Wifi connections to moving targets are not reliable. Both ends of the connection constantly monitor connection strength and change the connection speed according to that. You can try how far you can get, but do not expect to much. I got my rover to ca. 300m with video. That was with no obstacles between the antennas and with two 9dbi omniantennas on the rover and a 14dbi patchantenna on the tracker. Even the weather will affect the range. High humidity or even fog and you are lucky to get 50m. With a flying vehicle things get a little easier though. Line of sight is easier to maintain and you are not constantly inside the fresnel zone. Put your groundstation antenna on a mast, to reduce influence of the fresnel zone.