The Cambridge University Eco Racing team has designed a small, light and energy-efficient solar car in which it hopes to win the World Solar Challenge in 2013 – a gruelling 3,000km race across the Australian outback.
The team claim its design is “game changing” for solar vehicles. It has an aerodynamic teardrop shape that for the first time prioritises efficiency over solar surface area.
Usually cars that enter the race have a flat and wide planar shape, which is designed to have the largest possible surface area to harvest as much solar energy as possible. This design feature has barely changed over the past 10 years of the competition.
The Cambridge design, dubbed Daphne, measures 4.5m long, 0.8m wide and 1.1m in height. It will weigh around 120kg, making it the lightest vehicle ever to have entered the competition. Next year’s race will be run from Darwin to Adelaide.
Daphne has a weight-saving monocoque chassis made from aerospace-grade carbon fibre. The team is also working on a carbon-fibre suspension system that reduces the number of components needed as one composite arm can carry out the loadbearing, dampening and vibration functions. Investigations into the viability of composite wheels to minimise energy losses are under way too.
By locating the motor in the hub of the wheel the team says it can do away with gears, chains and differentials, which together can account for 15% loss in efficiency.
Team manager and second year engineering student Keno Mario-Ghae said: “This means Daphne will be 98% efficient, allowing us to exceed speeds of 82km/h, all on the equivalent power of a hair dryer.”
Daphne is powered by gallium arsenide solar panels at the rear of the vehicle on angled, movable plates which can track the movement of the sun as it passes through the sky. This gives a power boost of 20% compared with conventional flat-lying solar cells.
To maintain an aerodynamic shape, the solar compartment is contained within a canopy, which is made of a material containing micro pyramids that allow 97-98% of light to pass through.
