Cardinal Wuerl North Catholic High School students prepare to race their gravity-powered cars at the school in Cranberry Township. The event featured three teams, each with a uniquely built car, racing down a designated section of pavement. The race is part of an engineering class assignment.

CRANBERRY — An engineering class at Cardinal Wuerl North Catholic High School has spent the semester designing, constructing and now racing gravity-powered, wooden one-person vehicles downhill.

They raced for the first time Friday.

The event featured three teams, each with a uniquely built car, racing their creations down a designated section on the CWNC pavement. The cars' only propulsion is the pull of gravity or the push of a teammate.

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“This is a true test,” said Dean Petrella, the class's teacher.The teams wheeled their vehicles to the track, each talking shop and strategy, while predicting easy wins against the opposition.The students lined their cars up and Petrella laid down the rules for a fair race: cars must glide unaided down the track once released, and avoid running into other competitors.With that, they were off.Two of the three veered down the track swerving and colliding down the way, earning them each a disqualification. The third, lacking a steering system, ran afoul of the curb and took several minutes to right itself and cross the finish line. Still, it won that heat.“The students are learning a lot,” Petrella said.As students took their places for the second heat, the talk among teams increasingly centered on tweaks to the design and steering as well as reasons opposing teams should be disqualified.The second heat went better as the students made minor adjustments to the cars and the steering down the track, but damage was becoming evident and some collisions occurred halfway to the finish.“We had some unforeseen issues with the front tire because the screws that were holding it in got loose,” said Will Mann, a sophomore on the Red Rocket team. “It went OK.”By the final heat, the teams knew their cars better, with each eventually making its way down the track. No cars were too disabled to compete in all the heats.Students tallied scores and talked about fixes and future improvements to their cars as they wheeled their vehicles back to the school. Some vehicles needed significant repairs.Adam Cruttenden and Seth Benson, both also of team Red Rocket, considered the challenges after the race.“We need more time,” Adam said. “We should've worked on our steering system a little bit more.”“We should've picked bigger wheels,” Seth said. “Our back wheels slowed us down.”With the race done, the class has one last project.“They have to take the cars that they built and they have to motorize them,” Petrella said. “So the next part of the class will be how to use electricity efficiently ... What we really want them to do is to use their brains and figure out the best way to put the batteries together and the best way to tie in the supercapacitors.”While the class involves a lot of physical labor and construction, Petrella explains this is an engineering class, meant to teach complex topics to the students.“This is not a shop class, though some people on the outside looking in may think it is. We're not here to teach them woodworking, craft, but we are here to teach the strength of materials,” he said.“It really makes it about the design and how they think about overcoming friction and the different ways they might visualize that into a plan and implement the plan and build,” Petrella said.The class also gives students a glimpse into the field of engineering as a possible career or focus of study after high school.“When I was looking at electives to take this year, I was thinking about in college what I want to study and beyond that, and engineering is something that's really been appealing to me because my dad is an engineer,” Will said. “I've learned a lot about the geometric measurements of how to build it, how it all fits together. How certain tools can do different things.”Others said while they may not be interested in engineering for a profession, they still thoroughly enjoy the course.“Great class,” Seth said. “Mr. Petrella deserves a raise.”Word of the popular class seems to be spreading. Each year more students enroll, eager to engage.“Every year I'm surprised at the caliber of students that I see coming through this class,” Petrella said.This is the first year the class has had enough students to add a third car, he added.“The students are learning a lot,” Petrella said. “We're always doing interesting things here.