Safety and reliability are key if unmanned aerial systems (UAS) are to move from research and become an everyday part of our lives. How can safety and reliability be maintained when cost and timeliness are such pressing factors in small UAS development? In this paper, it is shown that with open-source flight control software (provided by the authors), sophisticated testing practices (hardware-in-the-loop) can provide rapid pre-flight verification of experimental control system designs. Using these methods increases the reliability of flight control software developed in many ways if tested properly Both PID and auto-generated PIλD control schemes are compared as examples of flight software under test, and simulated flight performance is shown.