Classic Upscale: Building a 1/50 scale Apollo/Saturn 1b

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Home / Features / Classic Upscale: Building a 1/50 scale Apollo/Saturn 1b

Classic Upscale: Building a 1/50 scale Apollo/Saturn 1b: Part 3

Project Review by Jeff Brundt

Sunday, December 27, 1998

Article Index
Classic Upscale: Building a 1/50 scale Apollo/Saturn 1b
Classic Upscale: Building a 1/50 scale Apollo/Saturn 1b: Part 2
Classic Upscale: Building a 1/50 scale Apollo/Saturn 1b: Part 3

Page 3 of 3

Final Assembly:

After the various components are painted the rocket is ready for final assembly. The first stage fuel tubes slip into their respective positions and are lightly glued in place with super tacky glue.

Next comes the main body tube to core tube join. The main body tube will slip over the eight fuel tubes and trap them into place. I put epoxy on the lower centering ring of the main body tube and slipped it into position.

I used 30-minute epoxy so it would give me time to position everything for line up. Here is where I used my ¼" launch rod again to assure correct line up of the two assemblies. Once the main body tube was lined up I epoxied the upper centering ring to the core tube. I then set these completed assembly aside to dry.

I next attached the command module to the LEM/SM stack. This was a friction fit only. This will allow me to add any nose weight to achieve proper CG/CP relationship later.

The LES tower is attached to the command module. This is a friction fit as well so I can take the tower off later for repairs if need be. The fit is very tight though so I am not worried about it coming off in flight.

Finishing/Detailing:

After all the epoxy has dried it is time to add the miscellaneous details. Using my 1/100 Saturn 1b for reference I attached all the ullage motors and conduits using super tacky glue to their correct positions.

I attached the four vernier motors to the service module as well. I fabricated the four antenna boards from sheet styrene and painted them white with silver antennas. These were attached at the four locations on the first stage.

A company in Texas called Model Graphics provided the decals for this model. They make custom vinyl self adhesive decals. I have used them before for custom work on my R/C airplanes. They do outstanding work.

I sent them a .tif file of the decal set from Estes’ 1/70 kit and they were able to scale them to fit my 1/50 version. I highly recommend them. It may be a bit pricey but it is definitely worth it.

Each set they furnish comes with complete instructions on how to apply their product.

I also ordered a set of decals from Tango Papa custom decals. From these decal sheets I used the ‘United States’ words and flags on the CM and SM plus the various smaller target markings.

Tom Prestia, the owner, has certain Estes decal sets available and will upscale them for an additional charge. These however, are water slide decals. So you will have to contend with silvering or clear edges if you don’t clearcoat.

Motor Mount and Stability:

I tried to model this rocket for CP using Winroc software. The only drawback was that the Barrowman equations for determining CP do not support an eight fin configuration.

I used six fins and added 10% to the fin dimensions to allow for this. I also compared the balance point of the Estes 1/100 kit to this upsized version and it is very close. The calculated CP is 31.45 inches from the tip of the command module cone.

I also believe that with eight fins the CP would move further aft. My actual CG is well forward of the calculated CP (27" from the tip of the CM) so I am confidant that this will be a stable flyer without addition of nose weight.

Since the core tube is a 54mm diameter tube I used a LOC 54/38mm adapter. I assembled the adapted per the LOC instructions and epoxied it in place in the core tube.

I used an AeroPac 38mm motor retainer. These things are the slickest set up going for my money. They are quick, neat and look so darn good.

Final Thoughts:

The all up weight for this rocket is 3 lbs. 12 oz. Which is not very heavy considering what has gone into it. There were no real problems encountered while building this bird. I was able to make everything with relative ease using common materials.

I flew the rocket at our club’s December 12^th launch. Prepping went uneventful.

I did not bring my dual 36" chutes for the main section so I used a single 54" ‘chute. Everything packed nicely into the recovery section with enough room. The motor was readied and loaded.

The weather that day was perfect. No wind and clear skies. I got a far pad since this would be a maiden flight. I had the photographers ready. And I prayed.

The motor lit right away and the Saturn left the pad very majestically (and stable). Then it happened. At about 300 feet the ejection charge fired prematurely. The rocket was still under boost from the H123.

The LEM/SM/CM stack separated and went off to the side. Its recovery ‘chute deployed perfectly. However, the main section was another story.

The air load ripped the chute away and actually broke the main bridle. The main section continued up for a little way, arced over then headed straight down for the ground ready to take a perfect core sample. Any doubts of stability were allayed.

The main section headed straight in, struck the ground dead on and then bounced back into the air about ten feet, flipped end over end twice and landed sideways on the ground. There was a hushed silence from the crowd. My only thoughts were "Oh well, time to build another." All that remained was the 54" parachute floating gently down.

I headed out to pick up the pieces. When I got to the main body I was very surprised. The damage was very minor.

I expected the whole forward section to be crumpled but it was not. There was no damage to the upper section, which recovered via the parachute and there was no damage to the fins either (this was always a concern of mine on this model). All in all I was very, very lucky that day.

The damage has since been repaired and I awaiting the final coat of paint. All I did was remove the corrugated wrap from the damaged portion, straighten the tube and reinforce with CA then cut some new wrap and glue it on, paint and finished.

The model will fly again. Post mortem indicated from all witnesses that the ejection charge went off too soon. As to why this happened I am clueless. There may have been a void in the delay element. Since the motor was still under boost while this occurred it seems the most logical assumption.

Never the less the Saturn will fly again. I have been told that my models are all too pretty to fly and that I must have nerves of steel to do this. But my thinking is I build them to fly, and if you fly ‘em they’re gonna break. You can always build another.

If you are interested in looking at any of my other scale models then you can visit my web page at: http://www.geocities.com/CapeCanaveral/Hall/4501/index.html

List of Materials: