Swarms of drones are increasingly being requested to carry out missions that cannot be completed by single drones. Particularly in the field of civil security, strong needs emerge in terms of surveillance and observation of hostile, distant or extended areas. Currently, existing solutions do not meet this demand, as they are generally based on too heavy infrastructures or over-processing, without consideration of quality of service (especially in terms of throughput). In this paper, we propose a light and efficient solution to synchronize and orchestrate a swarm of drones, based only on ad hoc communications to position drones. Our proposal operates a swarm by human piloting a drone (the leader), while all the others (the followers) are completely autonomous and follow the leader using Wi-Fi signal strength. We provide algorithms to realize a basic line scenario. Based on two software developed in the framework of this work, real flight tests have been conducted and experiment results are shown.