Model Rocket Building Blog

Estes Saturn 1B, #7251 Build, Part 1, Parts
The 1/100 scale Saturn 1B has arrived - A perfect shelf companion to the 1/100 Saturn V. Here's the front and back of the kit box. Notice the white Redstone tanks at the bottom, this is the Skylab Saturn 1B. The earlier Saturn 1Bs had the alternating black/white tanks. The paint pattern on the ...
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Estes Saturn 1B, #7251 Build, Part 2, More Parts
For me, this part is the highlight of the kit. I've built a few Saturn 1Bs over the years, the scalloped shroud has always been a difficult construction step. In the old Estes 1/70 scale version, it was cut out of cardstock. The original 1/100 Centuri version also had a plastic tank shroud. The ...
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Estes Saturn 1B, #7251 Build, Part 3, Tube Seam Fill
I'd recommend filling the tube seams before assembly. It is difficult to fill the seams after they are glued in place. The eight booster tubes end up too close together to reach the seams. With the vacu-form wraps attached it would be difficult to fill and sand the BT seams close to the wrap. ...
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Estes Saturn 1B, #7251 Build, Part 4, Engine Mount
There will be some posted steps that might seem out of order from the instruction sheet sequence.  I tend to prep some parts before they come up in the assembly steps.     Here's all the engine mount parts. Pretty standard, at the top is an 1" orange spacer if you use the D12-3 ...
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Estes Saturn 1B, #7251 Build, Part 5, Engine Mount Finish & Fin Prep
TIP: If you place the centering rings as shown in the instructions, you might add a drop of glue over the top of the engine hook bend slit. This is an "old school" thing, seen on instructions in the 1970s.  The finished engine mount. The new fins are molded of hard plastic, a great i ...
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Estes Saturn 1B, #7251 Build, Part 6, Fuel Body Tubes Primer/Filler
I did dry fit the fuel tubes in scalloped tank shroud. This is one of the best new parts in the kit! A very good fit. The eight fuel tubes needed a shot of Duplicolor Filler/Primer after the CWF was sanded to surface. I had to shoot all these side by side then turn the tubes and hit the backside ...
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Estes Saturn 1B, #7251 Build, Part 7, Fitting Low Wrap
The instructions say to trim off the bottom of the lower, narrower wrap to 1/32" below the corrugations. The top picture is the before - I've marked the 1/32" cut with pencil lines. Below is after the cut. Use a straightedge and a new, sharp knife blade.  The ends are trimmed to 3/16" from ...
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Estes Saturn 1B, #7251 Build, Part 8, Adhering Low Wrap
The 3M 77 adhesive will hold the wrap down, but the joint seams can lift. I squeezed a drop of medium CA glue onto some scrap cardboard. A toothpick was dipped into the CA glue and transferred, directed down the seam edge.  Immediately (before the CA glue can set up) a burnisher was pressed ...
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Estes Saturn 1B, #7251 Build, Part 9, Tower Assembly
I'm not building in the order of the instructions. I'll be bouncing around a bit -      One side of the tower has alignment pins, The other side has alignment holes the pins fit in. TIP: You can sand the side with the alignment holes a little smoother for a better fit of the two ...
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Estes Saturn 1B, #7251 Build, Part 10, Tower Nozzles & Clay Weight
The escape tower nozzles were slipped together. Liquid glue was brushed over the top of the "X" joint. Two clay weight "pats" are included in the kit. Together they weighed just over 1/2 oz. The first clay cube was formed into a cone shape for an easier start in the command module nose. The ...
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Estes Saturn 1B, #7251 Build, Part 11, Fitting The Larger Middle Wrap
TIP: Tape down the wrap before doing any straight edge trimming. You don't want it to slip under the straightedge and end up with a bad cut. When cutting the thin vacu-form wraps, it's not necessary to cut all the way through. Score the line about halfway in then flex and crack the plastic down ...
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Estes Saturn 1B, #7251 Build, Part 12, Upper Wrap GOTCHA!
GOTCHA: After the middle wrap is in place - Don't immediately adhere the upper wrap using the single pencil line drawn down the body tube. On my two builds, I found the longer tunnel would not sit  perfectly vertical in the upper wrap recess. If the edge is started on the pencil line, the ...
