2 KingDa Ka Questions

[IwantRevenge]

Okay there have been 2 things about KK that have been bothing me a lot lately, they may seem a bit idiotic...but hey...i'm an idiot

 

Okay first...We all know how KK is launched (I would like to assume) and we must all know that that catch car has to weigh a lot, and speed up to 128mph with the train, so how to tthey stop it? does it just hit a set of bumpers and stop?

 

my second question is probably the more idiotic of the 2, why is KK launch track so damn long!? if it goes from 0-128mph in 3 secs would'nt it only needs to be a few feet long?

[coastercrazed49]

The catch car if you watch some videos will stop pretty instantly. But it will bounce back and fourth a couple times.

 

Also the launch is more like 4 seconds,(correct me if im wrong) it needs to sustain that speed for a period of time so it will get all the way to the top of the hill and make it back down.

[yankees15]

1) There is a set of magnetic brakes in the track for the catch car to stop.

 

2) The launch is 0-128mph in 3.5 seconds but, once it gets to the 128mph it keeps that speed for a few seconds before the catch car releases and the train goes up the tower.

[coasterguy618]

1) What ^ said.

 

2) Heres the deal. To launch it, it only uses about half of the launch track..or a lil more. It stops accelerating. and the catch car releases. IF you feel closey, you can feel how the acceleration has stopped.

[steel]

Also, you have to realize that the train is going really, really fast even at the very beginning of the launch. Therefore, it would follow that you need a bunch of space to get it even faster in such a small period of time.

[willski]

Some very basic physics yields your answer:

 

If Velocity final=128 mph

 

So, V(f) is approx. 57 m/s.

 

Plug that into V(F)^2=2ad and say that acceleration is constant, even though it most likely isn't.

 

So a= 57/3.5=16.3 m/s2 or 1.66 accelerational g's, which is very high for a rocket coaster (Xcelerator has the most at 1.4, I believe).

 

Okay, plug that in and you get that the minimum distance required for the launch is right around 100m or about 330 ft.

 

 

This shows that KK does not have a constant acceleration rate, because the launch track is considerably longer than 330ft. At the beginning of the launch, acceleration rate is lower to prevent excessive rider jerk. Once the vehicle is in motion, the acceleration can increase. Also, based on my riding experiences, I would seriously doubt that KK really goes from 0-128 in 3.5 seconds. 4 seconds? Maybe. 3.5? I'm not so sure.

 

 

Using the same calculations and a four second launch time, the distance is closer to 130m or 425 ft., which I think is a more accurate presentation of the launch, especially with the acceleration dead zone at the end. Figuring in this and other factors, the total launch track length is about 600-650 ft., which seems about right given the ride's 3200 ft. length (or something like that).

 

 

These are really rough estimates though, as I didn't take into account friction or the fact that the launch must work slightly against gravity (the launch is on an incline of a few degrees, but it is negligible for this basic calculation).

 

 

You could also use d=.5a(t^2) for the launch distance.

 

 

Long story short, the launch track is very long so that the accelerational g's are not too extreme. I think the actual figures are near 1.1 or 1.2, which is nowhere near what I had them at (my lowest was 1.46).

 

 

And to answer the first quesiton, the catch car has a set of magnetic brakes it goes through after train disengagement (or maybe while the train is still attached, not exactly sure).

[kaliboiryda510]

I would think that it had to do with the weight of the train for each launch. The train is weighed and the drive system then determines how much power it needs to launch the train.

 

Its somewhat hard to believe that they can put a time on 0-128. If they were to get the train to launch 0-128, in 4sec, everytime, that would be a tremendous amount of stress on the drive system!

 

Obviously the heavier the train, the more power and longer distance it needs to get the speed, but i assume that they have a maximum on how much power to let the system have. So therefore they just make the launch track long enough to get up to speed, even at the MLW(Maximum Launch Weight).

 

Thats only my guess, but i believe it makes sense.

[saxman47]

Its somewhat hard to believe that they can put a time on 0-128. If they were to get the train to launch 0-128, in 4sec, everytime, that would be a tremendous amount of stress on the drive system!

 

ummm.......that's what it does lol

 

The launch time doesn't vary very much, since there is only a certain distance to achieve the required speed and therefore the acceleration and time are pre-determined by those two factors.

