Scooby Doo Carriages

[nev]

Hey guys, I haven't been a big poster since I joined but I think I've got enough experience on this to comment. I've spent a lot of time sitting on the Scooby Doo coaster and I work in theatre as a lighting designer, so I know a thing or two about fire regulations 1) The carriage LEDs - under Australian law, any fixture emitting a visible or invisible laser beam must have an emission sign (sticker or otherwise) attached to the point where the beam is emitted from. While these will not be visible on the lasers in the laser room section as you rip past them on a coaster, I can assure you they will be there. The light emitted from the carriage fixtures does not carry any of this signage. In addition to this, mounting laser fixtures on a moving device is costly and unreliable. The eyes on the trains are nothing more than low voltage LED lights that have a small beam angle. 2) The fire theory - there are two types of smoke detectors in general use in Australia. One type is a chemical based sensor, which analyses passing air for traces of carbon dioxide. The other type is a particle sensor, which uses an invisible beam to detect certain particles in the air between two points. Heat sensitive detectors are only ever used in very controlled environments, of which the Scooby Doo coaster is not one. The cars on the ride are subjected to substantial temperatures inside the laser room on a hot day. Particle sensors are a lighting guy's worst nightmare - it means that even a small amount of theatrical fog can set off a fire alarm. If particle sensors were installed on the ride, you'd be getting an alarm every time a car went into the laser room with the amount of smoke in there. Sensors that test for the presence of CO2 and other fire-related gases are expensive, and are usually placed inside air conditioning ducts or in areas of high airflow where they can quickly detect any hint of a fire. Suggesting that they would be built in to every carriage is a bit of a long shot, as there is no reason for it. Finally, smoke detectors are mounted in static locations (such as on roofs) so that a fire alarm system can quickly and accurately show the fire department where the fire is. A mobile system would not be able to pinpoint the location of any such fire, and would be largely useless to any fire crew attending the site. My 2 cents anwyay Cheers Richard

[Adam]

Thanks nev, I finally agree that for the cars to have motors and brakes is just stupid – I’m glad there is a place to discuss this stuff. Just to clear things up; I asked the question about the wheels locking up on the ride hoping to get the particular answer I was looking for. So far, two people have said this isn’t how they stop the cars; trying to help answer my question. But then I go and tell them they’re wrong. It doesn’t make sense as they were trying to help me! The reason I asked the question was because I was really sure in my mind that this is how they worked but I decided to ask as I was sure people would agree (and then this would also reassure me that this is how it works). I am sorry if it seems that “I know everything” and I am “Always right” but its going to take some convincing to change my mind (unless rich told me I’m wrong - and unlike last time - I would take his word for it and move on). The reason I think I am right is because I have been on the ride many times and I have witnessed the cars stopping and starting at the loading station and on the pre-lift track many times. I have also asked an engineer his opinion on the subject, and if they used Alex's/Gazza's way of stopping the cars he said it would stop the cars, but he thought it would be unreliable, but he is not a roller coaster engineer and it could have been the way I worded the question that made him choose that answer – so it doesn’t count. There are two ways that will make me change my mind What I really want, is Richard to comment on this, although I think Richard thinks I’m a smart arse that makes up stuff (and I sometimes comes across this way). If he was to comment on it, and disagree with me, then I will drop this. OR Next time I go to Movie World I will check. Thanks, Adam.

[DaptoFunlandGuy]

Adam, I'm going to concede something to you - you may be right. In considering this though, I have put the two explainations into detail. I would like your thoughts on it. Option 1) the wheels continue to turn, and stop as the car is dead on top of them. for arguments sake, lets say the car is 1.5 metres long, and so are the brake sections. For 1.5 metres that the car is crossing the brake panel, the wheels are applying an accelerating force (by continuing to turn) to the vehicle. At the last moment, as the front of the car reaches the front of the tyre drive, it triggers a sensor, which stops the wheels dead. Now let me ask you - ever see a car on the road accelerating, and then jam on the brakes? what happens? it skids. it doesnt stop immediately. There would be a small amount of slip before the tyres "grabbed" the car. this would also be affected, as you said before, by the cars wearing the rubber tread off the tyres. eventually, the cars would slip further and further across the catch point as the tread wore down. Also, allowing the vehicle to cross the full length of the catch point would mean there would be only 1.5 metres of acceleration to get the car moving again (explained below) Option 2: Wheels ahead of the cars are stopped. they are effectively a rubber stopper. The vehicle has an assumed amount of acceleration (force) and as it contacts the first tyre, this force begins to dissipate through friction with the rubber tyre. Using the same 1.5 metre measurement, this then gives the tyre drive 3 metres of acceleration (from the beginning of the tyre drive pushing the front of the car to the end of the tyre drive pushing the rear of the car) and thus allows the vehicle to continue on with more speed, with less effort, and reduce the amount of tyre drives required in the ghost train section of the track. Now please read both options a couple of times, until you digest it, before you respond. Then give me your thoughts. I am no student of engineering or physics, but it seems logical to me that version 2 is the correct one. And if you will forgive me for saying so, these forums are notorious for members posting the knowledge or advice of a maintenance employee at a theme park, only to discover they were either lying, joking, or just completely stupid.

[Richard]

Adam's method seems most logical on this one. When the ride first opened, as the trains were "launched" up the first straight through the doors, the acceleration actually caused a skidding sound. This suggests that when skidding is involved, these tyres do make a sound. At no other point on the ride was this sound ever heard, which means that there is no skidding anywhere else on the ride. The stops are all gradual on Scooby-Doo. As you come into the unload station, it is a steady breaking, and if you listen you can hear the motors speeding and slowing. These tyres are belt driven. A rubber belt isn't going to like cars coming in to a screeching halt in the long run, they need a steady force. It's not logical nor safe to be using these wheels in a skidding manner. There are too many uncertainties, and it would be too abrupt. What if somehow the tyres get wet? They're not going to be too effective when wet if you're trying to slow the cars with friction.

[Adam]

Thanks Richard for your great explanation. I was thinking the motors would just turn off and decelerate to a “locked up” or rest position (e.g. a high torque motor slowing down just because it has been turned off), but what Richard said about having variable speed control allows for even more control. Alex, I choose option one, but with some modifications. The track mounted motors continue to operate until a car reaches a carefully placed sensor which tells the motor to begin decelerating and bring the car to rest. This would in fact be smoother than skidding on a stationary wheel. It would also allow the carriage to be stopped in the same place each time; as opposed to option two in which case a number of factors can change the rate of deceleration. With this method it also allows the car to continue forward again with no hassles as the drive wheels will be located directly underneath the carriage.