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Estes Saturn 1B, #7251 Build, Part 13, RCS Nozzles - Little GOTCHA!
Jumping around and jumping ahead -  Don't cut the wire anchor slot yet - more on that later. This post is just for the RCS nozzles. Drilling by spinning a knife blade tip will make the holes too large! Check the back of the RCS nozzles to see how small the glue pins really are. The p ...
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Estes Saturn 1B, #7251 Build, Part 14, Display Engines
Before gluing the nozzle spacer tube onto the low plate -  These can be hard to center accurately. Center it visually, then trace around with a pencil. Check to see if the circle tracing is centered. If not, make adjustments, erase and trace again. The plate with the holes glues on the other ...
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Estes Saturn 1B, #7251 Build, Part 15, Wire Anchor Slot, Part A
This is one of the trickier parts of the build, bending and inserting the wire anchor. The upper section parachute will clip to this anchor for recovery. You are supplied with a length of brass wire.  The three bends of the inverted "U" shape should  all the same length. TIP: Place a ...
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Estes Saturn 1B, #7251 Build, Part 16, Wire Anchor Slot, Part B
Okay - Here's a weird one -  Instead of leaving an open slot after the wire is glued in, I cut a thin vertical hinge in the body tube. Think of the slot as having two sides. One side of the slot line is cut all the way through, the other side is scored. This makes a slot a vertical "flap" ...
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Estes Saturn 1B, #7251 Build, Part 17, Fill Anchor Slot & Prep RCS Nozzles
The wire anchor slot needed a shot of filler/primer and smooth sanding. This tube had already been filled with CWF and shot with filler/primer. This was the final fill. I did mask around the anchor area. Here's the finished Service Module after spraying with silver paint. TIP: Leave the RCS ...
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Estes Saturn 1B, #7251 Build, Part 18, Tunnel Mask & Capsule Tower Paint
The Antennas have raised vertical yellow bars. I wasn't sure about masking these, they would be a bear to hand paint. I figured I'd try to Scotch tape mask them Scotch tape is set on a plexiglass, black Sharpie lines are drawn down the strips. The black edges are needed to see the clear tape on ...
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Estes Saturn 1B, #7251 Build, Part 20, Gluing On All The Booster Tubes
Jumping around again: The centering ring with the small hole in it is glued even with the bottom of the core body tube. That small hole designates it goes on the bottom.  TIP: Don't make you fillet too wide, the eight outside tubes have to fit against the core tube. I thought it would be ...
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Estes Saturn 1B, #7251 Build, Part 21, Starting The Black Color Mask
The main upper body was spray painted gloss white. Three coats of paint, lightly sanding between coats 1 and 2.     Masking over corrugations isn't easy. I wish I could take credit for this technique - I learned it when I put together two Apogee Saturn Vs. This is the method that works ...
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Estes Saturn 1B, #7251 Build, Part 22, Outlining The Mid Section
The Ultra Fine Point Sharpie end nibs appear to dry out quickly. Keep a piece of paper handy to get the ink flowing again. The picture shows many scribbles from restarting the ink flow when outlining one model. I ended up using only one Sharpie from the five pen package.  The large middle ...
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Estes Saturn 1B, #7251 Build, Part 23, Spraying The Mid Section Tube
On the left is the mid section mask after the gloss black is sprayed. The tape was set down the middle of the wide Sharpie ink outlines. I used a combination of brown masking tape and grocery bags for the larger areas. When spraying over this mask, the outlined black borders help define just that ...
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Estes Saturn 1B, #7251 Build, Part 24, Outline Lower Body
The four painting pictures can be confusing.  TIP:  It's not mentioned in the instructions - starting from the left side, every picture (going to the right) is a quarter turn of the model. To get a better idea (and play it really safe) I first taped the lower body with the black areas ...
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Estes Saturn 1B, #7251 Build, Part 25, Painting Lower Body & Gluing RCS Nozzles
The black areas on the lower body has been outlined.  Notice the interior surfaces have been masked. If paint got on the inside of the scalloped shroud, it might drag and mark the white tubes when the shroud is slid down from the top. The fit of the scalloped shroud over the tubes is very ...
