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tahoe_rock_master
Feb 26, 2004, 1:49 AM
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I was wondering what Fall Factor was. I saw it mentioned as "Factor 2 fall". Although I have been climbing for about two years I have never heard of this expression.
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curt
Feb 26, 2004, 2:17 AM
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In reply to: I was wondering what Fall Factor was. I saw it mentioned as "Factor 2 fall". Although I have been climbing for about two years I have never heard of this expression.
Although the search engine on this site leaves something to be desired, you might try searching for "fall factor" because this topic has been covered several times.
Basically the fall factor is the distance fallen divided by the length of rope that is available to absorb the kinetic energy generated by the fall. The number is constrained between some number approaching zero on the low end, and 2 on the high end. It is used to calculate the force "seen" by the gear, climber and belayer in different fall scenarios. The higher the fall factor--the higher the force. Hope this helps a bit.
Also, you may want to reference this thread -
http://www.rockclimbing.com/forums/viewtopic.php?t=52735&postdays=0&postorder=asc&topic_view=&start=0
Pay particular attention to the posts by rgold (Rich Goldstone) who was one of the top climbers of the 20th century and is also a PhD. and Professor of mathematics.
Curt
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drkodos
Feb 26, 2004, 2:44 AM
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I think the concept of fall factor is much underappreciated and misunderstood.
Most falls people will ever take are much lower than a 1.0 on the scale that goes to 2.0, because you cabn never fall farther than twice the length of the rope itself, if you are tied in and want it to be used a safety measure by having it running through a system of protection.
Fall factor is feet fallen over amount of rope. It is an easy ratio to understand, I think despit the fact that I have no PhD in mathmatics for this is really arithmetic.
10 foot fall 100 feet up a climb would be:
10/100 = Fall Factor .10
10 foot fall 50 feet up? 10/50 = Fall Factor .2
The higher the number, the higher the force. Also, notice how the fall distance is not as important as the ratio. Certainly a 10 foot fall on 150 feet of rope is much more palatble than a 10 foot fall while only 10 feet off the deck! It's ll about the ratio.
A 20 foot fall while 22 feet off the deck would be: 20/22 == FF .909
In order to have a factor above 1, a person must fall lower than an anchor and be on an upper pitch, else a 30 foot fall 30 feet off the deck and you crater.
But high up a cliff, on a multipitch route, it is possible to be 50 feet off the belay and fall only to end up 20 feet below the original belay anchor. This 70 foot fall would then be: 70/50 = A fall Factor of 1.4 !!! Very dangerous! As anything over 1.0 is some sever sheet.
While I am not a PhD in manthematics, I feel this is an easy ratio to understand, and though I am sure to have oversimplified, I welcome any corrections, additions, or rearticulations of my layman's blatherings.
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............
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curt
Feb 26, 2004, 2:54 AM
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750 leader falls? Good God man, I hope you were wearing a helmet. Hahahahahahahahahaha. Have you considered shuffleboard instead? :lol:
Curt
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drkodos
Feb 26, 2004, 3:08 AM
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In reply to: 750 leader falls? Good God man, I hope you were wearing a helmet. Hahahahahahahahahaha. Have you considered shuffleboard instead? :lol: Curt
There are some tough routes at the Gunks that I have fallen all over..... :lol: and up. (Many of them with Dr. Goldstone's nome de plume on the FA)
Perhaps lack of helmet has conribulated to my latest affloctions, but I donut think it has hade an efect atoll.
I am stupefyingly proud that I have already logged 11 falls and a crater shot this year already!
Although recently an aquaintance suggested the actual idea inherrant in the pursuit of climbing was to make progress upwards, so I am thinking of giving that a try one of these daze.....
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allthetime
Feb 26, 2004, 7:48 PM
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Most falls people will ever take are much lower than a 1.0 on the scale that goes to 2.0, because you cabn never fall farther than twice the length of the rope itself.
