ECONOMICS OF RELIABILITY IMPROVEMENT FOR SPACE LAUNCH VEHICLES.

Abstract : Present methods for planning reliability improvement of launch vehicles are reviewed. A theoretical criterion for optimum allocation of resources for reliability improvement exists that requires equal marginal failure reduction for all elements to be improved. This is of little practical value because suitable expressions for failure reduction as a function of resource expenditure are not available for all elements of the launch vehicle. A key finding is that a good practical approximation for the marginal failure reduction is the failure/value ratio which can be computed from available information. This permits a criterion previously only of theoretical importance to be used in a practical situation. (Author)