Saturn SII - North American Aviation Model

Today, the various NASA "models" that we are all acquainted with are generally generated on the computer as strictly virtual entities. Actually, NASA and its manufacturers still rely heavily on physical models but not to the degree of the Apollo days. Those of us who are Apollo enthusiasts are familiar with the rather "famous" 1/10 scale end-to-end models that reside at several locations such as at Space Center Houston (JSC), US Space and Rocket Center (MSC, Huntsville), Kennedy Space Center, and the like. There was a 1/10 scale all-metal dynamic test model that was crafted to an incredible degree of fidelity to the real thing.

The manufacturers of the various Apollo and Saturn components also crafted some incredible models both for PR purposes and as engineering and design visualization. A rather incredible model of the SII stage was crafted by North American Aviation in 1964 in 1/24 scale (almost 17" in diameter).  The name plate says "Saturn S-II Stage Post Flight Evaluation Model." I'm not entirely sure why it was called the "Post Flight Evaluation Model" as it was crafted in a configuration with the interstage attached...and the Saturn was yet to fly for almost another three years.

The model was remarkably detailed and featured both internal and external details that rival those of the 1/10 scale models which were almost 2½ times larger. This model and timeframe that it was constructed (barely two years after the Saturn V design was initiated) is even more amazing when you stop to realize just how stabilized the design of the SII stage was so early in the program and just how close it is to what was actually flown. You develop a real appreciation for just how quickly the design was researched, developed, and ultimately flown.

The SII stage was the stage that continued to evolve the most even after the first flight of the Saturn in 1967. The stage gradually became stronger and much lighter with each mission. The final stages introduced the spray-on exterior insulation that is so familiar (and troublesome) on the External Tank of the Space Shuttle. Not so visible was the introduction of the rather exotic lithium aluminum alloy (again, common to the Space Shuttle and a key alloy in the Ares vehicle now under development) to greater and greater extents with each stage.

Though these are 1/4 the size of the original scans, they are still rather large (averaging about 1500 pixels on a side) and will take a bit of time to appear with a slow connection.

(Click on each image below for enlarged view. It may take a few moments to appear on slow connections)

Scans by John Pursley from original transparencies