The difficulties of any long-distance race are clear from an engineering standpoint, but completing the course in solar-powered cars presents international teams with a unique set of challenges. The World Solar Challenge rules and regulations were inspired by the original idea that a 1000 Watt car could complete the journey from Darwin to Adelaide in 50 hours. Ten percent of that energy projection is allotted to solar cars in the challenge: 5 kilowatt hours of stored energy per charge. After that, the Challenge hopes to encourage the development of the world’s most efficient electric vehicles technologies, pushing teams to maximize the power in every charge, source energy from the sun, and recover kinetic energy from the vehicle itself.
The race is split into three separate groups that compete simultaneously: the Challenger Class, Cruiser Class, and Adventure Class. Each of these classes focus on a different feat of solar power engineering, and teams that compete within them must meet a strict set of criteria. Here’s a breakdown of the 2015 race results.
Challenger Class Winner: Nuon Solar w/ Nuna 8
Challenger Class competitors race in smaller cars designed to carry one driver alone, and aim to beat the best time for each day as they reach checkpoints along the single, complete stage from Darwin to Adelaide. Entrants in the Challenger Class are also required to complete the entire stage with one battery charge, relying on solar power to fuel whatever is left of the journey after that charge expires.
This year, the Dutch dominated at the top of the podium, with Nuon Solar winning first place for the second consecutive time. Nuon Solar already has the first-place 2013 Challenger Class title to its name, and this year’s Nuna 8 is an improvement on the previous Nuna 7 model. The team’s strategy over the years has relied on the lightweight, durable quality of 3D printed materials to keep weight low and efficiency high. The spoiler on the Nuna 8 was completely 3D printed, and only weighed 250 grams. In their victory celebration at the finish line, some of the team’s leadership pointed out the trouble with cloud coverage when racing a solar-powered car.
Cruiser Class Winner: Team Eindhoven w/ Stella Lux
Cruiser Class competitors race with one driver and one passenger in each vehicle, and their times are scored based on two halves of the journey instead of day-long destination stages. The first stage in the Cruiser Class spans from Darwin to Alice Springs, the route’s midway point between Darwin and Adelaide. The stop in Alice Springs affords Cruiser Class competitors the chance to recharge their vehicle’s batteries, but that means that for two legs of the race (between Darwin and Alice Springs and between Alice Springs and the finish line in Adelaide) vehicles have to run completely on solar power to supplement their battery charge.
Eindhoven’s team won this year’s Cruiser Class in the Stella Lux: an updated version of their 2013 Stella vehicle. Their 2015 upgrades focused on a redesigned body that features a wind tunnel aligned with the center of the car. This kind of aerodynamic design helped to reduce the energy expenditure of the car while on course, which is crucial when competing in the Cruiser Class. Overall, the Stella Lux weighs 826 pounds and is made mostly of carbon fiber. Since Cruiser Class vehicles are required to carry more weight over a greater distance with less access to grid charging, 3D printing isn’t always a viable option.
Adventure Class Winner: TAFE SA w/ Solar Spirit
The Adventure Class allows cars built for previous editions of the event to run again, usually with new team members. This bracket is generally used as a catchment for under-funded teams that haven’t quite met all the strict race requirements of the Challenger or Cruiser classes — so it’s often filled with student teams and independent groups without a lot of sponsors. As such, this race is usually a bit less competitive
This year, no cars from the Adventure Class actually finished the entire 1,900 mile (3022 km) course. In the end, it came down to which car had traveled the furthest distance in the least amount of time, with the Australian student team TAFE SA taking the top spot in its Solar Spirit vehicle. The car managed to travel 809 miles in 47 hours before going out, at which point it had to be trailered to the finish line.
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