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cracklover
Feb 26, 2004, 9:58 PM
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In reply to: And last tiime I looked, 2.18 or even 2.2 .r even 2.3 is not a lot bigger than 2.0. This guy is claiming the increase can be infinite.
Okay, you can now see how it is possible to increase a FF over two. As a purely theoretical problem (because that's all it is) you should now be able to see how you can give a ff = 4, ff = 10, 100, etc. (infinite is hard).
GO
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timpanogos
Feb 26, 2004, 10:04 PM
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Heck, you guys are dealing with sissy + factor 2 fall scenarios.
Ok, My leader climbs up 200', no pro off the anchor and pitches.
Rope elongation on the lead rope is 7%, so, technically my leader falls 414 feet before bungy bounching back up.
so 414/ 200 = 2.07
But what is really the danger for the leader here, is after he climbs/jugs back up to the anchor, I punch his lights out for being an idiot.
Fall distance over rope out, and oh yea if you fall below your last fixed point (2, 2.07, 2.whatever) you're going to need to clean out your pants (and maybe get your ribs/spleen looked at).
Hey, it's not just a good idea - it's the law!
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drkodos
Feb 26, 2004, 10:07 PM
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Wrong.
20 feet above the anchor, as measured from where? You can't be 20 feet above the anchor unless there is 20 feet of rope out.
Then 20 feet above to below would be a 40 foot fall on 20 feet of rope.
40/20 = 2.0
You guys that got 37 feet are crazy. Your ARITHMETIC is faulty.
Yarding rope does not increase fall factor. Here is why:
It reduces both the fall AND THE LENGTH OF ROPE. Both variables are affected, not just one as in the above fallacious analysis.
It is simple arithmetic. Not mathematics.
When you pull ion rope there is less rope out and there is less distnace one can fall. Period.
You can never be farther from the belay than the amount of rope you have out.....if there is 17 feet or rope then you are 17 feet (or less!) off the belay.
It is possible though to be 17 feet up and have more rope due to slack. This DECREASES fall factor and is why people like me like having SLACK when I push my limits.
Then 17 feet up with 25 feet of rope and falling below the anchor would be this.
17 feet + 25 feet below the anchor = 42 feet.
42 feet over 25 feet...42/25 = 1.64
Fall factor can never be above 2.0 by its definition.
Both theoretically and in the real world.
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dirtineye
Feb 26, 2004, 10:13 PM
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In reply to: In reply to: And last tiime I looked, 2.18 or even 2.2 .r even 2.3 is not a lot bigger than 2.0. This guy is claiming the increase can be infinite. I think he's claiming that theoretically it can. You can never actually achieve infinity. You could achieve a large increase in the fall factor if the belayer could take in slack fast enough and the fall was short enough. -Jay
Sadly, I don't think he is being theoretical. I agree with the point that unless the fall is long, the belayer does not have much time to do a lot of reeling in.
What are you calling a large increase?
I've only seen about 3 feet be taken in in a 20 foot fall.
Something that is not theoretical however is the effect of friction on the rope running through the pro and rubbing against the rock. that can raise the fall factor, but in a fall on the anchors, I guess this is not an issue.
I've read in more than one place that actual fall factor can't even pass 1.77.
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drkodos
Feb 26, 2004, 10:14 PM
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In reply to: Heck, you guys are dealing with sissy + factor 2 fall scenarios. Ok, My leader climbs up 200', no pro off the anchor and pitches. Rope elongation on the lead rope is 7%, so, technically my leader falls 414 feet before bungy bounching back up. so 414/ 200 = 2.07 But what is really the danger for the leader here, is after he climbs/jugs back up to the anchor, I punch his lights out for being an idiot. Fall distance over rope out, and oh yea if you fall below your last fixed point (2, 2.07, 2.whatever) you're going to need to clean out your pants (and maybe get your ribs/spleen looked at). Hey, it's not just a good idea - it's the law!
rope stretch DECREASES fall factor by making both variable longer. You need to add the lenght of stretch to both sides of the equation. It is arithmetic. You cannot just add to one side and not the other willy nilly.
As the falls becomes longer, so does the rope!
The definition of fall factor is a closed end system that goes from 0 to 2.0.
Until quantitative analysis is presented in the form of some higher physics and mathematics, I maintain my position.
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jt512
Feb 26, 2004, 10:15 PM
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[quote="drkodos"]Wrong.
20 feet above the anchor, as measured from where? You can't be 20 feet above the anchor unless there is 20 feet of rope out.
Then 20 feet above to below would be a 40 foot fall on 20 feet of rope.
40/20 = 2.0
You guys that got 37 feet are crazy. Your ARITHMETIC is faulty.
Yarding rope does not increase fall factor. Here is why:
It reduces both the fall AND THE LENGTH OF ROPE. Both variables are affected, not just one as in the above fallacious analysis.
