Two bushfires burning north of Alice Springs have tested teams leading the Bridgestone World Solar Challenge on the event’s second day.
The Stuart Highway was blanketed in a haze of smoke between Barrow Creek and Alice Springs as the event continued its journey south to Adelaide, forcing teams to put pedal to the metal and expend battery power in the search for visibility and quality sunlight.
But that hurdle didn’t stop the lead car from Innoptus, which reached Alice Springs faster than any car in the past three editions of the challenge.
Their car, dubbed ‘Infinite’, averaged about 90km/h on Monday; overall, it’s completed 1500km at an average speed of 93 km/h.
Confirming speculation by some teams, Innoptus strategy has been to gain road position over its competition before hitting the South Australian border. Strong crosswinds infamously blew several cars off the road in the last edition of the race, moving Innoptus to develop a retractable rudder – the ‘fin’ – as a countermeasure to high-speed wind gusts coming from the Great Victoria Desert. Should crosswinds persist, it’s likely teams will need to reduce their speed to minimise risk.
“We had a lot of innovations implemented in the car to make it possible to be as far as we are now and one of these is the ‘fin’,” says Innoptus team manager Cedric Verlinden.
“Today we used it 70% of the time, and this really allowed us to make use of the crosswinds.”
Setting up camp about 56km behind them are Solar Team Twente, a fast-rising Dutch outfit that is now second overall after starting in 11th place. They overtook their compatriots – seven-time winners Brunel – shortly before Barrow Creek.
“Today was a very good day again – in two days we’ve gone from 11th place to 2nd place,” says Twente’s technical manager, Tim Woertman.
“We’re looking forward to tomorrow and catching the Belgians. We’re doing quite well on energy.”
Brunel is keeping to its energy strategy despite being overtaken by Twente, with team spokeperson Isis Prummel saying they were keeping their heads cool and focusing on maintaining their strategy speed. They are now 70km behind Innoptus.
Meanwhile the Sonnenwagen Aachen team is 148km behind the lead car. Having maintained a conservative strategy so far, it’s not been tempted to change tactics to keep pace with Innoptus.
“Probably we are too far behind Innoptus in order to catch them if they continue to drive as they are,” says Lina Schwering, team manager of Sonnenwagen. “But there’s still three days to go, and a lot can happen in those three days.”
“Our strategy is going really well. We are not taking into account the other teams’ strategies, that makes no sense given [ours] is the car we are driving with, and we are driving it to the optimum strategy that we’ve had over two years.”
Fire danger averted
It’s been relatively smooth sailing for the event, with only two entries in the single-seater Challenger class having been loaded on the trailer and most passenger-style Cruiser Class cars still competing.
But cars have contended with roadside bushfires at three points along the route. A small fire burned near Katherine on Sunday, but two substantial fires between Barrow Creek and Alice Springs blew smoke across the highway on Monday.
Smoke threw two challenges at teams: driving visibility was poor and sunlight quality was significantly reduced.
Low light quality forces teams to carefully manage their battery as they discharge stored energy and push into regions of less cloud. Ash falling on the array can also impede light penetrance and risks damaging the microstructure of the cells.
“We are now cleaning the solar panel just to get the ashes removed and that the microstructure will work like it should work,” says Verlinden.
Tactically, this requires teams to decide how much stored energy to use to speed through the smoke haze. There is also the risk of ash or particulate matter landing on the solar array and further diminishing efficiency.
“Coming from the Netherlands, we are not used to bushfires, as we very rarely see them,” Prummel says.
“These bushfires do have impact on driving the solar car, as the smoke causes reduced visibility for the drivers.”
Last week, outbreaks in scrub near a main testing area frequented by teams saw roads closed off by event organisers. On the highway, teams are surrounded by a fleet of safety cars patrolling the route, while observers are assigned to each team to act as conduits to organisers.
“Event mission control monitors all locations and potential issues working with local authorities,” the event organisers say.
“Teams are kept informed and if risk management dictates, they will not be allowed to pass into the next sector from the relevant control stop.”
Lead teams have safely passed through the fire-affected areas near Alice Springs, with midpack competitors likely to pass by tomorrow.
Most teams are still competitive, with UNSW’s Sunswift Racing leading the pack of Cruiser Class competitors camping overnight in Tennant Creek. The Cruiser Class is a slower-moving ‘road trip’ style class, where competitors build larger, multi-passenger cars and are ranked on scores. These factor in passenger kilometres, energy efficiency, and showroom-appeal ‘practicality’, as well as the ability for the vehicle to complete the journey from Darwin to Adelaide.
At current speeds, the first Challenger cars are expected to arrive in Adelaide no earlier than Wednesday afternoon. Cruisers are due at the end of the week.
Cosmos is the Scientific Media Partner of the 2023 Bridgestone World Solar Challenge Follow our coverage.