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MIT Takes Second Place In Solar Vehicle Car Race

Gabor Csanyi -- The Tech
The MIT Solar Electric Vehicle Team's car, Manta GT, named after its resemblance to a sting ray, placed second in Sunrayce 97 on June 28th.

By Yvonne Lai

The MIT Solar Electric Vehicle Team car Manta GT raced to second place in Sunrayce '97, an intercollegiate solar vehicle race held on June 28th. The ten-day, 1,150-mile race began on June 19th at the Indianapolis Speedway and finished on the 28th in Colorado Springs, Colo.

The team's vehicle finished eighteen minutes behind the car run by the team from California State University at Los Angeles.

Sunrayce competitors come from Canada, United States, Mexico, and Puerto Rico. Teams build cars within regulatory constraints, which limit the total battery power and solar-cell technology. Before the competition, all cars must first endure an eight-hour qualifying round.

This preliminary course determines the initial placements of the cars in the actual race.

All vehicles are then given a daily as well as an overall ranking at the end of each day.

According to Bonnie W. Tom '99, presiding president of the solar vehicle team, the Manta GT runs on 1500 Watts. "We have a car going on the power needed to dry your hair in the morning," she said.

A core of Sunrayce 95's winning team led this year's entry: then-Team President David A. Hampton G, Ivano Gregoratto '97, Masahiro Ishigami '97, Matthew N. Condell '95 and Wandy Sae-Tan '97. The team also included Jorge A. Barrera '99, Andy Buttner '99, Christopher E. Carr '99, Brian B. Graham '99, Stanley R. Hunter '00, Tasos G. Karahalios '97, Kudzaishe G. Takavarasha '97, Tom, and Jimmie D. Walker III '99.

Historically, MIT has done well competitively, placing first in the last Sunrayce and breaking the world record in 1989.

Team faced several obstacles

Manta GT, so named for its resemblance to a sting ray, began the race in third position; by the end of the second day, it had charged up to second place, leading the third place team from California State University at Los Angeles by 90 seconds.

That afternoon, the MIT team switched to a newer, more efficient motor to beat highway traffic. It cruised to first place for the next three days. However, at the five-day mark, disaster struck.

"GT's lost power," transmitted driver Gregoratto to the team. Subsequently, they replaced the controller, only to see the motor refuse to spin.

It was not until after another forty minutes that they discovered the true problem: a broken wire leading to the motor sensor. Replacing the motor generally consumes several hours. However, the team, now wary of the new engine and determined to keep going, reverted back to the original engine in twenty minutes.

This rapid work and the lead they accumulated during the past several days saved Manta from complete loss. They placed tenth for the day, but fourth overall.

With the original motor, Manta GT passed nearly half the field in the first fifty minutes after the replacement, and maintained speed while climbing the Colorado hills. It then raced to first place for the seventh and eighth day.

But on the last day, sharp rocks punctured two tires, costing the team valuable time.

Interestingly, MIT also accumulated the greatest time penalty: 53 minutes. Time penalties are given to teams who exceed the race's speed limit of 55 mph.

Team looks to future

One of the goals for their next vehicle, Manta GTX, is to make little changes in minute details, which eventually add up to major ones.

"Manta GT is a good car. We plan to experiment more on the new techniques we developed; we didn't have much time to research what we used, so we hope to do that next year. We will basically tweak the Manta GT a bit," Tom said.

Manta GTX's expected finish date is 1998, just in time for the World Solar Challenge 98.

"We will be competing not only against colleges but also against companies; but with a few modifications, we can beat the best," Graham said.

The Manta GT is an improved version of the Manta, the winning Sunrayce 95 vehicle. Construction of Manta GT began years ago in fall semester 1995, aiming to reduce weight, improve component reliability and increase the vehicle's overall efficiency.

In this direction, they used a Computer Numeric Controlled machine to create the body's mold, researched a new drive mechanism, and developed a new solar cell array technique.

The previous method of creating a body mold was largely manual, relying on hand-sanding to smooth the mold into the desired shape. Now, with CNC, a computer cuts the mold, given three dimensional cartesian coordinates designed by the team. This lends higher accuracy and thus, a finished mold more similar to the ideal.

Most teams usually arrange their solar cells in a matrix formation, without overlap. MIT SEVT used a roof-shingle formation for the Manta GT solar cells.

While this does not increase the overall power, it does pump up the efficiency.