Designed and built by students (some for fun, some for academic credit), the vehicles ranged in appearance from Bauhaus-inspired pup tents to sleek carp, covered with dark blue scales. When they reach the General Motors Technical Center in Warren, Mich., this Thursday, the entry with the fastest time will be the winner. More than crowning a champion, though, the race will prove “the unlimited potential of solar energy,” says James D. Watkins, secretary of the U.S. Department of Energy, for it will show that it is technologically feasible to replace the dirty internal-combustion engine with a tankful of sunshine.
The first challenge was to maximize the amount of sunshine gathered by the cars’ photovoltaic cells, which convert sunshine to electricity to run a motor. The Florida Institute of Technology team mounted cells under the chassis of its “Sunshine Special” to bag rays reflected off the road. Western Washington University tilted the panels on one side of its Viking XX; as the sun moves, the car can be turned around and driven in whichever direction points the panels toward the light. Still, no solar array generated more than two horsepower for its electric motor, so the name of the game was optimal use of the rays. A crucial strategy: using “power trackers” to send energy from the solar panels to either the motor or battery, depending on whether the car most needed speed or a topped-up battery for the next cloudy spell.
What separated tortoises from hares was lightness and aerodynamic efflciency. Team captain Paul Jeran of the Rochester Institute of Technology calculates that every extra pound would cost five minutes of time by the finish. So the students used everything from Styrofoam and NOMEX (a featherweight honeycombed material by Dupont) to graphite fibers soaked in epoxy. These materials could add strength and cut weight in passenger cars. To cut resistance, the California state-L.A. Solar Eagle has a nose shaped like a flying saucer; its tapered body gives it only a tiny target for crosswinds. Crowder College’s Star II has a carved underbelly that keeps air rushing through at a steady pressure, reducing turbulence and hence, drag. “The real technology is in the design,” says GM’s Jerry Williams. “These kids are on the cutting edge.”
‘G-Vans’: Despite Sunrayce, solar-electric cars won’t reach the neighborhood car lot for decades: they’re too light and have too little muscle for American drivers. But the race should point the way toward more aerodynamic designs, which save fuel, and may inspire better nonsolar electric vehicles. This year, 500 electric “G-Vans” will hit the roads: they can travel 60 miles between charges. The students’ innovations in battery design promise to make tomorrow’s electric cars even better than that; by the mid-199Os, GM plans to sell a batterypowered Impact that could hold a charge longer and thus cruise farther. However they reshape the American roadster, the students’ futuristic cars will have more days in the sun. GM will send the top three finishers to the 2,000-mile World Solar Challenge this November in Australia.
