WENATCHEE — Wenatchee Valley College physics students will be hurling tennis balls from their ancient artillery Friday during the school’s almost-annual catapult-building contest.

Initiated a decade ago by now-retired history teacher Celia Hall-Thur, the contest combines knowledge of ancient artillery with creative engineering. The competition pitted history and physics students in the past. The history department didn’t get involved in the challenge this year, so contestants will likely be only from the school’s two physics classes, said WVC physics instructor Bruce Unger. The contest wasn’t held last year.

“It’s always been open to all departments, but it’s predominantly history and physics classes that have been involved,” he said. Building a catapult and taking part in the contest is one of several options his 37 students can choose as a class project. He doesn’t know how many catapults will show up at Friday’s competition, but guesses between seven and 15. There can be either one or two students to a team. The students have had eight weeks to complete their project outside of class.

Brian Bird, 26, said he’s been working the last three weeks to build his throwing machine. The challenge, he said, is that it has to be made true to historical materials. No metal or man-made materials can be used. Only wood, natural fibers and stones can be used in construction. The catapult has be mobile, but wheels, if they’re used, must be made from wood. Catapults were used from about 400 B.C. to medieval times, when they were gradually replaced as heavy artillery by cannons.

Students can make their machines using an original design, or by replicating one of several historic catapult designs, Unger said. Tennis balls will be used as ammunition for the sake of safety. The competition will be judged on originality of design or historical accuracy, as well as how well they shoot, in terms of distance and target accuracy, he said.

“A lot of my students are on their way to being engineers,” Unger said. “This gets them to go through the process of designing something that has to function.”

Students who take the project on also have to submit a paper that describes their machine in terms of physics functions of energy, force and torsion, he said.

Rick Steigmeyer: 664-7151

steigmeyer@wenatcheeworld.com