Centuri Argus #KB-9, Finished

I was very happy with the finished models.
I know it was an Centuri A.R.T.F. (Almost Ready To Fly) but I got some satisfaction redrawing and printing the stick-on decals. The small upper wrap matched up perfectly!
This was the first time I ever printed stickers, the finished look is good. The sticker thickness isn't really noticeable. I could have made decals, but wanted to get it close to the original kit.
Beyond the simplicity of an A.R.T.F., there was still tube seam and balsa filling and improvements like the shock cord retention.

This will be a great model for the soccer field with a B6-4, C and D Q-Jets at the new NEFAR flying field.

Here's the two different fin can colors.
I actually like the yellow one better. The triangle fin stickers aren't a full opaque white over the red paint.

Tomorrow - Starting the newly released Estes Side Kick!

Centuri Argus #KB-9, Build, Part 11, Toughening Up A Balsa Nose Cone

TRIVIA: Centuri would often include "The Right Materials For The Job" in their instructions.
Note the "Nose Cone and Connectors" section: "Nose cone must have durable surface because upper section descends nose first."






From the same instruction set, this shows the two parts descending on separate parachutes. Mine is set up this way, but has balsa nose cone and adapters. The softer balsa nose cone could get banged up on a hard landing.





Here's one way to toughen up a balsa cone -
TIP: Wipe some CA glue over the nose cone tip with a Q-Tip. I probably should have done after filling and before the nose cone was spray painted. Even going on after the paint, it isn't noticeable. The finish isn't as shiny with the CA glue wiped over paint. It would be smoother if it were applied and sanded smooth before spray painting.

Centuri Argus #KB-9, Build, Part 10, A Variation & A Fix

I understand different kit runs had different color fin cans.
Spray painting plastic fin cans can be a problem. Because I was making two models, I decided to leave one in the Eliminator yellow and paint the second in red as shown in the catalog.
The fin can was washed to remove any mold release.

The upper end was masked on the inside.
I didn't have any extra ST-13 tubing  so two wraps of masking tape was set on a masking wand dowel with the sticky side out. This was pressed on the inside of the fin can, used as a handle for spraying.
 

I knew this fin can wouldn't take the paint evenly.
On the left is the second coat after drying. The gloss is uneven.

I don't like using acrylic clear coats, if your painting technique is good you shouldn't need a clear coat. Besides that, clear coats get sticky in humid weather.
I gave in this time and used the Krylon clear gloss acrylic. On the right is the even gloss coat.

Centuri Argus #KB-9, Build, Part 9, Finishing Up

The A, B, C, and D triangles fit on the lower adapter.
The straight sides were cut with a knife and straightedge, the curved bottom was cut with scissors. It took two re-draws to get the bottom curve correct.






TRIVIA: In the mid 1970s, Centuri kits had their silver coffin shaped shock cord mount. You laced a shock cord through three holes. While a great idea, those sticky backed mounts would release over time. In later instructions, Centuri would remind you to press the mount down with a pencil eraser before every launch.







I decided on another Centuri style shock cord mount. A shock cord is looped around a segment of tubing. This is glued in far enough to give room for the adapter shoulder.

Centuri Argus #KB-9, Build, Part 7, Prime and Paint Tubes and Balsa

Well, the blog posts are out of order - again! Yesterday got #8 when it should have been this one.

I had sanded to deep into the CWF filler and had to do more filling.
TIP: With the CWF filler you don't want to sand down too far, leave a very thin skin of the beige filler. If you see the pink balsa peeking through, you've sanded to far.

Here I'm using my sanding block to evenly sand the flat side of the adapter.







The paint on the body tubes was fine, I only had to re-paint the adapters.
The shoulders were taped together. I rolled some paper around the bottom for a handle to keep my hand out of the paint.

I didn't want any paint under the plastic fin can, the fit was tight enough already. The fin unit will slide on from the bottom. If you slid it down from the top (recommended in the instructions) you could scrape off paint down the length of the tube.

The fin unit was placed next to the body tube and marked to mask off the low end. Don't forget, that open area at the angled top of the  molded in launch lug will need paint coverage too. I masked below the open "U".

