Project: Solar powered car
School: Nelson Mandela Metropolitan University
Location: Port Elizabeth, South Africa
Director: Clive Hands
Students at Nelson Mandela Metropolitan University (NMMU) in South Africa are building a solar-powered car for the 2014 Sasol Solar Challenge, a two-week race through difficult terrain in South Africa covering more than 3,300 miles. This is the team’s second straight entry in the biannual race. Clive Hands, a lecturer in mechanical engineering, serves as project leader.
The novice car builders cut their teeth constructing the first car, called the Photon, for the 2012 challenge. “We are a very new solar car team and are basically trying to catch up to other teams that have a lot more experience,” says Josef Groenveld, a mechanical engineering student and the team’s mechanical head. “Our last car gave us lots of ideas where to improve.”
The Photon, which featured composites in its monocoque and body, was nearly 16 ½ feet long and powered by six square meters of silicon solar panels. It competed in the Technology Demo class in the 2012 Sasol Solar Challenge and completed approximately 185 miles.
More than a dozen students at NMMU are currently designing the car for the 2014 race, so a car name and many details haven’t been determined. But the team is considering using composites in more components – such as suspension members, the battery box and even rims – primarily to reduce weight. The Photon weighed 533 pounds – more than 220 pounds heavier than most international entries in the race. NMMU would like its car to weigh approximately 400 pounds. “It’s an ambitious target, but most of our team now has over a year’s experience building a solar car,” says Groenveld. “So we have a good chance of achieving what we want.”
While some teams use an aluminum space frame for the chassis, NMMU relies on carbon fiber to make its chassis extremely strong and rigid, yet lightweight. The body of the car also features carbon fiber, in part “because it’s relatively easy to shape to a mold,” says Groenveld. He explains that pressing the body from sheet aluminum would create a structure that was too heavy to be competitive. The tooling would also be too expensive, he says.
Another lesson learned from the Photon was that the car’s chassis and suspension were over-designed, says Groenveld. “We could get away with using a lot less material in some parts,” he says. “We visited a few companies that use composites to learn more about different layup techniques.” The team also discovered it used too much resin in the last car, which added a significant amount of weight. “So we’re investigating how we can saturate the carbon without using too much resin,” he says.