Most intense coaster/element?

[Bottom_Feeder_13]

^ It actually does, if there is more launch track than necessary then the ride would be liable to continue accelerating until it leaves the launch track, thus overspeeding the the tophat and operating outside the design specs.

 

[reddude333]

So then you are saying that:

1. Engineers can't control the speed of the coaster by changing the power of the launch (in this case a hydraulic launch)
2. RCDB is wrong

 

[Bottom_Feeder_13]

^ They can, but then the 0 to 80 in 1.8 seconds wouldn't be correct, there is only one acceleration rate that will work perfectly on a launch track of this length. The problem is in the design limitations of the hydraulic launch system, the motors can be sped up, but once they start accelerating they will keep on accelerating until the shut down sequence is initiated, which is usually as soon as the resistance on the cable decreases, signalling the detach of the train from the catch car, the other way it would work is with a sensor on the track that would indicate that the train is at the correct position to cease acceleration, the only problem with this method would be that the train would be liable to overspeed, quite often as well as the added strain on the cable, decreasing its lifespan and making the ride more maintenance needy.

Also RCDB has been known to be wrong, it just states the facts from the most reliable source they have, usually the park.

 

[owentaylor121]

Neither of them are as good as TTD though, that's for sure!

I have heard this of TTD many times and I always wonder why people say it. Me personally, I have only ridden TTD of the three in question and it makes me wonder how worth it it would be to do Ka (although obviously I would want to hit other coasters at SFGAdv)

Im not sure on this but I think that it's because of the Lapars, where as Ka has OTSR.

 

[reddude333]

^ I did enjoy that freeness :-D

^^ I personally don't agree with your reasoning but that is alright. Perhaps at some point in my engineering career I will get a better understanding of hydraulic launch systems.

 

[furie]

From an engineering view, Stealth has to go over the top hat element at a set speed +/- a tolerance.

For both maintenance and rider safety/comfort, it has to be within these tolerances. I think it's generally recognised that the Stealth computer system takes an average value of some kind (torque on the hydraulic rams or some such engineering gubbins) to make sure that the train is within the tolerances as close as it can be.

So if the day is windy straight down the launch track, the hydraulics work harder because the last launch was too slow due to wind resistance.

The problem with this is that I don't know if it's right or not - it could just be enthusiast bollocks. What isn't is the fact that it has to go over the top within a certain speed range.

So, if you increase the launch from 0-80 in 2.3 seconds (or whatever the figures are) to 0-80 in 1.8 seconds then you are changing the speed it can go over the top. It's actually worse than you think.

If the launch section (say station to the start of the uphill climb) is 100 metres, then in the first instance, the ride is hitting the uphill climb at 80Mph.

As Bottom_Feeder says, the hydraulics just keep on going, you can't set them to "cruise control 80mph". So as soon as the train hits 80mph in 1.8 seconds, it then has to stop accelerating. So it will hit the uphill climb at say 78mph.

Alternatively (and logic dictates this to me), the train keeps accelerating and the top speed has also increase. For that extra half a second it continues accelerating until the catch car hits' the release section* So in fact, it may actually hit the uphill section at 83mph.

Now, the important information we're missing here is "the tolerance". Is Stealth meant to hit the top hat at exactly 20mph +/-2mph? 30mph +/-5mph? We just don't know, but as you can see above, by changing the acceleration rate, you're pushing that tolerance out one way or the other. It may be that Thorpe and Intamin measured it all out and changed the tolerances so it has increased.

However, I'd like to leave you with three things:

1. PMBO is the tallest and fastest rollercoaster in Europe.
2. On The Swarm's first test run, several test dummies lost their limbs due to poor clearances and the church Thorpe have spent a year building needs dismantling and the ride needs adjusting (remember, this is national news).
3. Robosaurus!!!!

*The catch car is on a section inside the launch track that drops away, so it's set in stone when the ride is made at the exact point the catch car will release.

