Dr. Zooch Atlas Agena Build Thread

[hcmbanjo]

I've always liked building the Dr. Zooch kits. They can be as much of a challenge as you want, it all depends how much time and detail you want in put into them.
I had my eye on the Atlas Agena for a while. It turned out to be a great build.

CHECKING OUT THE PARTS
Opening the box looked to be typical of a Dr. Zooch kit- Good quality parts. All the instructions and cardstock wrap sheet were rolled inside the T-60 (BT-60) body tube. The picture doesn't show the three sheets of 3/32" x 3" x 6" balsa supplied in the kit.

A few unusual pieces were the pre-weighted balsa adapter. The front shoulder seemed a little short (1/4") and a bit loose in the upper T-50 tube. I may have to extend and shim it a bit.
Dr. Zooch uses a two ply Kevlar “ribbon”, not the usual Kevlar you’d find in a rocket kit.
A 10" length of T-3 tubing is included.
Number 3 on the parts list says: 4 CR25P centering rings. They are actually CR35P rings. I’ve never seen centering rings this small in a kit before.
The corrugated mylar is interesting. It is thin and metallic blue.

I don’t know if it is just me, but I always have a hard time unraveling the shroud lines. It seems to take a little more time than I’d like. When opening it up it seems to get kinked or knotted.
I dry ironed the instructions and wrap sheet flat. The cardstock wrap sheet was sprayed with a Krylon clear coat for protection against smearing and dirt.
The instruction sheets are not stapled or numbered. Be sure you mark page numbers on each sheet, they are easy to get mixed up.
With the Zooch kits (or any kits with wraps) I always scan the wrap sheets just in case I need to print off another copy. It’s just me, I’m very picky about wraps. If it doesn’t turn out right the first time, I’ll print and make another. This is the first Zooch kit I’ve built that just had one, single cardstock wrap sheet.

 

[hcmbanjo]

MAKING THE ENGINE MOUNT
I wiped off the three black centering rings with a paper towel. The laser cut edges can be a little “sooty”. I didn’t want to take any chance of the black getting on other parts.
The upper and lower CR-MOD templates are cut from the wrap sheet. I didn’t see any reason to cut out the centers, I did cut out the engine hook allowance and index notches.
I also didn’t cut out the two outer semi-circles yet. I thought it would be easier to cut them out after being glued to the centering rings.
Instead of glueing the templates permanently in place with white glue, I used spray adhesive and removed them after cutting out the semi-circles.

The rounded engine hook notch doesn’t quite match up with the template. I centered everything from the back of the rings.

The semi-circles take time to cut through. I didn’t cut a pie-shaped notch at the index marks, I simply cut a single line straight down to the depth shown.
The templates were removed and the rings marked upper and lower.

In order to clean up the cut semi-circles, I wrapped 400 grit sandpaper around the white barrel side of a Sharpie pen. The Sharpie pen is slightly smaller in diameter than the T-5 tube the circles will fit. I usually contour sand with something smaller in diameter as the sandpaper thickness will bring it up to the correct finished diameter.

At first, I didn’t notice any difference between the two templates. I laid the upper over the lower and you can see the slight difference in the size of the semi-circle cutouts. The cutouts in the lower one are slightly wider than the upper. This will give a slight angle to the engine “spoofs”.

 

[hcmbanjo]

THE ENGINE "SPOOFS"
While the instructions say to cut the 4" long T-5 tube in half, my T-5 tube was closer to 4 1/8" long. I removed 1/8" and cut it into two equal 2" tubes.
After trying to get the shroud line untangled it had some kinks in it. I didn’t want to try to glue them into “engine bells” with the hard kinks. I ran a warm iron over them and they straightened right out.

I “double-glued” the end of the engine bell strings to the ends of the T-5 tubing to prepare for winding.
I’ll dry wrap the strings to the 3/8" mark to get an idea of the spacing of the windings. On one test wrap I did it dry and held the end down with tape. I spread the string wraps as even as I could and used it for a spacing model for gluing on the second tube.

The strings were lightly coated with white glue for just a few inches. The glued area was wrapped and more glue is added to the next few inches. I continued up until reaching the end.
I decided not to use super glue over the thread bands as it could leave bumps and roughness between the wraps. Instead I coated white glue overall the thread rows at once and smoothed out the glue with a finger.

