Students learn to "fly" with hovercraft experiment

Gann Academy Freshman Jacob Rich "flies" around the gym on a hovercraft he made with seven other students.

By Kathryn Eident
Globe Correspondent

Waltham—Gann Academy freshman Jacob Rich had a serious look on his face as he gingerly sat on a chair attached to a large, plywood platform. The odd-looking contraption had plastic PVC pipes jutting off the side with wires running to battery boxes, switches, and a small vacuum cleaner engine.

With his teacher standing nearby in case something should go wrong, Rich leaned down, flipped a switch and sat back. The vacuum cleaner engine whined as the plywood structure shuddered, then lifted slightly off the ground. A cheer went up from the students gathered in the gym. “Hooray! It worked! He’s hovering!”

Rich and seven of his peers spent the week building this machine, a hovercraft that could lift a human off the ground, in the hopes that he and his fellow students could “fly” around the school gym as the reward for their hard work.

“At first I though I’d be scared, but I wasn’t,” Rich said, after his “flight” around the gym. “It felt kind of like you were floating on nothing, kind of like skating without friction.”

The students built the hovercraft as part of a school-wide “Exploratory University,” an annual week of hands-on seminars to enhance the students’ academic studies at the small, private, Waltham-based Jewish high school. In lieu of classes, students can travel the South to learn about the Civil Rights movement, work with children in area elementary schools for community service, or build elaborate science projects like hovercraft.

“We sort of pride ourselves on an intense, rigorous academic experience both in secular education and Judaics,” said Efraim Yudewitz, associate director of admissions for the Academy. “And we have a large and comprehensive experiential education program that focuses on character building, social dynamics and world wide citizenship.”

For the eight students who chose to build two hovercraft, the experience would challenge them to use their knowledge of physics to get the job done.

“A lot of you guys may have misconceptions about hovercraft based on the name,” Sophomore Joe Haber told the students gathered to watch the experiment. “It doesn’t actually fly. It lifts a few millimeters off the ground.”

The hovercraft can float, he said, because fans blow air through a vinyl skirt attached to the bottom of the plywood platform, lifting the structure slightly off the ground. Other fans, attached to the top of the platform in PVC tubes, provide the thrust, or the force that enables the hovercraft to move around once it’s off the ground.

“Theoretically, if we had a bigger cushion and much bigger engines, it could float on water like military hovercraft,” he said.

Their homemade hovercraft weigh more than 100 pounds, and can hold a person weighing up to 240 pounds. The hovercraft can go as fast as 20 miles per hour, as well, said Emmanuel Polizzi, a physics teacher and the hovercraft project adviser.

The students’ hovercraft wouldn’t go that fast in this round of experiments though, as they kept getting stuck on the gym’s wooden floor. But the students would not let this dampen their spirits, and enthusiastically tried to trouble-shoot the problem. Some students suggested the floor’s unevenness was causing the machines to drag along the floor.

Physics teacher Emmanuel Polizzi trouble shoots the problem with his students.

“The floor is shaped like a bowl,” Haber said. “The hovercraft are moving by the shape of the floor and they’re tilting in.”

Luckily, moving the experiment to another gym did the trick, and soon the students were careening around in large circles, tethered by a rope to an anchor in the center of the room.

“We learned that there’s always something that can go wrong,” Junior Ben Bernays said.

“Yeah, that’s called ‘Murphy’s Law,’” Polizzi said, watching the students running around the gym, pushing the hovercraft and adjusting the rope-tether.

This type of hands-on trial and error is exactly what the staff and faculty at the Academy hoped would happen during this year’s exploration week, said Yudewitz.

“It’s like really being in a candy shop; these kids really get to taste really whatever they want, and get to pursue all of their passions,” he said. “They’re not limited.”

One of two hovercraft the students made during "Exploration University" week.