In recent years, there has been a dramatic increase in both practical and research applications of unmanned aerial vehicles (UAVs). According to the literature, there is a need in this area to develop a more refined model of UAV system architecture, in other words, a conceptual model that defines the system s structure and behavior. The existing models mostly are fractional and do not account for the entire important dynamic attributes. Progress in this area could reduce ambiguity and increase reliability in the design of such systems. This paper aims to advance the modeling of UAV system architecture by adopting a conceptual model called a thinging (abstract) machine in which all of the UAV s software and hardware components are viewed in terms of the flow of things and five generic operations. We apply this model to a real case study of a drone. The results, an integrated conceptual representation of the drone, support the viability of this approach.