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Terry2124
May 13, 2009, 4:31 AM
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angry wrote: Terry2124 wrote: adatesman wrote: angry wrote: No battle today, just more misinformation. It wasn't as bad as normal, he was only off by a factor of 10.  Your looking for some excitement. None here You're
Can I blame it on the Red Wings game? They are losing to the Ducks.
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Terry2124
May 13, 2009, 4:32 AM
Post #27 of 211
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jt512 wrote: angry wrote: Terry2124 wrote: adatesman wrote: angry wrote: No battle today, just more misinformation. It wasn't as bad as normal, he was only off by a factor of 10. Your looking for some excitement. None here You're Angry, 5 stars. Terry, I've actually killfiled your proflile pic. Jay
Killfiled?
proflile ?????
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jt512
May 13, 2009, 4:56 AM
Post #28 of 211
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Terry2124 wrote: jt512 wrote: angry wrote: Terry2124 wrote: adatesman wrote: angry wrote: No battle today, just more misinformation. It wasn't as bad as normal, he was only off by a factor of 10. Your looking for some excitement. None here You're Angry, 5 stars. Terry, I've actually killfiled your proflile pic. Jay Killfiled? proflile ?????
In plain English, I no longer have to look at that annoying, and vaguely creepy, little picture underneath your username next to your posts.
Jay
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majid_sabet
May 13, 2009, 5:02 AM
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shockabuku wrote: majid_sabet wrote: angry wrote: I'm not sure that's how it works. I could be wrong but I've never heard of being able to calculate fall forces in KN based on the distance of the fall vs. the amount of rope out. Maybe it's some sort of approximation based on fall factors. 1KN = 224 lbs or so. It's a real weight applied to your gear, not a fall factor applied to your rope. Please correct me if I'm wrong, but I think you've got to be mistaken. wrong girl 1 KILO mean 1000 chingon you sould say 1N =100 kg or @ 224 lbs Dumbass. 1 KN = 1000 N = 1000 kg m/s^2 divide 1000 kg m/s^2 by 9.8 m/s^2 to get an equivalent mass = 102.04 kg = 224.49 lbs.
right after I post it I wanted to go back add the 9.8 meter whatever but then I said fuc* it, someone will catch it later.
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shockabuku
May 13, 2009, 5:10 AM
Post #30 of 211
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majid_sabet wrote: shockabuku wrote: majid_sabet wrote: angry wrote: I'm not sure that's how it works. I could be wrong but I've never heard of being able to calculate fall forces in KN based on the distance of the fall vs. the amount of rope out. Maybe it's some sort of approximation based on fall factors. 1KN = 224 lbs or so. It's a real weight applied to your gear, not a fall factor applied to your rope. Please correct me if I'm wrong, but I think you've got to be mistaken. wrong girl 1 KILO mean 1000 chingon you sould say 1N =100 kg or @ 224 lbs Dumbass. 1 KN = 1000 N = 1000 kg m/s^2 divide 1000 kg m/s^2 by 9.8 m/s^2 to get an equivalent mass = 102.04 kg = 224.49 lbs. right after I post it I wanted to go back add the 9.8 meter whatever but then I said fuc* it, someone will catch it later.
We all gotta contribute where we can.
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jt512
May 13, 2009, 5:19 AM
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rocknice2 wrote: I take a 6 footer on 10 feet of rope = 6kn [...] A 6 footer on 8 feet of rope = 7.5kn
Do you actually think that the definition of a kilonewton is fall factor times 10?
Jay
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USnavy
May 13, 2009, 6:18 AM
Post #33 of 211
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loyota wrote: Since we know that most, if any falls don't produce the kind of KN force generated by the x2 lab drop test, and 10KN+ gear isn't exaclty breaking left and right... etc etc Are there any studies or data out there regarding what range of KNs are typically generated in more real world falls (not necessarily factor 2). John Long cites scientist Craig Connally in his book who throws out a 5.5-8.5 KN max figure. JL also mentions that in an eight year period QA at Black Diamond hadn't seen any stopper over 10KN fail and only a few 10KN carabiners fail in closed gate mode. I guess if some yates screamers kick in at 2KN, we know we can get into that range probably without trying too hard :-D I can't recall of hearing of any 5KN type gear breaking, I hear of Micros breaking but I don't know how low they were rated. Anyway, just curious, be nice to know what's a little more based in the real world when you're forced / choose to start placing pro that's dropping into the lower KNs
On my off time I put a lot of effort into trying to calculate how much force random lead falls actually generate. In my (field) tests I have found that the max impact force of a typical sport lead fall ranging from a .2 - .85 FF fall with a fall distance of 5 – 15 feet will produce 3 – 8 kN on the top anchor. I tested those falls with everything from a soft catch with an ATC to the hardest possible catch with a GriGri using everything from my half-ropes to my low impact force trad rope to my sport ropes to my old project ropes. But I only weigh 165 lbs with gear. With additional weight, that value will increase dramatically.
