The World Solar Challenge is a 3000km road race down the Stuart Highway, from Darwin to Adelaide. This is the only road, so it's worth considering the fact that the small solar cars, some of which weigh only 140kg (that's 2 Miss Butlers carrying their big rucksacks), have to share the same road as all the big road trains and trucks. Also, though it is called a highway, it's just a single lane road either side. Throw in all the things that Australia likes to try and get you with - bush fires, smoke, storms, animals, extreme heat and dehydration and suddenly Lewis Hamilton's racing job looks a little easier. I'd seen some signs for the race in Katherine, and when I got to Darwin bumped into the Cambridge University team in the supermarket and got chatting.
Mrs Rees and the Stem group sent over some questions for me to ask, and in seeing the team again I also got to visit the centre where all of the team's cars were being held and checked (called 'scrutineering'). Some of the teams are very professional and well-funded, others are more hobby projects. If you look at the solar challenge website or use a search engine you'll find out how different they are.
Here's some of the info I found out from the team - i hope it answers most of the questions! You can always email if there's other things you'd like to know.
Designing the car:
The team have worked on the car as part of their degree/postgrad studies, and in their spare time. Much of the design has been done using CFD software. To test for aerodynamics very fine strands of wool were attached to the car and smoke passed over it - watching the patterns formed helped to refine the shape/design.
The car:
The car is two parts, the base with driver's seat and wheels, and the array, which is the top panel with the solar cells on. The area of cells is very closely regulated. The array lifts off easily, and this is done everytime the car stops, in part to angle it best to the sun. Teams spray the array to cool it, as ironically when it heats up it's less efficient (but has to be in the sun to work - crazy eh). The cars are very light, and the good ones are very energy efficient. The Aurora uses the same energy as a toaster to go at 100km/h (62.5mph); it's 98% efficient compared to a petrol car at 30%.
The driver's seat in the Cambridge car (and most others) is very small...
The Teams:
...Need to have small enough people to drive! Under 5ft10 and less than 80kg. The Cambridge team had two drivers to keep swapping - this is important as the temperature in the car can reach 45 degrees - very very hot, and it's very cramped in there. The rest of the team travel in support vehicles in front and behind to help keep the car safe, and also to fix any problems. They are all studying engineering subjects, and did A Levels such as maths, physics, further maths and chemistry. Their car's top speed is 70mph but because the intensity of the sun changes throughout the day this can't be maintained. Wherever the car gets to at the end of each day, the team camp out, ready to race again the next day.
There's loads more about this on www.cuer.co.uk so have a look if you're interested. Having driven the route in a normal, quite big car, I think you would feel very fragile next to the big road trains in a solar car. Also, I was lucky to avoid any major fire/smoke problems, but some of the race teams had to stop for a while due to the burning.
A great effort to get the team together and go the distance, I'd like to hope that better use of solar power is not that far away. There's a lot of homes here with panels on the roof - there is a bit more sun here though!
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