Thursday, February 16, 2012

3D View and Some Calculations Start

And here we have the NEW layout. (Again.) But I'm not changing it anymore. Promise. I've already started doing some calculations (which are beneath the picture), and even though they don't quite add up (for reasons explained below), I'm really happy with this very generic-inspired yet unique design. I really kept it close to the drawn layout as in the previous post, though I had to change a number of heights as we wouldn't want any track to hit other track because, well, it wouldn't be good.

3d view of the layout, taken from the previous post's sketched layout. And yes, there WILL be supports, just haven't put them in yet in case I need to alter anything as they make it so painful.

So, beginning calculations.
What's the first thing people ask about a roller coaster? "How fast does it go!?" And in order to find the velocity, we need to know a number of other things.

I'm looking at the entire train as a particle for right now, which could cause a number of errors as it's much larger than a particle. (The other way to look at something is a "rigid body". A particle has negligible size, which...this does not.) But just to sort of get a feel, this is how I'm doing it for right now. Assuming an average weight of 1400 [lb] per 2-across car (estimated from Philadelphia Toboggan Coasters, Inc website), at 6-cars per train, the weight of one train is approximately 8400 [lb].

Since velocity is the integral of acceleration, and we know the acceleration (GRAVITY!) we can find an equation for velocity. Now, this acceleration does not take into account the 5 [mph] lift speed, simply because the acceleration is 0 once the train reaches its 5 [mph]. If it were accelerating, it would be increasing speed all the way up the lift. So the acceleration is 31.17 [ft/s^2]. The equation (v = v0 - a*t) becomes v = 7.33 - 32.17t. The 7.33 is simply the 5 [mph] lift speed converted to [ft/s].

After getting the position equation (y = y0 + v0*t - a*t^2), we know that the coaster's hill bottoms out at 9.5 feet above ground. We can then solve for t in the position equation, plug that into the velocity equation and get a velocity of the train at the bottom of the first hill. After doing this, we get t = 1.907 [s] and v = 54.018 [ft/s] which converts to just over 79 [mph]. This does NOT seem right for a coaster only 112 feet tall. So what could have gone wrong?

Well, for one, there's no friction accounted for, and as I stated before, I've considered this as a particle, which it clearly isn't, and I should likely get something more accurate when I consider the train as a rigid body.

Until the next update!

Friday, February 10, 2012

So I've decided to scrap that other layout because it was giving me far too much of a headache trying to deal with scales and accurate heights and radii and things. The new much simplified, much condensed, much smaller, much more model-centric layout:


Now I'm working on the side-profile, then I'll be doing calculations on potential & kinetic energy, speed/velocity, acceleration, g-forces on the rider, and I suppose I'll have to do some support stresses.

When I chose this project I just sort of pictured that I'd make a NoLimits coaster, and boom it'd basically be done. NOPE. I WAS VERY WRONG.

Anyway, this is the latest update for all zero of you following along!

Friday, January 20, 2012

Layout

Here is the picture of the layout in an editor view. Quite a simple out-and-back style. The "out" part is basically just hills, whereas the "back" part is more about disorientation and transitions and bits of airtime. And lots of crossovers/unders.

Nitrogen:

Wednesday, January 18, 2012

Update

I completely forgot I even had a blog for this, hahahaha. Anyway, the virtual model is done for the ride, which I've renamed "Nitrogen" to keep it sort of generic and useless.

I'm having difficulty with the scale I want to use as I was originally thinking a 1":5' scale (That's one inch on the model equals five feet in real life) but as the ride's footprint is about 1350 feet long, it would make the model about 22 and a half feet long; which is ridiculous. So I thought a 1:8' scale would be ok, but then the numbers seem all weird and it's still quite long. Then I thought a 1:10' scale would work, as that'd make the model 11 feet long, but the ride is only 120' tall, so that means the model would only be one foot tall and 11 feet long; which makes it look odd.

Not to mention that if I decide to use wood to create the model then that means I'd have to find appropriately scaled wood for supports and track and very tiny coaster cars.

So there's one dilemma. Another is what I'm making the model out of. I'm leaning towards wood just because it'd be cool to see it fully realized, but it would be incredibly time-consuming, expensive, and would create a big hassle to try and figure out how the trains should stay on the track. (Though I was thinking of notching out and laminating/plastic coating the track and have slots that ball bearings attached to the cars are inserted into? Like this: |_| only sideways with a fin and ball bearing in there. But that'd have to be a lot of notching.)

Another option I've been thinking about is K'nex? However tacky and ridiculous that may sound, it makes the physics physically visible (rather than simulated on a computer screen) simply and fairly cheap. Though, looks and an accurate scale are the downfalls to this choice of model building.

Similarly, something called "spacerails" would not be accurate or visually pleasing but would get the point across.

I think I need to just contact my professor and see what he says about the material. Once I get more time I'll look into model-train scales (something called H0 or HO scale) and see what that's about. I think if worse comes to worst, I'll have to do with creating a non-working model, but if at all possible, I'd really like to get a working one just to say I did it. This is literally the biggest commitment and project I've ever done.

Looking forward to seeing this thing take shape!