 

[hcmbanjo]

BACK TO THE ENGINE MOUNT
The centering rings are lined up with the index line drawn earlier. Just to be safe, I set the “spoof” engine tubes in their semi-circle cutouts to be sure all lined up. The rings were tacked in place with small drops of thin CA. I followed with white glue fillets.

I decided to install the engine hook before gluing on the spoof tubes. This way I could add the tape wrap without the tubes getting in the way.
I’ll paint the spoof engine tubes with Walmart spray aluminum before gluing in place on the central engine tube. I’ve had great results with their inexpensive aluminum before.

I filled the seams in the spoof body tubes with Elmer’s Wood Filler.

Once again, Zooch uses a reinforcement band directly below the top of the engine hook. It’s a smart addition on the thin T-20 tube. This eliminates any chance (at ejection) of the engine hook pulling and tearing the tube.
The hook was set in it’s slot and a wrap of electrical tape went over it, between the centering rings.

I had some trouble getting the T-60 tube to match up with the marking guide. The guide was smaller that the actual tube diameter.
The spoof tubes weren’t glued on yet, so I was able to slide the engine mount in place. I made the marks using the semi-circles I had cut out earlier. This way I knew the cut out slots in the T-60 tube would match up with the spoof tubes.

 

[hcmbanjo]

MASKING, PAINTING and GLUING the SPOOFS
I set the spoof tube into the semi-circle cutouts with the ends of the thread bands facing towards to the central motor mount tube. I didn’t want the loose ends facing outward, they won’t as easily be seen in the center.

I marked the spoof tubes for masking. The masked areas would keep the gluing surfaces clean.
After a coat of grey primer and sanding , I followed with spray aluminum.

I first set the spoof tubes in their semi-circle cutouts without glue. The spoofs overhang the centering rings by 9/16". After being sure of the overhangs, I applied a small drop of CA to the spoof/centering ring joints to glue in place.
The remaining CR2060F Centering ring is glued to the top of the engine mount assembly. I didn’t glue it flush, but 1/16" down from the top of the motor tube. This was a stronger joint as I could fillet both sides with white glue.

I slid the engine mount assembly into the T-60 tube to check the alignment of the spoof tubes. Before cutting the T-60 tube I wanted to double check the alignment. I made slight adjustments to the pencil lines to fit the final spoof tubes locations.

 

[hcmbanjo]

ATLAS POD COVERS
To make the pod covers you laminate two pieces of balsa. One is 4 inches long, the other 2 5/16" long. Both are 9/16" wide.
The instructions have you round the cut tip before sanding to the body tube contour. I would recommend rounding the tip after sanding the inside contour. This way, you don’t round off the tip.

To sand the body contour, I didn’t sand it on the T-60 tube at first. I always start with the next size smaller tubing. In this case a BT-55.
The hardest part of sanding pieces to fit a tube curve is the middle, highest point of the curve. Starting with a smaller tube guarantees there will be enough removed from the middle. When you get it close, switch to a finer grit on the larger body tube you are going to glue in on.
The pods were filled with Carpenter's Wood Filler, sanded and primed before gluing onto the body.

I'm getting ahead on the next step:
When test fitting the Engine Nacelles, I found them a little wide in the front. No problem, a simple trim. In order to get the paper nacelles to fit better over the top of the spoofs, I sanded off the top of the T-5 tubes down with a sanding block.

 

[hcmbanjo]

FORMING THE NACELLE SHROUDS
As I expected, the Heat Shields required a bit of fitting. Mine ended up being closer to the height in the illustrations. The fit on each model is going to be a little different and would require trimming. In the third picture, the Heat Shield on the left is the original size. The one on the right is how I sanded it down for a better fit on my model.

