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USnavy


Nov 9, 2007, 12:07 AM
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60 meter fall (fall factor 1); will a 10.5mm rope hold?
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I noticed that the force calculator on Petzel's site is dependent on fall factor. The simulator basically states that the fall factor is what depicts how much stress the equipment sees, not the length of the fall. It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls). The simulator also states that a fall using the two examples I listed with a weight of 75kg produces a force of 10 kN on the anchor with a 10.5mm rope.

Well judging by the info that simulator provided me with I could tie a dynamic rope to a bridge, jump off of it, fall the full 60m of the rope (fall factor 1) and place only 10kN of force on the rope and bridge. Well that doesnít sound right. Is the simulator actually correct? I donít understand how you can fall 60m and produce as much force as if you were to fall 5m with a fall factor of 1.

Does anyone actually know of someone who used a dynamic rope as a bungee rope? Does it actually hold?


(This post was edited by USnavy on Nov 9, 2007, 12:08 AM)


flint


Nov 9, 2007, 12:25 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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Do they not teach you math, physics or engineering in the Navy... Some days I am so ashamed of my passport.

OK to the topic. You get a factor one fall at 40m when you fall 20m. This is because you have fallen half the length of the rope you have out. So lets simplify it and say you divided 20 by 40 and you got .5

Now, if you were to jump off a bridge with a 60m rope, you would also be falling the full 60m length... Causing a factor 2 fall, or 60 divided by 60 = 1

This is completely different as I hope this simplified example has shown. No the guys at petzl are pretty sharp at what they do...

Please don't bungee on your climbing rope... Amazing how much someone can learn from the names of the items they purchase... It is a CLIMBING rope, not a climbing/bungee rope.

j-


flint


Nov 9, 2007, 12:27 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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USnavy wrote:
I noticed that the force calculator on Petzel's site is dependent on fall factor. The simulator basically states that the fall factor is what depicts how much stress the equipment sees, not the length of the fall. It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls). The simulator also states that a fall using the two examples I listed with a weight of 75kg produces a force of 10 kN on the anchor with a 10.5mm rope.

Well judging by the info that simulator provided me with I could tie a dynamic rope to a bridge, jump off of it, fall the full 60m of the rope (fall factor 1) and place only 10kN of force on the rope and bridge. Well that doesnít sound right. Is the simulator actually correct? I donít understand how you can fall 60m and produce as much force as if you were to fall 5m with a fall factor of 1.

Does anyone actually know of someone who used a dynamic rope as a bungee rope? Does it actually hold?

Had to quote you, don't like to see people save face by deleting posts.CrazyCrazyCrazy


sbaclimber


Nov 9, 2007, 1:08 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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USnavy wrote:
Well judging by the info that simulator provided me with I could tie a dynamic rope to a bridge, jump off of it, fall the full 60m of the rope (fall factor 1) and place only 10kN of force on the rope and bridge. Well that doesnít sound right. Is the simulator actually correct?
Yes, Physics 101 Wink

Think of a longer rubber band, more "stretch" to absorb the force of the fall. Makes perfect sense.


spoon


Nov 9, 2007, 2:07 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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http://youtube.com/watch?v=VtP6D7S5LAk

Dan Osman's setups were more complicated than bungee jumping with a rope, but I think you get the idea.


notapplicable


Nov 9, 2007, 4:11 AM
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Re: [flint] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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flint wrote:
Do they not teach you math, physics or engineering in the Navy... Some days I am so ashamed of my passport.

OK to the topic. You get a factor one fall at 40m when you fall 20m. This is because you have fallen half the length of the rope you have out. So lets simplify it and say you divided 20 by 40 and you got .5

Now, if you were to jump off a bridge with a 60m rope, you would also be falling the full 60m length... Causing a factor 2 fall, or 60 divided by 60 = 1

This is completely different as I hope this simplified example has shown. No the guys at petzl are pretty sharp at what they do...