So it is possible for a biner to break on a single pitch lead fall if the gate is open well the biner is loaded. It’s unlikely it will happen way up high but during the first few bolts well the potential fall factor is high, exceeding the 7 kN UIAA open gate minimum for class D carabineers is possible.
However in a multi-pitch environment those values will increase quite a lot. A 25 foot factor 1.95 fall (quickdraw attached to belay station) with a person that weighs 200 lbs. and a belayer with an auto locking belay device could produce 15 kN or more on the top anchor in before the belay device slips.
(This post was edited by USnavy on May 13, 2009, 7:08 AM)
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USnavy
May 13, 2009, 7:12 AM
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If you’re going to reference a document to argue your point, it would be strongly favorable if you understood what the document said. Clearly you don’t. The physics behind calculating the impact force of a lead fall is so astronomically beyond you it’s unfathomable.
(This post was edited by USnavy on May 13, 2009, 7:13 AM)
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majid_sabet
May 13, 2009, 7:29 AM
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USnavy wrote: If you’re going to reference a document to argue your point, it would be strongly favorable if you understood what the document said. Clearly you don’t. The physics behind calculating the impact force of a lead fall is so astronomically beyond you it’s unfathomable.
go learn how to rappel and place some anchors first then come back and talk.
and do not talk big. I crush big talkers round here left and right JR.
move it
move it move it
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USnavy
May 13, 2009, 7:35 AM
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majid_sabet wrote: USnavy wrote: If you’re going to reference a document to argue your point, it would be strongly favorable if you understood what the document said. Clearly you don’t. The physics behind calculating the impact force of a lead fall is so astronomically beyond you it’s unfathomable. go learn how to rappel and place some anchors first then come back and talk. and do not talk big. I crush big talkers round here left and right JR. move it move it move it 
(This post was edited by USnavy on May 13, 2009, 7:43 AM)
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colatownkid
May 13, 2009, 11:42 AM
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adatesman wrote: angry wrote: shockabuku wrote: majid_sabet wrote: angry wrote: I'm not sure that's how it works. I could be wrong but I've never heard of being able to calculate fall forces in KN based on the distance of the fall vs. the amount of rope out. Maybe it's some sort of approximation based on fall factors. 1KN = 224 lbs or so. It's a real weight applied to your gear, not a fall factor applied to your rope. Please correct me if I'm wrong, but I think you've got to be mistaken. wrong girl 1 KILO mean 1000 chingon you sould say 1N =100 kg or @ 224 lbs Dumbass. 1 KN = 1000 N = 1000 kg m/s^2 divide 1000 kg m/s^2 by 9.8 m/s^2 to get an equivalent mass = 102.04 kg = 224.49 lbs. That's got to sting!! If Angry and MS are going to get back together I'm going to have to find some better snack food. At the moment the only things handy are sauerkraut and a homemade apple-vinegar-based coleslaw, neither of which are very good for the knock-down drag out lovefests they're A&M are known for. If only I had popcorn! EDIT- I thought about moving this to The Lab, but the first couple posts made me thing otherwise. BTW, I'm totally serious about finding a guinea pig at the NRR... This is one of those things that annoys me because there's lots of speculation and no hard data. If we could find someone willing to take the fall it would be easy enough to prove/disprove a good deal of the spray that's been going around. Hell, we'll even use my rope. Its due for retirement anyway. BTWx2- Not to say there's anything wrong with my rope; I've just been looking for an excuse to replace it since its got fuzz issues.
if you're seriously looking to do some real-world testing (which i think would be awesome!), what's stopping you from using an 80kg bag of rocks? sure, it's a little harder to move around than a person, but i'm guessing the rocks would be much more willing volunteers.
