>Brian Belmont & Erik Hansen
>Stanford Solar Car Project
>With gas prices at an all time high and a growing public awareness
>about global warming, the auto industry is hesitantly looking into
>new alternatives, such as hybrid technologies and fuel cells, for
>powering their vehicles. But the ULTIMATE goal would be to power
>our cars with renewable and environmentally friendly energy
>sources. Solar cars do just this, as they drive at highway speeds
>on sunlight alone.
>The Stanford Solar Car Project is a student group at Stanford
>University charged with the task of designing, building, and racing a
>solar powered car across the United States, without a drop of gas. By
>taking into account weight, custom components, and aerodynamics,
>the solar car can achieve high efficiencies and speeds. Stanford's
>latest solar car, called the Back2Back Burner, can travel 45 mph on
>the power of a toaster. Last summer the car and its team completed
>the American Solar Challenge, a 2300 mile race from Chicago to Los
>Angeles. Some members of this group will present what technologies
>go into a solar car, the major design challenges of high-efficiency
>vehicles, and how an automotive industry open to the potential of
>solar power could help our ailing planet in the future.
Brian and Erik began their talk by explaining that the Solar Car Challenge is a race from Chicago, IL to Los Angeles, CA that happens every other year. Student teams compete to make cars from scratch. Last summer had been their inauguration as a team, but it still had been a wonderful learning experience. Then they went through the various technology components that made up the back to back burner.
The Back2Back burner got its name because the driver faces forward and the passenger faces backward, and they sit back to back. They decided to do it that way because the rules specified they could build a machine a third long with two people in it, and that would give them much more space for solar panels.
The body was a composite box. They took sheets of black carbon fiber fabric and glued them on both sides of a plastic honeycomb structure, to achieve a remarkable strength to weight ratio. On top of this they molded a plastic shell that provided the maximum area for solar panels. Farings around the wheel wells were shaped so they interfered with air flow as little as possible. They even adjusted when the wheels turned so that the wind profile was smaller going straight than it would otherwise have been.
The entire body was covered with state of the art solar panels made for satellite use. These fed a box that adjusted the voltage across the array so they delivered maximum power to the system for sunlight available. This power was fed into a battery and brushless DC motor system that turned the wheels. The system works much the same way as that in a Toyota Prius or Honda Insight, except the power comes from the sun instead of a gasoline engine. Brian and Erik showed us a graph that indicated the Back2Back burner uses less than a twentieth of the power of a normal car.
When they got to Illinois, there were about thirty other teams with cars that showed up. Before the race began there were some road worthiness qualifying tests, and about ten cars flunked one or more of them. Of the rest, most of them made it down he entire Route 66 to the end in California. The Back2Back burner came in about fifteenth.
They are currently working on their car for the next race, which they expect to win with. This time they are going to send a one passenger car. Also, the design will be optimized for maintainability on the road instead of extreme state of the art. For example, this time they will have a steel frame instead of a composite box body, because that can be welded by the side of the road. Both speakers think they have learned much more about real life engineering from this project then they have from their classroom work.
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or email bjbel (at sign here) stanford.edu