Sunraycer

The Sunraycer was a solar powered race car designed to compete in the world's first race featuring solar-powered cars. This race is now called the World Solar Challenge. The Sunraycer, a joint collaboration between General Motors, AeroVironment, and Hughes Aircraft, won the first race in 1987 by a huge margin. One of its driver was Australian Touring Car racer, John Harvey.

The Sunracyer project started with a request from GM's Australian division to GM Headquarters to participate in the upcoming 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 immediately interested in the idea and he 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 their famous owner/engineer Paul MacCready was given the contract to build what would be called the "Sunraycer".

During the conceptual process, the constant goal was to create a very low-weight and ultra-low wind resistant vehicle. With this in mind, AeroVironment produced a design (resembling a futuristic streamlined cockroach) that proved to be very lightweight (only 585 pounds) and created a very low drag co-efficient (Cd: 0.125). Sunraycer was fast and capable of a top speed of 109 km/h (about 65 mph).

A total of 8800 solar cells were manufactured and installed by a team, from Hughes Aircraft, which had a great deal of experience with photovoltaic cells used in the many communications satellites that they created. At high noon, the car would generate about 1500 watts of power.

The engine was created for the Sunracyer by GM using a brand new magnetic motor based on Magnequench magnets recently invented by the GM physics department. This new motor was lightweight and efficient motor; GM stated its motor efficiency was around 92%.

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. The cars were allowed to charge their batteries from sunlight even when they weren't on the road.

The frame of the car weighed just 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, and it had no problems. During the testing period, the team had the time to set a new world speed record with the Sunraycer, achieving a speed of Auto mph|36|0 from solar power alone (breaking the old record by 10 mph).

The Race

The race, in November 1987, was from Darwin in the north of Australia, to Adelaide in the south. The race course followed the Stuart Highway for nearly the entire trip, going past Alice Springs in the middle of the continent.

The Sunraycer won the pole position with the fastest speed of all the 24 contestants (109 km/h) and from the start of the race to the end, it was always in first place. It raced the convert|1867|mi|km|0 with an average speed of Auto mph|41.6|1, finishing the race in just 5.2 days. This was 50% percent faster than the second place vehicle (which arrived in Adelaide two days after the Sunraycer). Roger Smith, the GM CEO, went to Adelaide to congratulate winning team.

In June, of the following year (1988), the Sunraycer smashed the solar powered speed record with a top speed of Auto mph|75.276|3 (set in Mesa, Arizona). For comparison, the winning car in the 2005 World Solar Challenge was the Nuna 3 which had a top speed of 140 km/h (87 mph).

On Tour

GM put the Sunraycer on tour and it was transported to many events across the U.S. GM also made a promotional film about the Sunracyer aimed at middle-school and high-school students. The film (about 30 minutes long) was narrated by one of the drivers of the Sunraycer. The Sunraycer was then donated to the Smithsonian museum by GM.

The Sunraycer was a very expensive car to build (slightly less than $2 million 1987 dollars all told) and at the time it was not considered feasible to create a car for the American car market based on solar power. Instead, the idea was to create an electric powered car.

The Sunraycer led directly to the creation of the GM Impact. An electric powered car (also designed by AeroVironment with help from both GM and Hughes). In turn, the GM Impact led to the EV-1.

References

* [http://www.evworld.com/archives/interviews/maccready.html Paul MacCready talks about the Sunraycer project]
* [http://americanhistory.si.edu/onthemove/collection/object_362.html Smithsonian article on the Sunraycer]
* [http://www.evworld.com/view.cfm?section=article&storyid=1053 EV-1 Timeline]
* [http://www.ucar.edu/governance/meetings/oct00/maccready.html Paul MacCready bio]
* [http://www.speedace.info/sunraycer_general_motors.htm Short history of the Solar powered car race]