STS - 124 : External Tank Changes

John Chapman, manager of the External Tank Project Office , discussed two major changes to the external tank being implemented in an effort to reduce icing and foam loss. The external tank(ET-128) being used aboard STS-124 is the first tank since return to flight to have improvements incorporated during the manufacturing process instead of being added post-production.

Feed line brackets have been redesigned to use titanium in stead of aluminum due to superior thermal dynamic properties. The amount of foam now required on the bracket has been greatly reduced. The shape of the foam surrounding the bracket has also been modified to reduce friction during movement of the bracket. This includes adding a Teflon material between the foam on the bracket and the foam surrounding the fuel lines to remove an air gap where ice could form.

BX manual spray foam has replaced PDL and NCFI foam in the base cut out for the ice ramps. Ice ramps are the large aerodynamic looking blocks protruding from the external tank that insulate the fuel lines and brackets from icing.

For more information about external tanks and design changes please visit http://www.nasa.gov/returntoflight/system/system_ET.html

Scott

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