A Case Study in NASA-DoD - The Black Vault

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(36 in. in diameter by 55.5 in. in length) is an existing flightqualified
design that was developed for the Viking Orbiter (VO-75)
program. It presently has a surface tension device for propellant
expulsion, which will most likely be replaced with an elastomeric
(AF-E-332) bladder. Such replacement would entail about a 25 percent
modification to the overall tank assembly. As indicated in Table E-l,
the structure weight is increased from 29 lb to 81 lb compared to
SPS-I. However, it should be noted that these weights include propulsion
module structure, drive electronics, remote interface unit, GN 2 ,
and other miscellaneous items; hence, some care in cost bookkeeping
appears warranted for both the SPS-I and SPS-II systems. The total
SPS-I system costs are estimated to be $500K nonrecurring and $750K
recurring on the basis that the SPS-I system will be built first.
In comparing these two MMS hydrazine systems with the STPSS cold
gas systems, the same comments apply as presented earlier in the comparison
of STPSS cold gas systems and the AEM hydrazine system, i.e.,
a different cost base is required for cold gas hydrazine components.
With respect to the STPSS hydrazine system, the same cost base should
apply with perhaps some minor adjustments for the required component
modifications noted herein. Moreover, the 0.2 lb and 5 lb thrusters
F
F
of the MMS systems are estimated at $12K each compared to $20K and $25K
each for the 0.1 lb and 4 lb F thrusters in the STPSS hydrazine system.
This difference is probably reconcilable on the basis that the MMS
thrusters have single-seat/single-coil propellant flow control valves
versus dual-seal/dual-coil valves in the STPSS thrusters and perhaps
less contractor testing and paperwork required, since the MKS thrusters
are standard NASA items.