Cedar Point says Top Thrill Dragster is done, sort of

I don't think any coaster has ever done that, and it sounds like a waste of electricity.

I agree. I thought that was what the original question was asking.

Shades:
That seems different than launching and falling and having the LSMs stop you from falling backwards and then push you forward.

Closest to that is probably the back spike on Superman:Whatever the heck they called it at Geauga Lake. When the train hit the top of the back spike, they ran a set of LIMs in reverse at stall to hold the train for a half a second.

After Cedar Fair took over, that feature went away when Wicked Twister blew out a motor contactor. It seems Intamin used the same contactor for the main drive as they did for the holding drive, so by cannibalizing that part from Geauga's ride they were able to keep both rides running.

--Dave Althoff, Jr.

Do any V2 clones still run the holding brake? Have any run them this century?

I believe V2, or Flash, at SFGAm did through last year. It didn't seem to be running the hold this year, at least not that I saw in the few cycles I watched.

PhantomTails:

I don't think any coaster has ever done that, and it sounds like a waste of electricity.

I freely acknowledge I have no idea what the energy load would be. In the version of TTD that the Dippin Dots guy did not tell me about, I'm imagining you'd get some floaty air as you stalled on the way up, and a big boost of positive Gs when the LSMs caught you and propelled you back skyward. I dunno, seems like it would be cool to me, but YMMV.

There's plenty of people who think amusement parks are a waste of energy.

(Would using the LSMs as a brake after the partial rollback allow you to generate electricity? My physics understanding stalled at electromagnetism.)

Yes, it is possible to use LSMs as brakes to generate electricity. Some, if not most, maybe even all industrial motor controls allow for regenerative braking, where the energy can be turned back into electricity. I don't know, but my instinct tells me they don't often use regenerative braking on roller coasters. Safety reasons maybe?

hambone:

I freely acknowledge I have no idea what the energy load would be. In the version of TTD that the Dippin Dots guy did not tell me about, I'm imagining you'd get some floaty air as you stalled on the way up, and a big boost of positive Gs when the LSMs caught you and propelled you back skyward. I dunno, seems like it would be cool to me, but YMMV.

I agree it would be cool, and I just don't know how practical it would be. According to wannabe electrical engineers on the internet, converting TTD to LSM would already be at the limits of energy storage, so having every train launch twice might be pushing it.

I did some "back of the envelope" calculations, and with the latest in super capacitor technology, it certainly possible to store enough energy to launch a dragster train.

Math: A dragster train weights 15 tons. I'll assume this is metric tons, so 15,000 kg. 120 MPH is about 55 m/s. ke = 1/2 * m * v ^ 2, or 22.7 MJ.

One of the first super capacitors I found runs at 300V, 5F. 1/2 * c * V ^ 2, or 225 kJ.

Thus, It would take about 100 of this particular capacitor to store the energy needed to launch a dragster train. This capacitor is not cheap, costing over $4000 each. So for about half a million dollars, you could buy enough capacitors to store the electrical energy of a launched dragster train. I would absolutely put this in the realm of practical. But, keep in mind, these are very rough estimates.

I can't remember who told me this, but I recall that replacing capacitors was one of the bigger expenses on Wicked Twister, and it may have contributed to the decision to retire it.

I assume one of the problems with using regenerative brakes as your primary braking system is that if the circuit is broken at any point for some reason, you don't have brakes anymore.

Precisely, in the railroad and transit industry regenerative, AKA dynamic braking, is secondary to the primary braking system, which is air brakes.

I hadn't heard that Wicked Twister was blowing a lot of capacitors, but I guess I wouldn't be surprised if it was.

In what I would consider a "well designed" system, the capacitors would not need to be replaced frequently. However, if the capacitors were not properly derated for the application, then there would be frequently blown capacitors. Adding more capacitors to the system would reduce the load on each individual capacitor, allowing the capacitors to last longer. Additionally, keeping the capacitors cool can dramatically improve the life of the caps as well. A general rule of thumb, for every 10C reduction in temperature doubles the expected life of the capacitor.

I don't have any specifics, but I get the general sense that when Intamin builds a ride, they spec out the power components to be "just" enough for the application. This helps reduce the up front cost, but results in more frequent failures of the components, and a higher maintenance cost.

Do any V2 clones still run the holding brake? Have any run them this century?

Voodoo/Possessed did for quite a while after it was relocated to Dorney, but I haven't seen it operating this season.

The holding brake on Voodoo/Possessed has not been operational as far back as at least 2018

Steel Venom at Valleyfair! had the holding brake going earlier this season.

The holding break on V2 'burned out' years ago, maybe a decade or more. My question is, why don't they take if off the track? It's just sitting up there, perhaps used as sensors?

What's the point of spending the money to remove it when it does no harm to stay up there?

^Good point. It's SF not CF.

BrettV:

What's the point of spending the money to remove it when it does no harm to stay up there?

I'm curious about the difference in cost between retrofitting TTD and tearing it down. Bringing those cranes back wouldn't be cheap, and imploding it seems dicey.