One Year Since Orion
hambone said:
Well, to try to get back on topic: I haven't ridden Orion, so this is not a criticism. But I find it amusing that the brake run appears to be 80+ feet above the ground - in other words, basically the height of Racer's lift hill. They could have built a whole second coaster from that point on!
Yeah, a common design trait with the B&M Giga's... Fury, Orion, Leviathan...
My only guess is heat generation in the magnetic braking system. As most are aware, magnetic braking systems require the magnets (cool side) with the non-ferromagnetic fins, such as copper/aluminum or comparable alloy. With an eddy current braking system, as the kinetic energy is reduced, heat is generated.
On newer Intamin's, the magnets are located on the train, with the fins on the track. So once the train passes, the heat generated is 'left' with the fins on the track. Where it can then radiate no problem to atmosphere. No real risk of overheating anything or burning someone. However, Millennium Force and other installs around that time were much like B&M, with the magnetics on the track. But perhaps the location of the fins off to the side of the train (vs. the undercarriage) is the primary reason.
With B&M hyper/giga's, the magnets are on the track, with the fins on the train. So the heat generated would stay with the train per-say, and radiate out to other parts of the chassis/riders/etc... The heat generated stopping from ~60mph (low to the ground brake run) would be quite a bit more than what is generated at half that speed from a higher elevation.
So with a high brake run, they can slow down from a slower temp, generating less heat but still avoid the use of friction brakes as the primary stopping device. Then they do a nice long ramp down, at lower speed, back to station level with a mix of the friction/magnetic brakes. Of course, magnetic braking systems can't stop the train and they still have to rely on other means (friction brakes, kicker wheels) to safely stop the train when need be.
This is an excellent video that puts the B&M Giga brake runs into perspective.
Good observations. One thing I would add is that Leviathan (5,486 ft) and Orion (5321 ft) are relatively short gigas, whereas Fury and Millennium Force are both about 1000 feet longer. Looking at pictures of Fury, it appears as though its brake run is lower to the ground than the other two B&M giga coasters. Having an extra 1000 feet of track to bleed off some energy makes a big difference. Less energy coming into the brake run means it can be lower to the ground.
Chris Baker
www.linkedin.com/in/chrisabaker
SteveWoA, because it acts as the mid-course brake run, only two of the brakes on the highest part are magnetic. The other 14 are traditional friction brakes. I don't think heat has anything to do with why the brake run is high.
Fascinating - I hadn't thought about the physics of stopping a train that's moving more slowly, although it's kind of obvious now that it's been pointed out. Thanks.
(Although it just proves my point - they're just wasting all that speed and momentum! They should have put another 3400' of ride after the brake run!)
/kidding
Fun said:
SteveWoA, because it acts as the mid-course brake run, only two of the brakes on the highest part are magnetic. The other 14 are traditional friction brakes. I don't think heat has anything to do with why the brake run is high.
It being a 'MCBR' is irrelevant. A MCBR doesn't need to be high off the ground, especially when the thing that follows immediately is more brakes. Those two brakes are enough to bring the train to the design speed necessary to get that train off that specific block at the design speed.
Thing is, it can perform the same function at a much lower elevation. Using (more) magnetic brakes to slow a bulk of the energy, the computer system can then reduce the brake force at a specific speed near the end of the brake run to expedite the train out of that particular block, to help with ride capacity. With the ability to use friction brakes, as necessary, for an e-stop or further speed control. It would be longer, sure, but wouldn't be 80ft in the air, either.
As far as "structure stresses" go, I guarantee it's much more complicated in structural design to design the MCBR on Valravn for example with it's minimal support structure, hefty sway, etc... Than a low-to-the-ground brake run that can be easily made more rigid with minimal costs. Adjusting the air-gap in the magnetic system, changing the alloys of the brake fins, etc... Can all vary the braking force and therefor the stresses on the structure itself. I am sure the MCBR on say, Kumba or some other hard-hitting friction brake system puts a lot more wear/tear on the structure than a magnetic system. A bulk of the first sets of magnetic brakes on a high-speed brake run can all be fixed, without need of actuators or moving parts (like the initial brake run on Millennium Force, before the train reaches an area of moving/adjustable magnetics to control speed).
Sure, the brake run would need to be longer to reduce the energy with a low-to-the-ground brake run on say, Orion. But would it be longer than what already exists anyway? Probably not. I don't know for certain, though.
