A Case Study in NASA-DoD - The Black Vault

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STPSS STRUCTURAL SUBSYSTEM
The description of the STPSS structure presented here provides
only the overall dimensions and configuration.
(1)
Additional details,
such as individual member materials and thicknesses, are not available
because no actual design has yet been undertaken. The STPSS consists
mainly of a core module and an orientation module.
Core Module
The core module has the shape of a thin hexagonal nut. It connects
to the shuttle orbiter at two trunnions and a stabilizing fitting.
Box beams spread the load from the trunnion to the central ring,
which is the primary load-carrying member. Honeycomb panels define
the hexagonal perimeter of the core module. They also provide mounting
surfaces for equipment on the interior and thermal radiators on the
exterior. The panels transfer the load to the trunnions and directly
to the central ring via the webs.
Orientation Module
Each orientation module is also hex-nut shaped and mates with the
core module at the central ring. The two versions of the three-axisstabilized
module (i.e., the "orientation" version and the transfer/
orientation version) have identified structure except for brackets
that connect the appropriate propulsion unit. The spin-orientation
module is thinner because its equipment does not require as much
volume.
Spacecraft Weights
Table F-2 summarizes the spacecraft structural component weights.
The TRW estimate of structural weight was deduced from HEAO data. The
HEAO spacecraft, which carries a 7000 lb payload with a safety factor
of 3, weighs about 20 lb/axial length (in.). Taking a 1500 lb payload
weight for the STPSS spacecraft, and a safety factor of 2, TRW deduced
a structural weight of 25 lb/sq. in.
High Energy Astronomical Observatory--a spacecraft that was
actually designed and analyzed by TRW.