Team creates LEDs, photovoltaic cells, and light detectors using novel one-molecule-thick material.
Despite a serious mechanical breakdown that cost almost an hour and a half of race time, the MIT Solar Electric Vehicle Team (SEVT) took second place overall in Sunrayce 97, a 10-day cross-country race held every other June.
MIT's Manta GT was one of 36 solar vehicle entrants from universities across North America in the race from the Indianapolis Motor Speedway to Colorado Springs, CO. It began the race in third position (as determined in a regional qualifier) and used the acceleration of the Solectria motor to gain ground in stop-and-go city traffic, quickly catching up to the second-seeded vehicle from California State-Los Angeles (CSLA).
The MIT team then switched to a new in-hub motor to improve efficiency even further in highway traffic. Over the next three days, Manta GT continued to pull ahead, rolling across the finish line first each day. By mid-race, MIT had accumulated an overall 20-minute lead over second-place CSLA.
"Initially, Manta GT dominated the entire event," said Richard Perdichizzi, a senior technical instructor in the aeronautics and astronautics and SEVT's faculty advisor.
But on the fifth day, disaster hit. Ten minutes after the start, "GT's lost power!" crackled over the radio from driver Ivano Gregoratto, shattering the cautious confidence that Manta GT's lead had conferred. Team members initially suspected that the problem was caused by a motor controller failure, the only failure the team had experienced at Sunrayce 95. However, after swapping the controller, the motor still would not spin.
After 40 minutes of desperate head-scratching, the cause was instead determined to be a broken wire leading to the motor's Hall Effect Sensor. Wary of the in-hub motor, SEVT decided to change the entire drive system. A process that normally takes hours, the in-hub motor was replaced with the team's Solectria chain drive system in 20 minutes.
After more than an hour of watching other teams pass by, Manta GT was back on the road, and rolled in 10th for that day's leg. With the help of the 20-minute lead saved up from previous days, Manta was seeded fourth overall at day's end.
"We floored it the whole way the next day, passing all 12 cars ahead of us in the first 50 miles," said team member Jorge Barrera. Thanks in part to the motor's ability to maintain speed up the steep Colorado hills, Manta GT placed first on two of the remaining four days, making up 34 minutes. Unfortunately, on the last day, two sharp rocks blew two tires and the team was only able to make up two more minutes. Manta GT finished in second place, 18 minutes behind CSLA.
"The motor failure cost the team so much time that we could never make it up. Oh, well -- that's racing," Mr. Perdichizzi said.
Manta GT was not the only car to suffer mechanical troubles. "Solar Eagle III from CSLA used the winning formula of the MIT '95 team. They had no breakdowns, and although they didn't have the most efficient car in the race, they had one of the most reliable," said Bonnie Tom, SEVT secretary.
Manta GT's motor trouble was not the only crisis faced by the SEVT. While being transported to an alumni picnic after the race, the car and its trailer were damaged in a single-vehicle accident. No one was injured, but the damage meant that Manta GT's planned August trip to Japan had to be canceled. Although the SEVT couldn't use the funds raised for the Japan trip, it recommended the Stanford-Berkeley team to its trip sponsor, Yomiuri Shimbun.
The Manta GT builders included a core group of students and alumni who were also involved in building Manta, the 1995 race-winning predecessor to Manta GT: team president David Hamp-ton (SM '97), Mr. Gregoratto (body group leader), Masahiro Ishigami (chassis group leader), and electronics group leaders Matthew Condell (SB '95, SM) and Wandy Sae-Tan. Other 1997 team members were Mr. Barrera, J. Andy Buttner, Christopher Carr, Brian Graham, Stanley Hunter, Tasos Karahalios, Kudzaishe Takavarasha and Jimmie Walker. Several former team members, faculty, staff, students and administrators also helped with the project.
A version of this article appeared in MIT Tech Talk on September 10, 1997.