I still think the reason is more heat generation and more unlikely, potentially the design limits of the magnetic brake design itself (equal and opposite reaction deal). But again, this can be adjusted via air-gap, alloy changes, etc...
For my senior design project, we designed a magnetic brake system for a car... With that, we made a prototype rig to demonstrate the design for our final presentation. Which was basically the same thing as what occurs with coasters. So we got pretty deep in to the science and adjustments over the course of a year for this type of system. Was pretty cool... (And we got an "A" on it!). Here is two pictures of it:
The "caliper" had (8) adjustable rare-earth magnets on it, which allowed us to adjust the gap from the aluminum 'rotor'. The rotor we would spin to a specified RPM and measure the time it took to come to a stop with various air-gaps. As well as the temperature increase in the rotor. The closer we were to the rotor, the more braking force and naturally, more heat. Was a cool little rig.
That video was informative (and super nerdy), but the primary reason for the tall brake runs was summed up in one sentence at the 9:02 mark:
Now, the reason the brake runs are placed so high in the air is because it's much better to slow a train while it's traveling at lower speeds than at higher speeds.
hambone said:
They could have built a whole second coaster from that point on!
The same could be said of any really tall coaster, regardless of brake run height. Any hyper or giga coaster could probably be 10+ times longer than most average coasters. If you really want to get technical, most shorter coasters (in height) could be much, much longer than they are as well. There aren't too many coasters that scrub off all their speed and come into the brakes at a crawl.
Vater said:
That video was informative (and super nerdy), but the primary reason for the tall brake runs was summed up in one sentence at the 9:02 mark:
Now, the reason the brake runs are placed so high in the air is because it's much better to slow a train while it's traveling at lower speeds than at higher speeds.
What does "better" mean?
Magnetic braking systems offer more deceleration/brake force at higher speeds. The brake force is directly proportional to the velocity (of the train). Again, more heat and all that, too.
At lower velocities, the braking force diminishes. Which is why magnetic brakes can't bring a train to a stop (ignoring friction) and all that. You will notice this on rides with magnetic-dominated brake runs, the initial "bite" versus later on down the brake run. You can feel it ease up.
I still believe is due to the heat generation with how B&M's in particular are setup on those trains. I think the last thing you want is generating a few hundred degrees of heat under those trains to radiate up to the riders/chassis/wiring/etc... Not so much of an issue on most rides having to burn off 30-40mph of speed... But get up to 60-70mph with fully loaded trains and things get a bit more intense.
SteveWoA said:
What does "better" mean?
Watch the video. While it can be summed up in one sentence, he further explains exactly what is meant by "better" after that one sentence.
Until there is a peer reviewed paper on coaster brakes I am not going to believe anything that is posted here.
Vater said:
SteveWoA said:
What does "better" mean?
Watch the video. While it can be summed up in one sentence, he further explains exactly what is meant by "better" after that one sentence.
I did... But as is my theory, his reasons are speculation at best. I offered my reasoning for my speculation, I just didn't make an long video with POV's and overlays on google earth to make my point.
Somebody get B&M on the horn and find out the real answer!
Intamin has done it in a few places as well. Kingda Ka and Storm Runner come to mind.
SteveWoA said:
Fun said:
SteveWoA, because it acts as the mid-course brake run, only two of the brakes on the highest part are magnetic. The other 14 are traditional friction brakes. I don't think heat has anything to do with why the brake run is high.
It being a 'MCBR' is irrelevant. A MCBR doesn't need to be high off the ground, especially when the thing that follows immediately is more brakes.
It is relevant to the constraints around building Orion. They didn't want to spend an additional 5 million dollars making the layout the same length as Fury, the train needs to stop completely on the MCBR block, they wanted to limit the number of brake pads they would be replacing constantly, they didn't want to use advancing tires until the transfer table, and they didn't want to extend the brake run into the Flight of Fear building. I have never once heard heat dissipation come into the conversation.
Are we to believe that the impulse coasters are melting their sensitive bits?
A midcourse block has to be high enough off the ground for the train to make it back to the station.
Jeff - Editor - CoasterBuzz.com - My Blog
Fun said:
It is relevant to the constraints around building Orion. They didn't want to spend an additional 5 million dollars making the layout the same length as Fury, the train needs to stop completely on the MCBR block, they wanted to limit the number of brake pads they would be replacing constantly, they didn't want to use advancing tires until the transfer table, and they didn't want to extend the brake run into the Flight of Fear building. I have never once heard heat dissipation come into the conversation.
