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How Rollercoasters are Mathmatically Modeled?


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Hi,

 

I was just wondering how engineers model coasters? By this I mean how are they able to determine normal forces on riders and so on, for the entire length of the ride. There is course at my university in differential geometry, where one of the projects that you can do is to model coaster by differential geometry but is that how they really do it?

 

Any answer would be appreciated,

 

 

Dane

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Well, I'm not sure about this but I was always under the impression that rollercoasters were designed using programs similar to NoLimits.

 

Computer programs are used to design the ride as you mentioned, but what the computer is doing behind the scenes is using differential calculus and geometry to make all those calculations that would take us a lot longer to do by hand.

 

And just think, somebody had to write the program

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To analyze forces on the train and such they would use a modified version of an FEA analysis. If you have ever used SolidEdge, SolidWorks, Pro Engineer, etc. the stresses can be calculated using these programs. They calculate dynamic forces at all points, as ever point on the surface is related somehow.

 

At the begining of the track initial conditions are set (speed, stress on each surface in each direction x,y,z, and so on), and the coaster is placed into motion so to speak. At the first time step, all new conditions are calculated based on those initial conditions and what equations of motion are available. The important thing to note is that each piece gets a new set of conditions, like the seat or the connection between the seat and the train.

 

The math can get very complicated, but most of these points do not actualy change so while it may seem daunting (sp?) the computer program can perform these calculations failry quickly.

 

if this is clear as mud as I am sure it will be, I will try and figure out your questions.

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I know GCI designs all of their coasters with math, they say so themselves on one of the Discovery Channel shows.

 

^Dang it so I have to go learn SolidEdge now. The meche's at school use it a lot but I've also heard tons of complaints that many companies don't use it and that it was pointless to learn.

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Don't learn SolidEdge, it is a waste of time and effort on anyone's part. They just have a force modeling program in there. ProE, AutoCAD Inventor, and SolidWorks are about the same.

 

Just remember they will use there own specialized software adapted to creating a roller coaster. Well at least to do all the stuff specific to a roller coaster, but if you learn the basics of a 3D CAD software, you will be prepared for the future.

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I know GCI designs all of their coasters with math, they say so themselves on one of the Discovery Channel shows

I know some of the guys from GCI read this forum...perhaps they could elaborate without giving away too many trade secrets?

 

How about it, guys?

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^I read that somewhere too, and yes its an advanced No Limits. Basically all the computer programs do are solve all the incredibly long and hard problems that designers would have to do by hand other wise to find the forces on riders, track structure ect. These programs also make it easier by including friction into the equation, which is hard to do by hand (yes ive tried, and failed miserably). My best guess is that they are a lot like AutoCAD except modified to work out specific problems.

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There are quite a few basic calculations you can do without a computer. In fact, it's VERY POOR design practice to start at square one with a computer modeling program. Meaning, you shouldn't start with the equations, you should first figure out what the heck you want to do. #1 is always using best engineering judgement. Something that comes with working with structures and equations... experience. I'm sure manufacturers use rules of thumb as well with regard to their coaster designs and what is achieveable. The computer should be used as a tool for fine tuning, and working out the bugs... Making sure the train doesn't valley would be a big one.

 

Lots of engineers fresh out of school have the computer mindset. Sit down and start "designing" and then end up locking themselves into a design. The intitial stages of design need to be fluid, lots of input and the ability to be changed quickly. The problem is that as soon as you start adding a lot of fidelity to your model, it becomes exponentially more difficult to change.

 

As far as solid modeling programs go... Industry standards: Pro-Engineer, Catia, SolidWorks and IDEAS. Once you learn one, it's a piece of cake to learn another. Parametric is the key. I spent the first 5 years of my career learning Pro-E, used a little Catia V5 and IDEAS. A couple of years ago, I made a switch to a different company that uses Catia V4... This is old antequated software that ties everything to a coordinate system, rather than to other solids. This was the most difficult transition and modelling program to learn because it doesn't act intuitively.

 

My advise to those aspiring Roller Coaster Designers out there...

 

In your home life: Take stuff apart, learn how stuff works, experiment and understand why mechanical systems work the way they do. There shouldn't be any mystery to mechanical devices. They were all built and designed by people, so if they went together, they've gotta come apart!

 

In school: Learn a "main stream" solid modeling program. Once you understand the parametric attributes, you can apply it to any program. The user interface changes, but the same basic knowledge is required. Take PHYSICS, understand vectors, statics and dynamics, once you understand the fundamentals, everything else will be a piece of cake!

 

Have FUN!

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CAD programs are great but first you have to know how to design a coaster yourself and understand the forces involved to properly know what you're doing.

