It's an airplane, designed to operate within the atmosphere. But it will be able to do things that no present type of aircraft can accomplish. Helicopters whirl their blades in utter frustration at altitudes where the air gets thin. Beyond 20,000 feet, they get almost no lift. The bigger it gets, the better it flies.
Efficiency increases with grid area.
Disturbing airflow around the grid edge becomes proportionately less important in larger craft. No practical speed limit has yet been determined. The ions themselves flashing from emitter to grid impart to the air very high-velocity impulse. Aerodynamic grid drag would be the chief speed limiting factor. B ut streamlining of the grid edge and careful contouring of the craft, could minimize air drag.