Roll back info

but..

but....

if that's all we do here....

is judge other people's mistakes...

then how can we...

talk about coasters...

?

Which is why you shouldn't point out simple mistakes...unless you're pointing them out to someone who is being hypocritical ;).

Earnhardt2,

I understood your question just fine. Ignore the Spelling police. ;)

Anyway, My advice would be to delete this thread and start a new one with the Title, "Why do Rollbacks Happen?" or "Why do Rollbacks Happenon KK and TTD?"

That will grab more peoples attention and will probably generate more accurate responses from those who know.

I am glad you want accurate info. I have a good idea how the ride works but since I do not know first hand I will not post my hearsay. I will say that I know for a fact some of the information posted here as being factual is indeed quite incorrect. So keep being diligent in sorting through this information.

Oh i agree...I think having to watch everything you type is crazy, I was more or less just stating how some people won't reply if its mistyped or what not.

This is a coaster site, not a grammer/spelling site lol

Says the person that can't spell GRAMMAR.

If you can't use real English, you should choose another site.

What I have noticed when I witnessed the trains launch on Top Thrill Dragster that the distributing of weight is a major factor for roll-backs. When I went last weekend to Cedar Point, the weather was not that warm and they were not loading the last few cars for Top thrill Dragster. So instead of loading 18, they were loading 14, and eventually 16.

The reason I think for this has to do with the center of mass and the distribution of weight in the car. When the ride crest over the top, you want the center of mass, to be more over the crest of the hill and lower. This can be accomplished by having more of the passengers seating near the front of the car, and none in the back.

For example when we got their in the morning and a ride operator took a ride by himself in the front, the ride roll-backed after just not making it over the crest. This is because there was only one person in the front, and not enough weight to help it over. However when the same train was front loaded with 14 passengers for the next run, it made it over.

However I am sure there are other variables that play a roll in whether it makes it over. You are dealing with a complex launch system which of courses has several factors that control if it launches at full speed. Also the principle frictional losses on a coaster are due to friction between the wheels and track, and amount of drag. The contact friction between the wheels and track are a function of several things such as the lubrication of the wheels and track, the ambient temperature outside, the amount of time the ride has been running, among other factors. The amount of drag, is a function of the cross sectional area of the train (should remain constant), the density of air, the square of the velocity of the train, temperature, among other things.

So whether it makes it over the top is not so simple. The major factors are the distribution of weight and likely the outside temperature. Typically coasters run faster the higher the temperature, likely due to the lubrication used for wheels and track being less dense and more smooth liquid like. So it is most likely to roll-back on a cold day, in the morning, and with more of the weight in the back.

Could one of you PLEASE point out where I said that his post had to be perfect? Yea, I mispelled a word by forgetting one letter. Look at his original post, it's not easy to understand at all, hence me posting that he should edit it. Everyone who posts on this site SHOULD read the TOS, as it is very clear about this sort of issue.

Learn how to write a readable post, or don't post at all. It really is that simple. You don't deserve the respect of an answer if you can't write a valid, readable question.

The problem is, you pointed him out for making the very same mistake you were making. It doesn't look good on you to point out someone who has pizza sauce on his face when you have pasta sauce on your own. That was the point. Did you go back and edit your post? Why should people listen to your post about how they should spell correctly, when you can't spell correctly yourself?

I must be ultra smart, or maybe I am just on the same wavelength as Earnhardt2. I completely understood the original post without thinking twice about it.

Like I said before. I know with KK rollbacks mostly happen when the trains are not full. When i was there they would not launch a train that was not full. I was told by one of the ride ops that when a car is not full they have to basically manually launch the train. THey set the power depending on the weight of the car .Rollbacks happen when they do not set the power correctly.

Also when its the first launch or so of the day . I have not witnessed a rollback on KK before that was not an empty test car.

Maybe KK is a little different then ttd when it comes to its launch system?

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Jeff said:
Says the person that can't spell GRAMMAR.

If you can't use real English, you should choose another site.

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thanks for your input. lol

but anyway. I would like to say... the video link was great thanks! dude *** Edited 6/1/2005 2:41:10 AM UTC by Earnhardt2***

LOL he has every right to add input to the thread, he does just happen to own/run the website!

Try this:

(from Cambridge University)

“I cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid. Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh? Yaeh and I awlyas thought slpeling was ipmorantt …”

Very interesting.

Rollbacks happen when the centre of gravity of the train does not crest over the top of the hill when the train loses all its inertia, because either the train was launched too slow, or the weight of the people in the car was too little, not providing enough momentum. Thus, gravity pulls the train down back the way it came. This can be attributed to a number of factors:

1. the weight distribution of the car.

2. wind, rain, even density of the air slows down the train

3. cold weather.

4. launch mechanism (quite uncommon)

5. anything else that slows down the train.

TTD and KK are built to be able to endure rollbacks, but they are not planned.

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RollrCoastrCrazy said:
Look at his original post, it's not easy to understand at all, hence me posting that he should edit it.

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QUIT IT!

The Cambridge University thing was interesting. On the other hand, if the moderators of the site don't want you to type like an idiot, yoo SHOODN't. *** Edited 6/1/2005 5:14:19 AM UTC by Word***

Tekno, you're a hypocrite for calling other people hypocrites. Oh wait....crap.

Quick physics lesson:

If you load up the extreme front and back of a train, the CoM actually travels less high than if you front load a train. I have no idea why CP does it this way, but I really don't buy the "it's so if the train barely makes it up, the front will pull it over."

A very easy analysis shows that, CoM-wise it should be easier to send a front & back loaded train over than a front & middle train.

Anyone have any other ideas?

I too have never seen a full KK train roll back, but I have seen a couple of empties, esp. the test ones right after a breakdown.

Like i said before i talked to one of the ops that actually runs kk. He told me when the trains are empty they manually launch the trains and they set the power. Soemtimes they set the power too low and it rolls back.

Now He told me that when that when the train is not at full capacity they have to set the power and sometimes its set too low.

Now He also said that kK checks the weight of the train. Maybe when the weight of the train gets too low they have to manually set the power?

Also when I was there they would not launch a train unless it was full. He would actually tell the people to go down the ramps and to the other side and fill in the empty rows.

Also it has to do with warming up to. I do not know how ttd works though. i know from talking to the op that in some minor ways kk is different regarding the launch system.

PS Most of the break downs are not launch related. Most of them that i have seen are related to the transfer track that transfers the trains onto the repair tracks.

I love you Andy! (((((HUGS Andy!!!)))))

:)

Apollo Andy, you are right about the center of mass. However if you think about it, if you have a car on the apex of the hill, you want more of the weight over the top than not over the top. That is where the weight distribution comes in to play and why you want more people in the front.

It would not be esier to have a front and back loaded train. The best is to just front load it. You want more inertia over the crest, that way it will pull it down. At least that is what I observed when watching Top Thrill Dragster launch. The day I went it was rather cold and they were loading 14 ( back two seats not being loaded).

Does this make sense. I am a mechanical engineering student, I should know something about this. I also was a ride op on the beast for 3 seasons.

thanks,

David