 

I'm thinking of getting this book to try and get an idea of what's involved

 

(Yes, I also cringe at the way it says "Exiting real life maths activities" How this is supposed to make you feel any better about buying it, I don't know)

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Soarin makes a few good points.

 

Early layout concepts look a lot like the things I used to doodle on my notebooks in school. We use lots of "rule of thumb" to get a feel for how the ride should flow, where high and low points should be, how wide turns should be, etc. Then we just start skecthing with pencil over printouts of the site.

 

Once we get a real *rough* idea of the layout and profile, we start entering *rough* shape information into our computers. The design programs we use were all developed entirely in-house by us, and we use LISP (AutoCad's programming Language), Maple (a math engine that performs the integral and differential calculus that Excel can't do efficiently) and Excel. Each is integrated with the other to create a system of programs (rather than a single do-all program) that helps us to refine the layout concepts into a true design.

 

By the way, not sure what Intrex is. I think maybe the reader is referring to "Intraxx", a company that created a 3-D animation of Lightning Racer for Hershey.

 

Final dynamic calculations are performed by Maple and organized for output by Excel.

 

But that's just us. Everyone does things a little differently.

 

Best advice for aspiring coaster designers: Keep with it, keep in touch, learn a programming language, learn AutoCad.

 

Jeff

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^Yes! We learned Maple in my diff. equations class in college. I'm actually in high school but I take college math and humanities courses.

 

 

As a brief aside, what are companies looking for in an engineer? I can do all of the things you listed (with the exception of a programming language, but I am learning).

 

Obviously a college education is preferred, but does the college you attend really matter? I ask this because I'm considering MIT and Georgia Tech right now for engineering (my intent is to become a roller coaster designer), but MIT is incredibly expensive and I'm wondering if it would even be worth the extra expense to attend MIT.

 

So basically my question is this: Would it make a significant difference in my chacnes of getting hired if I attended MIT over Georgia Tech?

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If you can get into MIT, by all means go, but only if you can afford it. Georgia Tech is an excellent engineering school, but MIT carries that "IT" quality. Now Georgia Tech vs. say Texas A&M (my school), take the one that costs the least.

 

What companies are looking for now are jack of all trades kind of guys. This is not roller coaster exactly, but anyway one of the most important things that you can do is learn to write technicaly. That is the most important job skill you can have at this time in the job market. Also remember that 4.0 is not the best, 3.75 shows diversity somewhat. Also make sure you can talk publicly, and show some friendliness.

 

Hope this helps.

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Also remember that 4.0 is not the best, 3.75 shows diversity somewhat. Also make sure you can talk publicly, and show some friendliness.

 

I disagree on the GPA issue. A lot of firms look at your GPA, and actually have a minimum GPA to be considered for hire. This is mostly for high profile positions, like a Chemical Engineer at a multinational oil company. Shell isn't going to take an engineer with a 3.0. For this situation, a higher GPA is always better.

 

Premedical students are in a similar situation, higher GPA is always better. You can get accepted with borderline grades, but higher is better. GPA is, of course, only a fraction of an overall application. You cannot get accepted on grades alone, but low grades will kill your prospects.

 

I agree with your second statement, but remember that high grades and social skills are not mutually exclusive.

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^That multinational company probably isn't going to hire someone straight out of college for such a high-profile position, at least based on my job-hunting experiences in a similar field.

 

As far as engineering universities goes, once you get past the big name universities (MIT, Cal Poly, etc), a lot of the programs are very similar. For me, it was either Minnesota or North Dakota State. But don't just make your decision based on money. Visit the campuses. See where you'll be taking a lot of your classes. Talk to the advisors. Having volunteered with the Office of Admissions here at Minnesota, I can't begin to tell you how important actually seeing the campus is. And while money is certainly a factor, it certainly shouldn't be the sole factor you consider where to go to college.

 

Getting this thread back on topic, a lot of the early design is the kind of back-of-the-envelope stuff you would expect.

 

Paul

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Since the subject matter has diverged from Roller Coasters specifically and melded more into an "Engineering Prep" type idea, here are a few more of my thoughts.

 

A good education with a good GPA from a good University shown on an Excellent Resume will ensure you get interviews. 75% of the interviews I've been through have not had an ounce of technical discussion. Three companies asked me technical questions... Apple asked simple statics questions. Underwriters Laboratories (UL) asked me to identify electrical symbols and Disney Imangineering asked me to calculate the size of a pump used in a certain size flume with required flow rate. I've interviewed with Boeing, Raytheon, Northrop Grumman, Pepsi, and a bunch of other not so well known companies. It's the personal skills that are going to sell you as an engineer. Running numbers and solving equations is something that can be relearned... It's really tough to teach someone how to NOT be an a$$.

