Moving Sculptures

Last May, a strange procession that included a giant crocodile, a UFO, and a towering blue poodle wove its way through the city streets of Baltimore, Maryland. Visitors may have done a double take, but locals were used to the bizarre sight. That’s because the huge moving artworks were part of the annual Baltimore Kinetic Sculpture Race.

Last May, a strange display moved along the city streets of Baltimore, Maryland. It included a giant crocodile, a UFO, and a huge blue poodle. Visitors may have done a double take, but locals were used to the odd sight. That’s because the huge moving artworks were part of the yearly Baltimore Kinetic Sculpture Race.

To compete in the race, teams build sculptures that operate using only human power—no motors allowed. The entrants race their contraptions along a 22.5 kilometer (14 mile) course. And the sculptures don’t just travel over pavement. They also have to cross through mud and sand and float across water to reach the finish line.

This past year, 24 sculptures were entered in the race, including some created by teams from local high schools. Students from Jemicy School in Owings Mills, Maryland, were among them. They’d worked all year to design and build their mechanical masterpiece. On race day, they finally found out whether their rolling artwork was able to go the distance.

To enter the race, teams build sculptures that run on only human power. No motors are allowed. The teams race their sculptures along a 22.5 kilometer (14 mile) course. And they don’t just travel over pavement. They also cross through mud and sand. They even have to float across water to reach the finish line.

This past year, 24 sculptures took part in the race. Teams from local high schools created some of them. Students from Jemicy School in Owings Mills, Maryland, were among them. They’d worked all year to design and build their moving masterpiece. On race day, they finally found out if their rolling artwork could go the distance.

Jemicy students began planning their kinetic sculpture when school started the previous fall. Morgan Metzbower, who’s now a senior at Jemicy, says her team started the project by coming up with a lot of ideas that sounded exciting. That is, until they did more research and realized their original concepts wouldn’t work. “Then we’d go back to the drawing board,” says Morgan. “We had one idea we changed maybe 10 or 12 times.”

When school started the fall before, so did the project. Jemicy students began planning their kinetic sculpture. Morgan Metzbower is now a senior at Jemicy. She says her team started by thinking up a lot of ideas that sounded exciting. But they did more research and found that those ideas wouldn’t work. “Then we’d go back to the drawing board,” says Morgan. “We had one idea we changed maybe 10 or 12 times.”

Team members created a small-scale model of the design they thought would be most successful. When they were satisfied that it would work, they began constructing their real vehicle. The students chose the children’s book series “Where’s Waldo?” as the theme for their artwork. They built a four-wheeled, red-and-white-striped vehicle called Wenda—named for a character in the books. Watching his teammates’ ideas develop into a finished sculpture was the best part of the whole process, says Robby Armacost, also a senior at Jemicy. “For me, it’s just being able to see where we get from where we start.”

The students had many factors to consider during the design process. Race judges award prizes based on sculptures’ art, engineering, speed, and pit crew, among others. The Jemicy team had set their sights on the ACE award, which they could earn by getting through the course without having to push or pull the sculpture.

Team members picked the design they thought would work best. Then they created a small-scale model of it. When they were sure it would work, they began to build their real vehicle. The students needed a theme for their artwork. They chose the children’s book series “Where’s Waldo?” They built a vehicle called Wenda, named for a character in the books. It had four wheels and red and white stripes. Robby Armacost is also a senior at Jemicy. He says the best part was seeing his teammates’ ideas develop into a finished sculpture. “For me, it’s just being able to see where we get from where we start.”

The students had many things to think about as they designed their artwork. Race judges award different prizes for sculptures. Some are for art, engineering, speed, and pit crew. The Jemicy team wanted an ACE award. They could win one by getting through the course without pushing or pulling the sculpture.

Like most of the race’s other kinetic sculptures, Wenda would run on pedal power, like a bicycle does. Bicycle wheels are great for multiplying speed (see Speed Boost). When pedaling, a person applies force to turn the axle at the center of a wheel. The spokes of the wheel work like levers to amplify the force on the wheel’s rim. That causes the outside of the wheel to turn faster. But skinny bicycle wheels can’t withstand the lateral, or sideways, forces that result from turning a corner with a large, four-wheeled vehicle like Wenda.

“When you ride a standard bicycle, you lean into a turn so it doesn’t put really heavy lateral loads on the wheels,” says Steve McHaney. He’s a kinetic racer and civil engineer at GHD, a company in California. “But when you use that same kind of wheel on a four-wheel machine and go around a corner, the wheel can just fold right under you.” To avoid having their wheels “taco,” the Jemicy students chose ones that were wide and sturdy.

