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An Article from the May 2002 JOM: A Hypertext-Enhanced Article

The author of this article is managing editor of JOM.
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Figure 1

Figure 1. The X, which debuted in January at Six Flags Magic Mountain near Los Angeles, California, adds a new twist to an old ride with seats that rotate 360 degrees. Photo by Six Flags Magic Mountain.
Figure 2

Figure 2. Steel Dragon, opened in Nagashima Spaland in Kuwana County, Japan in 2000. Photo by Joel Rogers
at www.CoasterGallery.com.

Figure 3

Figure 3. The Millennium Force, which opened in 2000 at Cedar Point in Sandusky, Ohio, has a descent angle of 80 degrees, a height of 94 meters and top speed of 148 km/h. When the ride opened, it was the tallest and fastest in the world. Photo by Cedar Point.
Figure 4a

Figure 4b

Figure 4. (a-top) Magnetic brakes installed in spring 2002 on the Jack Rabbit at Kennywood Park near Pittsburgh, Pennsylvania, replaced 80 year old manual brakes. Brakes are the rails in the center of the photo. (b-bottom) Magnetic brakes also were installed in Kennywood’s newest coaster, the Phantom’s Revenge, to ensure safe stopping of the high-speed ride. Photos by Magnetar Technologies Corporation.
Figure 5

Figure 5. The Wicked Twister, under construction at Cedar Point in Sandusky, Ohio, will use a linear induction motor to launch riders up a 90 degree twisting tower. Photo by Cedar Point.
Overview: Feature

Materials Give Roller Coaster Enthusiasts a Reason to Scream

Maureen Byko

INTRODUCTION

What are amusement parks hoping for in 2002? Mostly, to fulfill the demands of their thrill-seeking visitors for anything that’s bigger, better, and faster than in 2001.

Thanks to new technology and materials, the parks and their visitors will get their wish:

  • With linear induction motors, roller coasters will be launched like rockets, accelerating from 0 to 113 km/h in less than 4 seconds.
  • With urethane wheels, those same roller coasters will glide over steel tracks faster than ever, racing at speeds higher than 161 km/h.
  • Using sensors, the speed of the coasters will be continually monitored and automatically reduced if a ride surpasses its limit.
  • Using magnets, brakes will be applied automatically, leaving little opportunity for human error.
  • With finite element analysis, the structure of a ride will be tested thoroughly to ensure safety before passengers climb aboard
Just as they have for the last 100 years, amusement parks are relying on a combination of technology and imagination to give riders a new reason to scream.

“The big parks that we cater to, they always want what they call world-class rides—bigger, faster, something completely new,” said Wayne Nielson, sales manager for Arrow Dynamics, a Utah amusement ride manufacturer and pioneer in roller coaster materials and technology. “That’s what sells the next roller coaster. The one that captures the imagination.”

The need for controlled speed is nothing new—people began coasting down wooden tracks in steel-wheeled cars nearly 200 years ago, when roller coasters began to appear in public gardens in France. In the United States, the leisure activity had low-tech origins, on a railway built to roll coal down from a Pennsylvania mountaintop. When the coal mine switched to steam railroad transportation, the Summit Hill-Mauch Chunk railroad became a tourist attraction, as visitors paid to coast down
the track.

After a few enterprising businessmen found ways to mimic that ride in amusement parks in the mid-1800s, a technological race began that has not ended yet. In the early 1900s, parks competed to own the biggest, fastest, most innovative roller coaster. Today, the race continues, and Alan Schilke is a participant. An engineer for Arrow Dynamics, he designed the X, a roller coaster that opened to much acclaim in January at Six Flags Magic Mountain (Figure 1). The ride, which is the 15th roller coaster at Six Flags Magic Mountain, places passengers in cars that are mounted alongside the track, able to swivel and spin 360 degrees along the track’s climbs and drops. Just as the market demands, the X is bigger, faster, and something completely new. But, when taken in context of the thrill-ride history, this competition for the next new roller coaster experience is unremarkable to Schilke.

“Actually, I don’t look at what’s going on now as something that’s special,” Schilke said. “I would look at what happened between the ‘30s and the ‘70s as more of just a lull, because, with roller coasters back at the turn of the century and in the ‘20s, they had a race then. Basically, it fell apart with the Depression and the wars. If that wouldn’t have happened I think we’d be way beyond where we are now. I see what’s happening now as more natural, and even still, slow.”

