Cooling Period

Not a chance. An electric motor doesn't need to be warm to work.

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Jeff
Webmaster/GTTP, Sillynonsense.com
"As far as I can tell it doesn't matter who you are. If you can believe, there's something worth fighting for..." - Garbage, "Parade"

I keep hearing of alleged cooling intervals, but I'm not sure that any such intervals really exist. No one has given any solid proof as to why one would be necessary.

Jeff, with all due respect, there is in fact a 60 second cool down interval on V2 at SFGAm.  I obviously can't offer you any hard proof right now (no pics, etc), but remember how you didn't think the B&M Megacoasters had any "contacts" on the train to see where the lap bar positions were?  Well, we all know the outcome of that.

There is for sure a 60-second period on V2 at SFGAm in which you cannot launch a train in automatic operation.  I am unsure if SFWoA's SUE has this, but I have operated V2 at SFGAm last season, and there were many cases where we had to wait for the cool down period to be up, as we had checked the train faster than the 60 second period (yes, some SF parks can actually dispatch as well as CP).

So let it be known, the time interval on V2 does exist!

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#1 Steel -- MF
#1 Wood -- Legend
Track Record -- 210

True or not, the suggestion they need to be "warm" to work is a bit far fetched.

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Jeff
Webmaster/GTTP, Sillynonsense.com
"As far as I can tell it doesn't matter who you are. If you can believe, there's something worth fighting for..." - Garbage, "Parade"

Checked a train faster than 60 seconds at six flags..... Right.... Can that actually happen?

I found a good little blurb on the net, it talks just a little about LIM's but doesn't mention anything about a cooling period.
http://www.idsi.net/~delaney/Coasters/lims.htm

sorry couldn't put the link on, there's no button!
[link fixed -J]

*** This post was edited by Jeff on 2/21/2002. ***

I'm not sure I understand what you mean, Jeff.  The reason for the 60-second interval was to allow time for the LIM's to cool off.  That is why V2 at SFGAm went down all the time, a certain LIM was constantly overheating.  Could it be the fact that SFGAm cycled V2 at 60-75 second intervals, as opposed to SFWoA's 300 second intervals?  Possibly.  But all I know is that the 60 second interval was alive and well on V2 at SFGAm.

And to add to this, the mechanics would increase the interval from 60 seconds to maybe 90 seconds sometimes, to see if that made it operate more reliably.  Well, it didn't, for whatever reason.  In all honesty, I don't know why the interval was there, the only guess was to cool the LIM down (which is what everyone said at the park).  I guess you can take that for what it's worth.

And Blue Streak Adam, you'd be surprised how fast SFGAm ops can be.  The 2000 Bull Crew could *easily* keep up (and in a lot of cases, surpass) any CP crew.  I am not trying to sound arrogant, but I visited CP at least twice every month in 2000, and worked Raging Bull four days out of the week, so I think my observations are accurate.

FWIW, SFGAm and [most of] SFGAd crews can keep up with CP's any day of the week.  Medusa and Nitro 2001 crew wer two of the best I'd ever seen.

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#1 Steel -- Nitro
#1 Wood -- Legend
Track Record -- 347

The duty cycle rating on all of the LIM spec sheets I've seen (though I haven't seen those used for the Impulses) is around 15%, which I'm sure assumes no cooling mechanism. With the train passing through any given motor in about a second at full power, that's about five seconds each ride, plus the low power parking at the end. Bottom line, it never reaches its potential full duty cycle. Indeed, if the ride ran continuously without stopping, each motor would fire for about one second on every pass, with a full end-to-end pass lasting about seven seconds, that's 15%. If there's a necessary waiting period, I'm not convinced it's because the LIM's need it.

And you must be joking about SFGAm and SFGAdv having better crews. Bull is on top of things, sure, but the rest of those crews are a joke. Two people on Iron Wolf? Two on Batman? Ditto for the stack-o-rama on Nitro, Batman and Medusa. Any Magnum or Raptor crew in the last decade could take the Pepsi challenge and win (in part because Magnum outright can't stack without setting up).

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Jeff
Webmaster/GTTP, Sillynonsense.com
"As far as I can tell it doesn't matter who you are. If you can believe, there's something worth fighting for..." - Garbage, "Parade"

Ok, maybe you're right, maybe the waiting period isn't to cool down the LIMs, rather for something else.  But like I said, I have no idea what else it could be for.  If Wicked Twister is allowed to dispatch whenever the train has been checked and the all clears are given, I think they could easily hit 900-1000pph, which is fantastic for a one train coaster.

About the crews, how many people are actually checking sometimes doesn't matter.  Viper (SFGAm), for instance, almost ALWAYS runs with two ops, and when I'm up there we hit interval almost EVERY single time.  With more ops, it just makes everyone work less, basically.  But I do agree with you, Wolf and BTR (basically all B&M's) should use more than one checker per side.  With three trains on Demon though, we pulled 1,200 - 1,300 pph (yes, I didn't think it was possible either, but with a motivated crew, things can happen), and we only had three ops checking.

About Nitro and Medusa...I guess they sucked it up when you visited, because both days I went last year (June 28, 2001 and Sept 15, 2001) the crews were amazing.  Nitro would be dispatched almost as soon as it crested the lift (which is when the B&M mega's should be dispatched).

