Solar race cars this week began their nine-day, 2,400 mile chase from Dallas to Calgary, Alberta using only the sun for fuel.
The 24 teams in the American Solar Challenge race are mainly US college teams including entries from MIT, Ohio State and Northwestern. The University of Michigan's Continuum car is the defending champ, having won the Challenge in Australia last year. The University of Michigan has won four out of the eight North American Solar Challenges it has entered with its team of more than 100 engineering students, who have vowed to defend their title this year, the EE Times reported. The Continuum's blog can be followed here.
The cars do race, within limits of course. In the event's 20 year history, the average speed of solar cars has risen from 42 MPH in 1987 to a top speed of 65 MPH in the most recent race. the American Solar Challenge and Sunrayce, generally have been held every two years since 1990. With each event, the solar cars travel faster and further with greater reliability, officials said.
Over the years the challenge has become a test bed for all sorts of vehicle design from aerodynamics to tires. All manner of prototypes for testing the most efficient solar cell arrays, new types of car battery systems, including the latest Lithium ion packs, mechanisms for recharging batteries efficiently are also tested during the race. Most large car manufactures such as Ford, Honda and Toyota are usually well represented. Toyota is one of the major sponsors of the event along with Crowder College.
There are a number of restrictions including vehicle dimensions, daily travelling times (8am-5pm) and that vehicle propulsion may be derived only from direct global solar radiation. Each team must put its car through grueling qualifying and technical inspections before the race and teams that fail to meet the requirements will not participate. During the event, each team is escorted by lead and chase vehicles sporting rooftop hazard flashers, officials said.
According to the rules: Global solar radiation received by the solar car without artificial external augmentation is the only source of energy that can be used for propulsion, except for energy stored in the solar car's battery system at the beginning of the first day of Racing. Wind energy as well as direct and diffuse radiation are considered forms of global solar radiation. With the exception of the effects of wind on the basic shape of the car, all components used to convert global solar radiation for propulsion shall be considered part of the solar array.
In addition solar cars must have amber front indicators, red or amber rear turn indicators and red brake lights which must all be clearly visible from 30 meters in full sunlight. And all cars must have an audible horn because while they may be politically correct cars, the driver may still want to be obnoxious.
The National Oceanic and Atmospheric Administration is also playing a part in the race by offering up its Surface Radiation Network (SURFRAD) for information about solar energy reaching the Earth's surface. NOAA's Earth System Research Laboratory operates seven domestic and nine international SURFRAD stations measuring solar radiation. All sites gather data for long-term climate monitoring and short-term weather forecasts. SURFRAD also collects reflected solar and infrared energy emitted from the Earth and the atmosphere. The entire data package helps NOAA and NASA validate satellite estimates of radiation absorbed at Earth's surface.
NOAA said when the racers approach Sioux Falls, S.D., on July 16, the Michigan team and possibly others, will access online data available from the nearby SURFRAD station to help them generate as much power as possible from the sun.
This year's race is not the first time NOAA data have been used by solar car teams taking a shot at glory. In 2006 the Principia College team used historic SURFRAD data to develop a computer model of solar performance based on geographic location and date. The model helped them estimate the performance of their car's solar array at locations along race routes, NOAA said.
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