Revenge of the Mummy

[Adam]

Universal Studios spent a lot of money on a variety of advanced linear synchronous motors for their latest blockbuster attraction – Revenge of the Mummy. What sort of advantages are there when using this propulsion system? e.g. could they have used tyres in the track like Scooby, or is there a reason this wouldn't have worked in their situation? Thanks.

[DaptoFunlandGuy]

Adam your fixation with Scooby Doo, and Tyre Drive technology is starting to wear thin. I am no expert on the mechanics of rollercoasters, but ive been able to answer most of your queries in a single post... I dont wish to discourage you from posting on these forums, but let me tell you that the majority of your answers can be found in 30 seconds in a google search. to answer your query (after spending 2 minutes reading through a site found on google... Tyre drive systems impart energy through friction - the tyre rubs against the car, which pushes the car forward. the problem with this technology is it is not capable of high speeds without sufficient speed from the motor, and therefore, a lot of wear from the contact Disney's Test Track first opened with rubber tyres, and through the punishing they received, they were burning out tyres very fast because of the constant high speeds. They now use an aircraft composite wheel which doesnt burn out at high speeds. LSM's and LIM's rely on magnetic propulsion, and therefore, little to no contact is necessary with the car, meaning less wear and tear. LIM's can be used on an entire launch, however LSM's are capable of higher speeds (100mph in about 7 seconds) so, higher speeds, in less time, without the need for lift hills or a gravity drop, and less wear and tear from contact friction. here is info from the site -

LINEAR INDUCTION MOTORS If the lift hill at the beginning of a roller coaster ride can be eliminated, it opens a wide range of new possibilities for roller coaster layout, as well as theming. By adapting a technology from the transportation field, roller coaster designers developed an electromagnetic acceleration system using Linear Induction Motors that completely changed the rules. A Linear Induction Motor (LIM) has only two main parts, a stator and a rotor. The stator is wound with either two or three wires in a specific pattern, depending on whether the current is two or three-phase. When the appropriate current is supplied to this winding, a rotating magnetic field is produced in the air gap between the stator and the rotor. This magnetic field induces (thus, the name "induction") currents within the rotor, which at any moment oppose the direction of the magnetic field, thus causing the rotor to rotate around the stator. An induction motor is inherently a constant speed motor. The speed can be changed only by changing fixed parameters within the motor design. [Avallone, 1996] Therefore, in order to accelerate a roller coaster car, many motors must be used along the track, each one rotating at a slightly higher speed. This configuration creates a magnetic "wave" along the track, and the cars are pushed ahead of the wave with permanent magnets affixed to the bottom of the cars. LASER SENSORS A combination of sensors work together with the special software used on modern computer-controlled roller coasters in order to monitor the position and speed of the trains at all times. This ensures that trains are launched at the proper times and prevents collisions. In special cases like the Outer Limits: Flight of Fear coaster, these sensors are especially important, since the ride takes place inside a darkened building. Visual examination of the trains' positions by ride operators is impossible. Light from a laser source, which inherently is composed of only a single frequency, is directed at the train. The amount of elapsed time between the release of the pulse of light and receipt by the sensor of the rebounding light waves allows the computer to calculate the speed of the train; changes in the nature of the returning light wave allow calculation of the distance to the train. [Avallone, 1996] Figure 6. A linear synchronous motor. LINEAR SYNCHRONOUS MOTORS For years roller coaster designers have been dreaming of rides reaching speeds of 100 miles per hour. "Of course, for that, they'd need a 400-foot drop on the first hill," projected a spokesperson for Magic Mountain in 1991 [Turner, 1991]. Six years later, Intamin AG, the same company who developed the first method of mechanical propulsion (rather than gravitational acceleration). [Cartmell, 1989] uses linear synchronous motors (LSMs) (see Figure 6) to accelerate a six ton vehicle from standstill to the legendary 100 miles per hour (in only seven seconds!). The linear synchronous motor uses a two-step process. Because the LSM cannot start on its own, it includes a LIM as a starter. During the first step the stator is energized to near synchronous speed while the rotor is short-circuited. Once the motor reaches approximately 95% synchronous speed, the rotor winding is energized. The attractive forces between the opposite poles of the stator and the rotor pulls the rotor into step, slightly behind the stator. This produces a magnetic flux [Erickson, 1952]. As with the LIMs, these motors are placed along the length of the launching track. Computer software controls their timing so that the train (affixed with magnets) is attracted and repeled by the magnetic flux at intervals that create maxmimum acceleration [ThrillRide!, 1997]. The LSM has a high resistance to vibration, providing smooth operation with minimal resonance and instability. Its bi-directional start-stop operation allows use as both an accelerating and braking system [slo-Syn, 1997]. HYDRAULIC RESTRAINTS The comfort of riders on a roller coaster is determined by two parameters: the track and the restraints. As the track route has become more complicated, the role of passenger restraints has become increasingly crucial. Roller coaster restraining systems are not only designed to keep passengers in the cars but also to keep them comfortable. Keeping a passenger in his seat can be a crude task, but keeping him comfortable requires fine-tuning. Hydraulic power now allows passengers to do this fine-tuning themselves [Robbe, 1987]. The hydraulic restraining system of Kingâs Island stand-up coaster, King Cobra, is a notable example of this new technology. When the train pulls up to the loading platform, the operator shifts the valves in the car to their passing positions. This action releases the fluid, allowing passengers to board and adjust their restraints as needed. The flow control within the valves gives a little resistance to the adjustments so that passengers can have some "feel" as they position their restraints [Robbe, 1987]. The entire system is controlled by a closed hydraulic circuit composed of hydraulic cylinder ports connected by two-way valves. Each "seat" houses three restraints: a seat, a lap bar, and a shoulder harness. These restraints are attached to cylinders containing fluid. As the passengers are physically positioning the restraints, pistons within the cylinder mechanically force fluid movement within the cylinders. This fluid freely flows through the valve as needed, providing just enough resistance for proper adjustment of the restraints. Once all the passengers are comfortable, the attendent closes the valves so that no more fluid can pass through the valves. At this point all restraints are hydraulically locked into place until the flow is once again released at the end of the ride [Robbe, 1987].

[Adam]

Ok, thanks. Can you tell me what you typed into Google? I only get results of trip reports etc when searching for tyre drive systems.