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colatownkid
May 13, 2009, 12:02 PM
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pfwein wrote: loyota wrote: . . . and only a few 10KN carabiners fail in closed gate mode. What kind of a carabiner is only good to 10kN?--all I've seen are good to over twice that. And please excuse my ignorance , but can someone explain the pulley effect mentioned in this thread. In something like a FF2 situation, (i.e., at hanging belay, climber goes up and then falls without any other pro, except clipping the anchor), why would clipping the anchor cause more force? Isn't it just a function of how much rope is out, and it's slightly better to clip the anchor cuz slightly lower fall factor
the "pulley effect" occurs when a load on one side of a pulley is counteracted by an equal load on the opposite side.
suppose a climber has come to a stop after having fallen. the carabiner on uppermost piece of gear is effectively acting as pulley--the climber is hanging on one side, the belayer is hanging on the other side. simply hanging there, the climber's weight must exert some force downward (we'll call it x). in order for the climber to be stationary, the belayer must be exerting an equal force down (also x). therefore, that top piece of gear must be supporting both the full weight of the climber and the belayer or 2x. hence, the total force is double what the climber would place on the piece by himself.
the same principle applies in a moving system where the climber is falling, but we know that in reality the belayer will get pulled into the air, so the doubling is only an approximation.
this is significant in the scenario i described earlier because there is no pulley effect in a factor-2 fall. the climber simply falls directly onto the belayer's belay device. when the system has come to rest (hopefully it does so before both people have hit the ground) the anchor is supporting the weight of the fallen climber directly, not through a pulley. in the high-factor scenario where the anchor has been clipped, the anchor is supporting the weight of the falling climber through a pulley, meaning it has to hold double the force.
let's suppose the factor-2 fall resulted in a force of 8 kN and the high-factor fall resulted in a force of 6kN (totally arbitrary numbers for the sake of example). 2 x 6 = 12, so the high-factor fall actually results in a higher force (12kN) than the factor-2 fall (8kN) thanks to the pulley effect.
the real issue though is that it's extraordinarily difficult to catch factor-2 falls (no personal experience here, so somebody feel free to refute me). this is exacerbated by the fact that when catching a factor-2 fall directly, the belayer's ATC will invert, meaning that the locked position is pulling the rope up, not down, making a catch even more awkward and difficult.
because of this, it might be a good idea to clip the anchor despite the higher potential force simply so it is easier for the belayer to catch the fall.
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adatesman
May 13, 2009, 1:00 PM
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krusher4
May 13, 2009, 1:32 PM
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shockabuku wrote: majid_sabet wrote: angry wrote: I'm not sure that's how it works. I could be wrong but I've never heard of being able to calculate fall forces in KN based on the distance of the fall vs. the amount of rope out. Maybe it's some sort of approximation based on fall factors. 1KN = 224 lbs or so. It's a real weight applied to your gear, not a fall factor applied to your rope. Please correct me if I'm wrong, but I think you've got to be mistaken. wrong girl 1 KILO mean 1000 chingon you sould say 1N =100 kg or @ 224 lbs Dumbass. 1 KN = 1000 N = 1000 kg m/s^2 divide 1000 kg m/s^2 by 9.8 m/s^2 to get an equivalent mass = 102.04 kg = 224.49 lbs.
damn everyone knows this already geezzz...
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fresh
May 13, 2009, 1:40 PM
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in an attempt to answer the original question...
kolin powick writes this in his QC blog:
In reply to: sport falls are typically 2-5kN
I'm assuming that is the actual force on the anchor, which is of course twice the force the climber feels. I've heard that range mentioned a few other times but can't find any other sources. it's funny because this is quite a relevant question for anyone climbing trad, and there isn't much data on it.
does anyone know where the petzl fall simulator went?
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marde
May 13, 2009, 1:58 PM
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according to the german alpine club (DAV)
who did meassured forces on real falls:
3 to 6kN with a tube style device or munter hitch
and 7 to 9kN with a grigri on a bolt
on the pieces.
and not more than 6kN on the belay;
they put the belay devices right on the belay and did not use a dummy runner so there is not twice the force on it.
