The first general use of radio control systems in models started in the late 1940s with single-channel self-built equipment; commercial equipment came soon thereafter. Initially remote control systems used escapement, (often rubber driven) mechanical actuation in the model. Commercial sets often used ground standing transmitters, long whip antennas with separate ground poles and single vacuum tube receivers. The first kits had dual tubes for more selectivity. Such early systems were invariably super regenerative circuits, which meant that two controllers used in close proximity would interfere with one another. The requirement for heavy batteries to drive tubes also meant that model boat systems were more successful than model aircraft.