Centuri Argus #KB-9, Build, Part 8, Stick On Decor

The stick on decals were printed on some full sheet (8 1/2" X 11") self adhesive paper. 20 sheets were ordered through Ebay.
I used the same settings you would use for printing photographs so the ink color would be full and opaque.


Mark the centers of the bottoms of all the triangle pieces. Make small pencil marks. These tall triangles are difficult to set down straight. The center marks will really help with alignment.

The tallest triangles are centered directly over the fin leading edges.

TIP: Use your aluminum angle to draw a faint pencil line at the top of the triangle position. In the lower picture, the tip of the triangle is on that extended pencil line.

TIP: As with all stickers, lift and place them using the tip of your knife blade.
Line up the tic marks on the body tube with the center marks drawn on the bottom of the sticker.

Look close and you can see a center pencil mark on the ARGUS triangle. This lines up on a center mark made on the base of the fin.

ARGUS goes on the right side, the Centuri logo triangle goes on the facing left side.

Centuri Argus #KB-9, Build, Part 6, Prepping The Fin Can

The old Centuri instructions tell you to "Prepare the fin unit before sliding it down over the lower body tube." You are directed to use the "enclosed sandpaper" to smooth the inside edge of the fin unit.
I don't remember ever seeing sandpaper included in a Centuri kit. The New Way square tube kits include sandpaper.
There can be some rough molding flash on the inside lip of the fin can. This could scratch the tube if left on the inside.

Run your finger around the inside lip and you'll feel some slight molding "ribs". I used some 400 grit wrapped around an engine casing to smooth them.

The front end of the can wasn't even. The 220 grit block flattened it out. I followed with 400 grit.

The top of the molded in launch lug was cleaned up with a diamond needle file.

The Centuri instructions say to slide the fin can down from the top - all the way down to the bottom.

TIP: With a little wiggling, I was able to slide it on from the bottom up. This is a good thing, I'm going to paint the body tube gloss white. The fin can fit is tight and could scratch the paint if slid down from the top.

Centuri Argus #KB-9, Fin Can From Thingverse

In a blog comment, Metalhead 1986 let me know:
"For those with 3D printers, the fin can is available on Thingiverse."

To go to the web page: CLICK HERE
Thanks to Jack Hydrazine for all the hard work.

The webpage also listed all the models that used this fin unit:

ENERJET: 1340 Sounding Rocket, 1340/20 Sounding Rocket

CENTURI: Phoenix Bird, Argus, M.A.R.S. Project
ESTES: Longshot, Maniac, Challenger II, Eliminator, Eliminator XL

Centuri Argus #KB-9, Build, Part 5, Fitting The Balsa Parts

I like to clean up the shoulder bases on the nose cone and adapters. Not really necessary, just something I do.






The fit of the small nose cone was too loose for me. I'll have to build up the shoulder a little bit.







The adapter shoulder edges were rounded off.
To build them up and make the edges sharper, some CWF was brushed over the edge. The adjoining tube was slipped over and turned. This presses and forms the CWF leaving a raised lip that is sanded down after it has dried.

After the CWF and raised lip was sanded flat and even, it leaves a rough edge at the shoulder lip.

On the left it the lip edge before, on the right is the same edge lip after edge sanding, shown below. The difference is very subtle, but now has a better fit.

To clean up the edge, set the adapter or nose cone into the tube, almost to the lip edge, leaving a gap. Fold a piece of 400 grit in half and set in the gap. Lightly sand around the edge and check the fit. Repeat if needed.
This takes off any roughness and squares up the lip.

Centuri Argus #KB-9, Build, Part 4, Engine Mount Gussets

The outside diameter of the rings was a little small. I decided to add some balsa gussets for a better fit and a stronger mount.

Scrap balsa was cut to the width between the centering rings.
The glue fillets already in place didn't allow the balsa gusset to slide all the way to the engine mount tube. I sanded the corners off to fit over the fillets.

 A strip of copy paper was wrapped around the tube. After being cut to size, it was folded in thirds and marked. The mark locations were transferred to the engine mount tube.

The gusset pieces were cut wider than needed and glued to the 120 degree marks, with two centered around the engine hook.




