9.1 Introduction

The very first sentence in Raymer's text on aircraft design ^[1] makes a significant and often misunderstood point: Design is a separate aeronautical engineering subdiscipline that has an equal place with aerodynamics, structures, stability and control, performance, and propulsion. Although design can serve as a "capstone" course that pulls together skills taught in these other subdisciplines, it is more than the sum of those subdisciplines or simply an exercise of those subdisciplines at the undergraduate level. Design is set apart from these for several reasons. First, it contains two essential activities not required for the others: sizing (and its interactions with constraint and mission analysis) and optimization of the whole airplane while considering the interaction and constraints of one aspect of the airplane with all other aspects. For example, airfoils and wings must achieve some acceptable level of aerodynamic effectiveness and performance and provide sufficient volume for fuel and landing gear and do so without imposing unacceptable structural weight penalties or unnecessarily complicated load paths. Second, design is iterative and cyclical in these activities. ^[2] Third, in many cases, students are expected to exercise synthesis and decision-making skills that are fundamentally different from the analysis skills they have used so far in their training. The success of...