Blackbird Wind Car Propellor Thin Air Designs.JPG This wind-powered car was just clocked at almost 40 mph--on a day when windspeeds were hovering around 14 mph. How does it do it?

Despite appearances, the prop isn't turned by the wind at all--it's turned by the wheels. Once the car is moving (pushed by the wind, of course), the wheels turn the propeller so that it's pushing against the wind.

The car was built by Rick Cavallaro at Thin Air Designs. He was funded by turbine company Joby Energy and Google, and worked with the aeronautics department at San Jose State University. The car is made largely of foam, except for the 5-meter-high propeller. Thin Air Designs has a great blog (with lots of pictures) here. (via PhysOrg)