The gusset sides were sanded to allow a slip fit into the ST-13 (BT-56) lower tube.
While the fit of the mount is much better, I still have build up the outside diameter of the centering rings with a bead of glue before gluing it into the tube. The gussets add a lot of strength to the mount.

Centuri Argus #KB-9, Build, Part 3, Centering Rings

I used Centuri ST-7 for an engine mount tube. It's a little larger diameter than an Estes BT-20. The only engine blocks I have fit the BT-20.
I did two wraps of copy paper applied with a glue stick to fit the slightly wider tube.

I didn't know that the original kit had foam core centering rings. These were probably more robust than an regular centering ring at .050" thick.
The instructions say these rings are stronger and don't require a black coupler tube.

TRIVIA: Years back, all Estes and Centuri kits had black fish paper couplers between centering rings. Now most kits have just the two rings that center the engine tube in the larger tube.
If you ever tried to glue in one of these older style mounts, they would sometimes freeze in the wrong spot, not slid all the way into the main air frame tube! Maybe that's one reason they are no longer used in engine mounts. (That, and the vendor probably saves a nickel per kit.)




I'm making two Argus models so I needed to notch four rings for two engine mounts.

TIP: You can make the notch sizes consistent by stacking the rings and cutting with a sharp blade.

Centuri Argus #KB-9, Build, Part 2, Stick On Decor

There will be two Argus kit clones.
Why two? I had two Estes Eliminator kits in the build pile. I'm not fond of the yellow and purple Eliminator colors. Why not make something more interesting?
Too much time was spent redrawing the stickers to only use them once.
I have quite a few unopened kits, just trying to thin the herd.

Here's a scan of the original peel and stick decor pieces from Jim Z's.
All the long triangular pieces butt up against each other, side by side. It looks like the cuts down the thick black lines (die-cut, separating the pieces) aren't perfectly centered.

I could certainly print these and use it on the model, but I wanted a something cleaner without the die-cut shadow lines.










I worked in Corel Draw and came up with separate triangles I could cut with a knife and straightedge. Doing this myself made the build more worthwhile.
It's not an exact copy of the original art. Look close at the Centuri logos, the Centuri letters aren't black. It was changed so I'll recognize it if it shows up somewhere else, in a clone kit or online.
I ordered some 8 1/2" X 11" self  adhesive sheets from Ebay
.
Drawing and printing your own decals or wraps is always a crap shoot. While the tall triangles should be fine, that roll pattern on the upper left could take some re-sizing to perfectly roll around the upper ST-7 tube.

If youare a member through Patreon and would like a copy, email me at oddlrockets@bellsouth.net
and request the Argus Stick-On Decals.
This re-drawn art is meant for a single clone build, not for commercial kit production.

Centuri Argus #KB-9, Build, Part 1, Parts

The body tubes, adapters, nose cone and centering rings were ordered from Semroc. The fin unit came from an Estes Eliminator kit I had. I've already built an Enerjet 1340 and a few Centuri Phoenix Birds so the Argus was the next best choice. The screw eye for the lower adapter isn't shown.
Parts of interest:
That one piece plastic fin can. The Centuri Argus catalog page showed it in red, but I understand it could show up in different colors.

Centuri Argus #KB-9, Build, Background Research

The Centuri Argus was an A.T.R.F. (Almost Ready To Fly) model that used the molded one-piece plastic fin can from the Enerjet 1340 model. This fin unit was revolutionary. Strong and flexible with a launch lug molded between two of the four fins. The Argus was produced from 1973 - 1981.
The Centuri Phoenix Bird and later Estes kits used this fin can. Two that come to mind are the Maniac and Eliminator.
To see this Centuri catalog page, CLICK HERE





Jay Goemmer ("Centuri Guy" on the forums) has put together a great listing of Centuri kit parts. This includes nose cones and body tube lengths for almost all the Centuri line. To see the list: CLICK HERE
This gave me the correct sizes and lengths of the older Centuri ST tubing, nose cone and adapters for the Argus.

The above example shows just a small part of the 14 pages of Centuri kit information. A valuable source for clone builds. Thanks Jay!
Nose cones and body tubes were ordered from erockets.biz, currently the only source for Centuri diameter tubes.