866. Weight/Cost Systems Engineering


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L M McKay, L E Smith: 866. Weight/Cost Systems Engineering. 1970.



Perhaps the most common criticism of the aerospace industry today is the consistent underestimating of costs. Many factors (i.e., weight growth, increased requirements, etc. as well as cost uncertainties) have contributed to these underestimates. In direct contrast to the difficulties in estimating costs is the excellent aerospace record in weight estimation. In an effort to improve the cost record, cost is being introduced earlier, even during the definition phase, as a decision making parameter. This paper presents a cost control and analysis procedure and its interface with weight control and analysis. It will also discuss how many of the weight analysis techniques have been adapted for use in cost analysis. The goals of a weight/cost system engineering effort are, in general, to help define minimum weight and cost systems develop confidence in the weight/cost estimates, and to insure that there are low growth factors between the conceptual stage estimate and the actual hardware. To attain these goals we must develop estimating techniques, establish the validity and accuracy of these techniques, and develop control and reporting procedures. At the present time the weights engineer stands tall, when compared to the cost analyst, in all these areas. However, these developed weight techniques are useful in the catch-up task that faces the cost analyst, as he strives to become an integral part of the aerospace design team. One of the major problems of the cost analysis is the lack of a large historical data bank. Technical interchange of cost data is almost totally lacking because of its proprietary nature. The changing unit of measure, the dollar, used in cost analysis also presents problems. Variations in accounting systems, even within a single organization tend to shift dollars from one grouping to another when different projects are examined. The establishment of a standard reporting procedure for both weights and costs such as the Work Breakdown Structure, defined by NASA, is a major step forward in defining a common base for reporting of weight-and-performance, cost, and resource requirements during future programs. The development of cost estimating techniques for use in the conceptual development phase, a common format of reporting weights, costs, and other program characteristics, and an active monitoring of these parameters should help in defining program costs with confidence approaching that presently accorded to weight estimates.


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