Blackbird

Blackbird is an experimental wind-powered vehicle, built in 2010 to demonstrate that it is possible for such a vehicle to go directly downwind faster than the wind. Blackbird employs a rotor connected to the wheels and does not have a motor, battery or flywheel. It was constructed by Rick Cavallaro and John Borton of Sportvision, sponsored by Google and Joby Energy in association with the San Jose State University aeronautics department. In a test supervised and recognized by the North American Land Sailing Association in July 2010, Cavallaro achieved a speed of sailing directly downwind in winds: almost three times the speed of the wind. In 2012, Blackbird also demonstrated sailing directly upwind with twice the speed of the wind. Theory Rotor-powered vehicles are wind-powered vehicles that use rotors—instead of sails—which may have a shroud around them (ducted fan) or constitute an unducted propeller, and which may adjust orientation to face the apparent wind. The rotor may be connected via a drive train to wheels or to a generator that provides electrical power to electric motors that drive the wheels. A vehicle with a bladed rotor mechanically connected to the wheels can be designed to go at a speed faster than that of the wind, both directly into the wind and directly downwind. Upwind, the rotor works as a wind turbine driving the wheels. Downwind, it works as a propeller, driven by the wheels. In both cases, power comes from the difference in velocity between the air mass and the ground, as received by the vehicle's rotor or wheels.