Students' T-shirt-shooting cannon gives blast

Sunday, January 12, 2003

With his weapon of choice strapped to his chest, Todd Marchi scans for his target, aims his homemade cannon and fires. The double-chambered, metallic contraption blasts its ammunition -- whoomp! -- which soars through the air hitting its mark 100 yards away.

His target: the highest row of seats in the Show Me Center.

His ammunition: a rolled-up T-shirt.

Blasting free T-shirts into frenzied crowds has become a popular gimmick at sporting events across the country. But Marchi and Mitch Harpster do it with ingenuity and pizzazz -- with the help of the powerful air cannon they helped create.

The Southeast Missouri State University mechanical engineering students designed their T-shirt cannon along with other students in the Society of Manufacturing Engineers. Marchi came up with the idea and pitched it to the group at the beginning of last semester.

"It started with knowing that fans always like to take home free stuff," Marchi said. "The cheerleaders would throw the T-shirts, but people in the back rows never got anything. So we thought this would be a fun way to deal with that."

Marchi, 23, is the president of the university club and Harpster, 20, is the vice president. They started with a standard T-shirt cannon -- there are similar devices at universities everywhere -- and came up with their own design.

Along with about 10 other engineering students, they drew out several ideas, then opted for something basic: a two-chambered cannon basically made of 3-inch pipes. The two chambers would hold pressurized air that could be released with a nozzle and project the T-shirts out of a third pipe.

"We wanted it to look like a cannon," Marchi said. "We wanted it to look like something Rambo would use."

Over a total of roughly 100 hours, they built the cannon through trial and error -- but there is one error that still stands out. While testing an early design, they shot the T-shirt at the floor, and it ricocheted and ended up busting through a section of drywall. At another practice session, they shot it the entire length of a football field.

"It's got some juice," Harpster said.

Once they were finished, they were pleased with the design, and so was their faculty adviser, Craig Downing, an engineering professor.

"I thought it was a great idea," Downing said. "It's a standard design, but getting the right materials and actually making this work was the challenge. In the end, it looked great and had good functionality and appearance. It's a powerful piece of machinery."

It projects the T-shirts quickly, and they could shoot them out with the pressure of 120 PSI, or pounds per square inch. But Marchi and Harpster say they usually takes about 60 PSI to reach the farthest point they need to reach. They determine distance by how much air pressure they put in the tank.

First-place honors

The cannon was so well designed that it took first place at a chapter conference of the Society of Manufacturing Engineers. That was flattering, but the real test was yet to come: actually using the cannon at a home game, which they did in early January when the basketball Indians took on Southwest Missouri State.

"We brought it out, and people were like 'Wow,'" Harpster said. "At first they looked a little nervous. But when we were through, people were going crazy."

They've used it at each of the most recent home basketball games. The students say it can be used at any sporting event. They are working on updating their design and working out a few small bugs -- making it only have one chamber, for example. Marchi and Harpster said they are even talking about putting advertising on the cannon that the university can sell.

"We think it has some potential," Marchi said. "People really get into it, and it's fun."

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