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Original Date: 04/26/1999
Revision Date: 01/18/2007
Best Practice : NASA/Air Force Cost Model
Prior to 1990, no standardized cost estimating tool existed at NASA. Instead, numerous spreadsheet models were used. These models relied heavily on volumes of historical data that were searched, analyzed, and inserted into formulas. Additional drawbacks included no formalized training for users, inconsistencies between models, difficulty in showing data traceability, need for engineering judgement, and limited detailed relational analysis capabilities. These models, however, did perform Cost Estimating Relationship (CER) estimates, but provided little more in additional services. As a result, management frequently had to review the findings after cost estimates were generated. In 1990, Marshall Space Flight Center’s (MSFC’s) Engineering Cost Office visualized a better process using a single model to meet all needs. Within a few years, MSFC, in conjunction with the Air Force, implemented a viable prototype known as the NASA/Air Force Cost Model (NAFCOM). Since then, the NAFCOM has evolved into a cutting-edge cost analysis, modeling, and estimating tool.
The NAFCOM consolidates numerous existing cost models and databases used throughout NASA, and brings cost estimating into compliance with today’s state-of-the-art software environments. This fully automated software tool employs an easy-to-use spreadsheet environment to predict the cost of space hardware at the subsystem and component levels. The information within the NAFCOM represents the best of the aerospace project data from the Resource Data Storage and Retrieval (REDSTAR) library, NASA’s major repository of cost, technical, and programmatic information dating back to the 1960s. The REDSTAR library contains over 22,000 documents and one million pages of information, and maintains a website-based user interface to coordinate these components into a single user-friendly interface.
Creating cost estimates within the NAFCOM are based on specific analogy and database averaging techniques. Specific analogy CERs are created by selecting analogous data points from the database within the NAFCOM. The database’s average CER represents the average of the data population. To create a specific analogy CER, the user first selects the appropriate database (e.g., manned spacecraft, unmanned orbiting or planetary spacecraft, launch vehicles, liquid rocket engines) and then the appropriate data level (e.g., group, subsystem, component, unit). Within each data level, the user selects:
Group level items (e.g., structures, thermal, and mechanisms; electrical power and distribution; command, control, and data handling);
Subsystem level items such as typical aerospace hardware (e.g., thermal communications, attitude control); and
Component level data (e.g., batteries, support structure, rate gyros, cabling).
After making these selections, the user further refines the CER database by choosing from more than 100 filters within the cost model that relate to the technical and programmatic characteristics of the data points. The available filters are determined by the system and subsystem choices at the data level entry. Once the data levels and filters are applied, the user selects specific programs from a list of missions, enters weights, and applies complexity factors so the NAFCOM can determine the estimated cost. All users are trained on this tool.
Currently released as version NAFCOM 99, this tool is consistent, efficient, and effective at defending cost estimates. The NAFCOM operates as a single cost estimating system that meets users’ needs, and provides management with a standardized format for reviewing estimates. As a result, this tool reduced the frequency of reviews and greatly improved the credability of the system.
For more information see the
Point of Contact for this survey.
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