RMC Streak Photo Update - May 7, 2017

Plastic (nylon or urethane) wheels vs steel wheels. Higher friction.

I just left the park and that outside track next to the lift hill along perimeter road looks crazy. So out of the MCBR you dive under hill 2. You come up along a couple bunny hop hills and go into a heavy bank up towards the new wave turn and then dives back down into the structure towards the station. Now I'm not sure but it almost looks like another wave turn in the structure.

djDaemon said:
So, I've heard this whole "RMC's lose their speed faster" a few times, but I'm not sure anyone has explained why.

Yes, I've yet to see any science around this, but I'd love to hear theories. Wheel material sounds like a good theory, but the energy lost in a traditional wood coaster (especially Mean Streak) from bouncing around between the rails is I imagine several orders of magnitude worse than any difference caused by wheel material.

Exactly. Especially considering the huge range of material properties of "plastic" wheels.

True, but as designed, the plastic wheels are typically setup to pinch the track in a way to provide a smoother ride experience, versus the loose fit of steel wheels that never touch all three to the track at the same time.

What we don't know is how much energy Mean Streak lost compared to a perfect world example. Given that they haven't changed the height of the MCBR, I would suspect that any combination of three things is happening:

1.) The ride passes through the MCBR at a faster speed than Mean Streak.
2.) The second half of the ride is closer to the ground, on average.
3.) The second half of the ride is shorter than Mean Streak.

4.) Higher energy loss using RMC track is a myth promoted by coaster enthusiasts.

What if it doesn't hit the mcbr at the same distance into the ride as mean streak? It's in the same spot physically but could it be later in the ride?

Even though it's following the same path (at this point), the amount of track that has been added to the new layout could be more or even the same as it was with Mean Streak. But, the ride will be running much faster than it ever has, so it could very well be hitting the mid course at a much higher speed. We at least know that they've designed the ride to run the rest of the course at the old mid course height.

Because it will probably fly into the MCBR, the end of the ride will probably stay at a height similar to the old layout, just with much, much more airtime. It can't go much higher, or it won't be able to pass the "e-stop test."

I sincerely hope that they aren't designing this ride with trimming on the MCBR built in and designed into the layout (see: Valravn.) That would make for a huge waste of speed.

Valravn has to trim speed at the MCBR. I don't think people could take the forces of that immediate drop with any kind of speed going into it.

I'm pretty sure the answer can be summed it in one word: heartline.

What RMC has failed to account for in all their fabulous "updates" is that wooden coasters were designed with a certain heartline in mind, and one cannot just slap on steel track and different wheels and expect energy to not be lost at a greater rate.

There. Happy?

I'm pretty sure the answer can be summed in three words: coefficient of friction

Wooden roller coasters and steel roller coasters have a different coefficient of friction. Steel roller coasters lose potential energy at a faster rate, to heat energy, than a wooden roller coaster does. Hence why, for example, Shivering Timbers carries the same length as most B&M hyper coasters even though its drop is almost half their height. This is why all RMC conversions to date have added some height to their drop yet significantly reduced their length. The coefficient of friction is greater on the steel track/nylon wheels. Mean Streak had a height of 161 feet and was able to easily complete a course of 5,400 feet. I don't know of any steel coaster that is able to match that ratio. But raising the height to over 200 feet, they are able to complete that same course, but a lot of that initial speed will be lost to heat and by the time it's going through the midcourse it will have slowed down considerably.

There. Happy?

What if the MCBR isn't a mid course break run?..

CPGuru said:

Hence why, for example, Shivering Timbers carries the same length as most B&M hyper coasters even though its drop is almost half their height.

Again, this assumes equal velocity of each as they enter their final brakes.

Look at TTD as an extreme example. If we look only at track length, using your logic, one would reach the conclusion that for some inexplicable reason Intamin rocket coasters have an enormously high coefficient of friction compared to other steel coasters.

Of course we know that's not true. We know instead that TTD hits its final brakes at a very high velocity compared to other steel coasters.

Hence why (ahem) I still don't buy the "RMC high friction" argument.

I should have specified that it's a rule of thumb and there are some exceptions. Such as TTD and other coasters that are purposely designed to terminate early. Another good example of that is Leviathian, who's final brake run is elevated over 100 feet off the ground. This allows the train to hit the break run at a slower rate since it has more potential energy than kinetic energy as it would had the break run been at 20 or 30 feet above the ground.

And it's not a RMC specific coefficient of friction. It's a steel track to nylon wheel coeffient of friction as opposed to steel strip (on wooden track) to steel wheel coeffient of friction.

Again, as Jeff mentioned, your theory doesn't sound totally unreasonable, aside from the nagging issue of track tolerance's impact on energy loss.

But I would be more convinced if it didn't seem like this argument were emanating from your posterior. Where's the data? The science? The sources? I'm perfectly willing to be convinced, but not by a weak argument.

Oh man, this was something from back in high school physics, more than a decade ago. I went a different route with my career haha and this is nothing but from a vague memory. I can be completely wrong here. I hope there's someone more enlightened on the subject because I don't have any sources.

In other words, just throwing poo-poo to the wall and hoping it sticks.

http://www.roymech.co.uk/Useful_Tables/Tribology/co_of_frict.htm

No clue if this helps, again not my area of expertise, but if you scroll down to the list of example coefficients for rolling friction, steel to steel (wooden roller coasters) has a lower coeffient of friction compared to polymer to steel (steel coasters).

I'm confident Alan Schilke is a good enough engineer to take into account the friction differences due to wheel/track changes, stopping completely vs trimming vs rolling right through the midcourse and adjust accordingly in the layout design. I can assure you Lightning Rod finishes its course with PLENTY of speed left. I'm not sure there's a ride I can think of (outside of maybe Millennium Force) that comes into the final brakes any faster.

As far as I remember, heartline is relevant when trying to make inversions comfortable on the human body and takes into account the height of the seat over the track. I don't think it's the term you're looking for here. Coefficient of friction is relevant to this discussion and I'm sure there are different numbers for different wheels on different tracks, etc, but I'm not the least bit worried that they have it well under control in all of their designs.