Novel aerodynamic testing paradigms for free-flying drones

Nowadays, drones are often tested by flying them freely outdoors. Aerodynamic characterization of these vehicles is fairly difficult and poor, as the drones are often quite distant from the observer and fly in atmospheric conditions that are largely unknown, unpredictable, and not repeatable. In 2015, inspired by the observation that some birds can hover stably in turbulent wind conditions over terrain, we imagined the concept of an open wind facility, which allows a vehicle to fly freely in a controlled flow environment while remaining  stationary with respect to the laboratory frame. One realization of the idea makes use of fan array surfaces in conjunction with a Motion Capture system and/or drone onboard sensors intended to maintain the vehicle in a given spot or trajectory. The flow can be steady and laminar (as in a conventional tunnel, to simulate relative motion), but may also comprise gusts and shear. The wind speed in such a facility can be modulated in real-time using the instantaneous state of a freely-flying vehicle. The paradigm of aerodynamic characterization of a free-flying vehicle also requires re-evaluation.