This paper investigates the deployment of an SDN-based UAV network providing communication service. Such a network is extremely useful in emergency scenarios. In such a network, the mobility of UAVs is minimal. We consider the placement of the SDN controller and its implications in terms of communication overhead and end-to-end delay of the control packets exchanged between the UAVs and the controller. We also propose a scheme for reducing the overhead caused by the control packets, sent by each forwarding element (UAV) to the controller. We evaluate the performance of the proposed scheme using ns-2. Simulation results show that the controller should be placed in a central location to minimize the number of hops and hence reduce the delay experienced by control packets. Moreover, simulation results show that a tradeoff exists between control packet overhead and their end-to-end delay. Attempting to reduce the overhead causes the end-to-end delay to increase.