Our objective in this chapter is to describe the fundamental physics of heavier-than-air flight. We aim to understand, at a high level, how airflow can be used to create forces, and how we harness those forces for flight. This will be done at a high level only, as the course lacks enough time to go deeper (and, in fact, you’d need many courses if you wanted to really go ‘deep’!). A good reference for aerodynamics is the book by (McCormick 1995), or that of (Anderson 2011). This chapter will describe both fixed-wing flight, and propeller-driven (rotary-wing) flight; later though we will be primarily concerned with propeller-driven aircraft.