The University of NSW engineering team has withdrawn from the 2017 Bridgestone World Solar Challenge, due to a rear suspension failure on their solar car.
The Sunswift Violet, a solar racing car designed and built by UNSW engineering students, looks like a family sedan, but is built with a twill carbon-fibre monocoque chassis, weighs less than 400kg, and has a drag coefficient below 0.2.
With a top speed of 130km/h and a range of 800km running on just its rooftop solar panels, the Sunswift Violet was expected to do well in the 3,022km race across outback Australia.
Power converted from sunlight is stored in modular lithium-ion batteries, and the batteries themselves give the car a range of 400km.
The Sunswift Violet had to be withdrawn from the race after its rear suspension failed, causing the rear left wheel to buckle. The car swerved while travelling at 56km/h while under cloud cover and carrying the driver and three passengers. The driver brought the car to a halt safely by the side of the Stuart Highway.
Despite 25 engineering students from the UNSW Sunswift Solar Racing Team attempting to repair the vehicle, closer inspection found that a rod from one of the lower control arms had sheared through. No other damage was sustained to the structure or dynamics.
This is the second incident involving the Sunswift Violet’s suspension systems. During race testing at the Sydney Motorsport speedway in Eastern Creek, a bolt on the left-hand front suspension fractured during intense braking tests, causing the car to drop onto the roadway and skid for 30m.
According to Simba Kuestler, the team leader, the risk of another failure could not be ignored, and so the team decided not to continue.
“While we have confidence in our skills and the soundness of Sunswift Violet, we would have had to overtake road trains and other traffic on the Stuart Highway to complete the race,” Kuestler explained.
“Ultimately, it came down to the fact that while we could fix the problem, the underlying suspension issue can’t be addressed during the race. And another failure, while unlikely, could have had severe consequences.”
According to Mark Hoffman, UNSW’s Dean of Engineering, the decision, though difficult, was also a learning experience for the engineering students.
“It is utterly heartbreaking for the students, because Violet is an excellent car at the vanguard of the technology, really pushing the boundaries of efficiency," he said.
“But setbacks happen when you face demanding, real-world challenges and you are operating at the cutting-edge of what’s possible. This is painful, but it’s also a learning opportunity. But safety always comes first.”
The team plans to use the Sunswift Violet to race at the Sasol Solar Challenge in South Africa in a year’s time.
[Sunswift Violet. Photo: UNSW]