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The Launch Operability Index (LOI) - Background
DOWNLOAD >> LOI_Excel.zip (Winzipped MS Excel Files).

The Shuttle Transportation Systems goals were very ambitious in replacing the Saturn class expendable vehicles with a mostly reusable and more affordable system. After all, the primary recurring cost driver was thought to be expending the very expensive Saturn class hardware. However, after flying the Shuttle vehicle, which was to have a short ground turnaround and make forty flights per year from the Kennedy Space Center, it soon became apparent we were not going to achieve these goals. A study effort was kicked off to try and understand what we were doing wrong in operations that caused us to miss the flight rate, ground turnaround goals and mission costs so badly. This study was the Shuttle Ground Operations Efficiencies/Technologies Study (SGOES). We arrived at the conclusion that the primary discipline driver was propulsion and fluids and the focus here was on performance and support the design. The long lead element was the rocket engine, that was followed by a vehicle that had to support the rocket engine design, that was again followed by a ground support infrastructure to support the vehicle design.

Because of underdeveloped technology that gave the program a high risk cost and schedule environment, the primary focus was on non-recurring cost such as program acquisition cost. The results of the prior program development environment drove the space transportation system recurring cost toward being the result of this effort instead of being the controlling focus and driver.

During the follow on study, the Operationally Efficient Propulsion System Study (OEPSS), it became visible that an emphasis on operations (operability and supportability) was needed to correct this same event from occurring again, and that an effective communication technique was also required. Several things would be required, but the first thing we could do was build a software tool that would provide a transfer of experience, communication, and a method of determining operability by any user of the tool. This concept was called a Launch Operations Index (LOI) tool. This index tool would allow an architectural concept engineer, a designer, a manager, or an operations engineer to evaluate the figure of merit approaches to many experienced problem areas (major cost drivers). It would also determine the sense of goodness of the approach being considered relative to a reference. It would allow a new program to use the LOI to establish a requirement and be able to judge a proposals ability to meet this requirement. This would allow operations to be focused much like performance and reliability.

The user selects areas to evaluate, proceeds into a questionnaire characterizing the system, and recieves a relative LOI score, an operability comparison, from 0 to 1.

This LOI tool is only a first attempt at this method of both communicating and establishing a measurable sense of direction for conceptual space transportation systems. A complete report on the LOI accompanies the OEPSS (1992) study (NAS10-11568).

For further information contact Russel Rhodes at NASA Kennedy Space Center at russel.e.rhodes@nasa.gov.

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Website Contact: Edgar Zapata, NASA Kennedy Space Center