The use of flight simulation tools to reduce the risk and required amount of flight testing for complex aerospace systems is a well recognized benefit of these tools. However, some special challenges arise when one attempts to extrapolate these benefits to very low-cost Uninhabited Aerial Vehicle (UAV) flight testing. These types of vehicles are characterized by a lack of payload capacity (and therefore limited in their capacity for additional flight test instrumentation or telemetry), limited baseline capabilities (processing, instrumentation, and telemetry), and by a lower marginal cost of added flight tests (less fuel, personnel, etc. is required per flight test, and a lower cost associated with a failure). In this paper, flight simulation architectures for system design and integration of low-cost UAVs are explored, and the development of a simulation tool for a low cost UAV described.