The tenth solar car built by a TU Delft students team – called the NunaX – wants to use the wind as well as the sun to race through Australia as fast as possible. The latest version of the seven-time winner of the World Solar Challenge was presented today in Amsterdam. The tenth car from Delft is not only lighter and more efficient, but it is also built in such a way that the wind provides extra speed. In October, the students hope to win the world title for the eighth time during the Bridgestone World Solar Challenge in Australia with their NunaX.

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After more than a year of designing and building, the NunaX can finally be shown: the completely self-built solar racing car of the Vattenfall Solar Team. The team members are all students of TU Delft, who put aside their studies for at least one and a half years to participate in the Bridgestone World Solar Challenge. Despite the fact that the team has been world champion seven times before, the challenge is no less important, says technical manager Bruno Martens. “The rules for solar racing have barely changed in recent years. Where cars could still be very different in the first races, you notice that teams are looking closely to each other and the cars are starting to look more and more alike. So it’s more important than ever to innovate: the smart gadgets make the difference.”

NunaX, the newest solar car of the Vattenfall Solar Team – © Hans-Peter van Velthoven

The students from Delft won the previous edition partly thanks to an innovative smaller model of car – it is expected that many competitors will use the same size this year. The team members from Delft have now succeeded in making their new car even lighter, smaller and more efficient: the whole thing weighs only 135 kg now. In addition, a small wing has been attached to the car, which has been placed in such a way that the panels on it catch as much sun as possible.

However, the team expects the most from the aerodynamic design. Bruno Martens: “During the previous race we discovered that the small Nuna9 took advantage of the strong crosswind that we always have in the south of Australia. A bit like a sailboat sailing on the wind. This time we specifically took this into account in the design. The canopy and wheel covers are shaped in such a way that the car gets a push in the back when there is a crosswind. With this car, we not only use solar energy, but also a bit of wind energy.”

The batteries of the car, together with those of the teams from Eindhoven and Twente, are already on their way to Australia. In August, the team members will leave together with their NunaX. The race starts in mid-October.

About the car:

NunaX is the smallest and lightest (135 kg) car ever, and – unless the competition comes up with an even lighter car – the lightest car ever to take part in the solar race. To save weight, every part of the car has been redesigned. For some, the team uses different raw materials, while for others, material has been skipped: a difference of sometimes only two grams. The car is very streamlined: the side mirror of an ordinary car has more drag than NunaX. The solar panels consist of gallium solar cells, which are normally used in space travel. These are much more efficient than the silicon cells on roofs. Instead of the standard layer of glass that normally protects the cells, the team applies its own protective layer. This saves weight. This coating also contains prisms so that light always falls perpendicular to the solar cell.