Just to be accurate: the maximum fall factor is infinite. You can very easily fall more than twice the distance of the amount of rope out at impact.
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allthetime
Feb 26, 2004, 7:52 PM
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In reply to: I think the concept of fall factor is much underappreciated and misunderstood. Most falls people will ever take are much lower than a 1.0 on the scale that goes to 2.0, because you cabn never fall farther than twice the length of the rope itself
Just to be accurate: the maximum fall factor is infinite. You can very easily fall more than twice the distance of the amount of rope out at impact.
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allthetime
Feb 26, 2004, 7:57 PM
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In reply to: I think the concept of fall factor is much underappreciated and misunderstood. Most falls people will ever take are much lower than a 1.0 on the scale that goes to 2.0, because you cabn never fall farther than twice the length of the rope itself...
just to be accurate: the maximum fall factor is infinite. you can very easily fall more than twice the distance of the amount of rope out at impact.
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drkodos
Feb 26, 2004, 7:59 PM
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In reply to: Most falls people will ever take are much lower than a 1.0 on the scale that goes to 2.0, because you cabn never fall farther than twice the length of the rope itself. Just to be accurate: the maximum fall factor is infinite. You can very easily fall more than twice the distance of the amount of rope out at impact.
Incorrect.
Max fall factor with a rope in a climbing system and used properly is 2.0
I explained this in my first post. If both people are tied in and protection is being used and the rope and anchors work, the maximun fall is twice the length of the rope. Period.
Free soling does not count. There is no such thing as fall factor if there is no rope involved.
Any fall that does not weight the protection system does not count. Fall factor is all about force being transfered to the protection system and/or anchor.
Please think about it.
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allthetime
Feb 26, 2004, 8:13 PM
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In reply to: Incorrect. Max fall factor with a rope in a climbing system and used properly is 2.0...I explained this in my first post. Please think about it.
ok, fair enough...thinking...thinking...ahhhah! a climber is on the second pitch of a route, and is 20 feet out from the belay. as it's starting to get difficult the climber looks for the next bolt or place to put pro. the belayer sees his partner's legs start shaking and readies the belay. the climber slips and falls before finding any pro, and the belayer takes in one armfull of rope, say 3 feet, and locks off, and braces for the impact. what's the fall factor?
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voriand
Feb 26, 2004, 8:18 PM
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The INCREASE of fall factor would be small and pointless.
Besides you should be locking off for the impact. Not messing around trying to pull in rope.
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olderic
Feb 26, 2004, 8:54 PM
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This monthly topic seems to have surplanted long discussions on how to mark the middle of the rope, what shoes to buy, or whether or not to use the harness bealy loop to (gasp) belay off of. There will follow much arm waving and chest thumping as to whether 2.0 is the max. Foreign languages - via ferrata - will be invoked and the thread will lurch off in that direction. Then the idea of reeling in rope while a leader is falling will be spouted - could you, would you, should you... on and on an on
Question first - reserach later
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drkodos
Feb 26, 2004, 9:03 PM
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In reply to: In reply to: Incorrect. Max fall factor with a rope in a climbing system and used properly is 2.0...I explained this in my first post. Please think about it. ok, fair enough...thinking...thinking...ahhhah! a climber is on the second pitch of a route, and is 20 feet out from the belay. as it's starting to get difficult the climber looks for the next bolt or place to put pro. the belayer sees his partner's legs start shaking and readies the belay. the climber slips and falls before finding any pro, and the belayer takes in one armfull of rope, say 3 feet, and locks off, and braces for the impact. what's the fall factor?
2.0
If you fall from above the anchor to below the anchor it is always above 1.0
20 feet up and you fall with no gear and end up falling "ONTO" the anchor itself is a factor 2 fall, by definition, regardless of rope amount. It is a ration. Whatever rope is out, all of it, the leader falls the distance above PLUS the distance of that same amount below. Thus the formula which is:
Length of fall/Amount of rope
Were the first is X and rope is Y we substitute:
Y = 20 feet up. So feet of rope minus 3 yarded in is 17 feet.