That is why it does affect the fall factor. More precisely, the fall factor is a ratio, and when you pull in slack, you reduce the numerator and denominator by the same addititive amount. In order for the ratio to not change, the ratio would have to be 1. Otherwise, the numerator and denominator are not changed proportionately.
(a - c) / (b - c) does not equal a/b, unless a = b.
-Jay
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drkodos
Feb 26, 2004, 10:18 PM
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I will add 10 perecnt stretch:
20 feet above the anchor. 20 feet of rope out. Fall.
The 20 feet of rope streches 2 feet and becomes 22.
the fall then becomes ten percent larger and becomes instead of 40, 44.
Now our formula:
x/y = ff
x= 44
y= 22
44/22 = 2.0
It is simple arithmetic. It is a ratio, folks. That is the nature of a ratio.
Some of you guys are using math straight out of Spinal Tap.
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cracklover
Feb 26, 2004, 10:28 PM
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Doc, you are right. As the climber begins to fall, gravity will anticipate that the belayer will take in 3 feet of rope over the course of the 40 foot fall, and cause the climber to only accelerate for 37 feet, rather than the usual 40. :roll:
And can I just mention two other things:
1 - FF uses the fall length before the rope begins to catch you.
2 - In a high fall factor expect the rope to stretch 30% or more.
GO
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jt512
Feb 26, 2004, 10:32 PM
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In reply to: I will add 10 perecnt stretch: 20 feet above the anchor. 20 feet of rope out. Fall. The 20 feet of rope streches 2 feet and becomes 22. the fall then becomes ten percent larger and becomes instead of 40, 44.
No. The fall becomes 5% larger.
42/22 = 1.91
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shakylegs
Feb 26, 2004, 10:34 PM
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Ah yes, the famous fall factor going up to 11.
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dirtineye
Feb 26, 2004, 10:34 PM
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In reply to: I will add 10 perecnt stretch: 20 feet above the anchor. 20 feet of rope out. Fall. The 20 feet of rope streches 2 feet and becomes 22. the fall then becomes ten percent larger and becomes instead of 40, 44. Now our formula: x/y = ff x= 44 y= 22 44/22 = 2.0 It is simple arithmetic. It is a ratio, folks. That is the nature of a ratio. Some of you guys are using math straight out of Spinal Tap.
Actually the rope does not stretch til you fall on the pro right?
So 20 feet above the anchor, plus 20 feet below plus 2 feet for rope stretch would be 42/22, or less than 2.
There is a more advanced fall factor calcuation on the Beal web page, that takes into account things that the theoretical calc does not.
http://www.impact-force.info/anglais/impact.html
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olderic
Feb 26, 2004, 10:38 PM
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Stretch doesn't enter in to it - the ratio denominator is the unweighted length of the rope at the instance that the falling weight comes on it. But even assuming that stretch can be factored in you are failing to grasp or at least acknowlege that the length of rope between the belay and the faller can change between the time the fall begins and the time it starts to get caught. In the case of a free fall it might be unrealistic to expect that it will change much, but in the case of a sliding slab fall it is common - there are plenty of real like stories of unanchored belayers sprinting down the hill to take it in on a slab fall - and yes yarding some in too. Of course in the case of a sliding slab fall the fall factor is not especially important in talking about the severity of the fall. But since you seem to be hung up on the actual mathamatics - and it is obvious tfat FF-s > 2 can easily be produced in real word situations. I do not comprehend how you don't grasp the flaw in your own 20 feet out, no pro, belayer yards in 3 example.
the fall is 37 feet, the length of the rope decreased 3 feet while the fall was in progress. Oh I give up - I am going actually climbing - does anyone here do that?
In reply to: I will add 10 perecnt stretch: 20 feet above the anchor. 20 feet of rope out. Fall. The 20 feet of rope streches 2 feet and becomes 22. the fall then becomes ten percent larger and becomes instead of 40, 44. Now our formula: x/y = ff x= 44 y= 22 44/22 = 2.0 It is simple arithmetic. It is a ratio, folks. That is the nature of a ratio. Some of you guys are using math straight out of Spinal Tap. |
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alpnclmbr1
Feb 26, 2004, 10:55 PM
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Doc, I assume by this point you will concede the numbers.
As far as fall factors
If you take a static fall onto a anchor sling it is easy to surpass FF2
via ferrata equipment is designed for fall factor 7
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drkodos
Feb 26, 2004, 11:38 PM
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Via Ferrata and rope free climbing are not comparable systems for fall factor.
It is possible to have a greater number than 2 in Via Ferrat, I concede that.
But it is not possible in a roped free climbing system. The roped climbing system is a close ended system. Via Ferrata is not.
