Multidisciplinary design optimization of a transonic commercial transport with strut-braced wing

The multidisciplinary design optimization of a strut-braced wing (SBW) aircraft and its benefits relative to a conventional cantilever wing configuration are presented. The multidisciplinary design team is divided into aerodynamics, structures, aeroelasticity, and the synthesis of the various disciplines. The aerodynamic analysis uses simple models for induced drag, wave drag, parasite drag, and interference drag. The interference drag model is based on detailed computational fluid dynamics analyses of various wing-strut intersections. The wing structural weight is calculated using a newly developed wing bending material weight routine that accounts for the special nature of SBWs. The other components of the aircraft weight are calculated using a combination of NASA's flight optimization system and Lockheed Martin aeronautical systems formulas. The SBW and cantilever wing configurations are optimized using design optimization tools (DOT) software. Offline NASTRAN aeroelastic analysis results indicate that the flutter speed is higher than the design requirement, The minimum take-off gross weight SBW aircraft showed a 9.3% advantage over the corresponding cantilever aircraft design. The minimum fuel weight SBW aircraft showed a 12.2% fuel weight advantage over a similar cantilever aircraft design.