Cambridge University Eco Racing, Britain's sole entrant into the World Solar Challenge, has officially unveiled its radical challenger for this year's competition.
Members of the CUER team launched the car at the Science Museum in London yesterday in preparation for October's 3000-kilometre (1860-mile) sun-fuelled race across the Australian outback from Darwin to Adelaide.
The design of the team's electric vehicle – named Resolution after the HMS Resolution, in which Captain Cook made his second voyage of exploration to the South Pacific – marks a major departure from previous WSC vehicles produced by the student team.
A rule change for this year's race stipulates that competing machines must have four wheels, whereas three-wheelers had been more popular and successful in the past. Other changes relate to driver positioning and visibility out of the vehicle.
Faced with these new challenges CUER devised the teardrop-shaped vehicle in preference to the flat, rectangular designs that have been more common in the past. Those shapes are designed to optimise the solar panels' ability to soak up the sun, but Resolution puts the emphasis on aerodynamics.
Its rear-mounted solar array, which is mounted under a clear canopy, pivots to track the movement of the sun through the sky. This means the panels remain at the optimum angle to the sun, allowing them to gather 20 per cent more power.
Resolution's tiny dimensions are also influenced by CUER's decision to use high-efficiency solar cells. The regulations place a restriction on the size of the solar array depending on the type of cells used. CUER is using spacecraft-specification gallium arsenide cells and is thus restricted to three square meters of panels. Gallium arsenide cells are both lighter and more efficient than silicon-based variants.
Propulsion comes from a rear-wheel-mounted motor. The rules permit some of the excess energy produced by the solar cells to be stored in 5kWh lithium-ion battery cells, to power the vehicle when the sun isn't out or when an incline or headwind is encountered.
The 4.5m-long car produces about 1.5kW of power – about the same as a hair dryer – but is capable of a top speed of about 85mph, although during the race it is more likely to cruise at between 50-60mph. It weighs 120kg and uses low rolling resistance tyres that are designed specifically for solar powered cars.
CUER has the support of several key automotive and engineering companies, including Jaguar Land Rover, Cambridge Precision, Lenovo and SKF. It is testing the vehicle at Millbrook proving ground and has also had access to JLR's environment testing chamber, which has enabled the team to replicate the sort of conditions that it might face in Australia.
Resolution will have advanced on-board telemetry, which will take into account traffic, weather and driving style, to help advise the team on how to reach their optimum efficiency during the race.
Four drivers will take turns behind the wheel of Resolution. Each day has a 'racing curfew' of 5pm, so the emphasis is on completing as many miles as possible each day. After the curfew, teams can continue to use solar energy to replenish their cars' batteries.
CUER's entire team numbers 60, and all of the work on the project has been carried out in the students' spare time. About 20 members of the squad will travel to Australia for the race, which begins on 6 October.