I will, however, accept whatever definition a legitimate PhD of mathematics and physics has to say on the matter.
Until then, I maintain my position, but remain open minded as I have stated my bar level for burden of proof.
And that position is: In a closed system of free climbing with proper use of a dynamic rope and a system of protection, it is impossible to exceed fall factor of 2.0
I am willing to be shown the light, but it must be very clear and bright, for I am dense and deeply wooded in the mind.........
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dirtineye
Feb 26, 2004, 11:39 PM
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I found this link
http://www.geocities.com/Yosemite/Trails/8700/ropes.html
that details the fall factor testing method of the UIAA. Since they have a little rope (.3 m) between their carbiner like device and they only use a 2.8 meter length of rope( only 2.5m in the fall), they have a 1.77 ff in their 5 m test fall
So applying this to our belayer, he would have to be right up against the anchor biner or you will have to count that bit of rope between atc and anchor biner. Of course this little bit will make less difference as more rope is out.
As far a this discussion goes, ti was not about via ferrata or aind falls on daisys or falls on slings or anything but fall factors on climbing rope. Someone did predict that via ferrata woud lbe brought up and they were right hahaha.
As far as slab falls and belayers running down the slab, that is also not relevant to this discussion.
The 20 feet up with no pro except the anchor and the belayer yarding in three feet seems plausible. The situation where you have a ledge 20 feet below and no pro for 20 feet above this belay station sounds like one to avoid, but it is true that the theoretical FF would be 2.18 or so.
But what difference does this make?
Time to use the impact force calculator...
Using the calculation given here
http://www.impact-force.info/anglais/impact1.html
And a rope max impact force rating of 9,500N, I got for a ff of 2.18, 10,446N and for an ff of 2 10,041N
Still acceptable, and that is with a fairly high impact rope.
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jt512
Feb 26, 2004, 11:52 PM
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In reply to: Via Ferrata and rope free climbing are not comparable systems for fall factor. It is possible to have a greater number than 2 in Via Ferrat, I concede that. But it is not possible in a roped free climbing system. The roped climbing system is a close ended system. Via Ferrata is not. I will, however, accept whatever definition a legitimate PhD of mathematics and physics has to say on the matter.
By my count you've been corrected by one mathematician, one statistician, and one engineering student. Maybe it is time to take the hint.
In reply to: Until then, I maintain my position, but remain open minded as I have stated my bar level for burden of proof.
I've already stated an informal proof above. Here's a more rigorous one:
Let a, b, and c be positive numbers. Then, as c approaches the smaller of a or b:
If a < b, then (a - c)/(b - c) approaches a limit of 0, or
If a > b, then (a - c)/(b - c) approaches infinity.
-Jay
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vegastradguy
Feb 27, 2004, 12:05 AM
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If a climber falls frm 20 feet up and has no gear, and the belayer manages to yard in a 3 feet of slack, the fall factor is 2.18.
The climber falls from 20 feet up. He falls 20 to belay, during this time, the belayer yards in the slack. He then falls 17 feet past belay before the belayer catches him.
This translates to a 37 foot fall. 37 feet on 17 feet of line is a Factor 2.18 fall.
Of course, this sort of thing is rare at best, and for all intensive purposes, a factor 2 is about as bad as it can get, but not the worst it can get.
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drkodos
Feb 27, 2004, 12:05 AM
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In reply to: In reply to: Via Ferrata and rope free climbing are not comparable systems for fall factor. It is possible to have a greater number than 2 in Via Ferrat, I concede that. But it is not possible in a roped free climbing system. The roped climbing system is a close ended system. Via Ferrata is not. I will, however, accept whatever definition a legitimate PhD of mathematics and physics has to say on the matter. By my count you've been corrected by one mathematician, one statistician, and one engineering student. Maybe it is time to take the hint. In reply to: Until then, I maintain my position, but remain open minded as I have stated my bar level for burden of proof. I've already stated an informal proof above. Here's a more rigorous one: Let a, b, and c be positive numbers. Then, as c approaches the smaller of a or b: If a < b, then (a - c)/(b - c) approaches a limit of 0, or If a > b, then (a - c)/(b - c) approaches infinity. -Jay
I publically stand corrected.
Thank you for your patience as I did state that I am densely wooded in the brain.
That being said, I still have only ever taken 1 fall above factor 1.0 Of that I remain certain.
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dirtineye
Feb 27, 2004, 12:18 AM
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Jay that is not a proof, that is a set of statements that now must be proved.
Depending on what you will accept as true, a proof could get really tedious haha.
I think with a little more nudging though, drkodos will accept that you can contrive a ff of a little greater than 2. I'm not going to accept that you can get a really big ff by any action the belayer can take in reality, so let's leave out the idea about aproaching infinity, or even ff of 3.
