Hydraulic Launch Coaster Safety

Brad,
Following a rollback, the train moves VERY slowly toward the launch position. To speed it up, they will often lower the brakes for a few seconds to get the train back to the launch position faster.

I was on a rollback, in the second seat, one early evening many seasons back. It was one of the last trains on a slow day, so there were very few guests waiting. I remember now that it took forever to get back to launch position and once we finally did they asked if anyone wanted out. A woman and her daughter took them up on it and I think that caused further delay.
Our train made it over successfully the second time but then the train behind us didn't. It was past 8 o'clock by then so they just shut down and those last few riders were turned away.

The rollback was awesome scariness (especially toward the front) and I'll admit I worried for a second that it may not stop or something. But it never really occurred to me that every fail safe wouldn't be in place to prevent a collision. Knowing now about Knott's still has me shaking my head.

I sat through three failed launches in a row on Maverick one morning, but it was less eventful. Oh, except we eventually got the evac and had to walk the plank back to the exit platform.

RCMAC said:

Knowing now about Knott's still has me shaking my head.

Slightly related was the incident on Xcelerator a few years ago. Wasn't one of the fins misaligned when the train rolled back? Or the cable snap twisted something?

The cable snapped, cut through the train, and "sheared off 18 of the 20 magnets on the bottom of the coaster cars used for launching and braking."

They blamed the accident on park maintenance as well as the manufacturer.

http://articles.latimes.com/2011/aug/26/news/la-trb-knotts-xcelerat...t-08201126

Hopefully these incidents led to culture change at Knotts. Accidents happen, but to have two that would have been prevented by proper maintenance is inexcusable.

The video of the cable snap at Knott's still gives me nightmares.

Didn't Kingda Ka have an incident during testing where brake fins came up before the train launched last and the magnetic force ripped the bottom of the train off?

I vaguely remember hearing about that and about pieces of the train being launched past the launch mechanism shed at very high velocity. I think that was when the queue was moved from the area around the launch track to it's current location.

Intamin, it's Fantastic!

At least they push the envelope and test their boundaries. Wish I could say the same for B&M.

It took B&M until Thunderbird to create a launched coaster in house. Really?

Yes. Needless death is fine as long as you push the envelope.

B&M builds what their customers ask for, which is crowd pleasing rides that are reliable and easy to maintain. And also, no one dies on their rides.

ShaneDenmark said:

Didn't Kingda Ka have an incident during testing where brake fins came up before the train launched last and the magnetic force ripped the bottom of the train off?

I think you are referring to the 2005 incident on Kinda Ka. In that incident, part of the liner that houses the catch car came loose. This created a lot of friction that caused shards of metal to fly everywhere, and the flying metal is what created the problems. The failure did cause some of the brake fins to bend. I think the bending was caused by the flying debris, and not from trying to slow the train. From what I could tell, the brakes were down until the train cleared the launch section.

I would also highly doubt that the brake fins would bend from the train going over them forward rather than in reverse. I would really hope that the ride is capable of withstanding an aborted launch. While they should never happen, if the ride is not designed to safely stop the train, there is a real problem in the design.

PS: Its been a long time, but I seem to have a memory of seeing an aborted launch on Dragster in the early days.

Research and product development is one thing, and profiting in many ways from a well-established line is another. I see the value in plugging away with customer orders and letting others have a try at thing like launches for a minute. Good things come to those who wait?

B&M already has unique, successful products in that line like dive coasters, flying coasters, and wing coasters and high profile parks have lapped 'em up. They eventually found the time to perfect a launch and debuted a quality product for a great park when the timing was right for both.

0g said:
I would also highly doubt that the brake fins would bend from the train going over them forward rather than in reverse. I would really hope that the ride is capable of withstanding an aborted launch. While they should never happen, if the ride is not designed to safely stop the train, there is a real problem in the design.

PS: Its been a long time, but I seem to have a memory of seeing an aborted launch on Dragster in the early days.

An aborted launch or power failure is one thing. The brakes would slow the train to a near stop. Magnetic brakes playing tug-of-war with an active 10,000hp motor is another. Remember magnetic braking is exponential to speed, so if the motor was trying launch the train and kept pulling 100+ mph the brakes would provide a whole lot more braking power. I could see that causing some real damage.

Shouldn't make a difference, the hardware should be designed for that. Matter of fact, I've seen Dragster launch when a brake section didn't retract with no I'll effects for multiple launches. They wouldn't have run the ride if the hardware could be damaged.

Yes, you are correct that the force applied is dependent on speed. However, the brakes shouldn't care if the train is going 100 MPH at an abort and is just coasting, or is going 100 MPH with the motor pulling on it. The brakes, however, probably aren't designed to withstand debris from the launch, and that could easily cause the failure seen.

If a significant number of brakes were up during a launch, I suppose it could potentially cause a problem with the launch motor / cable. However there should be appropriate protection programmed into the computer.

I would think most of the damage from the described "aborted" launch would happen in the hydraulic room rather than to the train or track components. The tension on the pull rope could potentially cause it to break, but that might depend on where on the launch track the train is located when the failure occurs. It seems more likely that the computer would have a way of knowing that "launch" and "raise brakes" are mutually exclusive events, except in the case of a brake panel failure like Pete describes.

Speaking of the pull rope/cable, during Winter Chill Out tours at Cedar Point, the maintenance staff have commented that they change the cable 3 times per year. It takes approximately 10 hours to complete the switch, and they have perfected it to the point where they start when the park closes and can "almost" have it completed by opening the next morning. (In my experience, Dragster rarely opens on time anyway.) These interviews can be found on YouTube for those interested.

The newest coaster of this type from Intamin opened at Ferrari Land this summer and uses LSMs instead of a cable launch. I wonder if it would be a reasonable feat to convert a ride like TTD to LSMs, and would Cedar Fair consider it? Surely they can't be happy that one of their signature rides is still down as much as it's up.

PhantomTails said:

The newest coaster of this type from Intamin opened at Ferrari Land this summer and uses LSMs instead of a cable launch. I wonder if it would be a reasonable feat to convert a ride like TTD to LSMs, and would Cedar Fair consider it?

I also noticed that. Depending on the relative rates of acceleration, they might not have enough space to do that conversion (and also $$$$)

0g said:

I think you are referring to the 2005 incident on Kinda Ka.

Well, back then it wasn't quite 100% Ka.