RSO shows practical applications of math, physics to learn how to build hover crafts Edmund Meinhardt

Factoid:For more information, see the Hover Club’s Web site at www.howard.engr.siu.edu/tech/hover.

With some common materials and tools, SIUC students are creating hovercrafts that win competitions and captivate prospective students.

The SIUC Hover Club is a registered student organization that designs, builds, demonstrates and competes with hovercrafts, which are amphibious vehicles that ride on a cushion of air.

Bruce Chrisman, coordinator of undergraduate recruitment and retention for the College of Engineering, said hovercraft design is an effective way to demonstrate the practical application of math and physics to high school students.

“It’s a great project, particularly with high schools,” Chrisman said. “Students can see tangible results, not just theoretical. We want to see how math and physics are applied – that’s why we’re engineers and not mathematicians or physicists.”

Some of the vehicles built by the club are powered with a 10-horsepower lawnmower engine turning a fan that creates the air cushion and provides thrust to produce horizontal motion.

One vehicle, which is currently under construction, uses separate motors for lift and thrust.

The full-scale hovercrafts, bearing decals designed by club members, are five feet by 10 feet and can reach speeds of 32 mph.

Aaron Wall, a senior at John Ehret High School in New Orleans, looked at the hovercrafts built by the club on a recent tour of the campus.

“It’s impressive,” Wall said. “All that speed from a lawnmower engine.”

David Allabastro, staff adviser for the Hover Club, said the body of one of the prototypes was built with two-by-fours, plywood, Styrofoam, glass and epoxy.

“This is a show-and-tell model that we take to schools,” Allabastro said.

At high schools, Allabastro enjoys showing the students how math and physics are applied to the design of the vehicles.

“We take a machine to a school, and we can compute size and design with math products,” Allabastro said. “We can talk about physics-Newton’s Laws.”

Students respond enthusiastically to these subjects when they can see immediately how they are applied to designing and operating the vehicles, Allabastro said.

Fully functional and radio-controlled, the three-foot prototype also serves as a one-third-scale model for the larger manned vehicles built by the club.

Designed for a pilot with a weight of about 125 pounds, the full-scale hovercrafts are mostly piloted by high school students.

One of the full-scale vehicles is called Phoenix, named for a great bird born from the ashes of its former self.

“It was donated to the school. We literally picked it up in a bucket,” Allabastro said.

The Hover Club used Phoenix as a rebuild project.

In addition to traveling to area high schools, Allabastro organizes a hovercraft event with the Women’s Introduction to Engineering program in which high school students assemble and race miniature battery-operated hovercraft.

Allabastro said hovercrafts present a unique set of handling and steering challenges to new pilots, who sometimes have to learn to disregard their automobile driving skills.

“A hovercraft steers like a motorcycle on ice,” Allabastro said. “The best pilots we have are women who have never driven before.”

Allabastro added that the pilot must sometimes shift his body weight to effect a turn, otherwise the hovercraft may simply continue in a straight line while rotating. Fortunately, a hovercraft has a very low center of gravity that makes it very hard to turn over.

A single-engine hovercraft uses a “splitter,” which directs a portion of the propeller’s airflow to a chamber underneath the vehicle. A rubber skirt, wrapped around the chamber and inflated by the airflow, makes sure the air escapes from the chamber at a controlled rate, which creates the cushion.

The remaining airflow is used to provide thrust, and the vehicle is steered using rudders controlled by a joystick.

There is evidence that the design for air cushion vehicles appeared as early as 1716, when Emmanuel Swedenborg recorded a design for an air-cushion platform that resembled a boat turned upside-down.

Sir Christopher Cockerell, a British radio engineer, is credited with coining the term “hovercraft” and with kicking off the serious practical development of air-cushion vehicles.

Two of the world’s largest hovercrafts, the Princess Anne and the Princess Margaret, ferried vehicles and passengers across the English Channel for thirty years and were retired in 2000 when the Channel Tunnel, or “Chunnel,” was opened.

The SIUC Hover Club plans to sponsor an event for high school students in the fall, where they will be invited to learn about and try piloting the vehicles.