Vertigone???...then what is this????
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+ Josh M. +
"I will never doubt the forces of physics again"~Passenger leaving MF
Ripcord Crew '02
'02 MF Rides: 00
'02 Wicked Twists: 00
*** This post was edited by CoastFreak on 4/14/2002. ***
I think Stan Checketts was right about how it only happened because S&S instructed CP it would be safe to remove the cables for the winter and the one tower swayed to much and weakened and fell over. (Much like the every so popular swaying bridge in the 1940's?)
Hypothetically, I think if CP put the towers back up in a few years, kind of like a thing to make people who did see it and the fraction of the people who heard about what happened to it, would probably think the defect was fixed. If CP left the cables on for the following winters then we could actually see a safe and sounds ride which lasts year after year.
IMO, I now beleive CP did the right thing. I'm still not sure if CF made the right call for Knotts.
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- Chris -
http://www.thepointol.com/~simplycp
Vortex shredding seems to be what everyone has agreed on for the demise of VertiGo right? Well I doubt they have to worry about that very much in southern California. And remember, CP said that if it had been during the season, they would have caught it, and I'm sure SF does a good job checking all their rides. They may suck at running parks but they have to be safe too.
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Brent Haley
Gemini Crew '02
Vortex shredding does not mean an 80 mph wind came along and blew the tower down. Therefore I don't see how you can say that it is nothing to worry about in southern California. Winds were not any different the day the tower fell than during the operating season. I tried doing a search to get a good explanation of vortex shredding, but I didn't find much. Maybe someone smart can chime in. :)
I think CF made the right move for CP and Knotts. Personally, I don't think the stability of three 265 foot towers should depend on three cables and a ride unit. What happens when you have to replace the cables? Is that just a couple of hours where you are "at risk?" It just doesn't seem right to me. I love S&S, but I just can't buy that explanation. I'm interested in seeing what modifications they make to the SFMM version though.
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-Matt
2001 Magnum Crew
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Brent Haley
Gemini Crew '02
Yeah, obviously most peopl ewho remember that day, remember there was very little wind. I'm not sure what Vortex shredding is, but it sounds like it has to do with winds. There were many days I can remember in december that were fairly windy, plus there were several days in the beginning of January where there were High WInd advisories and the winds were pretty strong and fierce. It is possible to say the 5mph winds that might have been present that day were enough to topple an already weakend structure from previous wind storms.
We still have to wait for the official reason.
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- Chris -
http://www.thepointol.com/~simplycp
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Break the scream barrier in 2002!
Wicked twists: 0
VertiGo: (2001-2002) R.I.P.
...Or what if the exact opposite happens and another one breaks and someone gets hurt? The first words out of the lawyer's mouth will be, "You knew this could happen."
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Jeff
Webmaster/GTTP, Sillynonsense.com
"As far as I can tell it doesn't matter who you are. If you can believe, there's something worth fighting for..." - Garbage, "Parade"
Flisk said:
Much like the ever so popular swaying bridge in the 1940's?
I guess you mean the Tacoma Narrows Bridge, which collapsed on November 7, 1940. One of the best examples of wind-induced failures we'll ever see...
--Greg, who's been stuck in traffic on the replacement bridge, and notes you can STILL feel the whole thing moving, but they've worked around the problems the original had...
My Home
MF count: 52
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- Chris -
http://www.thepointol.com/~simplycp
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I'd rather die living than live like I'm dead
The basic theory is this: When a straight-line wind blows against a tower, the interference between the wind blowing past the tower and the wind being diverted by the tower will form little circular turbulent air streams on the lee side of the tower, creating alternating high and low pressure zones on either side of the tower. That's vortex shedding.
To bring the other important factor into play here, any standing object has a natural resonant frequency. When the resonant frequency is reached, the object can be induced to oscillate much further than would normally be expected as the oscillations exactly match the object's own resonance, which normally dampens those oscillations.
Now if we bring these two phenomena together, a straight-line wind will create vortex shedding which will apply lateral forces on a structure at right angles to the wind direction. If the transverse oscillations caused by the vortex shedding happen to be at the natural critical frequency of the tower, the tower will oscillate with an unexpectedly large amplitude, ultimately weakening at the nodal point (the place where it isn't moving anymore) and stressing the structure to the point of fracture or collapse.
At least that's how I interpret it. Here is the fairly clear explanation I found when I went looking.
(Not to be confused with another kind of "Vortex shedding" that some of us witnessed last weekend...if you were there, you know what I mean...)
--Dave Althoff, Jr.
GregLeg1 said:
Flisk said:
Much like the ever so popular swaying bridge in the 1940's?
I guess you mean the Tacoma Narrows Bridge, which collapsed on November 7, 1940. One of the best examples of wind-induced failures we'll ever see...
--Greg, who's been stuck in traffic on the replacement bridge, and notes you can STILL feel the whole thing moving, but they've worked around the problems the original had...
My Home
MF count: 52
The Macinaw Bridge was designed with a much different structure do to lessons learned from the collapse of the Tacoma Narrows bridge. The Narrows Bridge was designed with a very narrow road way, a flat bottom surface and a solid girder side wall several feet high. Because of this construction, The Bridge was both susceptible to lateral push and lift. As winds increased on the fateful day the bridge began to oscillate and rock, causing the cables to be constantly tensioned and untensioned eventually causing them to snap. Think of this the next time you fly the flyers. The Mackinaw Bridge is constructed using a lattice work deck structure that is very flexible and overly sturdy at the same time it also provides very little wind resistance. The deck of the bridge also has mesh center lanes to allow wind to flow up thru the structure and stabilize it. Incidentally there is a bridge in Maine constructed exactly like the Narrows Bridge; it has been fitted with a triangular box structure along the sides to allow the winds to flow evenly over and under the structure. The Anthony Wayne Bridge in Toledo is also of the same construction but its short span and added weight from its 4 lane deck allow it to be very stable.
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*** This post was edited by kneemeister on 4/16/2002. ***
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