College of Engineering News • Iowa State University

Bridgestone World Solar Challenge: Day 4

SOUTH AUSTRALIA, AUSTRALIA – The fourth day of the Bridge Stone World Solar Challenge proved to be the most productive for PrISUm solar car thus far into the race.

The team departed from a rainy Alice Springs – the race’s midway point – in the morning and arrived at the controlled stop in Kulgera in the early afternoon. Despite rainstorms in Alice Springs at the start of the day, the skies were mostly sunny as the team progressed southward, allowing the car’s solar array to capture its needed energy.

“The array performed admirably, especially with the cloud chasing strategy we adopted, going fast in shade and slowing to charge when necessary,” said Jason Cheng, one of the team’s race strategists and a sophomore in electrical engineering. “We were reaching almost peak efficiency, exceeding our expectation at 600 to 700 watts.”

Temperatures were in the mid-70s in the mourning and heated up to the low 90s by the afternoon. The battery pack did not experience the overheating issues it had in the previous days allowing the team to progress with minimal interruption. The team also maintained a slightly slower pace than previous days, averaging about 63 kilometers (or 40 miles) per hour.

“The slightly slow speed allowed the team to react to our changing environment with more certainty,” said Tom Burtnett, a mechanical engineering senior and solar car driver for the race. “We started off the morning with very rainy conditions and were not sure the extent of the system. “We also swapped drivers at an off-road location. This way fewer people needed to leave the vehicle and we could get back on the road faster.”

Many of the trees and mountains that lined the roadway earlier in the day we replaced by bushes and flatlands as the race progressed through Australia’s arid central region.

“We knew the terrain was going to flatten out today at some point,” said Burtnett. “Closer to Kulgera it did flatten out and driving turned into trying to keep a consistent speed instead of coasting down hills like we did up north.”

The team ended about 20 kilometers north of Marla, logging about 422 kilometers on the day. With just two days left in the race, the team is roughly 1080 kilometers from the finish line in Adelaide.

“We going to do everything we can to make our team, our university, and partners proud by getting Penumbra to the finish line,” said Cheng, a junior in electrical engineering. “We have a unique opportunity to gather data with the time we have left. We’ll collect data when we can and will push our team to finish in Adelaide on Friday in time for practicality judging with all of the other cruisers.”

The Bridgestone World Solar Challenge is a 3021-kilometer biennial race that began in Darwin in Australia’s Northern Territory on October 8 and finishes in Adelaide in Southern Australia on the 15th. 2017 marks the race’s 30th year and features 42 teams from more than a dozen countries.