The way that works best with our apparatus is to turn on an ungrounded Van de Graaff, bring the aluminum foil about 2 ft. from the dome and let go.  The aluminum foil rocket should travel toward the dome and fly about the bottom portion of the dome much like a hummingbird.

The traditional way to do this is to position a grounded point about 2 ft. from the Van de Graaff dome.  The rocket would then remain in the region between the dome and the point.