The Sunraycer project started with a request from GM's Australian division to GM Headquarters to participate in the upcoming World Solar Challenge. This race, to be held in
Australia in late 1987, would feature purely solar-powered cars.
Roger Smith, the
CEO of GM, was interested in the idea and agreed to fund a study to see if a solar powered car could be built within 10 months. Smith hired
AeroVironment to do the study. A month later, AeroVironment engineers concluded that a highly competitive car could be built within the time available. AeroVironment, led by
Paul MacCready, was given the contract to build what would be called the Sunraycer. During the conceptual process, the goal was to create a very low-weight and ultra-low wind resistance vehicle. With this in mind, AeroVironment produced a design that proved to be very lightweight (only ) and created a very low
drag coefficient (cd: 0.125). The Sunraycer was designed to be fast and was capable of a top speed of . A total of 8800 solar cells were manufactured and installed by a team from Hughes Aircraft. At high noon, the car would generate about 1500
watts of power. The engine was created for the Sunraycer by GM using a brand new
electric motor based on Magnequench
permanent magnets. This kind of
rare-earth magnet was invented in 1983 independently by the GM physics department and
Sumitomo Special Metals. Both companies discovered and eventually commercialized two significantly different manufacturing processes for this material class; the GM concept was commercialized under the Magnequench brand. The new motor was lightweight and efficient; GM stated its
motor efficiency was around 92%. In 2011 its constructor won the
IEEE Nikola Tesla Award. Aside from the driver, the single heaviest element in the car was the Hughes battery pack that utilized
silver-oxide batteries. These batteries were included to provide extra power when passing trucks, to smooth out the performance of the vehicle, and because the race rules mandated driving only between the hours of 8 AM to 5 PM, but the cars were allowed to charge their batteries from sunlight even when they were not on the road, allowing driving during allowed hours even when the weather was overcast. The frame of the car weighed 14 pounds. AeroVironment engineers made use of
Kevlar for the shell of the car. The Sunraycer was tested through the spring and summer of 1987. During the testing period, the team had the time to set a new world speed record with the Sunraycer, achieving a speed of from solar power alone, breaking the old record by 10 mph. The Sunraycer reportedly cost slightly less than $2 million to build. == Race ==