MEETING EXTREME DEMANDS

As of February, the tallest coaster in the world was Superman The Escape, at Six Flags Magic Mountain, with a height of 126 meters. The fastest was Dodona, at Fujikyu Highland, with a top speed of 172 km/h. Although this business and its rankings change rapidly, one fact remains the same: the demands placed on amusement ride materials are escalating. Perhaps it’s no coincidence, then, that more tools than ever are available to ensure rides are safely built and maintained.

Trevor Hite, general manager of the California office of Chance Morgan, said computer programs are able to tell whether rides will be safe before they are ever constructed. “We’ve made modifications in all our programs to be able to better analyze not only the effects on the structure and the human body, but the excitement of the rides, the aesthetics and thrill,” he said.

Of course, that was not always the case. In the early days of roller coasters, imagination outpaced technology. For instance, roller coasters were built in the early 1900s with looped tracks to send riders racing upside down. But few riders were willing to take advantage of the tracks, which were reported to offer such a rough ride that the thrill was not worth the pain.

Now, computer programs can predict the riders’ experience, Hite said. For instance, when D.H. Morgan Manufacturing (which was bought in 2001 by Mike Chance) built the Steel Dragon 2000 in Nagashima Spaland in Kuwana County, Japan, it was the longest, fastest, and tallest roller coaster in that country (Figure 2). Before the ride opened to the public, computerized accelerometer testing and biodynamic testing provided details on the effects on riders, Hite said. In addition, technology ensured the coaster was built to provide a smooth ride.

“With computer-aided design, we can do more calculations. You can get an infinite number of calculations,” Hite said. “In the past, you used to do a calculation every 5 or 10 feet. Now you can do every inch, every foot, whatever it takes.”

“We ride the ride before it’s biodynamically tested,” he said. “We know that it’s safe.”

Roller coaster development advanced greatly some 10 years ago, he said, when finite-element analysis programs and velocity programs became integrated to provide a more complete picture of how a ride will operate. The programs provide velocities and also forces on the members that support the coaster.

“The addition of more complete finite-element analysis and modeling has made it easier to dial in your material sizing and joint connections . . .you can dial things in tighter,” Hite said. That kind of precision allows rides to be built with structural integrity that was not possible in the past.

THE QUEST FOR SPEED AND SAFETY

For all the changes in roller coaster size and intensity, there have been surprisingly few major advances in the materials and technology involved in their construction. One most significant development came in 1912 when roller coaster designer and builder John Miller was issued a patent for under friction wheels. Those wheels, the third set on a roller coaster, locked the cars to the underside of the track even as it rounded sharp bends or plummeted down steep hills, opening the door to new generation of more thrilling roller coasters that could fill customers’ needs for bigger, better, and faster rides. Another of Miller’s inventions was the safety chain dog, which prevents the roller coaster cars from rolling backward if the lift chain breaks. Such innovations allowed roller coasters in the 1920s to reach speeds of 96 km/h and heights of 30 meters.

For decades, the coaster competition played out on wooden tracks with steel rails. The roller coaster experience changed dramatically, though, in 1959, when Arrow Dynamics built the Matterhorn for Disneyland in Anaheim, California. That ride was the first to run on a tubular, all-steel track. The cylindrical track allowed a new kind of twisting, turning, yet smooth ride that was previously impossible. At first steel wheels ran on the steel tracks, but wheels are now coated with a urethane compound that wear longer, reduce friction, and make even higher speeds possible, Hite said.

“The cost (of wheels) has gone way up, but the complexity and durability of the product has gone way up, too,” he said. Durability is especially important because when wheels need to be replaced, a ride cannot run. And if a ride is not running, a park is not profiting.

Wheels, which may be among the least exciting components of a new roller coaster, are among the most responsible for its speed, Hite said.

At the Uremet Corporation, founder Mark Moore has found a niche in the roller coaster arms race, not only selling new wheels, but also refurbishing old wheels in the off-season, stripping off old urethane and applying a new coating. Uremet, which also provides materials for aerospace uses (an industry with similar performance requirements), has helped push roller coasters to higher speeds. “There have been some great changes in the urethane compound itself to allow for higher speeds on the coasters,” Moore said. The new product, Hylene PPDI, was developed by DuPont. The product, which has been used on roller coaster wheels for about five years, lowered the hysteretic value of the material and increased abrasion resistance, Moore said. For roller coaster enthusiasts, those characteristics translate to a smoother, faster ride.

