DOWNEY, CALIF., ApriI 11, 1970--A slimmed-down version of the Saturn V's second (S-II) stage rocket will make its first flight in the Apollo 13 mission.Built by North American Rockwell's Space Division for NASA's Marshall Space Flight Center, the stage will have a launch pad unfueled weight of approximately 78,050 pounds. It is about 3000 pounds lighter than the comparably equipped and instrumented S-II for the Apollo 12 mission.
The weight savings is due to the use of a new closed-cell polyurethane spray-on foam insulation on the exterior of the S-II. The new insulation is easier to apply and work with than that used in the past, is much lighter, and provides better thermal protection.
Primary job of the insulation is to help keep the S-II's -423 degree F. liquid hydrogen from warming even a few degrees following launch pad fueling.
A honeycomb core purged insulation was on earlier models of the S-II. The insulation was made from a vented, heat-resistant fibreglass honeycomb core filled with an open-cell polyurethane and sealed with an outer coating of nylon and tedlar.
About 4500 square feet, or a tenth of an acre, of the new spray foam is used on the S-II. It is sprayed-on and then machined to the desired thickness.
The new spray-on foam was used on parts of the S-II stages for both the Apollo 11 and Apollo 12 missions.
The largest and most powerful hydrogen-fueled stage ever built, the S-II is 81.5 feet tall and weighs approximately one million pounds fueled.
The stage is powered by five Rocketdyne-built J-2 engines which develop more than one million pounds of thrust at altitude. The S-ll takes over from the first stage to boost its third stage Apollo spacecraft payload to an altitude of about 118 miles into space and a speed of more than 14,000 miles an hour.
Both the special equipment and the high-reliability foam application techniques developed in the S-II program were used by Space Division engineers in the recent insulation of a giant tuna clipper, one of the largest built in the United States specially for tuna fishing. More than 20,000 pounds of foam were utiIized in insulating the clipper's hull.
Space Division engineers and scientists are studying other potential applications of the space program-developed spray foam technology. Possible uses are in petroleum chemical storage tank insulation; pipeline insulation; maritime uses such as in fishing vessel and liquid- natural gas tanker insulation; in cold storage and other types of warehouses, and in prefabricated and mobile homes.
The 29th largest industrial corporation in the United States, North American Rockwell is engaged in 20 related engineering and manufacturing businesses involving high technical content products. It has major strengths in research and development, aerospace and commercial products, systems engineering, and a growing position in a number of the emerging industries.
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