So on a factor 2 fall it basically comes down to the braking force of the device/ hitch which is used.
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jrathfon
May 13, 2009, 3:46 PM
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colatownkid wrote: pfwein wrote: loyota wrote: . . . and only a few 10KN carabiners fail in closed gate mode. What kind of a carabiner is only good to 10kN?--all I've seen are good to over twice that. And please excuse my ignorance , but can someone explain the pulley effect mentioned in this thread. In something like a FF2 situation, (i.e., at hanging belay, climber goes up and then falls without any other pro, except clipping the anchor), why would clipping the anchor cause more force? Isn't it just a function of how much rope is out, and it's slightly better to clip the anchor cuz slightly lower fall factor the "pulley effect" occurs when a load on one side of a pulley is counteracted by an equal load on the opposite side. suppose a climber has come to a stop after having fallen. the carabiner on uppermost piece of gear is effectively acting as pulley--the climber is hanging on one side, the belayer is hanging on the other side. simply hanging there, the climber's weight must exert some force downward (we'll call it x). in order for the climber to be stationary, the belayer must be exerting an equal force down (also x). therefore, that top piece of gear must be supporting both the full weight of the climber and the belayer or 2x. hence, the total force is double what the climber would place on the piece by himself. the same principle applies in a moving system where the climber is falling, but we know that in reality the belayer will get pulled into the air, so the doubling is only an approximation. this is significant in the scenario i described earlier because there is no pulley effect in a factor-2 fall. the climber simply falls directly onto the belayer's belay device. when the system has come to rest (hopefully it does so before both people have hit the ground) the anchor is supporting the weight of the fallen climber directly, not through a pulley. in the high-factor scenario where the anchor has been clipped, the anchor is supporting the weight of the falling climber through a pulley, meaning it has to hold double the force. let's suppose the factor-2 fall resulted in a force of 8 kN and the high-factor fall resulted in a force of 6kN (totally arbitrary numbers for the sake of example). 2 x 6 = 12, so the high-factor fall actually results in a higher force (12kN) than the factor-2 fall (8kN) thanks to the pulley effect. the real issue though is that it's extraordinarily difficult to catch factor-2 falls (no personal experience here, so somebody feel free to refute me). this is exacerbated by the fact that when catching a factor-2 fall directly, the belayer's ATC will invert, meaning that the locked position is pulling the rope up, not down, making a catch even more awkward and difficult. because of this, it might be a good idea to clip the anchor despite the higher potential force simply so it is easier for the belayer to catch the fall.
wow, something useful in this nonsensical thread! i think i learned this a few years ago, but had forgotten it. this does generate some interesting questions about that FF2 preventer bolt clip or first jesus piece. another thing you can do is have your belayer lowered out a bit (like 6 or 7 ft) from the hanging belay, that way there is more rpe in the system. we used this a lot on prince of darkness as the climbing was a touch stiff up to the first bolt sometimes. oh, and roan way at j-tree, course you could jsut skip this belay...
but lets say you fall 5 ft above your 2 bolt anchor, where you clipped one anchor bolt as your FF2 directional. in one case (A), the belayer is hanging off the anchor with 2 standard shoulder length slings (2ft). in the other case (B) you have your belayer out 6ft. i typically achieve this by having the climbing line extended 4ft via a clove hitch from a knot limited sliding-x master point made from a double shoulder length sling (the 4 ft of climbing line can be backed up by another 2Xshoulder sling if you feel your climbing line isn't safe enough...).
in (A) you have a 10ft fall with 7ft or rope or FF1.43 with the pulley effect on your directional biner.
in (B) you have a 10ft fall with 11ft of rope or FF0.91 with the pulley effect on your directional biner.
in both cases you can have a softer catch by picking up your belayer, however in (A) you belayer can only move 2ft as the ATC smacks into the directional biner. in (B) you get 6ft, a much softer catch.
i just went to calculate the forces in this hypothetical fall, but that linked calculator is bunk! it'd be interesting to see how adding this bit of rope into the system dissipates forces on da' jebus directional.
to those who think you couldn't monopolize that full 6ft of picking up your belayer: on POD, on ~ the 3rd pitch, the height related 10bish crux moves, I was out about 8 or 9 bolts (~90ft) from the double bolt anchor, where my belayer had already removed the "oh shit FF2 directional thank jebus biner" and was tied in via the rope into the limited sliding-x master point with about 3ft of line. i was nearing the next clip (so ~10ft above my last clip) and unexpectedly whipped. the fall generated enough force to pull her up (she weighs 25lbs less than me 160 vs 135) almost taught between her tether and the climbing line, i.e. 10ft! with stretch and that give the fall turned into a 30fter! so really it was a 20ft fall on ~90ft of line or a FF0.22, not much!
p.s. majidiot, i stand by what i said last year. you're an idiot.