I formed the Engine Nacelle Shrouds in the soft fleshy heel of my hand. I pressed and rolled a dowel over the shroud until it was rounded. Instead of pulling a shroud over a table edge, I have better luck forming small shrouds on my hand. The smaller front end of the Nacelle Shroud is more of a rounded square shape.
The smaller heat shield pieces required a bit of sanding to get the shrouds to wrap all the way around and touch the tube.
Before gluing, I drew lines at the center and the intersection of the overhang.
Rather than use a slower drying white glue, I held the heat shields on their pencil lines and touched super glue to the joints. In the end it was a good fit on all sides.
The fairing wall support strips were cut - six pieces, 3/32" x 32" x 1". (The fairing wall support pieces are not shown in the pictures.) All were tacked in place with CA.
After test fitting I had to sand the middle support strip down a bit.

After I was sure of the Nacelle fit, I glued the Pod Covers onto the body. I ran a light coating of White glue on the underside and pressed them into place. I sighted from the rear making sure they were straight.
After holding them tight against the body for a few minutes, I could see some of the edges lifting. I ended up using a small amount of CA on those points, keeping a paper towel handy to pick up any overflow. This seemed to hold them down and would make for easier fillets later.

I was concerned about gluing on the Nacelles. Even with the supports in place there was a slight bowing of the outer fairing walls.
I decided to tack the upper corners of the Nacelles against the pods with small amounts of CA. On the bowed sides of the Nacelles, I held them down with the flat backside of a razor blade. This insured the sides would be straight while I touched CA along the long joint.
If any sanding is needed, the CA would strengthen the paper Nacelles. I also added CA to the back overhang of the Nacelles so they wouldn’t be bent when handling.

 

[sodmeister]

Very cool.I love those kits and must say the thread on tube to simulate engine bells is brilliant !

Great build

Paul

 

[hcmbanjo]

Paul,
I agree, wrapping the threads for an engine bell is a simple solution that looks great in the end. I had my doubts on my first Zooch kit, but I'm convinced now.
The other thing I've noticed in the Zooch kits is how the later steps "reinforce" earlier ones. If I have a concern about the fit of a part, another part or wrap covers up any seams or gaps. These are well engineered kits.

MAKING THE FLAME FINS
I jumped ahead to the Flame Fins. The fins are supposed to be a flame profile, so the outside edges shouldn’t necessarily be cut the same. But, the root edge, width and length should match the pattern.

I used 400 grit sandpaper wrapped around the white back end of a Sharpie pen to sand the small curves in the outside edges. The pen barrel kept everything squared up. I won’t bother trying to round the edges of the fins.

After I glued the small CR35P Centering Rings to the T-3 Tube, I set the root edge of the fins against the T-3 tube. The root edges were longer than the remaining gluing surface below the lower Centering Ring. I’ll have to re-taper the front of the fins so the rear end of he fin matches up with the (remaining) length of the T-3 tube. It’s a simple fix.

The fin illustrations in the instructions have the balsa grain going the wrong direction. The template is correct, a builder would cut from the template anyway.

I didn't find a marking guide for the T-3 Flame Fins tube. The fins are glued in a cruciform shape, three fins spaced at 90 degrees. This leaves an open area allowing for the engine flame.

When I was building my Zooch Shuttle, I looked online at pictures of the engine flame at launch. The flame pattern went from bright white to yellow. I tried to match this on the other Zooch kits.
Simply spray the fin assembly white overall and let dry. Follow up with bright yellow directing the spray at the lower half of the assembly. Try to get an even blend.

 

[luke strawwalker]

I had to "modify" the ends of the spoof tubes as well for the fairings to lay down smoothly on the balsa upper fairings... I didn't sand them though, I just sorta "pushed them in a bit" at the top, sorta flattening the top of the tube a bit so the paper fairing would lay flat.

https://www.rocketryforum.com/showthread.php?t=4923


I also "blocked up" the fairings as the glue dried with scrap balsa, rubber bands, and clamps to hold everything straight while the white glue dried. CA probably would be handier but the white glue is stronger...

Great build, KUTGW!!! OL JR

 

[Fred22]

Paul,
I agree, wrapping the threads for an engine bell is a simple solution that looks great in the end. I had my doubts on my first Zooch kit, but I'm convinced now.
The other thing I've noticed in the Zooch kits is how the later steps "reinforce" earlier ones. If I have a concern about the fit of a part, another part or wrap covers up any seams or gaps. These are well engineered kits.

