A system of unmanned aerial vehicles (UAVs) can be used to provide uninterrupted service to customers by handing the mission from a weary UAV to a fresh one in an automated manner. Toward such a system, we discuss the development of two components: ROS GPS waypoint tracking package and centralized task allocation network system (CTANS). The ROS GPS waypoint tracking package is the first open source software developed for the AR Drone 2.0 UAV that enables integration with a larger system. CTANS connects the UAV host computers to a central computer, receives the UAV status information and distributes GPS flight directives. CTANS is responsible for distributing the commands to the UAVs to ensure mission handoffs are conducted as required. This multi-UAV control software testbed was used to implement a small scale, outdoor, persistent, GPS based patrol mission with two UAVs.