LAUNCHING A NEW ERA IN ROLLER COASTERS

The evolution of roller coaster materials and technology can be witnessed at Cedar Point, in Sandusky, Ohio. The sprawling park, which was voted the Best Theme Park in a 2001 survey by the trade magazine Amusement Today, will open this month with 15 roller coasters. Its offerings include wooden coasters, such as the Blue Streak, dating back to 1964, and steel giants such as the Millennium Force, which opened in 2000 at 94 meters high with a maximum speed of 150 km/h. The Millennium Force, built for $25 million, was the 2001 Amusement Today winner in the Best Steel Coaster category (Figure 3).

Behind the hype and records at the park is Monty Jasper, vice president of maintenance. Jasper oversees a staff that works round the clock to make sure all rides are in top condition. Among its responsibilities, the crew is in charge of maintaining 13.4 km of steel and wood track. Using nondestructive testing methods, they examine the rails regularly, looking for parts that need to be replaced.

“I don’t think the steel rides 20–25 years ago got nearly as much inspection as they do today,” he said.

Jasper, with a master’s degree in mechanical engineering, said he has watched the amusement industry evolve dramatically since he began work in this business as a ride operator in 1973. “From a materials standpoint, there are lighter, less expensive, stronger steels today than there were years ago,” Jasper said. Some of the newest magnetic braking systems on roller coasters are equipped with aluminum alloy brake fins.

The braking systems themselves offer a safer, smoother ride experience. As recently as the 1970s, all roller coasters were built with mechanical brakes that needed to be manually adjusted and that could malfunction in bad weather. “If it rained that day they wouldn’t run a ride,” Jasper said.

The newest magnetic braking systems offer numerous benefits over the old, mechanical brakes: They have no moving parts, require no control system, have no contact surfaces, and thus, no wear and tear resulting from friction, according to Magnetar Technologies Corporation, which markets Soft Stop Brakes to roller coaster manufacturers. The brakes operate with a copper alloy fin (chosen for its strength over aluminum alloys) mounted on the roller coaster. The fin travels between two parallel rows of high-strength magnets. As the train rolls through the magnets, they bring it to a smooth, gradual stop. The magnetic brakes can be placed at points along a roller coaster track to slow the train down as needed.

The result, said Ed Pribonic, president of the company, is a passive system that can operate in any weather, even if ice or grease is on the track or fin. Magnetar has just installed the brakes on two roller coasters in Kennywood Park in Pittsburgh, Pennsylvania. One set went onto the Phantom’s Revenge, a steel coaster that opened in 2001 to replace the 1991 Steel Phantom, and the other onto the Jack Rabbit, a wooden coaster designed by John Miller, dating back to 1922 (Figures 4a and 4b). Until now, the Jack Rabbit operated with its original skid brakes, Pribonic said. Skid brakes involve two long blocks of wood built into the floor of the station. When the ride operator pulls a lever, the blocks are raised, sliding over plates of steel along the bottom of the car and dragging it to a stop.

Pribonic, who grew up in the Pittsburgh area riding Kennywood’s coasters every summer, said the new magnetic brakes will allow the Jack Rabbit to coast, rather than lurch, to a stop. On the Phantom’s Revenge, the revamped ride was running faster than the park owners expected, he said, so the magnetic brakes were installed to ensure that the incoming train would not approach the outgoing train.

Magnets are also being used on new thrill rides as a launch system. Using a linear induction motor, Cedar Point’s new Wicked Twister will propel riders through the coaster’s station at a maximum speed of 116 km/h in 2.5 seconds (Figure 5). The launch system, which is growing more popular in thrill rides and roller coasters, replaces the traditional lift chain that pulls roller coaster cars up a hill and releases them, allowing gravity to provide the energy necessary for the coaster to complete the track circuit. The Wicked Twister, which opens this month, will send its passengers up a 66 meter tall twisting steel tower.

The ride is propelled as a copper alloy fin passes through coils on the track. “When we get ready to fire, we press a button and an electronic current energizes the coils, projects a magnetic field between them, and the copper alloy fin is in between,” Jasper said. The fin is pushed forward to the next set of coils, and so on, picking up momentum along the way. The system, which also involves magnetic brakes, is energy intensive, Jasper said.

“Let me put it this way: We’re using such a massive jolt of electricity to operate Wicked Twister that it would be enough to power 550 average sized houses,” he said. Other launch systems are achieving similar results, such as linear synchronous motors or compressed air systems, reportedly taking passengers from 0 to 129 km/h in 1.5 seconds.