MAKING THE FLAME FINS
I jumped ahead to the Flame Fins. The fins are supposed to be a flame profile, so the outside edges shouldn’t necessarily be cut the same. But, the root edge, width and length should match the pattern.

I used 400 grit sandpaper wrapped around the white back end of a Sharpie pen to sand the small curves in the outside edges. The pen barrel kept everything squared up. I won’t bother trying to round the edges of the fins.

After I glued the small CR35P Centering Rings to the T-3 Tube, I set the root edge of the fins against the T-3 tube. The root edges were longer than the remaining gluing surface below the lower Centering Ring. I’ll have to re-taper the front of the fins so the rear end of he fin matches up with the (remaining) length of the T-3 tube. It’s a simple fix.

The fin illustrations in the instructions have the balsa grain going the wrong direction. The template is correct, a builder would cut from the template anyway.

I didn't find a marking guide for the T-3 Flame Fins tube. The fins are glued in a cruciform shape, three fins spaced at 90 degrees. This leaves an open area allowing for the engine flame.

When I was building my Zooch Shuttle, I looked online at pictures of the engine flame at launch. The flame pattern went from bright white to yellow. I tried to match this on the other Zooch kits.
Simply spray the fin assembly white overall and let dry. Follow up with bright yellow directing the spray at the lower half of the assembly. Try to get an even blend.

I like the fins
Cheers
fred

 

[hcmbanjo]

To Luke Strawwalker,
Those fairings took a little extra work to glue on. I only tacked the edges with CA, the back of the razor blade was held above the glue line to keep the fairing flat and true. Well, as true as I could get it.
The underside is held in place with white glue and the outside fairing / body tube seams got a few white glue fillets. It's not going anywhere soon.

I reread your build thread. I forgot about the chrome paint problems. I'm going with the cheap WalMart aluminum. It's not reflective, sort of silvery gray. It does dry quickly with almost no masking ridge.

To Fred,
Thanks for the comment on the flame fins.
The only drawback to blending two colors with spray cans is the second color surface (yellow on this one) can be rough to the touch. You can't sand or use rubbing compound on the blend, it won't be a blend anymore.

 

[dragon_rider10]

Looking great Chris. Looking forward to seeing this one.

What's a SPOOF?

 

[hcmbanjo]

Hey John!

That's what Dr. Zooch calls the fake engine tubes.
I was curious what the actual definition was so I looked it up.

Spoof: a parody or hoax
(from the Oxford Dictionary)

I guess it fits.

p.s. That was another great Squatty Body pic!

 

[luke strawwalker]

Looking great Chris. Looking forward to seeing this one.

What's a SPOOF?

They are the small side tubes glued onto the motor mount, which serve two purposes on this kit:
1) they "simulate" the look of the outboard booster engines on the Atlas, which is why they have string wrapped around them to simulate the "hatbands" around the nozzle of the engine bell, (hence the "spoof tube" name in the kit; and

2) they conveniently hold the inserted flamefins for stability of the kit in flight, while allowing them to be neatly removed for display.

Zooch kits are marvelously engineered... OL JR

 

[hcmbanjo]

BACK TO THE BODY DETAILS
The Mylar Corrugated Wrap went easier than I thought it would. The height is cut to 1 1/8". Set it onto the main body 5/8" from the bottom. It is pressed into the corners of the Nacelle / Body Tube joint for marking the cuts.
I checked and double checked the locations before cutting to size. You are given enough of the Mylar to cut an extra piece if a mistake is made.
It was glued in place and the edges stayed down. Fillets were applied to smooth over the joint.

The Adapter was sanded, filled, primed and painted white. You place the adapter in the Main Tube now. In the next step, long cardstock strips are glued inline from the above Wrap and over the Adapter.

I had to find the exact center of the main tube between the Nacelles. To find the center, I pushed a piece of paper into both sides of the Nacelle / body tube joint. I simply folded that length in half and marked the center. That mark was extended up the tube.

A 1/16" paper strip is glued to the body on each side. The paper strip was cut from the remaining template cardstock.

