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Climbing Disciplines:
Trad Climbing:
Re: [Perihelion] Most Worthless Piece of Gear:
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jt512
Oct 15, 2010, 6:47 PM
Views: 5117
Registered: Apr 12, 2001
Posts: 21904
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Perihelion wrote: Interesting. There are some things to think about here. I printed the pdf & will review that, however, there is an abbreviated version available at http://en.wikipedia.org/wiki/Fall_factor.
I know. I wrote most of the Wikipedia article.
In reply to: I need to work a few examples using real-world values before I comment further.
If you want an easy way to work with the equation(s), you can use my online impact force calculator. It reports results using two models: the standard model and another model that treats friction at the top anchor in a more accurate fashion [source].
In reply to: I will add one thing, in passing: Although it is mathematically possible to have FF=0, in practice, if that were true you would have no fall. FF is always > 0, even in a TR situation.
No, a toprope "fall" with no slack in the rope does in fact have a fall factor of 0. Fall factor is defined to be the length of the fall divided by the length of the rope out, where fall length is defined to be the height of the climber at the beginning of the fall minus the height of the climber just before the rope begins to stretch. Therefore, for a TR "fall" with no slack in the rope, the fall factor is 0 divided by a positive number; that is, the fall factor is 0.
Zero is a perfectly valid value for fall factor in either the standard or friction-adjusted impact force models. With a fall factor of 0, both models reduce to
T_1 = 2w ,
where T_1 is the tension in the climber's side of the rope and w is the climber's weight. This implies, perhaps surprisingly, that the maximum impact force (on the climber) in such a toprope "fall" will be twice the climber's weight, and perhaps more surprisingly, it will be so for a rope of any elasticity.
Jay
(This post was edited by jt512 on Oct 17, 2010, 5:24 AM)
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Edit Log:
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Post edited by jt512
() on Oct 15, 2010, 6:58 PM
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Post edited by jt512
() on Oct 15, 2010, 9:17 PM
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Post edited by jt512
() on Oct 17, 2010, 5:24 AM
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