When the trains are rolling in without stopping on Nitro, and then I look at Raptor where it very RARELY happens anymore (I only witnessed it happening consistently once last year, and even commented to the op about it, saying they were doing a fantastic job), it leaves the impression that while Raptor's crew is definitely good, they are better crews out there.

I will *totally* agree though, that overall, CP has the most efficient crews of the big parks.  I was just stating that there are some non-CP crews that can hold their own against them.  Unfortunately, they are few and far between. :-\

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#1 Steel -- Nitro
#1 Wood -- Legend
Track Record -- 347

One thing that could be a factor, and mind you I don't understand electricity the way some people do (RideMan is out of town this week), but I suppose there could be a waiting issue with regards to capacitance. I'm assuming that the thing isn't firing all those motors right off of the electric company's grid. Perhaps whatever means they use for capacitance requires a break.

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Jeff
Webmaster/GTTP, Sillynonsense.com
"As far as I can tell it doesn't matter who you are. If you can believe, there's something worth fighting for..." - Garbage, "Parade"

That would make sense. I assume that they would have some sort of massive capacitor on the ride and it probably would require some time for it to charge up. I've only worked with capacitors in high school physics labs but I always remember them taking awhile to charge.
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Brad Wagner
The Ohio State University
2002: Snake River Falls

They need a flux capacitor, powered buy 1.21 jigawatz for optimal performance.

That sounds like a line From "Back to the Future" Joe...

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- Chris -
Computer Science - Ashland University
Witches' Wheel/Monster - 2002
3rd Shift Trash Removal - 2001

...This is why that an impulse will never be created that goes past 87 mph. Otherwise, you would have a large guest decrease every time the ride was launched. :)

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MF count: 23

Uh, you mean 88 mph. Take it from a HUGE Back tot he Future fan.

--see you in the future!

No, I mean 87. Quoting the Doc, "I'f my calculations are correct, once this baby hits 88 mph, you're going to see some serious..." :)

So if the impulse went past 87 into 88 mph, we'd all see some serious--....--theoretically, of course. :)

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MF count: 23

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Jeff said:
"One thing that could be a factor, and mind you I don't understand electricity the way some people do (RideMan is out of town this week), but I suppose there could be a waiting issue with regards to capacitance. I'm assuming that the thing isn't firing all those motors right off of the electric company's grid. Perhaps whatever means they use for capacitance requires a break.

---

That's probably the best argument I've heard on this issue so far.

I would assume that Jeff's assumption is probably right. Look at Power Tower, now, I know it's not electricity, but air-powered, but I think it still follows the same logic. You have to wait for the air cylinders or electric capacitors to fill or charge so you can achieve the maximum amount of electricity or air, whatever the situation needs. Just think about running PT without stopping, basically meaning, load...launch...exit...load launch...exit. But it doesn't do that. It loads, waits (or lifts slowly--and even at the top you're there for at least 10 seconds--seems like it anyways), and then launches (or drops).

On Power Tower you have to wait for the firing cylinders to fill with air. Those rides rely on a large volume of low-pressure air, and it simply takes a while to move enough air into the pressure cylinder to fire the ride.

As for LIMs...Consider this electrical situation, one that left me stranded on the road once years ago: Electrical resistance increases with temperature. In my case, it meant that when the too-small feed wire from the car battery to the starter got hot, not enough current could flow to crank the starter and start the engine. In a LIM, the bottom line is that if there is too much heat built up, there will be increased resistance in the LIM coil, which will translate to decreased efficiency of the LIM.

Launching the train isn't going to heat things up too terribly much, as Jeff points out, although we are relying on air cooling here. Six Flags' ride has those squirrel-cage blowers that certainly can't hurt. It isn't clear to me whether they are blowing air onto the LIMs or if (more likely) they are pulling air across and away from the LIMs. In any case, the places where the most heat is going to be built up are the places where the motors are operated at stall...that means the holding brake at the top of the tower, which Wicked Twister won't have, and the station motors when they are used to start the train moving and when they are used to park the train.

As for why these actions are going to generate more heat than firing the train through a launch, consider this: Energy enters the motor in the form of electricity. It has to come back out somehow, either by accelerating a reaction plate, or by generating heat. So if the reaction plate isn't going anywhere, what's happening to the energy?

Something else to think about with LIMs: Most electric motors have a fan attached to the back end of the shaft, behind the rotor...or more exotic multi-speed motors tend to be the TEFC (Totally Enclosed Fan Cooled) type, where a blower keeps the coils from cooking themselves and keeps the bearings from welding together. But with a LIM, there are no moving parts except for the reaction plate. Just as with the rotating motor, the LIM is going to generate some heat, but it has to dissapate that heat through passive means unless there are blowers or other coolant systems in place.

As for whether there needs to be a cooling period, I can't say for certain. I suppose the way to figure it out would be to put a temperature probe on the station LIMs and fire the ride a few times. The normal loading delay ought to be enough to let the LIMs cool. The trick would be to figure out how frequently the train can be fired and still keep the LIMs at a stable temperature. Hopefully the interval would be shorter than a typical dispatch interval. But it would be hard to tell before the ride operates.

Long and rambling, I know...I hope it made some kind of sense!

--Dave Althoff, Jr.

Wow...i feel like i'm in school. But I think I learn more about physics and electricity here than there anyways. ;)

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Michael McCormack CP '01: 38
Millennium Force: 49
Raptor: 58
Magnum: 124
Lifetime CP Count: 410 (374 total laps in '01)