In this first lecture on aircraft performance Dr. Ir. M. Voskuijl explains the what goals of performance actually are. He then starts by defining an axis system to work in and deriving equations for the mechanics of propulsion. The goal is to define what would be the ‘best’ engine to use for a certain application. Because best is only what we choose to design something for, multiple options are explained. Comparisons can be made for thrust, power and efficiency, and for all of these expressions are derived to be able to say what is the best power or efficiency is.