Abstract
Propeller dynamics play an important role in the stability and controllability of multirotor unmanned aerial vehicles (UAVs), however are often greatly simplified or even neglected altogether when designing multirotor simulations. This paper presents a method for calculating and simulating the dynamics of a brushless motor and propeller typical of the size used in small multirotors so that the rotation speed and generated forces may be accurately reconstructed from an input pulse width modulation (PWM) signal. The system model is identified using a series of sine-sweep inputs. Results show that the force and torque generated by the propeller and the power required can be accurately modelled from a raw input PWM signal, even for the dynamic case where the propeller is changing speed.