Just steps from the beach you can launch yourself into a spiralling scream-fest. This is not just a coaster, it’s a double-twisting impulse coaster – one of the tallest and fastest in the world. You’ll be rocked, rolled and launched into two 450° spirals at each end of the tracks. You will be twisted – wickedly. This is the Wicked Twister at Cedar Fair in Sandusky, Ohio, which operates using state-of-the-art linear induction motors (LIMs) to propel riders up to a speed of 115 km/h. Motion Control’s editor, Kim Roberts, spoke to Monty Jasper, corporate vice president for safety and engineering, about the engineering behind the Wicked Twister and its counterpart, the Maverick.
Designed by Intamin, the Wicked Twister consists of two 66 metre tall spikes with 450 degree vertical twists. Between the towers, a horizontal track section incorporates the load and unload area as well as the LIM propulsion system.
Unlike most roller coasters the LIM launches horizontally and thrill seekers are treated to a powerful combination of five launches out of the station, three forwards and twice backwards, while reaching the apex of each vertical tower as it picks up velocity up to 115 km/h from the LIM propulsion system.
Jasper explains that each LIM is like the armature in a normal motor, with wire wrapped around a coil. These are positioned in pairs with a gap of 10 mm between the two blocks. “We pass a 3 mm aluminium fin between them,” he says. “Putting power through the coils results in a magnetic field on either side. Running the fin through them makes the fin want to jump out, thus propelling the train. The fin is on the top of the track and the train is hung from the bottom of the track with people’s legs dangling – there are no floors – while on top, the roller coaster is hanging from its wheels with the aluminium fins passing between the LIMs, which run from the station all down the track. They are powered in sequence and push the train down the track.
“It’s an eerie feeling,” says Jasper, “There is no mechanical contact yet you can feel the force of the magnetic field.” He adds that Cedar Point chose LIMs for Wicked Twister because horizontal launch options are limited and this electrical option is extremely innovative. However, LIMs come with some unique requirements and Cedar Point had to install a dedicated 34 000 V power line to power the coaster. “We’re using such a massive jolt of electricity to operate Wicked Twister that it would be enough to power 550 average-sized homes,” he says.
On the other side of the park is the Maverick, which operates with linear synchronous motors (LSMs). Maverick definitely delivers thrills. It has two cars which go out of the station up a shaft – there is no lift chain. The first hill is set at a 95° angle – that’s 5° past vertical – meaning you feel like you’re going to nosedive off the tracks. It twists and turns, switching back on itself in the first ever twisted horseshoe roll. Just when you think the ride’s over, Maverick hits 112 km/h in three seconds.
Here there is no aluminium fin, instead an energised magnet passes between the coils of two magnets on each side and the repulsion propels the train forward. There are hundreds of these magnetic fields along the track and they are energised as the train approaches and turned off as it passes.
A big advantage of using LIMs and LSMs is that maintenance is reduced. “There are no metal-to-metal contacts, no wear points, no chain moving around, no lubrication, no worn out pieces and parts, because nothing is touching,” Jasper says. “The only things touching are the wheels on the track.”
One difference between the two is that the LIMS are all air cooled, you can hear the fans blowing, while the Maverick is cooled with glycol. “It’s stealthy quiet,” Jasper said. “It’s awe-inspiring to stand there and not hear a sound as it goes up the lift. It’s almost ghostly.” There are also differences in torque and speed. The LIMS is designed for fast lift-off to reach maximum velocity quickly while the LSM allows you to get the height with more power. “This is a great ride experience,“ concludes Jasper. “It feels like flying and it’s very cool.”
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