Stanford students race across Australian Outback in sun-powered car
Cruising comfortably at 50 mph, a solar-powered car built by a team of Stanford engineering students is facing off against cars built by engineers from around the world in the Bridgestone World Solar Challenge in Australia.
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Thinner, shorter, flatter. That’s the recipe for success as the Stanford Solar Car Project’s newest solar-powered car, Arctan, zips across the Australian Outback in the 2015 World Solar Challenge this week.
Arctan is the 13th car the Stanford student group has entered into the World Solar Challenge, the biennial 2,000-mile race across the middle of Australia. The race draws dozens of teams from around the world. Stanford, one of the few entirely student-run groups, is looking to build off its 2013 success, when it crossed the country in about four and a half days, finishing in fourth place, best in team history.
“The Stanford team is great historically, but we’re about more than just doing well in the race,” said team lead Guillermo Gomez, ’16. “We care a lot about teamwork and education and what we learn from the project. We’ve been known as the helpful team; we get lots of emails from India and Europe asking about components that we use and how to install or design. It’s part of the team culture that we’re in this to do well and build a really great solar car, but we also want to learn a lot from the process and have a lot of fun doing it.”
The students working on Arctan – which was named for past team member Bryant Tan, ’14, who died shortly after graduation – are hopeful that some new design tricks will help them cross the Outback in record time.
Design reduces drag
For the first time, the team has adopted an asymmetric design: Instead of placing the cockpit in the center of the car, it’s set to the right side, with the driver sitting in the fairing and peeking over the edge of the car. This has allowed the crew members to make the car lower to the ground and more blade-like than their previous car, Luminos, an aerodynamic change that has netted a 10 percent reduction in drag.
This also made the top surface flatter, Gomez said, which the team’s simulations suggest will allow the solar panels that cover the car to produce more energy than on a contoured surface.
All told, Gomez estimates that the team built 90 percent of the car from scratch, from casting and forming the body, to designing and manufacturing the custom suspension and motors, to the wheels and all the wiring.
Although being involved with the team is a considerable time commitment – many students will spend hundreds of hours on the project through the full course of a cycle – Gomez said building something that has to be reliable and robust enough to perform well day after day has been a great supplement to regular academic work.
“You’re not just designing something for the good grade in class, you’re designing something that needs to be safe at highway speeds and will carry a person,” Gomez said. “Having that kind of responsibility really introduces a whole new level of learning, and is extra incentive to be really critical in the work we do. We will walk away with a greater sense of accomplishment.”
On the road
A typical race day in Australia starts around 6 a.m., when the students emerge from tents along the roadside to tip Arctan on its side so its solar panels can soak up photons from the rising sun. They hit the road around eight o’clock, and drive until about noon.
The race is actually a caravan, with lead and follow support cars sandwiching Arctan to provide both technical assistance – students monitoring the car’s photovoltaic performance and the weather will recommend a cruising speed – and warn of oncoming hazards, such as cattle or large trailer trucks. The car can top 70 mph, but it will spend most of its time cruising in the 50s for peak efficiency.
While the race organizers inspect the car, the students grab a bite, a fresh driver hops into the cockpit, and they race again until 5 p.m., when they’ll pull to the side of the road and begin making camp. The car goes back up on its side to lap up the last rays of sunset, and after a hearty dinner around a fire and analysis of the day’s performance, the students crawl into their sleeping bags and set their alarms.
Driving the car isn’t easy. The driver must muscle the car around, as the car lacks conveniences such as anti-lock brakes or power steering because “those don’t help the car go faster.” Air conditioning would add weight, and large ventilation holes would increase drag, so it gets warm inside the cockpit. But one of the team’s primary drivers, Anna Tskhovrebov, ’17, doesn’t mind.
“Driving the car is best thing ever. It’s super-fast and handles well,” said Tskhovrebov, a member of the mechanical team. “It’s really amazing to be inside something that your friends have built along with you. I can look around the driver cockpit and tell you who designed the steering bracket, who designed one pedal, who designed the other pedal. It’s incredible to know we can make these super-light and super-well-functioning custom manufactured parts.”
Regardless of whether the students make the podium or walk away with a trophy, the drive across the desert, and the two years of work that preceded it, they said, will have been worth it.
“I feel that I’ve learned almost as much from them as I have from any of my classes at Stanford. They’re all brilliant engineers,” Tskhovrebov said. “We’re effectively running a small automotive company at end of day. You come in and think you’ll just be building something or helping design parts, but along the way you learn a lot about how people work together and how effective management can bring people together to do things and how leaders help people make decisions without being overbearing. That’s going to be useful for everything I do for the rest of my life.”