FORMULATION OF A MUL TI -MISSION SIZING ME THODOLOGY FOR COMPETING CONFIGURAT IONS

The creation of long design cycle time vehicles such as aircraft often shrouds the true requirements the vehicle will face in its operational life. The requirements that seem to dominate decisions early in the design may be obsolete by the time the vehicl e reaches the operational stage. Other, formerly less stringent or less important requirements may come to the forefront and present challenges to a product already near production, resulting in high cost to change or diminished performance. This problem is compounded in the design of multi -mission aircraft, as the attributes of one mission that dominates decisions made today may not in the future. Furthermore, the design team may have several system configurations in mind at the early stages of multi -ro le vehicle design, and one configuration that appears attractive may ultimately not be in the face of evolving requirements. This paper presents a method that makes use of surrogate, reduced -order models to increase computational efficiency coupled with p robabilistic techniques to account for uncertainty in the requirements parameters. This method can ultimately be used to help a design team select a representative set of requirements for the design of multi -mission aircraft. It also provides for assista nce in selecting the overall vehicle configuration that can best meet these requirements. This process is partially illustrated on a notional multi -role fighter designed to replace three legacy aircraft.