Launch speed

I saw this video: http://www.youtube.com/watch?v=H2b6OaI0BXM and it made me bring up the question. Does Dragster have the capability of going about 140 mph? Xcelerator went 100+ mph. Do they not go that fast because it wears the engine out?

All hydraulic launching coasters can go faster than their intended speed but, because of the circumstances, they don’t. Dragster can go well over 120mph and I’m sure Xcelerator can go well over 80mph. Going faster would require more pressure which puts strain on the motor(s) and (I think) the accumulators among other things. I think it would also require a slightly longer launch run.
So it's basically capable of going faster, but they would probably never do it. Though if they wanted to, Kingda Ka could unleash its full potential with the length of launch track that it has. But if Dragster were to be able to release its full potential, it would be insane. Imagine launching to 140+mph in less than 3 seconds!!

On another note, Xcelerators launch looks incredibly quick right from the get go! It's 40mps makes Dragsters initial 32mps look slow! The thing with Dragster is that it doesnt stop at 80.;)

*** Edited 1/2/2007 8:17:40 PM UTC by TTD 120mph***

It should be noted that the 100+mph launch did a lot of bad on Xcelerator's hydraulic system. I forget exactly what happened.

TTD has the capability of doing a lot more than what it really does. Xcelerator's hydraulic system has something around 7,000 horsepower, Kingda Ka has around 7,000, and TTD has 10,000. I believe Kingda Ka and TTD use somewhere around 7,000 horsepower.

In reality, they have to whole how much it has and how much it uses thing is mixed up. Kingda Ka's motor has about the same potential hp as Dragster's, they just both use around 7,000 of it.
I remember talking to someone who said that they had actually lowered Ka's hp (I don’t know if it’s true). So since both used slightly more than 7,000 (not sure on exact measure), that would mean that Ka is either at or slightly below 7,000. And if it is true, I think it’s a good move on their part since it would relieve some pressure off of the motors and parts. I say make the launch speed equal to the launch track length.

*** Edited 1/2/2007 8:36:02 PM UTC by TTD 120mph***

The horse power ratings are worthless. The question is how much actual power does it take to launch the trains and how much damage do the launch systems take per launch.

Electric motors, at least those printed on the motor are under very tight regulations in terms of power. If it says 10 HP, you can put a 10HP load on it continuously and as long as it doesn't overheat, it's okay. A car engine has peak HP. You can run it momentarily at such power. Run it at peak power for more than a little bit continuously and the engine will explode. Aggressive use of a car engine will lead to premature engine failure. High RPMs put extreme forces on the reciprocating parts. Most stock engines are not designed to handle high RPM's for more than a few short periods of time.

Hydraulic launch coasters are aggressive as it is, any more and their life will be very short. The high speed launch on Xcelerator did damage to the launch system, most notebly are the motors. Each launch on TTD and Kingda Ka does a bit of damage. This is even more prevalent when there are other problems such as cavitation.

The HP's quoted are just peaks. When the power on actual launches peaks out, the most run damage is being done. When the launch stops, hydraulic oil vapor or nitrogen get into the oil and run through the motors. Because they change in volume when passing the motors which goes from around 300 bar to 1 bar nearly instantly, it's actually an explosion and causes cavitation on the motors. Kingda Ka and Top Thrill Dragsters's launch systems run great for a launch. In time they destroy themselves.

There is no need at all for Top Thrill Dragster to run any faster than it does now. It costs enough to maintain as is, they don't need any more downtime and higher costs.

*** Edited 1/3/2007 4:50:53 AM UTC by Jump to Conclusions***

We've seen what happens to the hydraulics when they are in certain circumstances. For instance, Dragsters hydraulic motor was rushed to be built for opening day and proper inspection wasn’t taken, thus many problems arose leading to new parts like a new drum and ultimately 2 new gearboxes. I don’t know much about the history of Xcelerators hydraulic motor, but it was the first implemented so problems were almost guaranteed to show up.

Plus, it wasn’t just the motor that proved to be a hassle. The cable, catch car, block system, and sensors (among others) have contributed to the many amounts of downtime.

SO not only cant the motor go fast without tearing itself up, but you also have to take into account the other parts that would be affected.....namely the cable, catch car, cc brakes and track/trough.

Hydraulic launch coasters.....gotta love em.:)

*** Edited 1/3/2007 5:44:27 AM UTC by TTD 120mph***

Since we're talking about launch coasters and the issues with hydraulic launches, I may as well bring up a question I've had for a while.

