Propulsion System Screening for Survivability and Effectiveness

Selection of engines has been traditionally concerned with performance capability. Although performance is still an essential element in all future applications, recognition of operational realities has placed importance on system survivability and ultimate cost. In advanced military aircraft design, it is necessary and feasible to evaluate propulsion systems in a combat context that will discriminate according to the cost of performing the required mission. Methods are outlined which can be utilized during parametric studies to permit the screening of candidate design options, and identification of trends and design drivers. This approach provides the analyst with the ability to assess the impact of survivability and vulnerability characteristics upon the selection of the proper engine and propulsion system for a given mission task in terms of a cost related figure of merit. The importance of early consideration of these requirements in the weapon system design process has been dramtically illustrated by a recent study concerning propulsion survivability and weapon system design. The first preliminary aircraft design was found to be unacceptably susceptible to radar-seeking threat missiles. Utilizing the analytical results, a modest redesign to the aircraft reduced the combat cost by a factor of sixty. The results present informative phenomenology, while the methods illustrated show an approach that provides early screening, rapid optimization and ability to focus on the significant design factors.