Next, you mark the line 3/8" up from the corrugated wrap. There is a discrepancy in the measuring. The two Vernier Engine Housings are ½" tall. This is taller than the 3/8" marking and gluing area clearance. If I started the cardstock strip at 3/8", the ½" tall Vernier Engine Housing would overlap the corrugated Mylar. The instruction illustrations show a small space between the top of the Corrugated Wrap and the bottom of the Vernier Engine Housings.
My mark ended up being 9/16" from the top of the Corrugated Wrap to allow the height of the Vernier Engines. I started gluing the bottom of the long strip down at the 9/16" mark.

The third picture shows how small the Vernier Engine Housings are. They were filled before attachment to the body. The Vernier Engines were glued on, the small tip touching the bottom of the cardstock strip.

 

[hcmbanjo]

FINISHING UP THE DETAILS
I still hadn't decided how to make the Nosecone Line Fairing. It’ll be difficult to make out of balsa. Anything that thin will be hard to fill and keep square.

I moved ahead to the dowel. The 1/8" dowel top is rounded and glued to the body. While the instructions don’t say to sand the dowel to a half-round shape, the illustration shows it. I sanded half off down it’s length and rounded the top. I recessed an area wide enough to fit it over the corrugated wrap.
It would be near to impossible to mask the dowel after it is glued. I’ll paint the rocket white, then mask and paint the lower body Aluminum. The dowel will be painted Aluminum then glued to the finished body.

After thinking about it for the day, I came up with a way to make the thin balsa Nosecone Line Fairing. On most models, I usually fill balsa before gluing it to the body. This is a 1/32" thin, long piece and would probably warp when painted with filler.
I decided to form and fill it while still on the balsa sheet, then cut off the thin strip and glue in place. Using my metal sanding block with 220 grit sandpaper I thinned the edge in a long “step”. Making the Fairing this way would help prevent warping and breakage. It’s easier to form and round the edge still on the balsa stock. The Fairing was filled while on the balsa sheet. Picture three shows it being cut off the sheet.
The tip of the Pod Cover was cut off and the Fairing glued in line to the top of the body tube. The end was sanded square at the end of the body tube.
The Fairing was continued up the Adapter. I sanded the angle to match the Fairing at the end of the Body Tube.

 

[hcmbanjo]

SHOCK CORD, PARACHUTE, AND FINAL PAINT
In an earlier Zooch build I thought the measurements for the Estes style Shock Cord Mount were too small. The instructions say to cut a rectangular strip ½” wide by 1" long. Folded in thirds this would be a small mount. I made mine closer to the Estes mount size. The enclosed Ribbon style Kevlar is 20" long, tied to the 1/4" wide elastic at 36" long. Total combined Shock Cord and Kevlar (once tied) is 52" long.
Instead of attaching the Parachute at the Screw Eye, I connected it 1/3 the way down the Elastic from the Nose Cone.

The instructions say to place the Screw Eye “off-set” from the Ballast Filler. The Ballast Filler is on the top, opposite end of the Adapter. I didn’t see any need to offset the Screw Eye, I screwed it into the center of the Adapter base.

Sorry, no pictures of the parachute construction. No reason to show it, we’ve all made too many in the past. I’d rather illustrate the more interesting aspects of the kit.

The rear Centering Rings and Spoof Nozzles were masked off by setting small squares of masking tape against the extended inside wall of the rear main tube. I stuffed scraps of paper towel into the recesses.
The entire model was sprayed with grey primer and sanded. Rustoleum Painter’s Touch Gloss White followed, sanding in between coats. I didn't want to paint the upper T-50 tube as it was going to get a printed wrap. For painting I joined the upper adapter and nose cone with some scrap BT-50 then sprayed all as one white unit. I know it should be flat finish, but flat finishes get dirty. I’ll hit it with a dull coat later on.

Earlier, the Nose Cone had been filled, primed and painted. I drew a line down the upper T-50 tube for the Agena Wrap.
I don’t have much luck using white glue on full body tube wraps. I cut out the wrap and hit the back with spray adhesive. The spray adhesive lets me reposition the wrap if necessary. Using White glue, you only have one try getting it on straight.
Using just spray adhesive the end edges won’t stay down. I lay a small amount of white glue on my knife blade and push it under the raised edge.