"chingon"? = 1 KILO means 1000 mexican badasses?
"right after I post it I wanted to go back add the 9.8 meter whatever but then I said fuc* it, someone will catch it later. "
yup, 9.8 meter whatever, you clearly have a grasp on this subject. because adding 9.8 meter whatever to:
"wrong girl
1 KILO mean 1000 chingon
you sould say 1N =100 kg or @ 224 lbs"
would have made this statement clearer and more accurate...
for the record, he was a factor of 10^3 off, not just a factor of 10. close only counts in horshoes and handgrenades.
"go learn how to rappel and place some anchors first then come back and talk."
typically i find rappellers are the biggest idiots you can run across at a climbing area.
"and do not talk big. I crush big talkers round here left and right JR."
is this a reference to when you kept saying sexually suggestive threats to angry in a long argument?
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majid_sabet
May 13, 2009, 5:19 PM
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colatownkid wrote: pfwein wrote: loyota wrote: . . . and only a few 10KN carabiners fail in closed gate mode. What kind of a carabiner is only good to 10kN?--all I've seen are good to over twice that. And please excuse my ignorance , but can someone explain the pulley effect mentioned in this thread. In something like a FF2 situation, (i.e., at hanging belay, climber goes up and then falls without any other pro, except clipping the anchor), why would clipping the anchor cause more force? Isn't it just a function of how much rope is out, and it's slightly better to clip the anchor cuz slightly lower fall factor the "pulley effect" occurs when a load on one side of a pulley is counteracted by an equal load on the opposite side. suppose a climber has come to a stop after having fallen. the carabiner on uppermost piece of gear is effectively acting as pulley--the climber is hanging on one side, the belayer is hanging on the other side. simply hanging there, the climber's weight must exert some force downward (we'll call it x). in order for the climber to be stationary, the belayer must be exerting an equal force down (also x). therefore, that top piece of gear must be supporting both the full weight of the climber and the belayer or 2x. hence, the total force is double what the climber would place on the piece by himself. the same principle applies in a moving system where the climber is falling, but we know that in reality the belayer will get pulled into the air, so the doubling is only an approximation. this is significant in the scenario i described earlier because there is no pulley effect in a factor-2 fall. the climber simply falls directly onto the belayer's belay device. when the system has come to rest (hopefully it does so before both people have hit the ground) the anchor is supporting the weight of the fallen climber directly, not through a pulley. in the high-factor scenario where the anchor has been clipped, the anchor is supporting the weight of the falling climber through a pulley, meaning it has to hold double the force. let's suppose the factor-2 fall resulted in a force of 8 kN and the high-factor fall resulted in a force of 6kN (totally arbitrary numbers for the sake of example). 2 x 6 = 12, so the high-factor fall actually results in a higher force (12kN) than the factor-2 fall (8kN) thanks to the pulley effect. the real issue though is that it's extraordinarily difficult to catch factor-2 falls (no personal experience here, so somebody feel free to refute me). this is exacerbated by the fact that when catching a factor-2 fall directly, the belayer's ATC will invert, meaning that the locked position is pulling the rope up, not down, making a catch even more awkward and difficult. because of this, it might be a good idea to clip the anchor despite the higher potential force simply so it is easier for the belayer to catch the fall.
note, The carabiner does not act as pulley device in FF but a friction device therefore it reduces the fall factor by small amont as mentioned in the PDF I provided above . During a leader fall, we are not getting a true FF2 but some thing like FF 1.75 +- .
I think the only way we could get a true FF2 is to attach a climber to solid steel cable and drop him above an anchor and without any protection in between.
