In this Build Week activity, shear forces and failures helped us understand the physics behind hovercraft design.  

 

For our February build week, we encouraged students to propose project ideas. On the request of some students and inspired by discussion with others during the commute to school, we decided to build a hoverboard.

Building a hoverboard at school is a daunting task! There are lots of models out there already. We knew we weren’t going to compete with Hendo or adopt a design where the magnetic force would provide the required lift—the students discovered that would require a special track and embarrassing volumes of liquid nitrogen, or we would have to pave the Maker Studio floor with copper.

Instead we relied on the humble leaf blower, some plywood, and a plastic sheet; our secret weapons were duct tape and a heavy-duty stapler. I cut plywood into a four-foot-wide octagon with a hole cut out for a handle. Proofniks descended on it with sandpaper of ever finer grits, smoothing it to a glass-like finish. True to the spirit of reuse and recycle, our sanding blocks were fashioned from Kathy’s children’s hand-me-down wooden blocks!

Once the plywood base was smooth, the students cut out a 6’ square sheet of plastic, then use our stapler and Gorilla tape to make it airtight. Then came the delicate process of cutting quarter-sized holes so the air could escape through the bottom of the hoverboard when the leaf blower nozzle was inserted on the rider side of the board. Upon completion, the first hoverboard adventurers took to the seat—the hardwood floors of the Maker Studio!

Our pioneering navigators wanted to push the envelope and cranked up the leaf blower, and to their dismay, the central part of the plastic cover got ripped from its moorings. This led to a wonderful discussion about design, repair, and shear forces, and students were able to bring back the maimed ship to shore and ride it again. The second group learned from the first and made interesting design tweaks, and their ventures brought up new and interesting questions about the actual mechanism behind hovering. If the Bernoulli brothers had seen us, they would have been proud.

--Kaushik Basu