FEATURE FOCUS Wild mouse in the funhouse Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/122/08/52/6354466/me-2000-aug2.pdf by guest on 24 September 2021 Combining spinning-coaster thrills with interactive special effects, a new amusement ride blends several control systems as well. By Paul Sharke, Associate Editor Controlling personalities may want to skip the ticket window for this ride. Any feeling of terror is partly the doing of sophisticated controls. 52 AUGUST 2000 MECHANICAL ENG INEERI NG LONG A SECT ION OF the Extenninator at Ke. n­ nator, French manufac turer Reverchon of Paris would nywood Amusement Park, riders in cars roll supply the roller coaster that eventually would take riders toward what park electrical director Bill Mar­ along the dark underground passages of the utility tunnel. venko calls the "infinite track mirror trick." Today, however, audiences depend on more than just :rhe track looks as though it's been gnawed roller coasters for their thrills. So Kennywood planned awayA by giant rats, which are loose in a subterranean utility the ride around a runaway-rat theme. For the animation, space, chewing their way out. A mirror perched trackside Kennywood brought in Jacksonville-based Sally Corp. reflects the scene of devastation back to the riders; the real The Exterminator combines a "wild mouse" coaster track remains safely intact beneath the cart. with the interactivity of a dark ride, said Sally Corp.'s Along another section, riders brace as fire and smoke eEO, John Wood. The old wild mouse ride was always from an industrial boiler threaten to consume them. The popular, but it has recently undergone a resurgence in rid­ effect is done partly with a fo g machine. ership. The typical wild mouse coaster sends four passen­ Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/122/08/52/6354466/me-2000-aug2.pdf by guest on 24 September 2021 What brings the ride to life is not smoke and mirrors at gers in a single car through a series of hairpins and drops. all, but the careful orchestration of a myriad of inputs "The hairpin turn is really where it got its history," Wood said. "The ride looks innocuous. It looks like it would just be fun." Because the carts use offset turning wheels, the wild mouse "gives you the feeling at every turn that you're going to go off the edge," Wood said. "You go straight and the turning wheel is back about 18 inches. When you make that turn, there's no railing or anything around you. You 're asking, 'What's keeping me up?' " As if that's not enough, the E xterminator dropped a box over the wild mouse, Wood said, putting the whole thing in the dark. " Dark ride" is amusement­ maker parlan ce for funhouse­ style frights that pop into view unexpectedly. Wood sa id that such rides, which his company specializes in building, are quite From the loading station, three passengers embark on their ascent up the first hill. At the top, the cart sophisticated in terms of the descends under the power of gravity alone with fin brakes and a PLC controlling its speed. audience participation level they can attain. and outputs by control sys tems behind the scenes. A "Our evolution of the dark ride has incorporated a combination of progranU1uble logic controllers, sound game component into the ride experience. Riders go on and automation controllers, and logic modules supervis­ a quest," Wood said, "and in order to participate in the es everything from directing the descent of the coaster quest they shoot at targets with fl ashlights or laser guns carts, to animating the figures and special effects, to initi­ or za ppers. Riders are scored as they go, either collec­ ating animation sequences. tively or individually." According to Marvenko, the Exterminator started op­ The Exterminator does not strive for that level of audi­ eratillg last year at the amusement park in West Miillin, ence participation. With the coaster and the animation, Pa., near Pittsburgh. As with any large-scale construction it doesn't need to. There's already plenty going on. But project, building the ride took the efforts of several ma­ Wood sa id that the sophistication of today's controls jor and minor contributors. Even more than on most demonstrates how technology is advancing the industry. projects, though, a great many finishing touches had to wait to adorn the ride until the coaster and the anima­ A RIDE ON THE WILD SIDE tion modules were bolted down. According to M arvenko, a trip aboard the Exterminator Ont!e Kennywood decided to introduce the new ride, it goes something