An Assessment of Varying Mission Requirements on Fighter/Attack Aircraft Sizing

This paper presents the results of a series of configuration studies conducted in connection with a NASA agility design study. The purpose of these in-house studies was to develop a parametric data base of configuration concepts and resulting mission performances for a variety of notional fighter/attack missions. This data base will then be used to assess the impact of the imposition of varying agility requirements on the configurations. Mission variations included range, payload, maximum dash Mach number, subsonic loiter time, and altitudes for air-to-air and air-to-ground missions. Ten design parameter variations were used including 5 “configuration” variables (Sw. AR, Taper Ratio, Thrust Vector Angle, Cvt) and 5 engine cycle variables (Design Thrust, Bypass ratio, OPR, T4, Throttle Ratio). A D-Optimal case set (i.e., one using a design-of-experiment [DOE] method to minimize analysis time by developing relationships between design variables and outputs such as weight, performance, etc.) was used with a numerical optimization scheme to develop an “optimum” configuration for each mission variation. The results indicate relatively small variations in mission requirements can have significant impact on the “optimum” design point, especially in engine cycle characteristics. Careful attention should, therefore, be paid to early selection of the desired mission and performance required to help determine optimum technology development strategies and avoid costly “misdirected” technology development activities.