The science of selecting the best air vehicle to satisfy the very demanding requirements of performance, cost, and schedule has led to some very
sophisticated airplane synthesis computer programs. Vehicle weight estimation
is one element of such a complex system. Structure weight estimation is the
subject of this SAWE paper.

Over the last decade, there has been a tendency to adapt complex structure analysis programs to predict weight. At Rockwell International, the
Mass Properties Group has developed programs designed primarily to predict
weight; structure synthesis is a secondary consideration designed only to
be adequate until the vehicle concept development has progressed sufficiently to justify the use of the more rigorous structure dynamics programs. In
spite of its planned secondary role, the structure simulation, with its gages,
stringer,rib, frame spacing, longer on dimensions, etc., has been extremely
useful in pricing exercises, and trade studies,

The Mass Properties programs were developed at the Los Angeles facility under IR?,L) funds as stand-alone component programs (wing, horizontal and
vertical tails, fuselage,landing gear, and air induction system). In August
1971, an Air Force contract was awarded to Rockwell to improve these stand-
alone programs,integrate them into one continuous interactive program, and
provide a detail documentation of the results. The contract was issued by
the Deputy for Development Planning, ASD/XR, at Wright Patterson Air Force
Base,and the work was accomplished at the Los Angeles Aircraft Division.
This integrated program is referred to as SWEEP, which is an acronym for
structural weight estimation program.

This SAWE paper will describe SWEEP and will emphasize the interdisciplinary considerations with the many options that give the user a very versatile tool.