The aerodynamics of airplanes designed before and during World War II springs from linear potential theory (discussed in Chapter 3) together with empirical data and lessons learned from previous airplane designs. Jet engines and rocket propulsion enabled vehicles to fly much faster. This uncovered high-speed aerodynamic phenomena that must be understood for the successful design of airplanes capable of trans- and supersonic flight and of space vehicles. This chapter presents the numerical methods employed in computational fluid dynamics (CFD) to treat shock waves. A complete recipe for inviscid nozzle flow is given, with accompanying tutorial software. Mature tools are now standard in the form of industrial-strength CFD codes. A perusal of the user manual for any one of them shows many options and functions. A basic understanding of the theory is needed for the user to set up the code properly for the intended case. While not focusing on constructing such a CFD code, this chapter lays the foundations for training the reader to become an "informed user" of these codes by learning CFD "due diligence." It spells out CFD fundamentals such as constructing the numerical flux, artificial dissipation, approximate Riemann, high-resolution schemes. explicit and implicit time integration, and convergence to steady state.

The prime focus of aerodynamic design is the shaping and layout of the aircraft's lifting surfaces. Introducing the subject matter of the book, this chapter also conveys some appreciation for, and fundamental insight into, how and why wings evolve into the configurations we see flying. Typical of the development process is that the new aircraft evolves in a succession of design cycles. This chapter describes three early design cycles. As Theodore von Karman implies, creativity lies at the heart of any engineering activity. Belonging to the cognitive aspects of the human brain, creativity is not in the realm of technology, but we indicate how and where it enters into the design process and encourage students to "think outside the box." The fundamental aerodynamic quantities of lift and drag are key to performance. Sizing the wing surface to the design mission is a crucial step in determining the baseline configuration, which then develops further in cycles 2 and 3. The chapter introduces the tools, tasks, and workflows of the three design cycles, explains how computational fluid dynamics and optimization procedures are involved, and maps out where in the coming chapters each of these is treated in depth.