Saturn V S-II
The first pictures show the thrust structure fitted with ringframes and the structure that will hold the 5 J2 engines.
Construction notes:
30 July 2004: The making of the cones for the J2 engines is essentially the same as for the F1's. The electrical device shown saves a lot of "sanding time" and ensures that the engines will be symmetrical.
Notes: 12 August 2004. Fuel lines have been installed, they are plastic tubes wrapped with fishing line which has a finely detailed appearance once painted. The shroud has been sprayed with layers of white primer and a protective layer of flat varnish. After the first white coating, the whole thing was checked for cracks and gaps that become visible when the part is painted. Also installed: some of the boxes containing electronics.
Notes february 2005. The body of the S-II stage is made from two large pieces of 0.5mm styrene. I was lucky to find styrene sheets large enough so I will only have two joints running along the stage. One will be covered by a systems tunnel. The cone shaped thrust structure has been installed into the tube on top of the LOX-tank dome and with the fuel distributor "trapped" in between. Making a cone that will fit neatly inside a tube is quite difficult. But lining the inside of the large tube with an extra layer of 0.3mm styrene made the two parts fit together very well. The broad ring frames extending inwards from the bottom edge of the stage are glued on in several pieces. The bottom of the LOX tank is almost covered now. Once the five engines and the heat shield are in place, it will be even harder to see. It takes a lot of work to make a dome this big out of balsa...
Notes: March 24, 2005. Upper tank dome painted and installed. Inside the forward skirt: a couple of electronics boxes and the fuel vent lines. On the outside: stringers, stringers, stringers.... Almost 300 little pieces of styrene on the forward skirt. There is only one way out: stop counting and start gluing!
You can maybe see it in the pictures: the upper frame of the stage is not completely circular. That is because the styrene that bonds the large sheets of the stage together is too wide. This causes the joints running along the stage to be too stiff - they do not bend easily. The trick would be to make the bonding pieces as narrow as possible... too late. Some of the kinks and bends are neutralised by forcing them into shape by supergluing them to the the frame.
January 2009 - Five years after I started on this stage, I'm back to working on it. First up were the LH2 feedline fairings. As with many of the details on this stage, these are complex shapes with comlex curves and bulges. The basic structure of the fairings is a styrene tube cut in half lenghtwise and with the "bulges" molded on with putty. Molding, sanding, filling, sanding, filling, sanding... The upper ends of the fairings were shaped from balsa and the lower, open ends where made from pieces of styrene heated and pulled down over the tip of a pen to give it the tapered shape. The LH2 lines on the outside of the stage are barely visible once the farings are in place, but I built the ends of the lines to be placed inside the farings.
The stage was first painted with ordinary gloss white spray paint from the hardware store and then the decals were applied. I took care to work the decals tightly around the raised lines on the stage with setting and softening solutions. After they dried, the whole thing received a coat of clear flat - "model building grade" clear flat, not the stuff from the hardware store that yellows. The black roll pattern was brush painted.
Now the stage was ready for detailing. And with the farings attached, it started to look like a rocket stage. I have done some preliminary work on the LH2 and LOX vent fairings, but again: these are a bit more complex to build than most other details, and I'm not quite satisfied with them yet - so they will have to wait some more.
Next up is figuring out how much of the wiring on the thrust structure is needed to make it look realistic. The goal is to make this end of the stage look "dense" enough. I decided to connect the various boxes to the ringframes on the thrust structure/lower end of the stage. The wiring is made from ordinary fishing line and held in place with tiny eyelets. I decided to paint the wires in shades of white - this matches with the reference photos, and the different kinds of white make the model look realistic - I think... Some of the wires cannot be installed before the engines are in place.
February 2009 - Next up are the engines... I think it will be possible to install the heat shield before the engines. I might be able to build them to "plug in to" the fuel lines already in place, and then insert them through the gaps in the shield.
I had build most of the parts for the engines a long time ago, but constructing the engines is still a difficult process. The LOX and LH2 lines must be at the correct distance from each other to match the fuel lines already in place on the stage. And there is no clear, positive way of fitting them to the engines - they just stick out from the small rings on the cumbustion chamber. So this part of building the engines takes almost endless testfitting. I made a small jigg for each engine to be able to check the fit and relative distances - "LOX" and "LH2" are mixed up on the jigg! I glued the fuel lines in place with "slow" plastic glue, and once they fit, I secured the parts with "fast" superglue.
March 2009 - Then engines are almost completed, they have been made to match the fule lines on the stage. So now the heat shield can be installed. At first, it is installed with 8 vertical supports and tweaked into the correct position. 
Then the central engine is plugged in, connected with wires to the control box and the remaining supports are inserted.
Next pictures: more engines are installed...
August 2009. The last two engines have now been installed:
And finally, the last fairings. The construction of the LOX vent fairing is shown in detail. It's a bit more complex than the others...
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