With the convention on-hold, I made a pilgrimage to the Mall of America this morning, and I mean it as no insult to say that the Metro Twin Cities area is what New Jersey would have been like had everything gone right. In any event, the MoA is a place of many wonders, not the least of which is its indoor theme park, which features not one, not two, but three roller-coasters. For coaster geeks, one of them–Sponge Bob Square Pants’ Rock Bottom Plunge–is notable. The Rock Bottom Plunge is manufactured by the German coaster firm Gerstlauer and is a wonderful pocket-version of big-time looping, twisting coasters you see at a Six Flags or Universal Studios. The ride contains a loop, a negative-g-hump, an inline-loop, a heartline-spin, an overbanked curve and a helix. But here’s the amazing part–it does all of these maneuvers using a start-height of about 70 feet (Wikipedia says its 67 feet tall, the Gerstlauer site says 74 feet, my eye couldn’t tell the difference) and with an incredibly small foot-print–remember, this is all inside a mall.
How do they generate enough energy to propel through so many maneuvers with such a short drop? The design is what Gerstlauer calls a “Euro-Fighter,” and it’s a pretty ingenious combination of two elements. The Rock Bottom Plunge employs only a single car which is pulled straight upwards. The car then encounters a hair-pin turn and is released heading straight downwards–actually more than straight down. To milk every last Joule of kinetic energy from the height, the car drops past the vertical at a 97 degree initial angle. With no potential energy wasted on a more gradual descent of the type most coasters employ, the Rock Bottom Plunge thus begins its paces with a kinetic store which belies its modest height. The single-car design then allows tighter turns, which conserve more energy than the more graduated turns of a bigger coaster–giving it the capacity for all of those ride figures.
