Brunel Solar Team reveals new solar car Nuna 13

Several technical innovations to Nuna 13 should make all the difference on the 3,000-kilometer course across the Australian outback. Most striking is the extendable and rotating fin: an aerodynamic innovation that converts crosswinds into extra propulsion. “Just like an airplane wing, crosswinds create a pressure difference on the fin, which generates a forward thrust,” explains Daan van den Dries, Chief Engineer at the Brunel Solar Team. “This means we consume less solar energy which is important, because new rules mean we are racing with a battery that is three times smaller than last year. And because the race is taking place two months earlier this year, we are racing in the Australian winter: the sun is lower, so we have less solar income.” Never before has a solar car been built with both an asymmetrical catamaran design and a fin. To make optimal use of the fin, a wind tunnel test was necessary. For the first time since 2011, the team tested with a full-size car again.

During the wind tunnel test on June 3rd and 4th at the Volkswagen Group in Wolfsburg, the team gained valuable insights into the performance and stability of Nuna 13. Working with the Volkswagen engineers was a pleasant and professional experience. During the test, a remarkable discovery was made: with sufficient crosswind, the fin generates more thrust than there is air resistance, resulting in net propulsive force. This can be used to charge the battery.

However, at the end of one of the last sessions, things went wrong and Nuna 13 was flipped upside down. The Brunel Solar Team had secured Nuna at several points, and the solar car came loose at one of those points. Van den Dries: "It was quite a shock, but we carry out these kinds of test runs to understand how the solar car behaves under different conditions. We started repairing the damage and today we are proud to present Nuna 13, which will soon be participating in the solar race in Australia. Based on the test results, we have a lot of confidence in the car. And we also have confidence in the team, which has passed this test really well. We are better prepared than ever before."

Progress has been made in terms of materials: this year, the team used the pre-preg method for the first time. Previously, carbon was manually coated with resin, which hardens quickly. Now, the resin is already incorporated into the carbon, so that the material only hardens when heated. This allowed team members to reshape the carbon repeatedly and work with greater precision. The result: a lighter chassis, less chance of defects, and a sleeker finish. In addition, Nuna 13 features an efficient ironless motor, an improved steering system with less energy loss, and silicon solar cells that are about 30 percent more efficient than standard solar panels.

Where solar energy was once a promise, it is now a proven driver of innovation. This anniversary edition of Nuna reflects 25 years of courage, knowledge, and innovation, as well as the ambition to position the Netherlands as a leader in the energy transition. “We're not just building a car, we're building the future of mobility,” says Elias Wawoe, team leader of the Brunel Solar Team. “With this car, we are bringing together 25 years of knowledge, ambition, and innovation. Since 2001, we have participated in the world solar racing championship in Australia every other year, and of the eleven times we have competed, we have won seven times. Without the knowledge of our predecessors, we would never have come this far. This year, we are going all out for our eighth world title.”

The exterior of Nuna 13 is a moving work of art full of references to the Netherlands and the four elements: sun, wind, water, and earth. In a Van Gogh-like style, a lion, windmill, seven golden tulips, and clouds are incorporated into the wrap, symbols of strength, innovation, and craftsmanship. Wawoe: “The seven golden tulips represent the seven world titles we have already brought to Delft. The bodywork was built by a Frisian boat builder, the fin refers to our sailing tradition, and the technology to 25 years of Delft innovation. The car is truly a tribute to where we come from.”

The Brunel Solar Team is a team of students from Delft who build a solar car every two years to compete in the Bridgestone World Solar Challenge: the world championship for solar racing in Australia. Since its inception in 1999, the team has competed eleven times, finishing as world champions seven times. The team combines innovation, sustainability, and teamwork and aims to contribute to a future of clean mobility with its solar cars.