The invention relates to a device which includes two longitudinal deflecting surfaces or two pluralities of longitudinal deflecting surfaces, which are symmetrical on either side of the plane formed by the roll and yaw axes of the device and substantially in line with the roll axis and parallel to same, an air flow generator including at least one axial fan suctioning ambient air by means of at least one propeller faired in a flow path and, downstream of said propeller, an air distributor-diffuser, consisting of two adjacent semi-distributors each defining a curved duct directing the air to an outlet opening and toward the longitudinal deflecting surface or plurality of longitudinal deflecting surfaces.