More commonly known as a “Lifter”… a simple structure (craft) of balsa wood, aluminum foil and copper wire is constructed. High voltage (20 – 30 Kv) is applied to the top wire creating the “effect” which causes the craft/lifter to spring or “levitate” upward. Tethering the Lifter provides for a more controlled flight. Among other more esoteric theories… we do know that positively charged molecules emit an ion down draft which is (in part) the reason for the lift. Anti-gravity, time warping and magnetic attraction are some of the more controversial hypothesis put forward.