Therefore Y = 17
Fall then would be the 17 feet of rope to the anchor PLUS the 17 feet the climber falls below the anchor. The additions of strecth is a little complicated,so befroe some jumps in a yells, I admit to an obversimplification here just to try to get at the basic os the ratio.
Therefore X = 34.
x/y = fall factor
34/17 = 2.0
The point is that it is a relationship between the amount of rope in the system and the distance fallen. And this ratio is more important in many cases than the actual amount someone may fall.
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allthetime
Feb 26, 2004, 9:08 PM
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In reply to: The INCREASE of fall factor would be small and pointless.
first, the increase in fall factor is potentially large-- infinite in fact. second, i would argue any increase in force when you get near the limits of your anchor is extremely significant. i think it's down to each climbing team to determine their level of risk, but to not know about a potential risk means you are precluded from making a decision as to whether it's acceptable or not.
In reply to: Besides you should be locking off for the impact. Not messing around trying to pull in rope.
what if there is a ledge 20 feet below the belay? what if the climber placed one shaky piece of pro before falling?
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allthetime
Feb 26, 2004, 9:14 PM
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In reply to: Fall then would be the 17 feet of rope to the anchor PLUS....
re-examine how far the climber is above the anchor when he starts falling. you said it earlier in your post:
In reply to: 20 feet up and you fall with no gear and end up falling "ONTO" the anchor... |
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drkodos
Feb 26, 2004, 9:15 PM
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In reply to: what if there is a ledge 20 feet below the belay? what if the climber placed one shaky piece of pro before falling?
These are two seperate questions.
If you hit a ledge, all bets are off. Fall factor is calculated based on not having momentum stopped by anything other than the protection system.
Two.
Placing a piece changes things. Let us pretend it holds and this is our new scenario.
Climber is up 20 feet and has shaky gear at 12 feet up. He then falls from 8 feet above the last piece and it holds. Now the factor is calculated thusly.
8 feet above the piece X 2 equals a fall of 16 feet.
We originally had 20 feet of rope out. So X/Y becomes 16/20 = .8 Fall factor.
Much better than 2.0!!! Anything under 1. is manageable, but anything over 1 becomes a nuisance.
Hitting a ledge anywhere in this process and now we have to talk impact physics without the use of dynamic ropes and protection systems, or some gray area in between.
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olderic
Feb 26, 2004, 9:20 PM
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[quote="drkodos"][quote="allthetime"][quote="drkodos"] Incorrect.
Were the first is X and rope is Y we substitute:
Y = 20 feet up. So feet of rope minus 3 yarded in is 17 feet.
Therefore Y = 17
Fall then would be the 17 feet of rope to the anchor PLUS the 17 feet the climber falls below the anchor. The additions of strecth is a little complicated,so befroe some jumps in a yells, I admit to an obversimplification here just to try to get at the basic os the ratio.
Therefore X = 34.
x/y = fall factor
34/17 = 2.0
I just have one question - was the leader a little upset when he was 20 feet out and you yarded in 3 feet of rope and pulled him down 3 feet before he fell?
In your over simplified version the numbers would still be 37/17 which is >2.0.
In the real world people can and do take rope in on a falling (hopefully not until afer (s)he falls) leader and produce factors greater then 2.0. Probably even more common is to give dynamic belays to lesson the fall factor - intentionally on steep sport routes - unintentionally in cases where a real fall on to the anhor is in progress.
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allthetime
Feb 26, 2004, 9:23 PM
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In reply to: In reply to: what if there is a ledge 20 feet below the belay? what if the climber placed one shaky piece of pro before falling? These are two seperate questions. If you hit a ledge, all bets are off. Fall factor is calculated based on not having momentum stopped by anything other than the protection system.
i'm afraid you missed the point. those lines of mine were in response to the person who said you should be locking off and not trying to take in rope. i gave two situations where a belayer might consider it appropriate to take in rope when the climber falls. can you see why? the first one is fairly obvious. how about the second one?