 

everything is under high levels of stress, hence why it breaks down all the time

[CycloneMan]

I also think the track is as long as it is so there is room forr the bunny hil and the breaks. Also, you have to consider roll backs!

 

-Dainan "I've witnessed 5 rollbacks" Rafferty

[Eric_Smith]

If you check, I think that there was a modern marvels done on KK.

[jamesdillaman]

^^Yeah, I think the simplest answer is usually the right one, and that is to fit the bunny hill and brakes on the other side, the launch side has to be the same length, to make the layout work.

[willski]

^Hope you're being sarcastic.

 

 

 

The launch needs to be that long so the train can safely accelerate to its top speed. Besides, if they didn't need that long of a launch, they could've added more track behind/in front of the station.

[Calaway Park]

^Hope you're being sarcastic.

 

 

 

The launch needs to be that long so the train can safely accelerate to its top speed. Besides, if they didn't need that long of a launch, they could've added more track behind/in front of the station.

 

Woo! For a 30 minute transport track....

[Vallean]

The eddy current brake system of the catch car has not only to slow down the catch car itself but also at least partially the cable and drum system. IIRC it's an Intrasys http://www.intrasys-gmbh.com brake design. The rollback braking section must also be long enough to take in account the possible failure of some brake fins, they're failsafe up and lowered pneumatically. After a fixed delay after the launch command or in case of any control system failure they're automatically raised.

[thrillrideseeker]

I really dont worry abou those things. I just ride the rides But there was a thing about Kingda Ka on Modern Marvels it was rathering intresting! You might be able to watch the show online. Just go to like Modern Marvels.com or something like it. Or mabey search for it at yahoo, google, or gahooyoogle

~Matthew

[coasterlover420]

I knew not to post here because the best answer you can get from a forum full of coaster nerds is an opinion. So I recently e-mailed Eric Lapp at Cedar Point with these questions:

 

1. Does the catchcar instantly release when the launch is over. In other words, is the launch finished right when the catchcar hits its brakes?

 

2. Is there some kind of system in which the train is weighed? Weight variables must have an effect on the launch speed, but is it really that much of a difference if the train is , maybe, 200 lbs heavier?

 

And this was the response:

1. The catch car slows down after the launch is over via magnetic brakes. The launch is usually done accelerating when the catch car hits the brakes.

 

2. The train is not weighed; rather the system keeps the acceleration constant. The system has enough power to accelerate heavier loads and keep the acceleration the same.

 

Sincerely,

Eric Lapp

 

I hope this answers any questions!

[thrillrideseeker]

I knew not to post here because the best answer you can get from a forum full of coaster nerds is an opinion. So I recently e-mailed Eric Lapp at Cedar Point with these questions:

 

1. Does the catchcar instantly release when the launch is over. In other words, is the launch finished right when the catchcar hits its brakes?

 

2. Is there some kind of system in which the train is weighed? Weight variables must have an effect on the launch speed, but is it really that much of a difference if the train is , maybe, 200 lbs heavier?

 

And this was the response:

1. The catch car slows down after the launch is over via magnetic brakes. The launch is usually done accelerating when the catch car hits the brakes.

 

2. The train is not weighed; rather the system keeps the acceleration constant. The system has enough power to accelerate heavier loads and keep the acceleration the same.

Sincerely,

Eric Lapp

 

I hope this answers any questions!

 

Ok the only problem I have with that is highlighted. How does the system know to accelerate heavier loads if it does not know that the load is heavier? Do you get what I am saying? Like the train has to be weighed for the system to know that it is heavier than other trains! Make sense? SEE it only makes sense the trains must be weighed before launch other wise the acceleration would always stay the same no matter if there was a heavy train on track or a light train and heavier trains would not make it to the top because the computer would think it was a light train! Or if the computer thought that the train was heavy and it was light there would be an over speed going over the hill... Do you see what I am saying? Did that make any sense?

~Matthew

[Vallean]

I knew not to post here because the best answer you can get from a forum full of coaster nerds is an opinion. (...)

But a few people post about engineering facts, not all are nerds. The 200 lbs difference you mention as example is negligible as you not only have to accelerate the train but also the catch car, the hydraulic motors, the reduction gear, the drive drum as well as the pulleys and the cable. Interesting is the design of the part which locks on the catch car, due to the rollback possibility a failsafe retraction is required as soon as the train leaves the catch car. It's a safety design feature to allow the train to roll back passing over the catch car wherever the catch car has stopped.