Most of the race’s kinetic sculptures run on pedal power, like a bicycle does. That’s how Wenda worked too. Bicycle wheels are great for multiplying speed (see Speed Boost). The axle is at the center of a wheel. When you pedal, you apply force to turn the axle. The spokes of the wheel work like levers. They increase the force on the wheel’s rim. That makes the outside of the wheel turn faster. But skinny bicycle wheels would cause a problem on Wenda. They can’t take the lateral, or sideways, forces that come from turning a corner on a large, four-wheeled vehicle.

“When you ride a standard bicycle, you lean into a turn so it doesn’t put really heavy lateral loads on the wheels,” says Steve McHaney. He’s a kinetic racer and civil engineer at GHD, a company in California. “But when you use that same kind of wheel on a four-wheel machine and go around a corner, the wheel can just fold right under you.” The Jemicy students didn’t want their wheels to “taco.” So they chose ones that were wide and sturdy.

Next, the team needed to find the vehicle’s center of mass. They weighed Wenda on bathroom scales, one under each tire, and calculated the point around which its mass was distributed. Around this spot, they arranged floats called pontoons to help the vehicle cross the water portion of the race. “You have to balance the center of mass of your machine with the center of buoyancy of your flotation system,” says McHaney. Buoyancy is the upward force on an object immersed in a gas or liquid. If Wenda’s pontoons weren’t sized and positioned correctly, the sculpture could end up capsizing (see The Pontoon Effect).

Next, the team needed to find the vehicle’s center of mass. They weighed Wenda on bathroom scales, one under each tire. Then they figured out the point around which its mass was arranged. Around this spot, they placed floats called pontoons. That would help the vehicle cross the water part of the race. “You have to balance the center of mass of your machine with the center of buoyancy of your flotation system,” says McHaney. Buoyancy is the upward force on an object in a gas or liquid. Wenda’s pontoons had to be sized and placed correctly, or the sculpture could tip over (see The Pontoon Effect). 

The team practiced pedaling Wenda through their school’s parking lot, but they had no place to test the flotation system before the race. They could only hope their calculations had been correct. On the day of the competition, the team lined up their vehicle with the other entries. At the start signal, Morgan and three other pilots began pedaling. Robby trailed his teammates as part of the pit crew on a bicycle he’d built himself from scratch.

The team practiced in their school’s parking lot. They pedaled Wenda, but they had no place to test the flotation system before the race. They could only hope they’d figured things out correctly. Race day finally came. The team lined up their vehicle with the others. At the start signal, Morgan and three other pilots began pedaling. Robby was part of the pit crew. He followed his teammates on a bicycle he’d built from scratch.

For about an hour, they followed the course through Baltimore’s streets. When they reached the harbor, they swapped Wenda’s smooth back tires for ones with a deep tread. They oriented the tires so the tread would help push against the water and propel the vehicle forward.

Wenda rolled down the boat ramp and splashed into the harbor. The students made it across without tipping. But the mud pit still awaited them. The group paused to flip the back tires around. That gave them better traction in the mud. The team got through the sludge but still had roughly 8 km (5 mi) more to go. “After you get through all of the obstacles, it’s just uphill,” says Morgan. The exhausted pilots finally crested the last hill and coasted down across the finish line for a successful ACE!

For about an hour, they followed the course through Baltimore’s streets. Then they reached the harbor. They switched Wenda’s smooth back tires for ones with a deep tread. They faced the tires so the tread would help push against the water. That would move the vehicle forward.

Wenda rolled down the boat ramp and splashed into the harbor. The students made it across without tipping. But the mud pit was still ahead. The group stopped to flip the back tires around. That gave them better grip in the mud. The team got through the muck, but they still had about 8 km (5 mi) more to go. “After you get through all of the obstacles, it’s just uphill,” says Morgan. The tired pilots finally made it up the last hill. They coasted down across the finish line for a successful ACE!

The team had the summer to savor their victory. But when school started again, they got busy planning for the next race. Morgan and Robby are building a new, three-person vehicle that will compete this May. They’ll have to wait to find out if their new sculpture also has what it takes to ACE the race.

The team enjoyed their victory over the summer. But when school started again, they got busy planning for the next race. Morgan and Robby are building a new, three-person vehicle. It will compete this May. Will their new sculpture also have what it takes to ACE the race? They’ll have to wait to find out.