An MDO investigation of the impact of practical constraints on an HSCT configuration," AIAA Paper No

This paper presents results from an MDO design procedure illustrating the eects of numerous trim, control, and performance requirements for a high speed civil transport. We optimize the design for minimum take o gross weight, including both aerodynamics and structures to nd the wing planform and thickness distribution, fuselage shape, engine placement and thrust, using 29 design variables and 70 constraints to insure realistic results. The constraints include the engine-out and crosswind landing requirements, as well as engine nacelle ground strike, rotation to lift-o attitude, balanced eld length and approach trim constraints. We found that the engine-out condition and the engine nacelle ground strike avoidance were critical conditions. The addition of a horizontal tail to allow take-o rotation resulted in a signicant weight penalty. We also examined the eect of engine technology and sizing based on cruise and balanced eld length constraints. The eld length has a large influence on weight. We included a subsonic leg in our mission analysis, which also resulted in a large weight penalty. The cumulative eect of these considerations leads to very large increases in vehicle weight. We conclude with sensitivity studies performed to understand the eect of some of the constraints and the accuracy of the drag prediction on the optimized results. 1