Tuesday, March 19, 2024

Estes Skytracer Clone #1361 Build, Part 4, Making The Nozzles

I've asked myself: "Why do I hang on to old parts?" The answer: "For builds like this!"
I switched over to some old, pre-flown 20 sized nose cones. The intake tip needed to be a bit wider.

This nose cone with the gold spiral stripe was off  a Wizard my daughter assembled at school.
I used the back of my knife blade like a cabinet scraper to remove the paint. Why use the sharp side and dull the blade? The back of the blade scrapes pretty well.


The second nose cone was already painted red/orange. It got scraped then smooth sanding.


The tips were cut off with a razor saw.
The tip was cut at a 1/2" length,
The nozzle cut off below that at another 1/2" down.

On the right - 
The rough sawn tip. Below that, the sawn edge sanded clean.

Here's the first try at the cut pieces.
This first nozzle (middle piece) was too short, another piece was cut at the better length of 1/2".


Here's what I meant about cutting new nozzle bells.
On the left is the first try,
on the right is the better longer nozzle.

Another reason I hang on to old rocket parts - I had to cut up two more surplus BT-5 nose cones from the spare parts drawer.

Monday, March 18, 2024

Estes Skytracer Clone #1361 Build, Part 3, Making The Nozzles

It's clever how the Estes designers used the old Centuri kit nozzle pieces. 
Flip around the intake cone and glue into the back end of the nozzle!
   

Here's the back end of my homemade nozzles from the recent Centuri Quasar clone.
I made this end from a plastic pen barrel and a segment of a balsa nose cone.
The intake was made from the tip end of a sharpened dowel.
Here's a link to the Quasar jet intakes and nozzles: 
Are these exact copies of the original parts? 
No, but they capture the feel of the design.


The ramjet tip end needs a base that will slide in and glue into the BT-5 tube.

Trace around a 13mm engine block onto some thick cardstock.
Cut out the circle piece with scissors.







Glue the circle piece over the end of the engine block ring.
Sand and even up the edges even.





Here's the two needed intake bases next to the short BT-5 tube.

The sides don't have to be perfect, they will be recessed a bit inside the tube edge.

Sunday, March 17, 2024

Estes Skytracer Clone #1361 Build, Part 2, Engine Mount


The original kit did not have an engine block. I added the engine block.

TIP: Instead of just cutting a slit 1/4" from the top (as shown in the instructions) I set the engine block beside the tube and mark the top edge with a sharp pencil. This puts the upper bend of the engine hook right above the bottom of the engine block. Quest kits are marked and slotted this way.
The centering rings were way too tight around the BT-20J engine tube. 400 grit sandpaper was wrapped around a finger and the inside burr was sanded down.

On the right, a notch was cut in the upper ring for the Kevlar and engine hook fit.

Here's a dry fit of the rings and engine hook. Kit  instructions typically have the upper ring even with the top of the engine tube.
TIP:  For a stronger mount - Position the upper centering ring down over the top bend of the engine hook.
TIP: Sand the face of the low centering ring flat before gluing onto the tube. That low face of the ring will be exposed on the finished model, when even with the end of the BT-50 main airframe tube. You'll want that flat surface smooth.
 

Fillets are applied to both sides of the rings leaving the Kevlar slot open.

Tie the Kevlar line around the tube. I lace the end under and over the loop a few times. You could use a knot but there isn't much room between the BT-20 engine mount and BT-50 body tube.

 


Cut off the excess and press the end into the wet glue fillet.

Mentioned earlier, a engine block was glued into the top of the mount even with the top of the tube.

Saturday, March 16, 2024

Estes Skytracer Clone #1361 Build, Part 1, Parts





All the parts:
You can see where I've penciled in the lengths of the pieces. 
Many dimensions come from the John Brohm list: CLICK HERE
Other lengths come from searching old catalogs.









Parts "K" that make up the nozzles will be fashioned from some spare parts. Cut-up 13mm plastic nose cones, cardstock and engine blocks.
The PNC-50S nose cone will be made from a Crossfire style cone with an added cardstock canopy drawn up by Greg Poehlein: CLICK HERE

Friday, March 15, 2024

Estes Skytracer Clone #1361 Build, Background


I often browse the old catalogs at Ninfinger.org looking for the next interesting build.
This one caught my eye! Here's the page: CLICK HERE

The Skytracer was only sold in 981 through 1982. Sure, it's a bit different, 
but that's what'll make it a fun clone.
Specifications: Length: 13.0", Diameter: 0.976", Weight: 1.9 oz.
Recommended 18 mm Engines: A8-3, B4-4, B6-4, B8-5, C5-3, C6-5


The two central fin nozzles (facing the rear in the photo above) are made by combining the front and rear of the old Centuri Shuttle SST jet engines. 
Centuri also used these nozzles on their Quasar kit. To see my Quasar clone build: CLICK HERE

If memory serves, my Shuttle SST kit originally had vacu-form nozzles. Later on the nozzles were injection molded. Estes found some use for the molds in the Skytracer. I'll be assembling the nozzles with segments cut from plastic nose cones.

The build starts tomorrow . . .

Tuesday, March 12, 2024

My Spray "Booth"

Here's where I spray my model rockets.
It's simply a walled patio between my townhouse to the right and separate garage to the left.

The block walls are 8' high which (somewhat) provides a wind break. That cardboard on the ground protects my brick pavers from any paint drips that might form on the nozzle. 

I haven't found any overspray paint on the walls, floor or glass on the house walls.

A windbreak is important. I did notice James Duffy's spray booth on his NARCON video. He sprays his models in a horse trailer.
 Why an enclosed horse trailer? No wind!

Monday, March 11, 2024

Clearing A Spray Can Nozzle?






Jmg8torr posts construction and home tips on YouTube.
To see the video: CLICK HERE

I haven't tried this one out, but am curious.

This might help with clogged spray can nozzles. 
I would recommend spraying a few passes away from your rocket to be sure any WD-40 is blown out.