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jt512
Feb 26, 2004, 9:24 PM
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In reply to: The INCREASE of fall factor would be small and pointless. Besides you should be locking off for the impact. Not messing around trying to pull in rope.
The mathematically inclined belayer will instantly realize that, if the leader is 10 feet above the anchor with no pro in, that the best course of action is to just let go of the rope and let the leader take the maximum 210-foot fall. The rusulting 1.05-factor fall yields the minimum impact force.
HTH
-Jay
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dirtineye
Feb 26, 2004, 9:37 PM
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In reply to: In reply to: The INCREASE of fall factor would be small and pointless. first, the increase in fall factor is potentially large-- infinite in fact. second, i would argue any increase in force when you get near the limits of your anchor is extremely significant. i think it's down to each climbing team to determine their level of risk, but to not know about a potential risk means you are precluded from making a decision as to whether it's acceptable or not.
In the first place, like Drkodos has said about twice now, the fall factor RATIO of fall length to rope length out depends on rope and anchor working correctly, or it is meaningless.
Please explain how this ratio can grow large, as in much larger than 2, let alone approach infinity. If you can sucessfully show that the increase in fall factor can be infinite under any circumstance where fall factor has meaning, you will have invented a new math and a new physics, and your Nobel prize is waiting. More than likey you will just win an Ignoble prize.
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cracklover
Feb 26, 2004, 9:42 PM
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In reply to: In the first place, like Drkodos has said about twice now, the fall factor RATIO of fall length to rope length out depends on rope and anchor working correctly, or it is meaningless. Please explain how this ratio can grow large, as in larger than 2, let alone appraoch infinity. If you can sucessfully show that the increase in fall factor can be infinite under any circumstance where fall factor has meaning, you will have invented a new math and a new physics, and your Nobel prize is waiting. More than likey you will just win an Ignoble prize.
Oh please. He's already done so (and it's been done countless times before). Please check my math for me, dirt. By my calculations 37/17 is roughly 2.18.
Allthetime's point about the ledges is merely that if you know there's a ledge below you, as a belayer you may choose to take that risk and haul in rope, knowing that it may save your climber from decking, despite putting a larger force on the anchor.
But unless it's some kind of monster fall, the whole idea of yarding in is, or should be, purely theoritical. Do the calculations yourself as to how long a fall takes (they're not hard, you don't need anything more than simple multiplication, division, and the formula 10m/s/s.) Anyway, my point is that you're just going to have time to brace yourself for impact and hang on for a nasty ride - the idea of taking in rope in such a situation is really silly.
GO
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alpnclmbr1
Feb 26, 2004, 9:44 PM
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In reply to: 20 feet up and you fall with no gear and end up falling "ONTO" the anchor itself is a factor 2 fall, by definition, regardless of rope amount. It is a ration. Whatever rope is out, all of it, the leader falls the distance above PLUS the distance of that same amount below. Thus the formula which is: Length of fall/Amount of rope Were the first is X and rope is Y we substitute: Y = 20 feet up. So feet of rope minus 3 yarded in is 17 feet. Therefore Y = 17 Fall then would be the 17 feet of rope to the anchor PLUS the 17 feet the climber falls below the anchor. The additions of strecth is a little complicated,so befroe some jumps in a yells, I admit to an obversimplification here just to try to get at the basic os the ratio. Therefore X = 34. x/y = fall factor 34/17 = 2.0
37/17 = 2.176
Yarding in the rope can increase a fall factor beyond 2.0
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dirtineye
Feb 26, 2004, 9:47 PM
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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.
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jt512
Feb 26, 2004, 9:55 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.
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
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