Why do you think Intamin went with hydraulics? I remember an interview with Stan Checketts where he said he could launch the space shuttle with the compressed air technology used on Skyhawk and Power Tower. (I think the interview was during the opening of Power Tower.) Also, on that supercoasters show a while back, they were talking about steam being used on aircraft carriers for decades to launch planes WAY faster than TTD. They even said it was a much simpler system with far less breakable parts.

Is it just me, or does it seem like Intamin chose an overly complex system to launch a coaster?

Well they also said that the price for a launch of that magnitude would be great and it would be extremely loud.

Intamin choose a system that was new and effective......though problematic. It's simple in how it works but complicated in what it takes to make it work.

Though its not to say that Intamin isnt already comming up with something. We just have to wait and see.

*** Edited 1/3/2007 6:35:31 PM UTC by TTD 120mph***

Rides at Cedar Point don't have to worry about noise very much, but Knott's is located right next to homes. Xcelerator had to fit in a small spot (LIM don't allow) and be very quiet (Pneumatics don't allow).

While I don't know the full reason, looking at all the rocket coasters built the past 5 years (minus TTD and KK) all the rides all seem fairly efficient and the cost to build such a dynamic and modern thrill ride was very little. I've heard nothing but good reviews on various sites about Xcelerator, Storm Runner, Rita: Queen of Speed, and Superman: Escape. The smaller versions have all done very well and other than Xcelerator's first year, they've all been reliable.

I would still consider TTD before its time and it really pushed the limits to where technology is currently at. Building a ride that has to launch trains out at 120mph every 45 seconds or so for six months out of the year is no easy task. Especially with a budget. TTD's performance in 2006 is a great example of how far trail and error has come. The ride's uptime has greatly improved.

This year is going to be fantastic. Though I cant see it doing much better than it did last year. Most of downtime was weather related and the only thing that can be improved is the block system which IMO seemed to prove the most problems.

I will say that when they took the gearboxes out, I got a bit shaken. Thank god it was nothing.:)

^ Almost everytime I went to CP this past year at least once a day that I went to ride TTD they were constantly manually reseting the blocks, and man does that suck up a bunch of time.

As for using steam as a power source, it is a great resource and very powerful. With that said it does take a lot of energy to create steam as well as if there ever was an accident where the pressurized steam was violently released the cable snap incident a few years back would look like someone bumped their elbow on a railing.

Top Thrill Dragster resets it's own blocks automatically. The problem is it only does so when the trains go forward. When you reverse trains, the block system doesn't reset the blocks after the train passes. The employees have to manually reset the blocks in this case to be able to move another train over that section or run the train forward over that section.

More in depth, there is actually two sets of block occupations. There is the Master and Safety.

The Master is connected with the sensors that detect if there is in fact a train in the block. If there is, then the master block detection will be active. If you try to reset the block when a train is present or a sensor fails on, it will not work. If all of the sensors show that a train is not present in the block, the master block goes back to a clear state.

The Safety is an implied block state. If any of the sensors in a block are triggered, the safety calls it occupied. It will remain in that state untill either the block reset sensors are triggered correctly or a manual block reset is used correctly. This means if the train back up over a block, there is no block reset sensors for that direction and the safety remains occupied. When a train rolls forward, the train will trigger block reset sensors after exiting that block and the safety state will clear.

This is a picture of the sensors. You will notice two rows. There is a row slighly to the right from the middle that has few sensors and a near solid row to the far right. This represents 2 of 4 sensing positions. I will call the ones just right of the drive dires the main sensor row and the ones off the the far right the block reset sensor row.

There are 3 pair of main sensors for the station block and more pairs in the brake run. There are also a couple other sensors in the block that are used for train positioning. The 3 pair represent the front, the middle and the end of the block. If a train is sitting in position, the front is under the front of the train, the middle is under the 3rd car, and the end is under the last car. The picture above shows the end of the load 1 block uncovered because the picture is of a 4 car train, not 5.

A train stopped in position should trigger most of the 6 sensors in the 3 pair, but at least one of each pair. The reason for this is that between cars there is no sensing plate but there is one from the front to back of each car. The rear sensor will turn off as the gap passes over when the train is moving but will turn back on before the sensor in front of it turns off. Basically a Make before Break situation. If the train stopped and one of the sensors in a pair is uncovered, it means nothing.

Now look at the far right and gasp. There are about 15 pair of sensors per block. Now here is the easy part, forget about all of the sensors except 1 pair. This pair is just beyond the end of the block going forward. It is the block resent for the block behind it. The main position sensors detect the train everywhere except for the gaps but a second is there to catch that gap and for redundancy. The block reset is different. It only triggers in one spot on the entire train. This point is the very last wheelset of the very last car. There is a plate there just to trigger these sensors.