[Vallean]

Didn't see the other message as I was writing. The acceleration is regulated, more precisely the speed is regulated. A simplified explanation: Many times each second the speed is computed (indeed based on the position difference based on signals from incremental or absolute rotary encoders) and a digital regulation algorithm issues a signal to drive proportional valves or servovalves which modulate the hydraulic oil flow sent to the hydraulic motors.So if the acceleration is too low somewhat more oil is sent to the motors which increases the power. A fraction of second later the system may accelerate slightly too much and the power will be reduced and so on many times per second. Of course the regulation is so fast that you don't notice oscillations, their frequency is above the one which the system can respond to.

 

What does it mean? That the speed profile (during the launching), and therefore also the acceleration, do not depend e.g. on the weight of the train and friction losses... But it also means that unless the control system adjusts the final launch speed according to parameters like wind or temperature, you need some margin to make sure there will be no rollback. If you don't you just guarantee a constant final launch speed.

 

This is a somewhat simplified explanation, reality is more complex as several regulation loops are nested and you also require multistage valve systems due to the relatively high hydraulic flow rates reached toward the end of the launch procedure. The motors used by Intamin are internal gear motors (therefore obviously with fixed displacement), the accumulators are of the piston type.

 

(Edited to add some text.)

[kayoss]

Doesn't Dodonpa in Fuji-Q Highland have the fastest acceleration by quite a large margin?

[Vallean]

One should be very careful when comparing claimed accelerations. It's not only about the acceleration itself but also about directions, rate (jerk) and durations. It's not that easy to perform really comparable measurements and the publicized figures are not necessarily true either.

[The Undead Creature]

I apologise if I'm repeating anyone

 

Okay first...We all know how KK is launched (I would like to assume) and we must all know that that catch car has to weigh a lot, and speed up to 128mph with the train, so how to tthey stop it? does it just hit a set of bumpers and stop?

 

my second question is probably the more idiotic of the 2, why is KK launch track so damn long!? if it goes from 0-128mph in 3 secs would'nt it only needs to be a few feet long?

_________________

 

First answer, the catch car hits it's own set of magnetic brakes in the guideway, this happens just after the clutch disengages the drive. It also happens regardless of the speed it is at.

 

Second answer, the launch only uses about 80% of the straight track, the rest is used to stop the catch car. The length of the catch cars braking area is made to suit the catch travelling at 160mph, which is the maximum speed available, or there abouts.

[kayoss]

One should be very careful when comparing claimed accelerations. It's not only about the acceleration itself but also about directions, rate (jerk) and durations. It's not that easy to perform really comparable measurements and the publicized figures are not necessarily true either.

 

again..... isn't Dodonpa's 0-106.9Mph is 1.8 seconds the undesputed champ? After all, we're talking about the ride I personally waited 1 1/2 hours to ride before it broke down just as I was about to board. Although I never got to ride it (yet) it did look much faster then Xcellerator, and honestly, quite painful. Most people agree that Dodonpa is probably the edge of.... shall we say.... good taste... with it's G's.

 

If there's one that's faster, point me in it's direction so I may also wait 1 1/2 hours to ride it only to be turned away.

 

(can anyone tell I'm still upset?)

[307]

That's what she said.

[coasterlover420]

I apologise if I'm repeating anyone

 

Okay first...We all know how KK is launched (I would like to assume) and we must all know that that catch car has to weigh a lot, and speed up to 128mph with the train, so how to tthey stop it? does it just hit a set of bumpers and stop?

 

my second question is probably the more idiotic of the 2, why is KK launch track so damn long!? if it goes from 0-128mph in 3 secs would'nt it only needs to be a few feet long?

_________________

 

First answer, the catch car hits it's own set of magnetic brakes in the guideway, this happens just after the clutch disengages the drive. It also happens regardless of the speed it is at.

 

Second answer, the launch only uses about 80% of the straight track, the rest is used to stop the catch car. The length of the catch cars braking area is made to suit the catch travelling at 160mph, which is the maximum speed available, or there abouts.

 

Exactly!!