Brunel Solar Team reveals secret weapon during static scrutineering of Nuna 13

Darwin, 19 August 2025 - During the technical inspection of solar car Nuna 13 today, the Brunel Solar Team unveiled a striking innovation: a new, innovative swordfin that allows the solar car to sail even more on the wind, reach higher speeds and be more aerodynamically stable. On Sunday 24 August, the world championship for solar racing, the Bridgestone World Solar Challenge, will start in Australia. The day before, the qualifying round will determine the starting positions of the participating teams.

Until now, the team had only revealed the retractable canopy fin, but they had another secret weapon up their sleeve: the swordfin. This fin is considerably larger than the canopy fin and is mounted on the solar car when the wind is favourable. Mounting the swordfin en route can cause the team to lose a lot of time, which requires strategic choices. Every morning and during scheduled stops, the team decides whether to attach the fin, depending on the expected wind direction. When the wind is favourable, Nuna 13 extracts more energy from the air currents and the solar car can reach higher speeds. If the wind is unfavourable, the swordfin actually creates extra air resistance. ‘It was a challenge to keep the new fin a secret for so long, but we succeeded and we are very proud of it,’ says Elias Wawoe, team leader at the Brunel Solar Team. ‘The name swordfin says it all: it looks like a sword and cuts through the air. We expect that this innovation, under the right conditions, can give us an advantage during the race.’

In addition to extra speed, the swordfin also contributes to greater stability on the road. Its shape and placement create a so-called dart effect: the solar car stays better in the direction of travel and swerves less in strong crosswinds. ‘Especially in the open plains of the Australian outback, the gusts of wind can be fierce,’ explains David Mol, aerodynamic engineer at the Brunel Solar Team. ‘Our drivers then have to steer hard to keep Nuna straight on the road. That not only costs energy, but also time. Thanks to the swordfin, Nuna automatically turns a little more into the wind and stays on course more tightly. While driving, it feels a lot more stable. The less we have to correct, the faster we ultimately race to the finish line.’

Today, Nuna 13 underwent a static inspection, during which the race organisers checked whether Nuna 13 meets all technical and safety requirements. The solar car went through several stations, including measurement, weighing, electrical and safety inspections. The drivers were also tested on getting in and out of the vehicle safely and as quickly as possible (within 15 seconds) and on meeting the minimum body weight of 80 kilograms, which is supplemented with ballast if necessary. 

‘The inspection is always an exciting moment, because the organisation then determines whether Nuna complies with the regulations and can safely take to the road,’ says Thijmen God, technical manager of the Brunel Solar Team. ‘The day went well and our swordfin got the green light from the organisation. I am proud of our team and we are looking forward to the qualification this Saturday with confidence and energy.’