Earlier I painted the model Gloss White. I didn't touch the model for a few days to give the paint time to set up.
I masked around the Pod Cover with Scotch tape. Masking Tape went over the edges of the Scotch Tape widening the masked areas. I cut up a plastic grocery bag and wrapped that around the larger areas of the upper body.
The masked areas around the Engine Mount were left on for the Aluminum paint. I’d had good luck with the cheaper WalMart Aluminum before and decided to use it again.
I did my typical process of light coats then a final heavy coat. The WalMart Aluminum dries clear and even.
While Scotch Tape gives me the best masking lines, it can be hard to remove in one piece. It’ll tear quite a bit when removing but the results are worth it.
The third picture shows what I used to burnish down the Scotch tape used for masking. It’s simply a sharpened, then rounded tip dowel. The rounded point lets me burnish the tape edge in sharp corners.

The upper T-50 Body Tube was glued to the Adapter. Before gluing in place, I used a Sharpie pen to blacked the lower edge of the Body Tube and wrap. This gave a sharper color separation line between the wrap and Adapter section.

The 1/8" Dowel was left off during painting. It’d be too hard to mask around it. I sealed, primed, sanded and painted it Aluminum. It was positioned and glued in place over the Corrugated Wrap.

The Launch Lug had its seams filled, then Gray Primer. After sanding it was sprayed White and cut in two. Both pieces were glued in line using a short length of 1/8" dowel to line them up.

 

[sodmeister]

Beauty !! I had no idea that kit was so nicely detailed....although I should have known ,being from the good "Doctor"
I have a Zooch Merc.Redstone ,but can see more of these beauties in my collection !

Again ,looking good

Paul

 

[hcmbanjo]

Hi Paul,
Most all of the Zooch kits are detailed. I have seen a few where the builder left off some of the small stuff. The models still looked and flew great.

FINISHED!
Overall I'm happy with the results. Sure, the lower half could be more reflective, but I stayed away from using chrome paint after reading about problems with it in forum threads.

I like a challenge and that I can build a semi-scale model in a manageable size. I hope to fly it next Saturday at our Orlando R.O.C.K. section launch.

I emailed Wes before I did this build thread. I had a question about a measurement in the instructions and one suggestion I made.
He wrote back: "Those are all very good points- be sure to work them into your build thread and I will change the instructions to reflect there..." Thanks, Wes

As I've mentioned: great, well engineered kits, a challenging build and great flyers.

Next up - I'm thinking about a Jupiter C, Mercury Little Joe or the Saturn 1 SA-5.

 

[Fred22]

Man that looks great
Cheers
Fred

 

[Dr.Zooch]

I'm taking a good look at all of the tips and faults outlined here so I can make corrections in the Mercury Atlas instructions as well as amend the next set of Atlas Agena instructions.

Good stuff- rocket looks terrific!

 

[sodmeister]

That looks great Chris ,nice detail for small scale rockets....gotta love it .


Paul

 

[luke strawwalker]

Nice job! OL JR

 

[hcmbanjo]

I got the Atlas Agena in the air this last Saturday at our Orlando R.O.C.K. Section launch.
I was reluctant, there was a wind and didn't want to hang it up in the trees. After a little persuasion from the group I gave in and loaded it up with a Quest B6-4.
Straight boost and good parachute deployment. After the flight there wasn't any engine scorching on the flame fins, just a very slight blistering of paint on the tube.
Thanks to Roger Smith (jonrocket.com) for the pictures!

 

[Fred22]

Great job
Cheers
fred

 

[Bone Daddy]

Those flame fins look great!

 

[Rocketeer41]

Nice Dr. Zooch Atlas Angea hcmbanjo.:headbang: It`s on lift off.:roll: And why did you put mini feather like fins?:confused2: 3.2.1 lift off!:cyclops: It`s like a space shuttle.:eyepop: If it were a Coulumbia would you be happy? And did you have fun building your Dr Zooch Atlas Angea?:cyclops:

 

[hcmbanjo]

To Rocketeer 41,
Thanks for the feedback.
Those aren't feather fins, they are the Zooch trademark "flame fins".
And yes, I had a great time on the build.

 

[DM1975]

Looks like an absolutely wonderful job on the rocket. I have got to try a few of these kits.