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The solar racing car drives - but still without solar power

17/6/2023

Translation: machine translated

A crew of ETH students is building a car for the world's largest solar car race in Australia. After months of preparatory work, it recently covered its first metres.

Three wheels, battery, electric motor, brakes, steering wheel, a bunch of electronics. Even if what is rolling across the apron of the airfield in Dübendorf does not yet look like a racing car - it is one. Students at ETH Zurich have been working towards this moment for months. They have recruited sponsors for their big project, made sketches, had components milled and calculated CAD models. All for the big goal: on 22 October, their car should be at the start of the World Solar Challenge. And ideally be the first to cross the finish line on 29 October.

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A lot of work awaits the 40-strong team before then. On the Whitsun weekend, the chassis of the single-seater left the workshop in Technopark for Zurich West. In a delivery van, it travelled almost 15 kilometres eastwards to the airfield in Dübendorf. The team had a few days there to prepare the car so that it could complete its maiden voyage.

When I visit one of the hangars, Alexandr Ebnöther is trying to get the brakes working. A car that can't brake is not allowed on the test drive.

Team meeting in the hangar.
Source: Martin Jungfer

It looks like there is not enough oil in the hoses that hydraulically control the brakes. So it has to be pumped in. By hand. A job that Frederike Brockmeyer has taken on. She pumps and pumps and pumps. Until Alexandr says that's enough. Another step accomplished.

The future racing car is jacked up in the hangar. A black carbon chassis. The lower rear section contains the battery pack. The electric motor is ready to drive the single rear wheel. The steering wheel, reminiscent of a Formula 1 racing car, is mounted in the Cockpit.

Drive on the rear wheel: This is where the permanent magnets are located, which are supplied with power and set the wheel in motion.

Everything is connected to everything. Cables connect small control boards that are screwed onto the chassis in four places. The man who knows what is happening here is Pascal Burkhard. He knows the order of the chips and circuit boards, which all look the same to me. A lot of the testing is still improvised and only attached with duct tape.

Function is more important than design at this stage of the project.
Source: Martin Jungfer

"First and foremost, the electronics should work," says Pascal. For the first driving test, the power will come exclusively from the battery. The cover for the car, to which the solar cells are attached, is still being worked on. The team has therefore already charged the batteries at the Technopark. The battery has a maximum capacity of five kilowatt hours and weighs a total of 26 kilograms. The battery cells alone weigh 20 kilograms. By comparison, the Tesla Model Y, currently one of the best-selling cars in Switzerland, has 79 kilowatt hours, but easily weighs half a tonne. On the other hand, the ETH students' solar racing car drives just as far with its five kilowatt hours as the Model Y.

The price for this? Less luxury, much less. Well, actually none at all. The Cockpit doesn't look as if a driver will be able to drive for hours on Australian roads in October. "Comfort will come later," Aaron Griesser explains to me. "At least a little," he adds with a laugh. The ETH team's racing car is designed to be as light as possible so that it can travel fast and far using the sun's energy. That's why the tyres are particularly thin and the driver sits low in the car to keep wind resistance to a minimum.

The aim of the World Solar Challenge is to cover a distance of 3000 kilometres across Australia. The start is in Darwin in the north, the finish in Adelaide in the south. The competition has been running since 1987, with teams from universities and industry competing in different classes. The aim is to promote the research and development of solar-powered cars and to show the public the state of the art. The second race in 1990 was won by the Biel School of Engineering with its car «Spirit of Biel».

The winning car from Tokai University in Japan in 2009

It's driving!

In the early evening, the two brake circuits are ready for use. The car can finally take to the track. Driver Jonas Rudin takes a seat and the wheel firmly in both hands. Once again, the car is connected to the laptop and the electronics are checked - and then it slowly rolls off.

It is a moment that fills the team with pride. The young men and women have managed to turn theory into something that works in practice.

Selfie time at the end of a successful day: the ETH team at the military airfield in Dübendorf.
Source: Jonas Rudin

Even though sunset is already approaching in Dübendorf, for the crew it is more of a departure for the next stages. More articles about the project will follow here in the magazine.

Cover photo: Jonas Rudin

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Martin Jungfer

Head of Content

Martin.Jungfer@digitecgalaxus.ch

Journalist since 1997. Stopovers in Franconia (or the Franken region), Lake Constance, Obwalden, Nidwalden and Zurich. Father since 2014. Expert in editorial organisation and motivation. Focus on sustainability, home office tools, beautiful things for the home, creative toys and sports equipment.

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