Monday, October 26, 2009

Kurt, Roger, Ryan and David build a trebuchet - and it's a big one!

A few of my friends in St. Paul got together and build a really enormous trebuchet, a type of medieval hurling machine or catapult. I knew that Richard Chin, the great features writer for the St. Paul Pioneer Press would immediately understand the import of such an undertaking. I called him up and told him about it and he got out there. This story appeared in the yesterday's Sunday paper. 

Have trebuchet, will fling
Four friends go medieval and build a 'siege engine' (basically a catapult) because they can
By Richard Chin

"This is kind of chancy. We've never done anything this wide and big," warned Roger Bacon. "OK. Let's do it."
There was a countdown, a whoosh, and suddenly a wheelchair was soaring hundreds of feet in the air, hurtling through the skies above Hugo at an alarming rate of speed.
That's what happens when four 30-something guys decide to build a trebuchet, a siege engine resembling a catapult originally designed in the Middle Ages to pummel castle walls with projectiles.

There are no castles in Hugo, so the builders of this trebuchet are content with seeing how far they can fling a bowling ball. They're at about 700 feet so far. They're hoping to reach 1,000.

They're also testing the flight and crash-landing characteristics of obsolete consumer electronics by launching old television sets, a VCR and a computer. Thanks to the Hugo trebuchet, mankind now knows that a flying microwave oven will bounce about five feet into the air after hitting the ground.

Eventually, the trebuchet team hopes to send a clothes dryer into flight.

Built by Bacon, of White Bear Lake; Kurt Modert, of Hugo; Ryan Krueger, of Maple Grove; and David Proehl, of New Hope; the machine is just the latest and biggest, but not necessarily the craziest, project taken on by the four friends.

"We like destroying stuff," Bacon said.

They used to combine snowmobiles with upholstered furniture, resulting in a La-Z-Boy mounted on an Arctic Cat and a couch that was towed on skis.

They've shot each other with potato cannons loaded with hot dog buns and marshmallows and went golfing with a motorized golf caddy made from an old snowblower.

Then they went through a phase in which they took plastic bags filled with a mixture of creamed corn, elbow macaroni and oatmeal and concealed them under their coats.

They would go to bus stops or the entrances of movie theaters and pretend to feel queasy. While a friend would make helpful comments like, "I told you that shrimp wasn't cooked," they would bend over and spew a stream of pseudo-puke on the sidewalk to the horror and disgust of bystanders.

So when Modert decided in 2008 that his New Year's resolution would be to build a trebuchet, maybe the only thing that surprised his friends was how big it would be.

"I thought it would be a desktop model, you know, something to launch paper balls at the office," said Modert's girlfriend, Sue Ruby, of Minneapolis, who wants the record to show that she met Modert after he was done with street-theater vomiting.

Modert actually planned to build something that would go in the back yard of his mother's 12-acre property in Hugo.

Construction began in the spring of 2008 with the erection of a massive wooden frame capable of supporting an 18-foot throwing arm.

It was built with construction lumber, landscape timbers, recycled aluminum plates and salvaged panels from a garage door.

"It's stuff you can get at any Menards," Bacon said. "Kurt doesn't have much of a life, so he was working on the trebuchet all the time."

The swinging counterweight used to propel the arm was fashioned from an old 265-gallon fuel oil tank they got for free off Craigslist.

They spent a lot of time with calculators trying to figure out what to put into the tank to get the best performance. Water leaked. Navy beans weren't very heavy. Mercury would give more than enough heft, but "it turns out it would be difficult to get a large amount of mercury," Krueger said.

They ended up putting sand in the tank, about 1,300 pounds so far. For more power, they can get it up to 3,750 pounds.

The arm is moved with an electric hoist, and it's released by a trigger mechanism that was fashioned from a device originally used to hold and release a theater curtain rope. That piece of hardware cost less than $5 at an Ax-Man Surplus store.

At one point, Modert's mother asked where they were going to move the trebuchet when they were done.

But the machine, situated only a few yards from the house, is anchored with lengths of pipe driven several feet into the ground.

"This one is permanent. It's too big to move," Modert said.

The builders are not sure how the $2,500 project will affect the home value.

"The tax assessor did come out earlier this year, and we're waiting to see what he says," Bacon said.

Bacon said when asked if any changes had been made to the house, Modert's mother told the assessor, "Well, there's less shed and more trebuchet."

"At every step, it was like 'Let's take it one step bigger than we originally planned,' " Proehl said.

"It kind of got a little carried away," Modert said. "Why do it if you're not going to do it big?"

"Most people who build stuff like giant catapults are doing what they're doing because they're seeking a challenge, the challenge of creating something big and wonderful in a physical, tangible way," said William Gurstelle, a Minneapolis author of books such as "Backyard Ballastics" and "Absinthe & Flamethrowers: Projects and Ruminations on the Art of Living Dangerously."

The original ammunition used by Modert and his friends were defective bowling balls, acquired for free at local bowling alley pro shops. They started arcing over the field behind Modert's boyhood home in August.

"They haven't told you about the mistakes they made," Ruby said.

Once, a bowling ball was tossed about 150 feet in the wrong direction.

"Toward where my car was parked," Ruby said.

The team uses a number of safety measures to make sure no one gets hurt. But when asked if it's dangerous, Bacon said, "Yeah. Well, no. Yeah."

"There's the potential for things to break," Modert said.

During a recent hurling session, a bowling ball was launched almost straight up in the air, sending everyone ducking for cover.

"All right. So let's not do that one again," Krueger said.

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