Why no LIM on Hulk?

Tuesday, August 14, 2001 8:50 PM
Anyone who has been on the Hulk at IOA has probably noticed the tire launch system used instead of LIMs. Does anyone know why B&M didn't just use LIMs?
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Tuesday, August 14, 2001 9:13 PM
I think it had to do with power consumption. The park didn't want to waste so much energy just for a 40 MPH launch, so they asked B&M to come up with something else.

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Wednesday, August 15, 2001 4:55 AM
The launch system was in part designed by the park and its contracted engineers, not B&M, according to a Discovery Channel special.

I doubt very much that the LIM's would have consumed more power. Quite the opposite, in fact. The launch system uses so much power in a short amount of time that the electricity is first stored up as mechanical energy, then released all at once to the motors. According to one of the Discovery specials, Orlando would have a massive brownout every time they launched if they were to draw directly from the city's electricity.

And if you think about it, that makes sense. What is an electric motor? It's a series of magnets around a coil. What is a LIM? It's a series of magnets around the fin on a coaster train. Which would require more motors?

I personally think that a LIM launch would have made a lot more sense.

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Jeff
Webmaster/Admin - CoasterBuzz.com
"From the global village... in the age of communication!"
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Wednesday, August 15, 2001 5:32 AM
Jeff is correct, B&M had nothing to do with the launch system. They designed the ride so that, provided the train was brought up to a certain speed (about 67mph), it would complete the course. They were also very apprehensive to changing any part of their sitdown train's design; hence why the idea of using pinch wheels came about. A system could be designed to utilize the same principle that B&M uses to advance trains into and out of the station.

The launch system itself was a collaboration between Universal and MTS Systems. More specifically, the MTS office in Eden Praire, Minnesota. The 240 motors that are needed to launch the train do use up quite a bit of power. The park has to be constantly pulling in power off of the local grid, and then dumping it into storage for use later. Each launch uses up a good deal of the electricity stored in the time since the last launch. As Jeff said, the city would suffer brownouts if not for the park's ability to "save up" power.

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James Draeger
http://draegs.tripod.com/
"Legend is a wooden Jesus"
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Wednesday, August 15, 2001 6:54 AM
Sorry to make a more or less off-topic comment, but it just strikes me as hilarious that the city would suffer brownouts each time the coaster launched (of course I believe you, I'm not making fun of it) -- I can see that driving us enthusiasts nuts, knowing that it was launching and we aren't on it, or realizing that it must be down mechanical because it hasn't launched in awhile... Sorry, I just think it's humorous. :)

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Wednesday, August 15, 2001 7:06 AM
The thing is, though, that the motors are always spinning, bringing the train slowly up the hill until they speed up and launch. So I would think, like Jeff, that less energy would be spent in an LIM launch that would just consume a certain amount of energy in a short period of time, rather than a set of motors that are always spinning, slowly draining small amounts of energy, and THEN expending a larger amount when the train actually launches.

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The Luv Monkey has spoken...
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Wednesday, August 15, 2001 7:23 AM
Working in the electric utility industry, maybe I can shed a little bit of light on this (and oddly enough, my company supplies equipment to Reedy Creek power, the same people that supply power to Disney and Universal).

LIM's use a considerable amount of energy, and it's in "peaks", it's not a continuous draw of electricity. To effectively store the amount of current they draw you'd need several dozen fuel cells to store up the load drawn.

Where as with regular electric motors, while they do draw a large amount of electricity, they don't draw it in such a sharp "peak" as the LIM's do. It's a more gradual curvature of the load curve. The best way to think of why it does this is that LIM's INSTANTLY have their energy. A traditional motor has to wind up from a lower position, so it "curves" the load as it uses more energy. Businesses are charged not as you and I as residents are (actual energy consumed). Businesses are charged daily based on their highest peak load. Keep in mind, these utility lines carry 3 phase power at 768 kV each, so it's carrying a LOT of power.. I don't think 'brownouts' are much of a concern based on one coaster.... At any given time, producing plants are constantly monitoring the transmissions and increasing or decreasing supply in real time. Your wattage can not exceed the demand or your transmission grid will fail.

My *theory* on the matter, knowing the Reedy Creek transmission grid very well, is that they use the fuel cells to store electricity to help keep their load curve down, and the tires because it doesn't peak the voltage quite so high.

I'm sure that the correct answer may be way off base from this, but this may be one consideration that they did this.

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Panther Modern
SixFlagsHouston.Com
An Astroworld Tribute Site
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Wednesday, August 15, 2001 8:10 AM
As I mentioned, they're actually converting the electricity to mechanical energy. A big set of turbines store the energy. I know in principle how turbines work, but I'm not technically savvy enough to explain it. (RideMan is the one with the article on LIM's vs. traditional motors.)

In any case, I don't know if rides like Flight of Fear or Volcano store energy prior to launching a train. Having seen the open cabinets of Superman (SFWoA), I'm guessing they're not. I'm also not convinced that fuel cells could charge quickly enough, which would explain why Universal used mechanical energy.

With regard to LIM's, it's my understanding that they're fired in sequence to propel the train. Not every motor in the run is firing simultaneously. I don't know what kind of power consumption is involved, but I doubt it would be enough to require storing energy. That is very different than Hulk's 240 traditional motors being driven at the same time.

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Jeff
Webmaster/Admin - CoasterBuzz.com
"From the global village... in the age of communication!"
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Wednesday, August 15, 2001 8:45 AM
Ok here goes.

One of the resons for deciding on wheel power for the Hulk rather than LIMs was the amount of trouble that LIM coasters were having at the time that the Hulk was designed. They wanted to make sure that the coaster worked.

Accelerating a launched coaster at typical rates (except for Hypersonic) takes in the vicinity of 2000-3000 horsepower delivered to the coaster for a few seconds. Even at a low efficiency, this is not enough to brown out Orlando, though it might have some effect on Elysburg's 2000 residents if Knobel's put in a launched coaster. Parks like to exagerate this. It makes good publicity.

However, it is enough to increase the size of the transformers and other equipment that the park requires. Also, on LIM's the amperages can be extremely high for millisecond periods hence the need to store power. The power is stored in capacitors since this is the best way to get power for those momentary bursts.

If I remember correctly, the Hulk actually stores up it's launch power by using a flywheel system. Since the flywheel is only transmitting it's 2000 or so horsepower to the train for a couple of seconds out of each minute, the motor that drives the flywheel doesn't need to be very large. 100 HP would probably do the job nicely of getting the flywheel back up to speed in a minute or so and ready for the next 2 second burst. As for all of the other roller wheels, when the train actually isn't on that particular roller, the motors don't draw much power since they aren't really doing anything.

Hypersonic uses compressed air to store its energy for the bursts of power required. The compressors in use at any one time are in the 400 to 500 horsepower range as I recall. Actually at the current launch spacing they can probably get away with one of their 250 horsepower compressors. Compressed air is a simple way to store up a huge amount of energy, but it is not very efficient. *** This post was edited by Jim Fisher on 8/15/2001. ***
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