Dragster's Balancing Act: 10/25/08

Did the Halloweekends thing this past weekend. Not much of note to report (food service sucks, decorations and entertainment are great, Saturday pretty busy, etc. etc.)

Well, with one exception. At some point in the early afternoon, Dragster had a train balanced on the top hat. Someone eventually went up the elevator and gave it a nudge to get it over. It was the talk of the park for much of the day---especially amongst the operations staff.

Pretty nifty. Bummer I wasn't on it.

I bet it will be on YouTube within a couple of days. I know it stalled at least one other time and it's on YouTube. I would settle for being on a train that rolled back at this point. Getting stuck is a pipe dream :)

It's on now.

http://www.youtube.com/watch?v=_WGn5Du0IS0

It's on the Cedar Point blog as well!

That is awesome! I have seen it stop at the top before but only for a few seconds before rolling back. ;)

-Tina

That would be totally awesome. At this point I would be very happy with a rollback as I have never had one. My son and I have been trying for years for a rollback. We always ride in the morning and on cold windy days etc... But no such luck as it is always the train before us or after us, never ours!

Not to hijack this thread, but it's kinda sad that it was early afternoon and they were still only loading 4 per train. That's 1/4 capacity! I understand the temps are lower and wind and such, but did Intamin not do anything to make the trains more "front-heavy"?

Actually to only have 4 people on Dragster at 12:30 when they just opened at 12:00 is normal from what I have always seen. They had only been open for 30 minutes. The dragster also no longer has ert time for resort guests and platinum pass members. It seems to take a while before they run full loads.

Making the trains front heavy shouldn't help. The height of the center of mass (whether it's middle, front or back) is all that matters.

I don't full understand the "partial" loading when they open dragster. I only really have two theories:

1.) The ride does use a algorithem system that calculates the power of the launch needed by averaging the past three train speeds that go over the hill. If too fast, it uses less power. If too slow, the power is raised a bit. This is used to adjust for temperature and weight, among other things to ensure the train makes it over. By running lighter loads it gets the computer to adjust to the additional loads anytime they add more rows so it doesn't roll back. This is why when they do add another row of loading, the train may crawl a bit usually. The computer isn't ready for that extra weight. Only problem is, why not full-out load full trains right away? Let the first few roll back and the computer will be ready to go for full-weight trains? Maybe to ensure consistant full-train loading on slower days? No idea.

2.) Warm up. Maybe Intamin has procedures for proper warm-up of the hydraulic systems? For example, your car's oil takes about 10-15minutes of driving to get up to temperature for the strongest lubrication protection (212* F) inside the engine. This is why you avoid aggressive driving while the engine is getting up to temp, to prevent higher wear until the system is up to temperature. Maybe it is similar with this system. Running light loads until the system is ready to go?

Anybody (*ahem* Dave?) have the correct reasoning why they do this?

:)

We had a vigorous debate about that on PointBuzz a few years ago, and I was making the case that what you suggest in your first point made sense. People who ran the ride insisted what they do makes sense, and even tried to prove it with physics.

I almost wish MF would somehow get stuck on a hill crest, just so somebody could mention there was balance to the Force . . .

The center of mass (and thus energy needed for the train to make it) will be lower if the train is front and back loaded rather than middle loaded. But that doesn't explain why they only load the front.

Well, the center of mass in the Y-axis is at the same place if it is front loaded *or* back loaded. But, front-loaded train has a center of mass in the X-axis that is "farther forward". So, there is a launch-energy where the front loaded train makes it, but the back-loaded one doesn't.

At least, that's my I-passed-my-undergrad-physics-class intuition.

Hmm. I think I disagree. I think we agree on what's going on in the y-axis. I don't think the x-axis has anything to do with whether the train clears. Either the launch put in enough kinetic energy to lift the CoM to a certain point (which is lower for a front/back loaded train than a front loaded train) or not. What happens when it stalls and where the CoM or train is in the x-axis isn't relevant, right?

Either there's enough kinetic energy to change into potential energy or not.

I think it matters only because there is friction in the system. Let's say that the launch has the energy to get the y-axis CoM exactly to the top of the top hat, but no more. In a back-loaded train, the x-axis CoM is "behind" the crest of the hill, so the train rolls back. In a front-loaded train, the x-axis CoM is "in front of" the crest, so it rolls forward.

Again, I haven't taken physics in almost 20 years, so keep your salt shaker handy.

I've mentioned this before, and it still amuses me...by having the top-hat *face* West, into the prevailing winds, they are increasing the risk of stalls and rollbacks. Perhaps that orientation was dictated by the space constraints, but it is true nonetheless that a strong Westerly wind has the potential to cause the train clearance to...errr, FAIL! ;)

I think this is where the confusion arises. For the same amount of energy and the same amount of y-axis CoM lift, the train will actually travel a different distance.

Just for argument, imagine if the people on the train weight a whole lot more than the train itself. To lift a front loaded train up to the balancing point where it gets perfectly stuck, the front car will barely be past the crest and the rest of the train will be hanging down the "up" side. If the train is back loaded that same balancing point will be when the back of the train is almost to the crest and the front of the train is hanging down the "down" side.

So, in Brian's scenario, if the train is symmetcially at the top and is front loaded, it's already lifted the CoM to a higher point than a back loaded train that is symetrically at the top has. So it must have had more launch energy in the first place to get to that point.

Sounds good to me.

rollergator said:
I've mentioned this before, and it still amuses me...by having the top-hat *face* West, into the prevailing winds, they are increasing the risk of stalls and rollbacks. Perhaps that orientation was dictated by the space constraints, but it is true nonetheless that a strong Westerly wind has the potential to cause the train clearance to...errr, FAIL! ;)

I imagine putting the launch track right up next to the midway had to be a big consideration. I suppose they could have done it Deja Vu style with the tracks criss crossing in order to reverse the top hat direction, but even with the current configurations roll backs aren't all THAT frequent...