New Launching Idea

Think for a moment about how ropeway systems work. You have a moving wire rope, and you pull a vehicle out to connect to the wire rope. A serious problem is that when you clamp the vehicle to the wire rope, you don't want the clamp to move relative to the rope. Slippage is a Bad Thing. It's a Bad Thing because it will quickly destroy the wire rope. For reliability, the ropeway systems rely on getting the gondolas synchronized with the rope so that at the point where the gondola is clamped to the rope, there is no relative motion between the clamp and the rope. Then the ropeway runs at a constant speed,

Well, that's no good. What we want on a launched coaster is a *launch*. What we want to do is take a whole lot of energy and release it into the train all at once. Rather than accelerating the train directly, it's simpler to use some kind of intermediate device. On Dragster, that's a launch-wagon which is rigidly attached to the haul ropes. No slippage because the wagon is attached to the end of the rope. The hydraulic system shoots a huge amount of energy into the motor (actually system of motors) that turn the cable drum.

The bottom line is, the problems with Dragster are not, for the most part, in the launch clutch and cable drive system. They're in the energy system, where the hydraulic energy is released into the motors.

--Dave Althoff, Jr.

Cable pulls are not unusual. Think of the cable cars in San Francisco. The cable moves at a constant speed (about 8 mph, if I recall properly) and the individual cars use a manually operated clamp (called a "grip") which connects the car to the cable. In order for the car to come up to cable speed from a full stop with out breaking peoples necks, the operator (gripman, excuse me, grip person) must increase the grip tension slowly, intentionally make it slip until the car is up to cable speed. At this point the grip is at it's maximum tension.

The grips jaws, which if I recall are made of wood, have to be replaced daily,due to the immense friction that is generated by not only by the starting but of the coasting with the grip in a "relaxed' but not released position. This also creates a lot of friction.

My point is that this is all happening at a speed of 8 MPH. Multiply that times fifteen and watch the smoke fly. The launch sled with the nylon ruuners is a much better solution. Not perfect, but then, what is?

If I recall correctly, the grips on the San Fran cable cars are some type of metal. It is the brake applied to the track that is made of wood that must be replaced daily.

Not to change the subject, but Tremblant is an awsome resort.

Quick trip to my reference library, and yes the grip jaws are made from steel, with an average life of four days, depending upon the skill level of the grip operator.

Are we missing the obvious problem of propulsion here? How do you get a cable to continuously turn at 120 miles per hour with the torque required to drag a 4 ton train up to speed in 4 seconds? The hydraulic turbine works becuase huge battery of energy is stored in pressurized tanks then released on command thrusting the hydraulic fluid into the turbine generating up to 10,000 horsepower and prodigeous amounts of torque! No gas powered engine can match that level of performance without either being the size of a house (such as a marine diesel) or blowing its self up (like a nitro V8). I know there are electric motors that can produce 10,000 horsepower but I don't know about their torque. Maybe three or four gas turbines could do it if they were geared together.. but I'd hate to see the daily fuel bill. :) *** Edited 1/7/2004 8:54:32 AM UTC by Phyter***

While it is feasable to use a constant speed cable, it's not really practical, as has been pointed out, particularly by Rideman. The stress on the cable would be just too great to make the system reliable. My comments were to show what the problems are with such a system at 8 MPH. There is a great deal of maintenance invloved with the cable system, with cable repair, grips, sheaves, etc. At every point where a grip engages, the cable is stressed. At high speed it's a invitation to failure, if not disaster *** Edited 1/7/2004 3:26:34 PM UTC by Dutchman***

I think it might be more fun to use giant springs. ;)

Actually, how's the Navy been doing it for years? Why don't coasters use steam?

---

janfrederick said:
Actually, how's the Navy been doing it for years? Why don't coasters use steam?

---

The problem is that steam is generated by nuclear power.

A coal or gas burning method of generating that kind of steam would be horribly inefficient.

The Navy generated that steam for the catapults (and propelled those carriers around) for years using oil-fired engines. Steam locomotives produced a lot of pressure to move those trains. Actually it's the nuclear powerplants that are horribly inefficient, hence the use of diesel-electric to power large ships other than Navy vessels which don't worry so much about their cost of operation. Price a nuclear reactor lately? Although I suppose Intamin reactors would be cheaper than B&M's. Would you want to rely on a Vekoma reactor for your next launch?

But how often do you need to refuel a nuclear powered vessel. In an unfriendly situation, it might not be all that easy to stop in to the nearest gas station.

I still like springs. ;)

See? :P (re: link) *** Edited 1/7/2004 9:01:16 PM UTC by ApolloAndy***

---

Ride of Steel said:
well obviously dragsters launch system hasn't worked out to well...:/

---

The launch system worked well. No launch system out there hasn't had problems. Remember, a launch system like Dragster's has to bring a train weighing over 6 tons to 120mph in 4secs every 30-40 secs 12-14 hours a day. Dragster was able to do that with a very few delays in September and October, after the glitches were worked out in June and July. These delays were caused by rollbacks, which have nothing to do with the launch. *** Edited 1/7/2004 9:49:06 PM UTC by gomez***

I agree with RideMan that you can't just snap a train instantly onto a cable. Because the train isn't going to instantly accelerate to the speed of the cable, it'll be traveling slower than the 120 mph cable, and tearing it to shreds in the process.

As for the Nimitz carriers, I thought being able to cruise around for 15 years without "refueling" was pretty good, but I guess I was mistaken.

I *still* like my idea of just running the launch sled like a maglev to reduce friction. Have the sled float over a magnetic field rather than through the channel in the coaster track. At least, I assume it runs through a channel in the track, that's how it seems to work on Xcelerator (the only rocket coaster I've ridden). The only thing I would worry about is hitting magnets on the end of the launch run, I would imagine it could potentially shove the launch the sled instead of just stopping it.

I think the main problem with the idea is the strength of the cable grip. All the cable grips I've seen on ski lifts, and for that matter on CP's Sky Ride, use springs to clamp the grip together against the cable. I bet there would be problems with the grip slipping under the weight and acceleration of Dragster.

Also, think for a minute if something went wrong during the release and the grip didn't detach? The consequences would not be good, the way Dragster launches now makes such a scenario impossible.

Everyone who thinks Ride of Steel is insane, remember the wise words of Stan Checketts:

" I generally don’t work with my engineers a lot at first. I generally go out in my back yard, with tons of metal, cable and pistons and start playing with all kinds of models. I’ve got all kinds of projects out there behind the shop where..... My wife was standing there and she said “Wow, you’ve got problems.” I said, “I just see challenges.” "

I'd like to see what Ride of Steel has come up with in about 5 years :)