Nov 10 '97 -- OTA's Draft Report on "Big Dumb Boosters"

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 costs.

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 technology.)

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:

By public law, the ALS was to seek a reduction in recurring costs by a factor of ten^A 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 booster^B." 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 report-writing lexicon.

In his article on the method of design analysis used in the ALS program⁵, William Strobl^C 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.

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:

"... 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."

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:

"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.

References

"Launch Options for the Future: A Buyer's Guide," OTA Special Report OTA-ISC-383, July 1988^E.
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 1988^E.
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 1989^E.

Notes

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.

Does 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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