Hey Angry. you want to try this for me?
come on, I buy a candy
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jrathfon
May 13, 2009, 5:35 PM
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majid_sabet wrote: colatownkid wrote: pfwein wrote: loyota wrote: . . . and only a few 10KN carabiners fail in closed gate mode. What kind of a carabiner is only good to 10kN?--all I've seen are good to over twice that. And please excuse my ignorance , but can someone explain the pulley effect mentioned in this thread. In something like a FF2 situation, (i.e., at hanging belay, climber goes up and then falls without any other pro, except clipping the anchor), why would clipping the anchor cause more force? Isn't it just a function of how much rope is out, and it's slightly better to clip the anchor cuz slightly lower fall factor the "pulley effect" occurs when a load on one side of a pulley is counteracted by an equal load on the opposite side. suppose a climber has come to a stop after having fallen. the carabiner on uppermost piece of gear is effectively acting as pulley--the climber is hanging on one side, the belayer is hanging on the other side. simply hanging there, the climber's weight must exert some force downward (we'll call it x). in order for the climber to be stationary, the belayer must be exerting an equal force down (also x). therefore, that top piece of gear must be supporting both the full weight of the climber and the belayer or 2x. hence, the total force is double what the climber would place on the piece by himself. the same principle applies in a moving system where the climber is falling, but we know that in reality the belayer will get pulled into the air, so the doubling is only an approximation. this is significant in the scenario i described earlier because there is no pulley effect in a factor-2 fall. the climber simply falls directly onto the belayer's belay device. when the system has come to rest (hopefully it does so before both people have hit the ground) the anchor is supporting the weight of the fallen climber directly, not through a pulley. in the high-factor scenario where the anchor has been clipped, the anchor is supporting the weight of the falling climber through a pulley, meaning it has to hold double the force. let's suppose the factor-2 fall resulted in a force of 8 kN and the high-factor fall resulted in a force of 6kN (totally arbitrary numbers for the sake of example). 2 x 6 = 12, so the high-factor fall actually results in a higher force (12kN) than the factor-2 fall (8kN) thanks to the pulley effect. the real issue though is that it's extraordinarily difficult to catch factor-2 falls (no personal experience here, so somebody feel free to refute me). this is exacerbated by the fact that when catching a factor-2 fall directly, the belayer's ATC will invert, meaning that the locked position is pulling the rope up, not down, making a catch even more awkward and difficult. because of this, it might be a good idea to clip the anchor despite the higher potential force simply so it is easier for the belayer to catch the fall. note, The carabiner does not act as pulley device in FF but a friction device therefore it reduces the fall factor by small amont as mentioned in the PDF I provided above . During a leader fall, we are not getting a true FF2 but some thing like FF 1.75 +- . I think the only way we could get a true FF2 is to attach a climber to solid steel cable and drop him above an anchor and without any protection in between. Hey Angry. you want to try this for me? come on, I buy a candy
majidiot, the FF does not depend on the rope used. as per YOUR reference, FF = the total distance fallen / rope out. if you want to calculate peak force, you must factor in the elasticity of the rope. using a steel cable will increase this max force, but NOT the FF.
b) THEGUY provided the references explaining the friction factor of the pulley effect decreasing force in the system, NOT FF. you did NOT provide this information.
again, you're an idiot. or perhaps i should translate this into rc.com vernacular: "your' an idiot's."
