June 27, 2005
On Sunday, July 17th, a small group of engineering students will leave Austin racing a solar car they designed and built themselves in the longest solar race in the world. It will be a grueling 2,500 mile-long, 10-day trek from Austin to Calgary, Alberta following U.S. Route 75 and the Trans-Canada Highway.
Nine student drivers will switch off every 3 hours. Even though the University of Texas Solar Vehicle Team entry, the Solar Steer, has a steering wheel and pedals like an ordinary car and drivers will obey all traffic laws, it is a quite different driving experience. For starters, the driver is almost lying down, close to horizontal. The seat has padding, but it is minimal and the suspension is stiff, like a sports car. The car is very close to the ground and uses thin, high pressure tires for maximum efficiency.
The body is a composite of carbon fiber and protective shell laminates, over an aluminum frame. This allows for a rigid yet very lightweight structure. The team began by building a full scale model of the car’s body from dense foam. This was used to create a mold. Fiberglass and carbon are epoxied together in the mold and allowed to cure. Then aluminum ribs and a roll cage are added to protect the driver.
Most of the surface of the car is covered by over 600 photovoltaic (solar) cells. The solar cells are arranged into modules (50 total) and then in 3 independent subarrays. The solar array produces about 1200 watts in full sunshine allowing it to cruise at about 45 miles an hour. Extra electricity is stored in large lithium batteries. When it is cloudy, the car runs off the batteries. If it stays cloudy too long, more than a few hours, the batteries will be depleted and the car must stop until the sun comes out again.
Solar car races are timed events, and the team with the lowest elapsed time for the entire multi-day event is declared the winner. Each day’s race is staged, with the cars leaving at preset intervals from a starting point. The goal is to travel a certain segment of the race that day, in the shortest possible time.
Faculty advisor, Dr. Gary Hallock, says that while battery capacity and aerodynamics are extremely important, “the real key to winning is reliability. If nothing breaks, a team will probably do well (as they pass the faster team on the side of the road fixing things!).”
The University of Texas Solar Vehicle Team’s members are comprised of various undergraduate engineering majors, including three aerospace engineering students: Andrew Cave, Thomas Deconinck, and Tom Schipper. The team has been working on the solar car for about a year and a half. “This is a tremendous project,” says Professor Hallock “full of complexities, challenges, deadlines, and teamwork. There are three main subsystems: mechanical, electrical, and body.
The Department of Aerospace Engineering and Engineering Mechanics is a Platinum Sponsor for the UT Solar Vehicles Team.
