Abstract: The disclosure concerns a vehicle which is both lifted and propelled by air flow. The vehicle comprises an upper deck, a depending peripheral side wall and a flexible, perforated sheet secured beneath the bottom of the side wall, thereby defining an open plenum. A propeller in an air flow directing cowl seats atop the deck and part of the air flow is directed into the plenum and the remainder of the air flow is directed to move the vehicle. The underside of the upper deck disperses air in the plenum. Alternatively, the propeller is part of a duct which directs air into and disperses it around the plenum. The cowl includes an air dam for trapping reverse flowing air. A rudder directs the motion of the vehicle. The plenum narrows in width toward the front and diminishes in height away from the plenum inlet through the upper deck.

Abstract: A technique is disclosed for protecting against electrocution or shock resulting from contacting an exposed conductor which is connected to a power supply. The flow of power to the conductor, whether DC or AC, is periodically interrupted and during the interruption, contact between a body and the conductor is sensed. If the body is not contacting the conductor, power is restored, but if the body is contacting, the interruption is maintained. The circuit may also distinguish between contact with the body and contact with an electrical device which receives power from the conductor. The electrical device includes a barrier circuit, such as a diode, which switches to an electrical state, such as a high impedance state, when power is interrupted. Because the electrical characteristics of the barrier circuit, such as its capacitance, differ from those of a body, the circuit is able to detect contact with a body.