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Sleek Solar Car Cruises to Victory in 9-Day Race

By Daniel C. Stevenson
Editor in Chief

At speeds sometimes exceeding 60 mph, the MIT Solar Electric Vehicle Team's car raced to victory last month in Sunrayce '95, a 1,150-mile solar car race from Indiana to Colorado. The MIT car, named Manta for its flat, sleek shape, beat out 37 collegiate competitors from around North America in the 9-day race.

Manta finished with a time of 33:37:11, just under 19 minutes ahead of the second place finisher, a University of Minnesota car. The result was the closest in the race's history.

The race generally traced along 55 mph back roads, said driver Goro Tamai G. The MIT car generally traveled at the speed limit, but did receive some time penalties for driving too fast. In the rare 65 mph zones, the car reached speeds of 62-63 mph, Tamai said. The MIT car's average speed was 37.23 mph.

The team is composed of about 20 students, with a core group of about 6 or 7, Chien said. Other members include Matthew N. Condell '95, George J. Delagrammatikas '95, Eric L. Gravengaard '96, Ivano Gregoratto '97, Iaki Gutierrez '96, Masahiro Ishigami '97, and Michael B. Wittig '96.

The car derived its power from solar cells that charged 340 pounds of off-the-shelf lead-acid batteries. The car began the race with the batteries fully charged, and drained them at times to 20 to 40 percent capacity, although the cells charged the batteries all day long, both on and off the road, Chien said.

The race was composed of roughly 160-mile stages and teams were given about 8 hours to finish each stage, Chien said. The MIT car generally finished each stage in three and a half to four hours, Chien said.

Although the MIT car never had any serious problems with the road conditions, some cars spun out on the last day of the race due to rainy weather. The same weather slowed down the MIT car, bringing the Minnesota team within striking distance of first place.

Reliability pays off

"The main reason we won was because our car was extremely reliable," Chien said. "We didn't even have a flat tire," he said, which was a common problem for Manta's competitors. The team spent a year and a half building the car, including design and construction, Chien said.

The only mishap occurred on the final day of the race, when the car's motor controller failed. The team suspected the controller, which sets the motor's speed, as the cause of the problem and was able to quickly diagnose and repair the problem, Chien said. The repair took only about 15 minutes, compared with typical repair times of 30 to 60 minutes for other teams, he said.

Building the vehicle and preparing for the race cost about $70,000; two-thirds of which came from corporate sponsors, with the remainder from MIT. By contrast, the defending champion University of Michigan team spent $1.4 million on its car, which was unable to complete the race.

Manta was built so cheaply because "we did everything ourselves," Chien said. Students designed and made almost everything associated with the car rather than contract out for work.

"We wanted to build a new car based on a previous car called Galaxy," said Chien, who designed the body of Manta. The one major difference between Manta and other entries, Chien said, was the driver's bubble canopy was in the center, rather than the front, of the vehicle. The rest of the car was kept very flat to maximize the efficiency of the solar cells, Chien said.

Vans, car in constant contact

Despite long stretches of back country road, the drive was not boring, Tamai said. "We were in the lead most of the time," which made the entire race exciting, he said. Also, the driver was in constant radio contact with the lead and chase vans.

The lead van navigated for the team and spotted potholes that the driver couldn't see because of a mirage effect created by the blacktop roads, Tamai said. The chase van contained the strategists who advised the driver and kept track of the car's status through a computer hookup, Tamai said.

Driving Manta was very much like driving a regular car, except it had handlebars and the driver had to lie down, Tamai said.

The Solar Electric Vehicle Team was started in 1986 by James D. Worden '89, Tamai said. Worden went on to start Wilmington-based Solectria, which manufactures electric cars.

Sunrayce is a biennial race sponsored by the U.S. Department of Energy and General Motors to promote student interest in technology and the environment. The 1995 race began in Indianapolis, Indiana (the qualifying round took place at the Indianapolis Speedway) on June 20 and finished in Golden, Colo. on June 29.