 

[reddude333]

Perhaps. Probably the main reason I am not totally understanding this argument is that I have not first-hand witnessed the launch system for Stealth. Maybe I was relying too much on the fact that with LIMs or LSMs (and I realize this is neither) you can set the final speed to essentially whatever you want (in the sense that you can slow the train down if it were to be adjusted to a higher acceleration so that it would still be the desired speed as it reaches the base of the top hat. I was going off the assumption that the computer-controlled system would be able to control both acceleration and tops speed as it would with magnets. I'm less familiar with hydraulic systems.

And btw, Robosaurus is definitely an intense element!!!

 

[Hixee]

Perhaps. Probably the main reason I am not totally understanding this argument is that I have not first-hand witnessed the launch system for Stealth. Maybe I was relying too much on the fact that with LIMs or LSMs (and I realize this is neither) you can set the final speed to essentially whatever you want (in the sense that you can slow the train down if it were to be adjusted to a higher acceleration so that it would still be the desired speed as it reaches the base of the top hat. I was going off the assumption that the computer-controlled system would be able to control both acceleration and tops speed as it would with magnets. I'm less familiar with hydraulic systems.

This might seem obvious (and I hope this is right), but I'll try to explain. With LIM/LSM systems the only thing you'd have to change to increase the speed would be the frequency of the electric current powering the magnets. Provided the cable can support the higher loads, there's much nothing to stop you ramping up the current/speed. With hydraulic systems the mechanisms (tanks, cables, driveshafts, clutches, valves etc) are all designed to operate under certain loads (give or take natural tolerances), so you can't really increase the hydraulic pressure, and thus the speed, without potentially breaking/over-stressing the launch components.

So, within reason, the speed and power of a hydraulic launch is pretty well fixed at the time the ride is made.

 

[reddude333]

^Which actually supports why an increased acceleration could be dealt with. I'm not saying it is or was but simply that the argument of "the train will go over the top hat too fast" is unfounded because the magnetic braking could easily regulate speed. I think, as has been mentioned, the only restriction is the maximum potential energy of the hydraulics (which I doubt any of us actually know the value for Stealth) and that would determine the acceleration.

 

[Hixee]

^Which actually supports why an increased acceleration could be dealt with. I'm not saying it is or was but simply that the argument of "the train will go over the top hat too fast" is unfounded because the magnetic braking could easily regulate speed.

Not quite. The catch car rests behind a stud on the underside of the train (for simplicity at this point, but it's pretty much how it works). The catch car is pulled down the track and, technically, pushed the train up to speed. As soon at the catch car starts decelerating it simply releases the train (ie, drops away from the stud). Imagine it like pushing an object across a table with your hand then suddenly stopping your hand, the object slows down only under the friction force from the table top, your hand has no effect. The difference here is that the catch car is moving much faster, and has much more mass, that your hand, so it takes longer to stop, even under magnetic braking.

The magnetic brakes on the catch car are positioned a certain distance along the launch track (around 1/3 of the way down according to UC, I don't know), so you have no more room to keep accelerating the car, so the only way to get it to go faster is to increase the force pulling the catch car. This then reverts back to what I was saying before about the design of the components.

I think, as has been mentioned, the only restriction is the maximum potential energy of the hydraulics (which I doubt any of us actually know the value for Stealth) and that would determine the acceleration.

I think you probably could work out the potential energy stored as you know roughly how far it takes to accelerate a train of a certain mass. Simple work done type situation. You'd probably be able to get a ball-park figure neglecting losses and rounding/estimating lengths and masses. It wouldn't be hugely accurate (and I can't imagine what percentage of energy you'd lose in all the workings), but you could probably do it. You'd also need to factor in the factors of safety for a system like this, meaning it could probably handle pressures much higher (say 2-3 times) in a critical situation.

Still doesn't stop the fact that the designed launch system on Stealth wouldn't be able to give the train more than about 10mph extra speed (at a guess) without needing to be redesigned.

 

[reddude333]

I agree with that...and personally I don't know or care if they have altered the ride over time. I was simply trying to rationalize why RCDB might have the statistic of 1.8 seconds. I understand they are not always perfect but I thought it was perhaps worth contemplating.