November 10, 1997
OTA's Draft Report on "Big Dumb Boosters"
As reported in the preceding Column, Congress set aside the preparation
of the report on the outcome of the workshop on "Low Cost, Low Technology
Space Transportation Options." Apparently Congress opted to receive a report1
in which combinations of existing and proposed launch systems were identified
that would support an array of possible mission models, together with projected
The existing systems considered were the Shuttle, Titan IV, Delta II,
the Atlas Centaur II. The proposed systems considered were the Shuttle-C
(a cargo-carrier Shuttle derivative) the Titan V, and the Advanced Launch
System (ALS). OTA considered other proposed systems although they were
not actively worked on; such as, the Shuttle II (an all-recoverable Shuttle)
and the Transition Vehicle (a partially reusable vehicle based on existing
The report is well prepared and is typical of OTA's high standards.
It is comprehensive, well organized and tuned to the audience for whom
it was written. It contains several interesting statements relative to
the MCD criteria that are worth noting:
In his article on the method of design analysis used in the ALS program5,
William StroblC followed OTA's "party line"
by not using the term minimum cost design. He did not even acknowledging
the fact that a new design criteria was involved, although his description
of the analysis clearly pointed to the use of the minimum cost design criteria.
He described the cost-weight tradeoff, the most significant analysis conducted
under the MCD criteria, by explaining that cost-weight relationships were
developed "for every element of the launch system." He further explained
that these relationships were used in a computer program that derived the
optimum hardware and the minimum cost design.
By public law, the ALS was to seek a reduction in recurring costs by a
factor of tenA less than costs current at
that time (about $3000/pound of payload) for a payload weight of 110,000
pounds to LEO2.
The Air Force had asked the ALS contractors "to emphasize cost efficiency
rather than performance as the primary goal3."
I view this as a well-defined break with the use of the minimum cost/maximum
performance design criteria.
The Big Dumb Booster4, described as a "concept"
that uses "simple technologies," was not included in the studies because
"no thorough analysis has yet been carried out on the life-cycle costs
of using such a boosterB." It is noted,
in this and in other OTA reports discussed later in this Column, that OTA
omitted the fact that the BDB was designed in accordance with the minimum
cost design criteria. The term "minimum cost design" was not in the OTA's
In the same article, Strobl noted that historical cost estimating relationships
(CERs)D were inappropriately used in determining
ALS vehicle nonrecurring cost. By using these CERs, the nonrecurring cost
was estimated to be about twice the cost computed by the design analysis;
vehicle recurring cost was not discussed. However OTA2,
in a comparative vehicle analysis, assumed that the ALS would reach its
recurring cost goal, and noted that the program was still underway and
final vehicle configuration has not been selected.
In September 1988, OTA issued a second report dealing with existing
launch vehicle systems6. This report was
extensive and also very well prepared. Discussed in great depth was the
feasibility of significantly reducing launch, operations, and management
costs. They concluded that such costs could be decreased by some small
amount. However, I found the report of great interest because it related
to the MCD criteria.
MCD criteria, as described in the previous Columns, achieves minimum
program life-cycle cost by considering all elements of a space system simultaneously
in the design process. Specifically, launch vehicles and payloads are designed
by trading cost, weight and reliability while the configurations and costs
of all other system elements (such as, R & D, manufacturing, operations,
launch facilities, and management) are also determined. Employing this
criteria assures that the space hardware is not designed in isolation,
and that the sum of the cost of all system elements are minimized. For
instance, flight hardware may be off-optimum in weight in order to minimize
program life-cycle costs.
With this definition in mind, here are some of the findings in the OTA
report that I felt were in consort with and supportive of the MCD criteria:
In October 1988, I received a draft copy of the report on the workshop.
The cover letter explained that the preparation of the reports discussed
above prevented them from completing this draft sooner. The letter also
contained the following paragraph:
"... launch system designers have traditionally focused greater attention
on achieving high performance than on operational simplicity or low cost7."
"... designing to cost rather than for performance would lead to significant
reductions in the costs of launch operations8."
"... vehicle design significantly affects launch and mission operations
and plays a crucial part in the ability to reduce costs9."
"Include all segments of the launch operations team (including logistics
personnel) in the design of any new launch system9."
"... new launch systems, especially designed for low-cost operations, appear
to offer the potential for significant savings10."
"The issue of Big Dumb Booster continues to be of interest
to Congress, especially in light of NASA studies on liquid rocket boosters
and the Air Force/NASA ALS Program. Both efforts are exploring technologies
that bear on Big Dumb Booster concepts."
I was happy to learn of the recognition the MCD criteria was getting. I
answered their request for comments with a 9-page, single-spaced letter.
I started by suggesting a different title to the report. Besides listing
specific comments, I provided relevant background information. I also analyzed
the issues, as I saw them, that might explain why it has been so difficult
for the MCD criteria to be accepted by the aerospace community.
I received the final report11 in February
1989, but found that very few of my comments were incorporated.
"Launch Options for the Future: A Buyer's Guide," OTA Special Report OTA-ISC-383,
Ibid., p 71.
Ibid., p 12.
Ibid., p 10.
William C. Strobl, "Cutting space launch costs with simulation," AEROSPACE
AMERICA, September 1997, pp 23, 24.
"Reducing Launch Operation Costs: New Technologies and Practices," OTA
Technical Memorandum OTA-TM-ISC-28, September 1988E.
Ibid., p 4.
Ibid., p 16.
Ibid., p 59.
Ibid., p 75.
"BIG DUMB BOOSTERS A Low-Cost Space Transportation Option? An OTA Background
Paper," February 1989E.
Where and when did I hear that before? See Column dated Feb. 5, 1997.
In the first place, Minimum Cost Design has not been presented as a concept
but as a design criteria that is more appropriate for the design of most
space hardware. Moreover, the life-cycle costs of an MCD/SLV will remain
unknown so long as the attitude of the government remains the same as at
the time the Air Force program office established for its development was
closed down. See Column date May 15, 1997.
As a representative of General Dynamics, he assisted and supported OTA
in the preparation of several of their reports on space vehicle design.
Available CERs are based on accumulated cost data for hardware designed
to the minimum weight/maximum performance criteria, and generally would
not represent the cost of cost-optimized hardware.
OTA reports may be accessed for reading/downloading at a single URL: http://www.wws.princeton.edu/~ota/ns20/year_f.html.
anyone familiar with the design of NASA's LRB or the Air Force/NASA ALS
Vehicle care to elaborate on the methods of design analysis used?
[no discussions were submitted for this question]
Next Column: My Comment Letter and
OTA's Final Report.
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