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Estes Saturn 1B, #7251 Build, Part 26, Masking & Painting The Fins
I used the height of the black/white body separation line to draw a mask line on the fin sides. I stacked some CD cases to get close to the correct height. A piece of cardboard between the cases got it to the right height. A horizontal pencil line was drawn on the fin. TIPS: Keep track of the fin ...
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Estes Saturn 1B, #7251 Build, Part 27, Painting The Fins, Outside Edge Color Separations
TIP: When the tape on the leading edge tape was lifted, the paint line was rough. A Mister Clean Magic Sponge was wetted and wrung out. Wipe a Q-tip on the damp sponge, picking up some of the cleaner. Run the wet Q-tip down the white side leading edge and a little over onto the rough black paint ...
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Estes Saturn 1B, #7251 Build, Part 28, Engine Hook Notch
A notch is needed in the low centering ring to allow engine hook movement. The notch location is set between two of the booster tubes. Slide the engine mount in place and mark the width of the hook in pencil. The instructions imply the notch is cut and removed. I decided to make a smooth "ramp" ...
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Estes Saturn 1B, #7251 Build, Part 29, Scalloped Fairing & Centering Rings
I applied a small fillet and removed the excess with a Q-tip. You don't want the glue to get in the way of the centering ring position. You can use a little more glue on the bottom ring. The scalloped fairing won't touch the inside joint glue. The scalloped fairing is slide down from the ...
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Estes Saturn 1B, #7251 Build, Part 30, Command Module Mask & Shroud Line Harness
It isn't pictured here, but I did do quite a bit of touchup to the white and black mask areas. I'll add 20 minutes time below for the touchups.     The umbilical is painted silver. I used five pieces of marked Scotch tape on the smooth plastic. Notice the fourth and fifth pieces are set ...
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Estes Saturn 1B, #7251 Build, Part 31, Gluing On The Fins
Most builders would glue on the fins in order of the instructions, mask and paint afterwards. I thought this would be too difficult especially in the tight fin root areas. This is why I painted the fins before assembly. In the picture, the glue tab has had the paint scraped off for a better glue ...
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Estes Saturn 1B, #7251 Build, Part 33, More Decals
I understand these are "camera focus" markers.  They are tiny! You don't want to be fishing these off the bottom of your decal soaking dish.  TIPS:  Your soak water shouldn't be deep. Using tweezers - float these on the surface of the water , don't submerge them. On the right, the ...
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Estes Saturn 1B, #7251 Build, Part 34, Antenna Gluing
I still have a paper wrap around the body for protection while handling. The antennas are set to the side of the glue area and a pencil line is drawn. Do the same on the right side - draw a line inside the right side of the antenna. Carefully scrape off the paint down the pencil line. This scraped ...
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Estes Saturn 1B, #7251 Build, Part 35, Upper Shock Cord Sling, Glue Sections Together
GOTCHA : You are supplied with a long piece of shroud line to tie up the upper body recovery harness. Try to break the string with a tug - I found mine too weak to be trusted with a strong ejection charge. I replaced it with some #10 embroidery thread. Tie the sling up so the tower is angled up. ...
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Estes Saturn 1B, #7251 Build, Part 36, Shock Cord & Launch Lugs
A standard tri-fold mount is to the shock cord and  the 18" chute on the lower body. TIP : With a pencil, mark the shock cord 2" from the top of the tri-fold mount. Use the pencil mark as a depth gauge when set over the top lip of the body tube.  Trace around the launch lugs. Some of the ...
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Estes Saturn 1B, #7251 Build, Finished
This one was a good build adventure. There have many improvements over the original 1/100 scale Centuri kit format. It took a little over 28 hours to assemble and paint. Most builders would glue on the fins and mask afterwards. I didn't think I'd be able to get a clean mask if the fins were glued ...
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Estes Saturn 1B Paint Patterns
Here's some detailed four sided views of the Saturn 1B. This is for the SA-205 version, with the alternating black and white tanks. Still a good reference, courtesy of Apogee: CLICK HERE Note that the Position 1 View is looking directly onto the Fin to be marked with the  Number 1 decals ...
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