High tech wins out in duel in the sun. SOLAR POWER ROLLS ON

RACING along the burning bitumen, past vast stretches of Australia's Tanami Desert, the General Motors Sunraycer pulled wide of a rust-scarred truck hauling a trailer. ``It was only doing about 76 kilometers per hour [47 miles an hour],'' recalls driver Terry Satchell. ``So I just put my foot down and passed it.'' A car propelled by mere sunlight charging past 100 years of fossil-fueled internal-combustion technology was one of many poignant moments inspired by the Pentax World Solar Challenge - the first transcontinental international solar car race. This Darwin-to-Adelaide race amounted to a grueling 1,950-mile test of man and machine across Australia's belly.

Twenty-five race teams, from the United States, Australia, Japan, Switzerland, Germany, Denmark, and Pakistan accepted the challenge. The result: low budget high school ``techies'' squaring off against corporate brawn. And chariots ranging from backyard buggies - a German arrived with his vehicle in three ordinary suitcases - to the victorious GM Sunraycer, the most advanced solar car ever built.

Australia's news media quickly dubbed the car ``the Kitty Hawk of Solar Cars.'' Participants likened the technological stimulus of the event to that of the Soviet-US moon race.

``This is pure competition and development on the order of something you normally only see in the space program or, unfortunately, in wars,'' says Hans Tholstrup, the race organizer.

Competition rules were simple. Cars must meet maximum size specifications and run on energy from the sun (battery storage allowed). Racing started at 8 a.m. each day. At 5 p.m., the cars had to stop - wherever they were.

Hopes were high on Nov. 1, when the green flag dropped in Darwin. The sun-kissed contraptions dashed past thousands of curious spectators. But within hours, enthusiasm and machines began to wilt. The hills and tropical swelter took their toll.

Indeed, after a day, the Solar Challenge was no longer a race. It became a demonstration of the GM team's preparedness and outright technical superiority.

The sleek Sunraycer was achieving average speeds of just over 40 m.p.h. through rugged terrain and tire-shredding roads. When the 30-odd-member GM team (including engineers, cooks, helicopter, scout car, media bus, radio car, satellite communications truck, spare-parts truck, telemetry van, and weather car) set up camp the first night, their nearest rivals were some 90 miles astern. The gap only got wider as the race progressed.

At one point Mr. Tholstrup told a gaggle of reporters dogging the GM vehicle: ``It's a matter of the new technology being ahead. The old tech is still having a great race back there.''

While other designers put a priority on getting a large solar panel to collect power, GM sacrificed some photon-power for a cleaner aerodynamic shape. And the strategy paid off; the second-place car averaged speeds 25 percent slower.

The architect responsible for the Sunraycer's ``flying cockroach'' form is the guru of low-power, lightweight, low-drag designers, Paul MacCready. Dr. MacCready's credentials include winning the Kremer Prize for the first successful human-powered aircraft. He also built the first solar-powered aircraft. And his Monrovia, Calif. firm, AeroVironment Inc., worked on the hull design of the America's Cup winner, Stars & Stripes.

MacCready refined the Sunracyer design using a NASA aerodynamics program. Wind tunnel tests at GM and the California Institute of Technology showed the machine achieved the lowest drag coefficient ever measured at those sites for a road vehicle. In laymen's terms, MacCready describes its design as ``functional.'' ``It has low drag, low aerodynamic drag, which means it doesn't disturb the air much after it goes by,'' he says.

Of course, GM didn't stop with aerodynamics, ``almost everything in the vehicle is leading-edge technology,'' says MacCready. The car is covered with a scaly layer of 7,200 midnight blue-solar cells. These gallium arsenide cells made for satellites were just hatched months ago in the labs of a GM subsidiary, Hughes Aircraft Company.

``They put out 25 percent more power than any previously made cells,'' says Howard Wilson, a Hughes vice-president and Sunraycer project coordinator.

The tiny eight-pound electric motor is also just out of the labs at GM. Officials claim it's 30 to 40 percent more powerful than commercially available motors of similar design. Using specially developed magnets, the motor comfortably propels the 550 pound Sunraycer down a good road at 45 mph. For short spurts, the motor can generate as much as 8 horsepower, which has pushed the Sunraycer to speeds over 70 mph.

Does this mean a solar-powered car for the general public is just around the corner? No. It's five to seven years away, but there are solar cars for short commutes available now, Mr. Wilson says. ``You drive it 10 or 15 miles to work. It sits in the parking lot all day and the solar cells charge it up. The technology is here already for that.''

GM officials foresee cooling devices and other electric accessories being charged by rooftop solar panels within three or four years.

If a Chevrolet Sunraycer does become an assembly line product in the near future, MacCready figures ``it will probably occur three years earlier [than it would have] because of this race across Australia.''

``Competition improves the breed,'' agrees Wilson. ``When you get into competition like this, you find yourself pushing harder at the frontiers of technology. Some of the electronic efficiencies achieved here have never been achieved before.'' Whether solar catches on or not, he adds, ``this car's light weight, aerodynamics, electronics, are all features that will be important in the future, especially if fuel prices go up.''

Sunraycer took the checkered flag at the Adelaide Oval cricket grounds, just 5 days after leaving Darwin. The machine has survived the ocher dust storms of Australia's Red Centre, dodged an emu, passed wild Afghan camels, opal mines, and bleach-white salt flats, and endured the buffeting of countless 150-foot-long, triple-trailer road trains.

While the Sunracyer sailed almost the entire race beneath China-blue skies, most of the field crawled along beneath foul bush country weather. Eight teams dropped out, including the heralded John Paul Mitchell Systems car from Hawaii. High winds flipped one vehicle. Golf-ball-size hail damaged another. Flooded roads slowed some. The Swiss Spirit of Biel team spent a half-day repairing its car after a fender-bender with a fossil-fueled car, yet still managed to finish third just behind the Ford machine.

Still hundreds of miles away from Adelaide when Sunracyer crossed the finish line, a band of stalwart Crowder College (Missouri) students dined on canned spaghetti, coaxing their solar buggy along. And the Massachusetts Institute of Technology Solectria continued the race on a motor donated by the Sunraycer team.

And while the underfunded Pakistani Solar Samba team was the first to bow out, it has already tendered its entry for the next trans-Australia Solar Challenge, in 1990.