Purdue Solar Racing enters new car in Shell 'Eco-marathon'

April 4, 2011

Ted Pesyna, at left, president of Purdue Solar Racing, and Brian Kelley, a junior in computer engineering and member of the solar-car team, show their new vehicle, Celeritas. The car will compete April 14-17 in Houston in the Shell Eco-marathon Americas, an international contest for college and high school students to design and build the most fuel-efficient vehicles. (Purdue University photo/Andrew Hancock)

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WEST LAFAYETTE, Ind. - A team of Purdue University students has designed and built a new solar car that will compete this month in the 2011 Shell Eco-marathon Americas.

The Shell Eco-marathon Americas, April 14-17 in Houston, is an international contest for college and high school students to design and build the most fuel-efficient vehicles.

The Purdue Solar Racing team has won the Eco-marathon's solar-car category the last three years, achieving the equivalent of 4,913 miles per gallon, the most ever recorded at the event. Purdue's team has driven a car called Pulsar since 2008 and unveiled a new car, Celeritas, during an April 1 banquet.

Celeritas will compete in the solar "urban concept" category, which is more difficult than the prototype category Pulsar competed in because vehicles must be designed for practical use on public roads and highways, said Ted Pesyna (pronounced Peseena), president of Purdue Solar Racing.

"It's the team's first four-wheel car in recent years and the first urban concept vehicle," he said. "We've always focused on making vehicles that are optimized for efficiency - very small, slim vehicles that tend to look more like an airfoil than a conventional vehicle. Celeritas is different than any car we have ever designed. Our focus is not only on maximizing efficiency but also usability and aesthetics. It's a vehicle the consumer could see themselves driving."

The single-seat vehicle has a cruising speed of 30-40 mph and a top speed of about 60 mph.

About 50 undergraduate students are working on the project in teams focusing on the car's carbon-fiber body; the propulsion, braking and suspension systems; as well as critical business, marketing and fundraising functions.

"The car will end up costing about $100,000 to design and build, so the team focuses on marketing and relies heavily on the support of our sponsors," said Pesyna, a mechanical engineering senior from Carmel, Ind.

Major project sponsors are Lockheed Martin Corp.; Exelon Nuclear Corp.; Tyco Electronics; Airtech; Purdue's schools of Mechanical Engineering, Aeronautics and Astronautics, Electrical and Computer Engineering and Materials Engineering; Purdue Libraries; and the Office of the Provost. A list of corporate sponsors is available at http://www.purduesolar.org/sponsors/

The solar-car effort provides valuable experience because it is organized like engineering teams in industry, said Galen King, a Purdue professor of mechanical engineering and an adviser to the group.

"It's really invaluable experience for the students," he said. "They design and build the vehicle, see their mistakes and see what they did well. They also work in a multidisciplinary team-oriented structure much like a corporate environment, where communication is important between various parts of the overall team."

The work is entirely voluntary - the students receive no course credits - and contains an outreach component, with project members giving presentations in public schools and at events throughout the state and across the country.

"You have to give the students high praise for this project," said Purdue Provost Timothy D. Sands. "They handle the demands of a rigorous degree program while pursuing an ambitious solar-car project, all in the interests of learning and career goals."

Purdue students have been designing and building solar cars since 1991 and have completed eight vehicles since then.

Work on Celeritas began about two years ago. The car weighs about 275 pounds, is made primarily of a lightweight material of carbon-fiber sheets sandwiched around a honeycomb center to add strength. More than 200 photovoltaic cells convert sunlight into electricity to charge 48 lithium iron phosphate batteries, which then power a motor that drives one of the rear wheels.

The car's electrical systems are among the most innovative aspect of the vehicle, said Brian Thompson, vice president of Purdue Solar Racing.

"The electronics in this car are drastically different than any other car we've built," said Thompson, a mechanical engineering junior from Evansville, Ind., with a minor in electrical engineering. "It's the first car we've designed to be computer controlled."

The vehicle has an ultra-efficient electric motor and high-level computer logic embedded in many components. This electronic intelligence makes it possible for the driver to change cruise control and other settings on the fly to maximize performance. A battery management and protection system ensures that the lithium iron phosphate cells operate properly and don't overheat or explode, and logic circuits relay diagnostic data to a laptop computer monitored remotely by the team, Thompson said.

About 80 teams will compete in the solar-car race, coming from universities and high schools in the United States, Canada, Mexico and Brazil. Because the Shell Eco-marathon Americas is held in Houston, the design must take the urban landscape into consideration, Pesyna said.

"There are a lot of skyscrapers, which cast shadows, so we created models of where the shadows are at certain times of day around downtown Houston."

The car's design was tested in a wind tunnel.

"Tests verified our computer results showing we had a pretty low drag coefficient," Pesyna said. "This is difficult to do because maximizing the number of solar cells compromises the aerodynamics of the vehicle, so you have to properly balance the two."

Pulsar was a three-wheel vehicle designed to achieve the most efficiency at the expense of practicality. The driver sat in a reclined position a few inches from the road surface. The car weighed about 170 pounds and had a top speed of 25 mph. The four-wheel Celeritas, Latin for swiftness, is designed more like an ordinary car, with the driver sitting upright. The car, which was designed and built from scratch, has only a driver's seat.

Also leading the Purdue solar-car project are Rachel Bodien, secretary and a sophomore in aeronautical engineering; Zack Lapetina, treasurer and sophomore in aeronautical engineering; Sam Schreiber, marketing director and a junior in computer graphics technology; Justin Krull, aeronautics team director and a junior in aeronautical engineering, Zach Smith, electrical team director and a junior in electrical engineering; Bradley Weiler, mechanical team director and a junior in mechanical engineering; John Padgett, safety director and a junior in mechanical engineering; and Kenneth Roush, special projects director and a sophomore in aeronautical engineering.

John Nyenhuis, a professor of electrical and computer engineering, also is an adviser.

Writer:  Emil Venere, 765-494-4709, venere@purdue.edu   

Sources:   Galen King, 765-494-6518, kinggb@purdue.edu

                    Ted Pesyna, 317-217-9172, president@purduesolar.org

                    Timothy D. Sands, 765-494-9709, tsands@purdue.edu

                    Brian Thompson, 812-455-5843, brian.thompson@purduesolar.org

Note to Journalists: Broadcast-quality video of the Purdue solar car unveiling is available for download and use at ftp://news69.uns.purdue.edu/Public/SolarCarUnveil/

For more information, contact Jim Schenke, Purdue broadcast media relations, 765-237-7296, jschenke@purdue.edu