One more time, climber places no pro above anchor, climber falls 20 feet above anchor, belayer yards in 3 feet, climber falls the 20 feet down to the anchor plus the 17 feet past for 37 feet. 37/17 is about 2.18.
This adds about 440 Newtons or so the the impact force the climber feels in a factor 2 fall, as I calculated above using the impact force calculation I linked to.
Now unless you can come up with a REASONABLE way to get a much higher ff, enough to get over an impact force of 12kN, it don't matter.
By the way, for the example of running down the slab, that will not really raise the theoretical ff even if your belayer were jumping off a ledge, because THE ROPE IS STILL IN THE SYSTEM.
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shut_up_and_climb
Feb 27, 2004, 12:30 AM
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do you know how to find the resting "kn" on the fall of an 8" draw from a 4' fall on an 11mm static rope? lets say the climber weighs 120 pounds.
-kyle
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dredsovrn
Feb 27, 2004, 12:31 AM
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In reply to: In 30 years of climbing and over 750 leader falls I have only one time ever taken a fall with a factor in excess of 1. I have taken over 10 falls with factors of 1, all of them right into the ground itself. That probably explains much............
Holy Crap! They should build a statue of you. I am going to guess that you have gotten over your feer of falling on gear. I hope to do the same someday.
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allthetime
Feb 27, 2004, 3:27 AM
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i don't think a belayer yarding in one armful of rope is "theoretical". The natural movement of bringing your brake hand from in front of you to back by your hip in a lock off position can take in 1-2 feet of rope. In addition, if the belayer is paying attention it can be readily apparent when a climber is going to fall, and if you anticipate the fall, you can easily yard in a full arm's length of rope.
good dr., now that you've gotten some of the intricacies of fall factors straightned out, how about revisiting the case where the leader is able to get one sketchy piece of pro in before falling. should the belayer take in rope if possible during the fall?
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drkodos
Feb 27, 2004, 3:39 AM
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In reply to: good dr., now that you've gotten some of the intricacies of fall factors straightned out, how about revisiting the case where the leader is able to get one sketchy piece of pro in before falling. should the belayer take in rope if possible during the fall?
I have already conceded this one as well, but I will do so here again publically.
Damn' it, Jim, I am rhetorician, not a mathmatician!
A piece is better than no piece.
Fall factor can be higher than 2.0.
What other hot button topics I am on the cannabis-addled-brain side of?
Act now, while I am down and ready for a good kicking. A window of opportuntiy like this is fleeting.
http://www.rottentomatoes.com/...&dateline=1054664104
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jt512
Feb 27, 2004, 3:44 AM
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In reply to: i don't think a belayer yarding in one armful of rope is "theoretical".
No, it isn't theorectical. Gumby belayers do it all the time.
In reply to: The natural movement of bringing your brake hand from in front of you to back by your hip in a lock off position can take in 1-2 feet of rope.
I disagree with that. The natural movement -- or at least the correct one -- is to bring your hand directly to your hip, which doesn't pull in any slack at all. To pull in slack, the belayer would have to straighten out his arm, which is neither natural nor correct, unless the situation really calls for pulling in slack.
In reply to: In addition, if the belayer is paying attention it can be readily apparent when a climber is going to fall, and if you anticipate the fall, you can easily yard in a full arm's length of rope. some people do that as a reflex.
Yes, that is a common gumby mistake, and the main reason I am very selective about who I allow to belay me. Pulling in slack like this can slam the leader violently into the wall, as has been discussed many times on this site.
Whether or not pulling in a foot or two of slack would make any practical difference in a factor-2 fall is not clear to me, though. Using a non-auto-locking belay device, a lot of rope is going to slip throught the device, resulting in an impact force much less than that which would result from a statically belayed factor-2 fall. Perhaps with a grigri, pulling in slack would be a problem, but then again, taking a factor-2 fall on a grigri is a problem itself.
In reply to: good dr., now that you've gotten some of the intricacies of fall factors straightned out, how about revisiting the case where the leader is able to get one sketchy piece of pro in before falling. should the belayer take in rope if possible during the fall?
I was going to go into that next, but I'll hold off to give drkodos a chance to respond.
-Jay
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vertical-rockrat
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Feb 27, 2004, 3:49 AM
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Anyone got a calculator?
Hmm 50 feet up and i don't think fall factor is running thru my head about then lol. Im shaking with a possible 15 foot fall knowing its gona hurt some if i land hard and my harness shifts.
OHHHHH wait ya i need to know this so when i make my first homemade rope i will know if it can take the fall.. LOL
I can understand wanting to know what fall factor is but i think what is most important is to know how many falls you have taken on your 6 fall rated rope.
just my opinion. alltho i would like to thank those for explaning it simple and giving the ratios. nice knowledge.
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