Without a doubt, materials-driven technologies such as magnetic brakes and high-powered launch systems have taken the roller coaster competition to new heights. Pribonic, who has worked in this business for more than 20 years, believes materials are going to have to improve to keep up with the increasing demands of high-intensity rides. “Materials, by and large, haven’t changed,” he said. Although rides are towering higher and moving faster than ever, old, familiar, and somewhat mild steel, grade A-36 or higher, remains the preferred material for roller coaster structures. Better options would be high-strength steel alloys, titanium, or even advanced fibers, to fill the need for high-strength materials for roller coaster structures.

“They’ve been meeting those challenges with mass rather than material changes. . . . if they want to go any higher and faster, it’s going to have to force a change in engineering approaches,” Pribonic said.

 


THRILL RIDE SUPPORT SNAPS DURING OFF-SEASON

Figure A

Figure A. Known by its manufacturer as Insane, this sling-shot type ride involves a carriage suspended between three carbon steel posts that stand 81 meters tall. Vortex shedding was found to be responsible for the collapse of one of the towers in January. Photo by S&S Power.
A towering thrill ride collapsed early this year at Cedar Point in Sandusky, Ohio, after one of its three steel support poles cracked. The ride opened in August, just months before the collapse. The cause of the crack has been found to be vortex shedding.

The VertiGo was a slingshot ride that consisted of three 81 meter columns, made of carbon steel, that held a triangular-shaped carriage. The carriage was connected to the columns with steel cables. With passengers strapped in, the ride used compressed air to shoot the carriage 91 meters into the air, reaching speeds of 80 km/h. S&S Power, the manufacturer of the ride, calls the ride Insane. An identical ride is in operation at Six Flags Magic Mountain in California, under the name of Thrill Shot (Figure A).

The VertiGo collapse occurred in January, when the carriage and steel cables that supported it had been removed from the structure for winter storage, said Ned Hansen, chief engineer for S&S. One of the three poles was found to have broken off about 20 meters above ground. No one was injured when the accident occurred.

Afterward, S&S hired Barry J. Vickery, an independent engineer and professor of engineering science at the University of Western Ontario, to find the cause of the collapse. Vickery’s findings, released in March, attributed the collapse to vortex shedding.

According to Hansen, vortex shedding occurs in slow, steady winds that are sustained for a long period of time. The cold temperatures and location near Lake Erie made Cedar Point an ideal location to generate the type of winds that induce vortex shedding, Hansen said. The critical wind speed is a function of the cross-sectional shape of the structure, structural vibration modes, and structural damping. Vortices are generated as wind travels around a structure. If the wind speed is such that the frequencies of the vortices match any of the structural modes, Hansen said, then the excitation of the structure can amplify. The direction of oscillation is perpendicular to the direction of the wind. To prevent the phenomena, appropriate structural damping is needed.

Since the park was closed for the winter, no one actually observed the events before the pole failed. However, the phenomenon was observed several weeks later, Hansen said, when one of the remaining poles was seen oscillating at approximately 4.5 meters. The movement stopped before the pole failed. The VertiGo was designed to meet structural engineering code requirements that it withstand winds of approximately 130 km/h, he said. On the day of the collapse, winds were estimated at 16 km/h.

If the ride cart remained attached to the poles, it would have absorbed the vibrations and no failure would likely have occurred. For prevention, future rides will be equipped with a 45 kg, m chain to be hung from the top of the structure in a 150 mm pipe. Wind would cause the chain to bang against the structure, dissipating energy, Hansen said.

“Now that the cause has been determined the fix is actually very simple. . . . We believe we could have made this ride 100 percent safe,” he said. Hansen added that vortex shedding could not have occurred with passengers on the ride.

The VertiGo ride will not be rebuilt, according to Cedar Point. A similar ride will be removed from Knott’s Berry Farm, a sister park in Buena Park, California. Cedar Fair owns both parks.

“We have decided to disassemble and remove the VertiGo rides from our parks,” said Richard L. Kinzel, president and CEO of Cedar Fair, in early March. “. . . We believe the unfavorable perceptions resulting from the incident will negatively impact the popularity of the rides. With the opening of Cedar Point less than two months away and Knott’s Berry Farm nearing its peak season, we feel the best decision is to remove the rides from our parks.”

