The Belgian solar car team Innoptus leads the Bridgestone World Solar Challenge on the third day of the event despite having its large lead cut.
After reaching Alice Springs faster than any team in the past decade, Innoptus’ pace dropped on Tuesday, with headwinds and low light levels slowing teams as they crossed into South Australia.
The event’s defending champions are camped in roughly the same position as they were on day 3 of the 2019 event – about 40km west of Coober Pedy.
But they are still confident of their chances, having comfortably led the race since Sunday morning.
Innoptus again deployed its retractable ‘fin’ to help reduce the effects of Tuesday’s headwinds. While designed primarily to combat crosswinds, the sail-like extension helps reduce aerodynamic drag in all conditions and remained up for about 70% of the day.
Stronger and more variable winds are expected as teams approach Coober Pedy and head towards Port Augusta on Wednesday morning.
“Today it helped us reduce the additional cost of riding against the headwinds,” says Innoptus race strategist Frederik Vanmaele.
“We hope to have a very good morning charge [on Wednesday], we have to look at the control stop at Coober Pedy to make sure our car doesn’t flip over with the wind and then afterwards there should be more crosswinds before Glendambo. We’re expecting quite a fast race from now.”
Solar Team Twente averaged over 90km/h on Tuesday to halve Innoptus’ start-of-day advantage. They are now camped 24km behind the race leaders.
“We determined our ideal strategy to get to Adelaide as fast as possible,” says team leader Kirsten Bouwman. “I can imagine [Innoptus] are maybe a bit surprised. They’ve been at the front of us since the beginning and now we’re actually getting close.”
Another Dutch team – Brunel – maintained touch with the lead cars and sits 115km behind the lead. The gap is not insurmountable but will rely on particularly advantageous conditions. As the only lead team running a ‘catamaran’ body, Brunel’s vehicle is aerodynamically optimised to harness Coober Pedy’s crosswinds.
“Tomorrow, the winds are going to be way, way more,” says Lennert Hessels, Brunel team leader.
“I think with the unsurprising conditions that we always see around Coober Pedy, more wind and more clouds only will help us, because that’s exactly what we’re preparing for.”
Further back, the University of Michigan team continued its impressive charge through the field. After starting Sunday in 31st position, it now sits fourth on the road – 193km from the lead. It overtook Germany’s Team Sonnenwagen Aachen early on Tuesday and is camping in Marla overnight.
“Being at the ‘back of the grid’ was a big hit, it was really disappointing, especially since [our car] ‘Astrum’ was performing really well on the track just the day before,” says Michigan spokesperson Bonnie Zhu.
“However, we knew that this challenge is a marathon, not a sprint. Our strategy was always to focus on ourselves and not let our competition distract us from doing our best. We’re expecting good things tomorrow.”
The race is now led by four teams with new state-of-the-art batteries from American manufacturer Amprius.
That power pack, which is expected to be the standard across all teams by the time the 2025 event rolls around, offers at least another kilowatt on previous power cells used in solar car competition. These four teams reported around 30% better capacity in the battery for roughly the same amount of weight of units used by other competitors.
Winds to challenge the challengers
Tuesday’s conditions were clear and afforded good solar coverage throughout the day, however late cloud may have limited the amount of light available to teams to charge their batteries.
Despite updated safety regulations forcing teams to improve their cars’ aerodynamic stability, forecast southerly winds approaching 40km/h will test competitors again on Wednesday.
In the 2019 event, cars from Twente and Sonnenwagen were blown off the track owing to 70km/h gusts just outside of Coober Pedy. Barring another unforeseen event, Twente’s more stable 2023 vehicle will surpass that crash point early on Wednesday.
The single-seater ‘Challenger class’ cars occupy the top 10 positions on the road. Sonnenwagen remains fifth ahead of teams from Tokai University (Japan), Top Dutch Solar Racing (Netherlands) and Kogakuin University (Japan). Durham University (UK) overtook several cars to take 9th place – currently that team’s best ever road position – while JU Solar Team (Sweden) is 10th.
In the Cruiser class, four competitors remain in contention having reached Alice Springs overnight. The UNSW Sunswift team, which is a favourite to win the category this year, is in the lead. Given its car has capacity for three passengers, it’s also likely to have accrued substantial person kilometres.
Rather than simply being the first team across the finish line in Adelaide, Cruiser cars are scored on total person-kilometres (distance travelled by each passenger on the 3,020km journey), energy efficiency and vehicle practicality.
Sunswift leads the University of Minnesota (US), Solaride (Estonia) and Deakin University teams. Cruiser cars must reach Coober Pedy from 5:30-6:00pm local time on Wednesday to remain in the race.
Only two other Australian teams remain competitive. As of Tuesday night, the Western Sydney University team (Challenger class) was camped in Alice Springs, while Adelaide University (Challenger) is in Barrow Creek, NT.
Flinders University (Cruiser) and privateer outfit Team Arrow (Challenger) have trailered their cars. After damage to their solar array prior to the event, the ANU Solar Team has also retired their challenger.
The Bridgestone World Solar Challenge resumes at 9:00am local time on Wednesday morning, with a 6:00pm scheduled finish for the day. The first car is expected to arrive in Adelaide on Thursday morning.
Cosmos is the Scientific Media Partner of the 2023 Bridgestone World Solar Challenge Follow our coverage.