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majid_sabet
May 13, 2009, 6:07 PM
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jrathfon wrote: majid_sabet wrote: colatownkid wrote: pfwein wrote: loyota wrote: . . . and only a few 10KN carabiners fail in closed gate mode. What kind of a carabiner is only good to 10kN?--all I've seen are good to over twice that. And please excuse my ignorance , but can someone explain the pulley effect mentioned in this thread. In something like a FF2 situation, (i.e., at hanging belay, climber goes up and then falls without any other pro, except clipping the anchor), why would clipping the anchor cause more force? Isn't it just a function of how much rope is out, and it's slightly better to clip the anchor cuz slightly lower fall factor the "pulley effect" occurs when a load on one side of a pulley is counteracted by an equal load on the opposite side. suppose a climber has come to a stop after having fallen. the carabiner on uppermost piece of gear is effectively acting as pulley--the climber is hanging on one side, the belayer is hanging on the other side. simply hanging there, the climber's weight must exert some force downward (we'll call it x). in order for the climber to be stationary, the belayer must be exerting an equal force down (also x). therefore, that top piece of gear must be supporting both the full weight of the climber and the belayer or 2x. hence, the total force is double what the climber would place on the piece by himself. the same principle applies in a moving system where the climber is falling, but we know that in reality the belayer will get pulled into the air, so the doubling is only an approximation. this is significant in the scenario i described earlier because there is no pulley effect in a factor-2 fall. the climber simply falls directly onto the belayer's belay device. when the system has come to rest (hopefully it does so before both people have hit the ground) the anchor is supporting the weight of the fallen climber directly, not through a pulley. in the high-factor scenario where the anchor has been clipped, the anchor is supporting the weight of the falling climber through a pulley, meaning it has to hold double the force. let's suppose the factor-2 fall resulted in a force of 8 kN and the high-factor fall resulted in a force of 6kN (totally arbitrary numbers for the sake of example). 2 x 6 = 12, so the high-factor fall actually results in a higher force (12kN) than the factor-2 fall (8kN) thanks to the pulley effect. the real issue though is that it's extraordinarily difficult to catch factor-2 falls (no personal experience here, so somebody feel free to refute me). this is exacerbated by the fact that when catching a factor-2 fall directly, the belayer's ATC will invert, meaning that the locked position is pulling the rope up, not down, making a catch even more awkward and difficult. because of this, it might be a good idea to clip the anchor despite the higher potential force simply so it is easier for the belayer to catch the fall. note, The carabiner does not act as pulley device in FF but a friction device therefore it reduces the fall factor by small amont as mentioned in the PDF I provided above . During a leader fall, we are not getting a true FF2 but some thing like FF 1.75 +- . I think the only way we could get a true FF2 is to attach a climber to solid steel cable and drop him above an anchor and without any protection in between. Hey Angry. you want to try this for me? come on, I buy a candy majidiot, the FF does not depend on the rope used. as per YOUR reference, FF = the total distance fallen / rope out. if you want to calculate peak force, you must factor in the elasticity of the rope. using a steel cable will increase this max force, but NOT the FF. b) THEGUY provided the references explaining the friction factor of the pulley effect decreasing force in the system, NOT FF. you did NOT provide this information. again, you're an idiot. or perhaps i should translate this into rc.com vernacular: "your' an idiot's."
First off, try to learn how to communicate with people instead of using the word idiot or whatever. 7 years old kids call each other idiot. You are a college grad and I thought at least they teach you how to talk to people.
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Rudmin
May 13, 2009, 6:08 PM
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majid_sabet wrote: I think the only way we could get a true FF2 is to attach a climber to solid steel cable and drop him above an anchor and without any protection in between. Hey Angry. you want to try this for me? come on, I buy a candy
That would be a theoretical fall factor approaching infinity: a fall of some distance with 0 rope out. If nothing in the system is dynamic, then it produces an infinite force. Of course, even steel cable is elastic to a degree, but you still would get extremely high forces.
If you replaced your steel cable with a dynamic rope, then it would be a theoretical fall factor of 2. But of course real falls aren't one dimensional, and humans aren't the same as iron weights, that's why it would be nice to have actual data.
The point of a fall factor, is that it models a number that scales linearly with the forces acting on the falling climber. So in general, you can say that the higher the fall factor, the higher the forces the climber (and thus the rest of the system) experience.
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hafilax
May 13, 2009, 6:08 PM
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Majid just sucks at explaining things and I think he gets some enjoyment out of stringing the tongue wagging dogs along. He's hinting at other factors like the cinching of the knot that effectively lowers the fall factor.
The fall factor calculation that everybody loves so much is an approximation and often a very poor one. It doesn't take into account friction (around the biner, rope drag etc), knot cinching, the movement of the belayer, rope slipping through the belay device, the climber dragging down the wall and a host of other significant energy dissipating mechanisms.
A modest approximation for the efficiency of a biner as a pulley is around 75% I believe. This is where Majid's factor of 1.75 for the force from the pulley effect is coming from. That's not even including the cinching of the figure 8 which can effectively add a couple of meters of rope to the system.
It's an amusing academic exercise to try to calculate real world forces but there is an infinite number of results even for one given fall factor depending on the actual boundary conditions of the setup. There are some rules of thumb but you will never be certain that climbing another meter will end up with a fall that will snap the RP you're nervously climbing away from.