 


PRESERVATIONISTS HOPE TO DOCUMENT ENGINEERING OF 100 YEAR OLD RIDE
As parks and engineers soar to new heights in roller coaster technology—tubular steel tracks, magnetic brakes, high-tech launch systems—a wooden roller coaster in Pennsylvania has chugged into the record books as the world’s oldest operating
roller coaster.

Riders of Leap the Dips in Lakemont Park, Altoona, do not shoot out of the station, they are pushed by hand to the lift hill. As a motor takes the wooden car up the track’s 12 meter lift hill, boards that rest horizontally across the track are pushed out of the way, then fall back onto the track to stop the car from rolling backward. At the top of the hill, gravity takes over, pulling the car down the gentle dips as the coaster completes a series of figure-eight maneuvers at speeds no faster than 16 kilometers per hour (Figure B). After about one minute, the car rolls back into the station, where the operator pulls on a lever that puts on the brakes.
Tame by today’s standards, Leap the Dips was state of the art when it was built in 1902, and evidently, made to last.

“It’s not sophisticated by any means but it works,” said John Kazmaier, president of the Leap the Dips Preservation Foundation, which owns and operates the coaster. That
foundation, with significant support from the American Coaster Enthusiasts (ACE), was responsible for the $1 million restoration of the coaster that was completed in 1999. The coaster had been closed for 14 years before it was refurbished and reopened.

The Foundation still has a major debt to pay off, even after a $150,000 contribution from ACE. But the preservationists are committed to the historic significance of the ride, and hope to continue their work by documenting the engineering behind it. Kazmaier would like to recruit an engineer who is also a roller coaster enthusiast to lead that effort. The goal: “To tell the Leap the Dips story from an engineering standpoint, or the physics side of it,” Kazmaier said.

The information could be used to educate the public, especially
school students, on the history and technology of Leap the Dips, he said. Detail could be included on the principles behind the coaster, how it worked, why it continues to work, and how it compares to today’s coasters, “from an engineering standpoint in laymen’s language,” Kazmaier said.

Anyone interested in volunteering for the project should e-mail Kazmaier at jkazmaier@westsylvania.org or call (814) 696-9380.



Figure B  

Figure B. Leap the Dips, the world’s oldest operating roller coaster, has no restraint system, wooden cars with tongue-and-groove floors, and top speeds of 16 kilometers per hour. Photo by Joel Rogers at www.CoasterGallery.com.

 

Top 10 Fastest Roller Coasters in the World*

Coaster

Park

Opened

Speed
km/h

Dodonpa
Fujikyu Highland
12/21/2001
172
Superman the Escape
Six Flags Magic Mountain
3/15/1997
161
Tower of Terror
DreamWorld
1997
Steel Dragon 2000
Nagashima Spa Land
8/1/2000
153
Millennium Force
Cedar Point
5/13/2000
150
Goliath
Six Flags Magic Mountain
2/11/2000
137
Titan
Six Flags Over Texas
4/27/2001
Phantom’s Revenge
Kennywood Park
5/19/2001
132
Fujiyama
Fujikyu Highland
7/1996
130
Desperado
Buffalo Bill’s Resort & Casino
1994
129
Hypersonic XLC
Paramount’s Kings Dominion
3/24/2001
Nitro
Six Flags Great Adventure
4/7/2001
Son of Beast
Paramount’s Kings Island
5/26/2000
126
Superman–Ride of Steel
Six Flags New England
5/5/2000
124

*   Source: Rollercoaster Database, www.rcdb.com



Top 10 Tallest Roller Coasters in the World*

Coaster

Park

Opened

Height
(m)

Superman The Escape
Six Flags Magic Mountain
3/15/1977
126
Tower of Terror
Dreamworld
1997
115
Steel Dragon 2000
Nagashima Spa Land
8/1/2000
97
Millennium Force
Cedar Point
5/13/2000
94
Fujiyama
Fujikyu Highland
7/1996
79
Titan
Six Flags Over Texas
4/27/2001
75
Goliath
Six Flags Magic Mountain
2/11/2000
72
Nitro
Six Flags Great Adventure
4/7/2001
70
Speed
Nascar Café
4/28/2000
68
Mr. Freeze
Six Flags St. Louis
1998
Mr. Freeze
Six Flags Over Texas
1998
66
Son of Beast
Paramount’s Kings Island
5/26/2000

*   Source: Rollercoaster Database, www.rcdb.com


Copyright held by The Minerals, Metals & Materials Society, 2002

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