provide additional program confidence, both near- and long-term
contingency planning was implemented. Alternative designs, which
might be incorporated into the flight program at discrete decision
points, include field-joint graphite-composite overwrap bands and
alternative seals for the field joint and case-to-nozzle joint.
Alternative designs for the nozzle include a different composite
lay-up technique and a steel nose inlet housing.
Alternative designs with long-lead-time implications were also
developed. These designs focus on the field joint and cast-to-nozzle
joint. Since fabrication of the large steel components dictates
the schedule, long-lead procurement of maximum-size steel ingots
was initiated. This allowed machining of case joints to either the
new baseline or to an alternative design configuration. Ingot processing
continued through forging and heat treating. At that time, the final
design was selected. A principal consideration in this configuration
decision was the result of verification testing on the baseline