 

I've also done quite a bit of interviewing for the company I previously worked for at Cal Poly San Luis Obispo. I can tell you... When there are a lot of candidates and only a handful of positions, you have to start using some pretty crazy criteria. First off... a resume with a misspelling immediately gets dumped. I remember one interview I had where the guy had a pen and he clicked the thing for about 20 minutes straight. I stopped the interview half way through and gave him some advise on how not to screw up another interview... Unfortunately, of all the other potential candidates, he interviewed the worst, so he went to the bottom of the stack.

 

Everything you do in school gets your foot in the door, but it's up to you to sell yourself. Don't be afraid to tout your accomplishments, but maintain a humble attitude. Remember, the guys that's interviewing you is thinking to himself, "would I really want to WORK with this guy?"

 

Good luck guys!

 

By the way... my experience mostly comes from the aerospace industry, so keep that in mind with regard to the advise above.

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Personally, I think the University of Louisville has a good engineering program and I'm sure some other posters here would agree...

 

However, it doesn't really matter where you go to school for engineering degrees especially as long as it's ABET accredited. That's about the only requirement I've seen companies look for when searching for engineers. I work for a large corporation, and in my office there are engineers from pretty much all over the place. So, I think the most important thing is that you go to an accredited school, get involved, and try to learn practical engineering techniques as opposed to being just "book smart" (and get decent grades too obviously).

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From what I've seen most companies (aside from engineering as well) want at least a 3.0. Essentially what they are looking for as people have said is people skills and some technical knowledge, because for most schools what you learned in class doesn't look a thing like real life. They want to know that you do things outside of school as well. If you have a 4.0 and did nothing but school, they might not be as impressed as the kid with a 3.4 who was a student union senator, played in band, and did im sports.

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As far as engineering universities goes, once you get past the big name universities (MIT, Cal Poly, etc), a lot of the programs are very similar.

 

Paul

 

 

Cal poly? You mean Caltech?

 

 

I don't think a company puts that much emphasis on GPA depending on what school you attend. A lot of the people I met at MIT have terrible GPAs (high 2s and low 3s at best), yet they were immediately hired by firms like Boeing, Ferrari, Northrop-Grumman, etc. for summer jobs. I think the main reason for that is that big name companies understand that MIT is a big name school and that classes are incredibly demanding.

 

 

Just like college applications, job applications aren't all about numbers-other things can get you the position over someone else.

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Cal poly? You mean Caltech?

 

No, CalPoly, the public version of Caltech.

 

To analyze forces on the train and such they would use a modified version of an FEA analysis. If you have ever used SolidEdge, SolidWorks, Pro Engineer, etc. the stresses can be calculated using these programs. They calculate dynamic forces at all points, as ever point on the surface is related somehow.

 

Well, none of those can actually do stress calculations, but all integrate into FEA programs that can. SolidEdge uses Femap, Solidworks uses Cosmos, and Pro/Engineer uses Pro/Mechanica.

 

Most smaller firms use Autodesk Inventor, where as big corporations use Solidworks (IE: Ford, GE, Caterpillar). I have used SolidWorks more than Inventor so I would have to say I like it more.

 

Not quite true. Most larger companies tend to have dedicated CAD departments that use programs like ProE or CATIA, which are supposedly too complex for "regular" engineers to learn (despite the fact that WPI taught me exclusively on ProE, I wasn't allowed to touch a CAD program where I worked last year and instead had to farm it out to the CAD division).

 

Smaller companies like the one I work for now, where the engineers do the modeling themselves, tend to use SolidWorks or Inventor, which were actually designed from a user interface standpoint. However, most companies I've talked to and interviewed at tend not to touch Inventor, since they see it as a toy, not a tool. If you have the opportunity to learn ProE, go for it, since anything else will be much easier by comparison, but if you are learning on your own, stick with Inventor or Solidworks.

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  • 1 year later...

I'm getting My Degree in Civil Engineering soon and roller coasters are done with pen and paper doing numerous calculations before you even use a computer. You also spend time surveying the land. You use a modified version of AutoCad for drafting and calculations. Certain simulators like No Limits are only used to show the park a 3d visual for the final product.

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Oh! You want me to post a reply to this? Picture me turning blue and dropping dead.

 

"Why did I choose to answer to this? I should just hit delete, forget the whole thing, and go out for a pizza."

 

What I know about roller coasters is that they are powered by gravity after the trains are lifted up a lift hill, so as long as the next hill is much shorter than the previous hill, then your coaster train is going to continue to speed along the track. Another thing I know about coasters is that I love to ride them.

 

Shoot, I might as well delete this.

 

"Rats, I accidently hit 'send' instead. I'm going to be blackballed for the rest of my life."

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