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pfwein
May 13, 2009, 6:28 PM
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Thanks to all of you who addressed my Q re: pulley effect.
One thing I don't think I've seen addressed: at a hanging belay, the anchor is also holding the weight of the belayer, so when the fallen climber comes to rest, the anchor will be holding both the weight of the belayer and the climber, regardless of whether the climber clipped the anchor, right?
And before the climber comes to rest, it seems that the rope will just be elongating based on the climber's weight, the length of the fall, and amount of rope between the climber and the belay device, which again doesn't depend on whether the anchor is clipped,except the fall will be slightly shorter when the anchor is clipped (maybe I'm wrong on this point??).
I'm just having a hard time visualizing why clipping the anchor increases the force on the anchor when the only thing it seems to do is redirect the direction of the force and slightly decrease the length of the fall (both definitely good things), but thanks again to you who attempt to explain it.
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jrathfon
May 13, 2009, 6:34 PM
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hafilax wrote: Majid just sucks at explaining things and I think he gets some enjoyment out of stringing the tongue wagging dogs along. He's hinting at other factors like the cinching of the knot that effectively lowers the fall factor. The fall factor calculation that everybody loves so much is an approximation and often a very poor one. It doesn't take into account friction (around the biner, rope drag etc), knot cinching, the movement of the belayer, rope slipping through the belay device, the climber dragging down the wall and a host of other significant energy dissipating mechanisms. A modest approximation for the efficiency of a biner as a pulley is around 75% I believe. This is where Majid's factor of 1.75 for the force from the pulley effect is coming from. That's not even including the cinching of the figure 8 which can effectively add a couple of meters of rope to the system. It's an amusing academic exercise to try to calculate real world forces but there is an infinite number of results even for one given fall factor depending on the actual boundary conditions of the setup. There are some rules of thumb but you will never be certain that climbing another meter will end up with a fall that will snap the RP you're nervously climbing away from.
Yes, Majidiot sucks at explaining things, he also sucks at understanding the fundamental concepts in the first place.
I understand the concepts of fall factor and how it is an approximation to represent forces in a complex dynamic situation. You bring up lots of the intracacies involved in the dissipation of forces in a real world fall. It's definitely an interesting problem. The UIAA paper that "theguy" presented actually has some values for frictional dissipation of forces in the system.
Rudman: according to the paper majidiot replied with force scales to the square root of FF.
Majidiot: i think i can communicate quite effectively, i would hope others in this forum agree upon this point. you however, DO NOT communicate effectively, and in fact it is quite enraging to have to sift through your absolute crap that you would call posts. in fact it's usually so enraging i feel obligated to chime in and state the obvious, that a) you never said anything you claim you said, rather you just take credit for other people's additions to the discussion and b) you have NO idea of what you are talking about.
and "idiot" is actually the perfect word to describe you:
Idiot is a word derived from the Greek ἰδιώτης, idiōtēs ("person lacking professional skill," "a private citizen," "individual"), from ἴδιος, idios ("private," "one's own").[1] In Latin the word idiota ("ordinary person, layman") preceded the Late Latin meaning "uneducated or ignorant person."[2] Its modern meaning and form dates back to Middle English around the year 1300, from the Old French idiote ("uneducated or ignorant person").
"Idiot" was originally created to refer to "layman, person lacking professional skill", "person so mentally deficient as to be incapable of ordinary reasoning".[6][7] Declining to take part in public life, such as democratic government of the polis (city state), such as the Athenian democracy, was considered dishonorable. "Idiots" were seen as having bad judgment in public and political matters. Over time, the term "idiot" shifted away from its original connotation of selfishness and came to refer to individuals with overall bad judgment–individuals who are "stupid". In modern English usage, the terms "idiot" and "idiocy" describe an extreme folly or stupidity, and its symptoms (foolish or stupid utterance or deed). In psychology, it is a historical term for the state or condition now called profound mental retardation.[8]
so, i am leary to use this as then i wouldn't be able to counteract majidiots BS, but does anyone have that rc.com fix where i can ignore his posts?
also, majidiot, why do you harass people for not answering your questions, but always dodge everyone else's queries?
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