Team from Polytechnique comes second in big race
École Polytechnique’s vehicle takes second place at competition
A group of students from École Polytechnique harnessed the power of the sun to propel their solarpowered vehicle to a second-place finish at a prestigious competition last month.
Through three days of competition in stifling heat, the engineering school’s Esteban VII vehicle was able to complete 192 laps for 658 miles (1,059 kilometres), with only a team from Iowa State University able to do better at 223 laps.
The Formula Sun Grand Prix competition for solar-powered vehicles built by university engineering students was held in Austin, Texas, from July 29-31 on the Circuit of The Americas, the same site of the Formula One U.S. Grand Prix. The Polytechnique team was also presented with an award for the best teamwork.
After a fourth-place finish last year, the team had set a goal of a third-place finish, so finishing second exceeded expectations.
But they had to overcome hurdles to achieve that goal.
After 35 hours on the road to drive from Montreal to Texas, the team discovered that a tool had fallen on the vehicle, damaging a delicate solar panel that the team scrambled to repair before the competition.
But that wasn’t the biggest hurdle they would face in Texas, said Esteban VII project director Vincent Gariépy, 23.
“The biggest challenge we faced was the high temperatures,” he said. “That was a determining factor because the car that finished first had a temperature limit that was higher than all the other vehicles. That is why they won.”
For Esteban VII, the maximum battery temperature is 45 C, so the team was constantly monitoring the Lithium-ion batteries to make sure they didn’t overheat. When the temperature neared the maximum, the team brought the car in for a rest to cool them down. Had they allowed the batteries to overheat, the car would have shut down, almost like a breaker being tripped, Gariépy said. That would have cost the team valuable time while resetting the car.
“At the end, we were tied with two other cars, but they overheated and because of that they had to stop. But we kept lapping,” he said.
Esteban VII is capable of a top speed of 115 kilometres per hour, but its average speed during the competition was 55 km/h. Its propulsion system uses 1,000 watts, or the equivalent of a toaster.
Since it was completed in 2014, it has been driven for more than 4,500 kilometres, but it will be replaced by Esteban VIII in May 2016.
Esteban VII has 390 solar cells, divided in to 12 panels covering six square metres. The team opted to use solar cells that are ideally suited for diffused light experienced during cloudy days like Thursday, when the car was shown off for several hundred young children who are taking part in the Polytechnique’s science summer camp.
Gariépy says opting for those types of panels, rather than ones made for direct light, was a gamble but one that ultimately paid off since the final day of competition in Texas was overcast.
“When we do rallies, we cross the United States and a variety of climates. We said we would pick panels that are different than anyone else so that if we have the weather we need, we will get ahead,” said Gariépy, who has just graduated in mechanical engineering and spent four years with the team.
A newcomer to the team, which is made up of 45 students, is 20-yearold Viviane Aubin, who was also one of four drivers in Texas.
“Driving the car is relatively simple,” said Aubin, who said the heat was probably the biggest challenge. “The fact you are closed in a cage with two small holes for ventilation … it gets hot in a hurry, and on top of that it’s humid.”
To keep drivers hydrated, there is a CamelBak hydration pack that allows them to drink water.
While there aren’t many creature comforts behind the wheel, Esteban VII does have cruise control and a rear-view camera, things many drivers are familiar with today.
On top of driving Esteban VII, the mechanical engineering student is part of a team already working on Esteban VIII.
“I have worked on the steering for the next Esteban, and I am doing research on components that could help our aerodynamics,” she said.
The vehicle has evolved tremendously since the project began in 1998. One goal for the next generation of the vehicle will be to reduce weight. Esteban VII tips the scales at 290 kilograms, which is already 30 per cent less than Esteban VI. A goal of 250 kg or less is envisioned for the next generation.
The team has an annual budget of $100,000, most of it from sponsors. Each Esteban, which takes two years to design and build, costs roughly $150,000. The remaining funds are spent on travel and competition entry fees.
At the end, we were tied with two other cars, but they overheated and because of that they had to stop. But we kept lapping.