The PU tyres were cast for them by Sunray, based in Rutherfordton, North Carolina. Neisen has also been speaking to Aend Industries in Huntington Beach, California. ‘You can now buy polyurethane bicycle tyres that are airless, and I believe they are also starting to get into the car industry in spare tyres,’ he said. ‘And in the construction industry, where I work, you need good, tough, strong tyres that do not go flat.’
Between now and their July entry in the World Drivers’ Championship at the European Eco-marathon in the UK, Neisen said that they plan to build a second set of wheels that are slightly softer. By having two different sets of wheels, they will be able to better match the tyre to the road conditions.
‘Every [road] surface has an optimum durometer, and you are not sure what surface you are going to be driving on,’ he said. ‘The smoother the surface, the harder the tyre can be while still being efficient. But if the surface gets a little bumpy and your hardness is too great, then your wheel starts bouncing a little on the bumps.’ This reduces energy efficiency.
The PU tyres helped the team win their class in the Americas and, their Supermileage 2 car broke the local record. ‘We raised it from 63 miles/kWh to 68,’ he said. ‘And we qualified to go to the drivers’ world championship in London in July.’
In the drivers’ world championship, qualifying cars are given the same amount of energy, equalised across different energy sources. They then drive a fixed number of laps around the track. The winner is the team that crosses the finish line first. As their energy supply is limited, they have to go fast enough to win, but not run out of fuel. The prize is to drive their car on the Ferrari test track at Maranello, Italy.
‘When you look at the numbers in Europe, we will have to make big improvements to be competitive. Their top car is at about 115 miles/kWh!’ Neisen said. The softer tyres might help, but he thinks there is a balance. ‘If we went too soft, maybe the rolling resistance would go up, as happens when you run tyres too low on air. This was our first attempt, so there’s a lot of room for improvement, maybe even in our polyurethane tread design. We are optimistic that we can improve this and hopefully post a better number in Europe.’
Shell’s Rosen believes the competition is a great way to get students interested in science and technology careers. ‘These are people who are going to lead us into a cleaner, better energy future,’ she said. ‘From the Shell perspective, it’s an incredible experience.’