for all six sides.

Make straight cuts, parallel to the 12" dashed lines above. 

Rotate the chute make the next five cut lines.

Here's the 10" chute with the plastic reinforcement rings in place.

The finished chute using #10 cotton embroidery thread for the shroud lines.

Estes Mini Bomarc Clone, Kit #TK-5, Part 5, CWF Sand & Filler Primer

The old Estes instructions don't mention it,

but I rounded the leading edges of the wing, stab and rudder.

I also rounded the leading edge of the nacelle support. You've got to be careful because of the balsa grain direction.

The balsa pieces were taped down to a piece of cardboard and shot with filler/primer.

Sanding follows.

On the left the nose cone is shown with the CWF applied.

I realized the nose cone was also used in the Estes Stinger (K-53) kit.

After sanding, the filler/primer was sprayed and sanded.

Here's the rudder and stabilizer after the filler/primer was sanded.

I tend to sand down more filler than others might.

The filler/primer soaks into the balsa a bit and still seals the surface if most is sanded off.

Estes Mini Bomarc Clone, Kit #TK-5, Part 4, Filling Nacelle Nose Cones

The small (BT-5 size) nacelle intake nose cones are difficult to fill. There are some inside angles that should be sharp and remain round.

On the left - the CWF has been brushed on.

On the right - the CWF has been sanded down and smoothed.

The secret? A good sanding block with 400 grit.

The sandpaper is only on the bottom surface, not rolled up on the sides. You can't sand into the corner of the intake cone at the top.

On the left - the nose cone balsa grain is filled. It a second round of CWF to build up the low areas.

Note the tubes seams have been filled with CWF and sanded.

 

I'd recommend filling all the balsa surfaces before gluing everything together.

It'll be difficult enough to get spray paint into the nooks and crannies.

A SHOT DOG Find and a Question

This design goes back to 2008, and entry in the old EMRR Odd Ball Design Contest.

A flying Hot Dog, or SHOT DOG.

Open bun, with empty condiment packages surrounding the balsa fins.

You can read about the ups and downs of the Shot Dog here - 
https://www.rocketreviews.com/scratch-shot-dog-by-hans-chris-michielssen.html 

I was looking at some 3D parts on Makerspace and came across a 3D printed Shot Dog by Scott Dee. Scott also drew up the 3D Centuri Skylab parts I was interested in.

Scott Dee (Mills)

https://www.thingiverse.com/thing:3272143

Scott's model looks to be a bit taller with four fins instead of three. This would make it more stable!

3D PRINT QUESTION: Anybody interested in printing the Centuri Skylab parts for me?

https://www.thingiverse.com/thing:2881947

Looking for all the 3D printed parts, as smooth as possible (no real ridges). Resin print preferred.

Send a price estimate to oddlrockets@bellsouth.net

Estes Mini Bomarc Clone, Kit #TK-5, Part 3, Engine Mount

The original kit instructions don't mention it - 

I did have to cut a relief notch for the engine hook. Here I've marked it with pencil.

The burrs inside the rings needed some light layer peeling to fit over the BT-5 engine mount tube.

I don't like using a tri-fold mount in smaller diameter tubes so I laced some Kevlar below the upper ring. After pulling tight, a glue fillet will lock it in place.

The lower ring slides up to 1" from the bottom of the BT-5 tube.

The upper ring is even with the top of the tube.

There wasn't an engine block in the original kit. I added one.

Slide in place against the upper bend of the engine hook, then add a glue fillet and smooth with a Q-tip.

Also added was the new heat shrink tubing slid over the first four inches of the Kevlar line.

This is butted up against the top of the centering ring and hit with a heat gun.

After heating, the shrink tube ends up tight around the Kevlar line.

Estes Mini Bomarc Clone, Kit #TK-5, Part 2, Fins & Decals

The balsa scan was copied, dropped into Corel Draw and traced. There was some resizing to lock into the ruler reference underneath.

The kit used 1/16" balsa. The sheet is 3" x 9".

The decals were redrawn.

These will require some white decal material under the Canadian circle logo and flags.