At night you can walk by the transfer area and there are some vertical sensors that you can see the green LEDs. There is an amber LED for when the sensor is triggered. You can watch the train from an angle and see where the plate is located by when the amber light is on. Check the other wheels and you won't see this.

For these sensor to operate, the train must be rolling forward, the main sensors must not show occupied and the rear sensor must be triggered first and then the front sensor triggered right after. When the plat passes this particular pair, the block is reset. when you back a train in manual, there are no resent sensors and the block is still occupied. If things happen in the wrong order, you will get an out of sequence error. If something happens during the time the train leaves the block but does not reset the safety, or the block reset is done incorrectly, then you will get a Master Safety block disagreement error. If a sensor does not turn off, or after a sequence of a block being occupied and reset and a sensor does not trigger, then it gives you a prox not okay error.

With the main sensors in place, they also signal to the control system when to slow the trains and stop them at the front of the block. This is a video of a train positioning at the transfer then proceeding to launch. Before the train stops, you can see a pair at the end of the block where the train stops. This is the front of the transfer and also the sensors used to stop the train. If you look closely to the far left there is a sensor sitting there. This is the approch sensor which causes the control sytem to swtich the motors from full foward to slow forward. If the train was going to launch instead, it would ignore that sensor and the train will go forward to the launch position then approch the front of that block.

There are two other positions for sensors. One is for launching only. There is a bar on the 3rd car wheelset that triggers some kind of a analog sensor. This gives the control system critical launch information. The other position is simular to the block reset except it's on the far left and the only trigger plate is on the front of the first car. I think it's only used on the top of the tower.

If I were to discuss why launching TTD at a high speed is a very bad idea in detail, expect a post about 10-15x longer than this one. Simply put, it will destroy the hydraulics faster than they have in the past at normal launch speeds. I think most of us remember June of 2003, that was not nice to anyone.

*** Edited 1/4/2007 5:15:14 AM UTC by Jump to Conclusions***

Wow, that's some detailed information. Are you an engineer of some sort?:)
Now all I have to do is read it a few more times so I can make sense of it so that I might be able to explain it to my friend.

It seems like the blocking system was way over built. In perfect situations, it works great, but with that many sensors, the chance is much higher of one misreading. Which is obviously the main problems that occurs on a hour to hour basis.

Thanks for the great info by-the-way. :)

*** Edited 1/4/2007 8:00:13 PM UTC by Gomez***

If i remember correctly dragster was launching over 120 closing day

Yes it was. Early in the morning, they were launching trains with only 2 rows filled then they gradually kept filling more rows. But as they were filling rows, the trains were barely making it over the tophat so they were increasing the speed every launch. At times trains were being launched at 125, 123 etc.

Gomez said:
It seems like the blocking system was way over built. In perfect situations, it works great, but with that many sensors, the chance is much higher of one misreading.

Note how I mentioned to ignore all but one pair of the near solid row of sensors? All the others are in the program but they are not needed. They were going to use them in dry mode, but that completely failed and was removed by the engineer in 2003. The idea was to move the trains close like Millennium Force in the unload station, but also move them faster. As it turned out, they couldn't stop the trains in position in unload. No matter what they did, 6 trains could not move more people than 5 even though it was much more aggressive. Now all of the sensors except the pair I mentioned are worthless.

I knew it!

So the only reason theyre still there is for the early morning tests when they cycle all 6 trains and for when they do a transfer train switch?

So technically if they had just 5 trains, they wouldnt need the other sensors? *** Edited 1/4/2007 10:18:48 PM UTC by TTD 120mph***

TTD 120mph,

The reason for that is that the launch system starts at a default hydraulic pressure. When conditions allow for a pressure increase including train times being too slow then it will step up. Sometimes it takes several steps in pressure before the train can make it over the tophat.

They add weight slowly to allow the control system to bump up the pressure and when it does, they add more weight to get it to step up again. The speed will increase as the wheels get warm, the temperature increases and of course the pressure in the hydraulics goes up. When they can, they will run fully loaded trains. Since the control system looks at the last 3 launches, it takes some time to adjust from empty to full trains on some days.

As the day goes on and the trains run full for a long time and the temperature outside goes up, the pressure will bump back down. I've rode Dragster when the pressure went down below the default and the ride was reset to the default pressure. This caused an overspeed over the tower. Fun stuff.