RMC Streak Photo Update - May 7, 2017

CPGuru said:

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

...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).

Sure, I don't contend the steel-polyurethane friction factor specifically.

But friction is only one of many factors when talking about consumption of energy. It's the other sources of loss that are unique to wood coasters that give me pause:

• looser track tolerances
• greater variability in track dimensions due to wear and tear, weather, etc.
• losses to the supporting structure (wood structures "give" more, which absorbs energy from the train)

I mean, just stand next to a wood coaster and listen. All that noise you hear is lost energy, as potential energy is converted to sound. Modern steel coasters (including RMCs) are quieter.

You're right, I agree is multifactorial. On the flip side, we can even consider aerodynamics and wind resistance. Millennium Force's trains appear way more aerodynamic to me than PTC trains or even B&M's floorless and dive coaster trains, which I assume produce a lot of drag.

Which actually theoretically plays against them when it comes to wind resistance. Pretty sure Newton's second law applies here. The heavier the train, the less it is affected by an opposing force, ie wind. Hense why I think MF's heavy trains can retain speed so well.

Edit: This was referring the last about RMC's light trains, which appears to have been deleted.

From RMC's website, regarding train design,

"We also boast the lightest weight trains which minimizes wear and tear on both track and train..."

I think it's a matter of momentum. We can safely assume RMC trains are significantly lighter than the PTC trains. Momentum relies heavily on mass. With less momentum, you are easier to stop/slow. Imagine a 18 wheeler in a head on collision with a Smart Car. The 18 wheeler doesn't exactly slow down all that much, because of it's mass. Friction essentially is just a force in the opposite direction of movement. If the momentum is high enough, the train just doesn't care about the jostling and jerking and shrieking it does (IE, 18 wheeler vs Smart Car). The lighter the train, however, the more susceptible to friction forces (drag, wheel material vs. track, etc.) it becomes.

Just my two cents on the matter.

CPGuru said:

Edit: This was referring the last about RMC's light trains, which appears to have been deleted.

It didn't display my whole paragraph the first time, which was unfortunately more eloquent than my second attempt above. So no worries.

No sir, that second post is very eloquent. You basically said what I was trying to say in a much better way. I just didn't see it the firs time around. So thanks

Some food for thought, wheel friction alone would play very into the slowing of a coaster train provided that the wheel is spinning at the same speed as the track is passing it, which in general should be the case. Rolling resistance would be the larger loss of energy (besides the post a couple up that talked about lighter vs heavier trains and the associated difference in potential energy). You can see the difference in rolling resistance by comparing a fully inflated tire to one with just a few psi less - even with the same coefficient of friction the wheel that doesn't deform is much more efficient. Similarly, a steel wheel deforms less than a polyurethane or nylon wheel, reducing the amount of energy lost.

And as always I'm sure there are many other forces at play as well.

Just this civil engineer's 2 cents though...

Still quite a ways to go.

Can we just agree that Friction is F=u•N?

Jotham Povich said:

Just this civil engineer's 2 cents though...

Mechanical (myself) and civil engineers for the win!

That said, I agree with you.

Now I'm sad that I don't have an official degree to join the club...

^Just state your coaster count, that's a neat trick.

I guess I was ambiguous about that. 6 years of college and I left engineering school for personal and financial reasons. It's still a hobby of mine, though.

And I probably rode 150 different coasters in those 6 years. How much is that worth?

Yaaasss: https://instagram.com/p/BUPl_GfFe1l/

Wow, just wow

Love that new photo!

I don't think anyone is questioning that the wheel composition affects performance. Anyone who watched Millennium Force the first year knows all about the wide variety of wheel materials used then. The thing being called into question is an unattributed claim without data, relative to the extraordinary loss of energy from a PTC train bouncing around. Mean Streak had its share of valleying moments, and part of the reason most of us hated it was that it was slow and boring. To Matt's point, there's little danger of this ride being slow at any point, if we're to consider the design of RMC's other reprofiles.

It's taller so it can end faster.

Maybe they'll keep the first drop trims so we can do the math on these wheels.

I remember reading, someplace, that RMC Medusa at SF Mexico has steel wheels. Of course, I am unable to find that statement for citing. *IF* that is true, there's the possibility RMC Mean Streak could also have them.

Do the Medusa trains have steel wheels?

The difference between the sound and track wear between it and, say, New Texas Giant, leads me to believe it does.

Examples...

Medusa:

New Texas Giant:

Did anybody save the most recent pic from instagram? It's been taken down :(