like this: Before loading, riders form a brought in R&R Creative Amusem.ent Designs of Ana­ line along a queue-up ramp. They walk up and through heim, Calif., to create a theme, look, and story. Although a control room replete w ith a television anchor an­ no two anlUsement rides are alike, many share common el­ nouncing a city takeover by rats. Almost a thousand ements from different suppliers. In the case of the Extermi- lights blink randomly at the panel. Along the walls of the MEC HANI C AL E NG INEERING AU G U ST 2000 53 28-foot building hang maps depicting West Miffiin's util­ onto scrim, bounce among the breaker's three giant elec­ ity underground. The effects sequence repeats at inter­ trodes. Frayed cables hang helter-skelter, obviously the vals of about 20 minutes, Marvenko said. work of furry Luddites. After riders enter the loading station, which extends The cart then descends, climbs, rounds a bend, and along the coaster track for about 50 feet, they climb into comes upon a giant ra t arm, M arvenko said. The arm cars by groups of fo ur. The roller coaster uses seven in­ lowers in front of the oncoming cart, surely ready to dependent cars in all. The load station, serving as a por­ sweep it off the track. At the last moment, the track falls tal to the underworl d, plays up this effect with ro ots away and the occupants slip benea th the rat's surly grasp. overhea d , red lightin g (fo r the sake of safety), and, In the next scene, an animated exterminator in orange down-track, where the ca rs enter the tunnel, a giant, coveralls stands ready to fire a gun loaded with what pas­ slow-moving exhaust fa n powered by a small motor. sengers know can only be high-strength rat poison. This Once loaded, the cart makes its one and only powered is also where the track disappears in the mirror trick. Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/122/08/52/6354466/me-2000-aug2.pdf by guest on 24 September 2021 climb to the top of the first hill. From there, the cart will The cart speeds on to a darkened room. As it starts ne­ freewheel, with only brakes controlling its descent. gotiating the serpentine section of track, a patented lock­ The first scene is the electric room, where the 10,000- ing mechanism releases the cart body from the chassis. pound shell of an Alstom circuit breaker (for which Ken­ Up until this time, the cart body has been locked to the nywood paid $30,000) shows sure signs of trouble. Elec­ rolling chassis to ensure safe passage th ro ugh the upper tric arcs , the result of a digital video image projecting drops. Now fre e to spin, the cart body and its four occu- A proximity sensor, positioned after the coaster and animation went in, begins the action sequence for this figure just as the riders come upon it. 54 AUGUST 2000 M EC H AN ICAL ENG INEERI G pants begin winding one way or another while the chas­ the cars as they enter the zones, the PLC knows the ap­ sis chases the hairpins. A rotation cam between body and proximate whereabouts of as many as six cars at once. chassis controls spin speed, but each trip through is dif­ N ine d o uble pneumati c fin brakes are distributed ferent because the direction of spin can reverse and its around the trac k circuit, one for every zone, he said. At ro tati onal rate depends on w hether the ca rt holds four each location, two lengths of angle, each 2 meters long, portlies or three slims. Still spinning, cart and passengers bac k up against air bladders. Actuated by air pressure fol­ enter the maw of the boiler. lowing a PLC signal, the angles force opposing strips of Alive after escaping the fire and smoke of the boiler, the brass toward each other. The soft metal provides wear passe ngers continue spinning as they ride over a series of surfaces that rub along the sides of corresponding metal camelbacks-small hills-that dissipate the coaster's en­ fin s projecting from the cart undersides. ergy before it returns to the loading area. The coaster PLC keeps all the ac tive carts under surveil­ lance. If a cart starts gaining on the one ahead of it, the Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/122/08/52/6354466/me-2000-aug2.pdf by guest on 24 September 2021 THREE-PART CONTROL PLC claps the appropriate fin brake to slow it, he said. If Bringing the Exterminator up to speed was a matter of a cart does not pass a sensor w ithin a certain period of controlling the coaster, controlling the animation, and time, the PLC assumes it is dead on the tracks and stops controlling the inter­ the car trailing it.