Are we to believe that the impulse coasters are melting their sensitive bits?
The train can stop on the MCBR whether it is 80ft off the ground, or 20ft. Height is irrelevant as long as it's at an appropriate height to make it back to the station (as Jeff mentioned).
Limiting the amount of brake pads... OK, well, you can do that again regardless if the brake run is at 80ft, or 20ft above station elevation. It's magnetic, after-all, with friction brakes as a way to bring the train to a stop or adjust speed, if need be. Just as it is at 80ft up in the air.
You still can avoid the use of friction tires by not having the brake run 80ft in the air, like most other coaster installations. Most B&M's don't hit kicker wheels until right before the station or transfer area. Remember, this design feature is only found on these giga installations for the most part at such heights. I'm not saying the brake run should be at ground level by any means, it's just interesting they go so high up with them with these installs. It's interesting to say the least.
Heat dissipation very may not be the reason, it's just my guess. Only B&M knows the real reason for what they do. I just don't buy the "MCBR" excuse for it being so high up in the air when the same function can be done lower to the ground. Wear and tear and structural considerations can be addressed by design and I'm sure B&M has a handle on that, considering they have no issues with all their other installs with 'traditional' brake run setups, magnetic or not.
As far as impulse coasters go, those rides have passive cooling systems to help with heat (blowers along the launch train to aid with cooling). Here is a cool paper about a similar type of system... It's for potentially launching commercial aircraft with LIM/LSM's, but same idea... Discusses the heat generation, cooling, etc...
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=...e7RqWlKpdD
"In conclusion, if only a passive cooling system is desired along the track of LIM, the electromagnetic design methodology that determines the parameters of the motor in Table II,must be combined with the thermal analysis to select the rated current density of each stage and the mover thickness. Although the aluminum plate withstands the temperature increase caused by a single launch, an active cooling system is needed to cool down the mover at the end of the acceleration to cope with multiple launches"
Keeping it simple, seems to me the main point made in the video is pretty spot on. Stopping a train at a higher speed will result in more stress on the track and wear and tear on parts. I'm going to be replacing my car's brakes, tires, and other parts often if I repeatedly come to screeching halts from 80mph vs. easing into them at 35.
Yeah, I would think it would be structural strain more than heat dissipation? But both are probably good reasons to brake the train starting at 30 mph instead of 60 mph. I also wonder about the logistics of getting the train through that block quickly. You will almost never park a train there except in an e-stop, so you want to be able to clear that block as quickly as possible I wonder if the neccesary slope of the next block to get the train out of the "MCBR" has anything to do with it.
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Calvin: "If your numbers go up, it means you're having more fun."
Vater said:
Keeping it simple, seems to me the main point made in the video is pretty spot on. Stopping a train at a higher speed will result in more stress on the track and wear and tear on parts. I'm going to be replacing my car's brakes, tires, and other parts often if I repeatedly come to screeching halts from 80mph vs. easing into them at 35.
Wear and tear on what parts? If it's fixed magnetics, there is no wear/tear. Regardless of speed.
Cycling stresses on mechanical components given higher braking forces, perhaps. But that is a pretty easy thing to overcome in design, if you are approaching limits of any sort. It's not like these things are designed/built like spacecraft near the edge of FOS/MOS's in order to save weight. If they want to bump up from M14 to M16 fasteners, increase fastener count or need to beef up the structure with thicker gauge steels and so on, I doubt it's any big deal. Once you get to a certain point, you don't really have to worry about the cyclical stresses. Much like the axle of a car going through the tension/compression cycles per rotation (look at the fatigue/endurance limit of a material, if curious). It just has to be engineered properly.
Of course you would replace your brakes/rotors and brake fluid at higher intervals if you abuse them. But again, we are talking magnetic braking here, not friction. Regardless if the train is stopping from 70mph or 30mph, there is no frictional wear occurring. Just thermal and mechanical stresses. But again, mechanical issues can be designed out if not cost prohibitive or some other restriction. But who knows.
I still don't think the choice to keep the brake run 80ft in the air is structural. It's easier to stabilize a structure closer to earth.
It's likely the combination of a weird way to manage the blocking, speed (for various reasons) and mechanical. They certainly have their reasons, we are just speculating of course.
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