Please don't bungee on your climbing rope... Amazing how much someone can learn from the names of the items they purchase... It is a CLIMBING rope, not a climbing/bungee rope.

j-


The fall you described (bold is mine) only generates a FF of 1, as your math showed. Where do you get a FF of two?

To create a FF of 2 you have to fall twice the distance of the rope out. So if the guy attached the rope at street level then climbed 60 meters up the bridge supports and took a whip he would be looking at a FF of 2. 120 meter fall divided by the 60 meters of rope = 2

I think your attitude was a little harsh to have given the wrong answer to the mans question. Perhaps the low levels of oxygen up on that high horse are causing your problems in math?




Edited to add: OP, I would guess that the rope would hold atleast one of those jumps but you will quickly trash the thing. DONT DO IT, BUY A BUNGEE CORD. (Emphasis on the period)


(This post was edited by notapplicable on Nov 9, 2007, 4:14 AM)


Carnage


Nov 9, 2007, 6:29 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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USnavy wrote:
http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=markup_help;
Get Markup Help
Does anyone actually know of someone who used a dynamic rope as a bungee rope? Does it actually hold?

read up on dan osman, know mainly for being a free soloist, but died doing this. he did many jumps and his gear held. ive heard 2 explanations of why his gear broke on his las jump. 1) cause ropes crossed and the heat from friction melted 1 rope, 2) cause crossed ropes put an unholdable amount of stress on a knot.


jt512


Nov 9, 2007, 6:44 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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USnavy wrote:
I noticed that the force calculator on Petzel's site is dependent on fall factor. The simulator basically states that the fall factor is what depicts how much stress the equipment sees, not the length of the fall. It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls). The simulator also states that a fall using the two examples I listed with a weight of 75kg produces a force of 10 kN on the anchor with a 10.5mm rope.

Well judging by the info that simulator provided me with I could tie a dynamic rope to a bridge, jump off of it, fall the full 60m of the rope (fall factor 1) and place only 10kN of force on the rope and bridge. Well that doesnít sound right. Is the simulator actually correct? I donít understand how you can fall 60m and produce as much force as if you were to fall 5m with a fall factor of 1.

Does anyone actually know of someone who used a dynamic rope as a bungee rope? Does it actually hold?

Oddly enough, they sometimes even hold factor-2 falls.

Jay


Partner rgold


Nov 9, 2007, 6:46 AM
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Re: [Carnage] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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USNavy, there are sources explaining how dynamic ropes work all over the web. If you don't want to look too far, you could jump to my post here, download the attached StandardEqn.pdf, and read up. But this is just one of many sources.


(This post was edited by rgold on Nov 9, 2007, 6:47 AM)


zealotnoob


Nov 9, 2007, 6:56 AM
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Re: [flint] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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flint wrote:
Do they not teach you math, physics or engineering in the Navy... Some days I am so ashamed of my passport.

OK to the topic. You get a factor one fall at 40m when you fall 20m. This is because you have fallen half the length of the rope you have out. So lets simplify it and say you divided 20 by 40 and you got .5

Now, if you were to jump off a bridge with a 60m rope, you would also be falling the full 60m length... Causing a factor 2 fall, or 60 divided by 60 = 1

This is completely different as I hope this simplified example has shown. No the guys at petzl are pretty sharp at what they do...

Please don't bungee on your climbing rope... Amazing how much someone can learn from the names of the items they purchase... It is a CLIMBING rope, not a climbing/bungee rope.

j-

Yeah man...this is pretty damn bad. ...wouldn't want you deleting it to save face.


jt512


Nov 9, 2007, 7:01 AM
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Re: [zealotnoob] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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zealotnoob wrote:
flint wrote:
Do they not teach you math, physics or engineering in the Navy... Some days I am so ashamed of my passport.

OK to the topic. You get a factor one fall at 40m when you fall 20m. This is because you have fallen half the length of the rope you have out. So lets simplify it and say you divided 20 by 40 and you got .5

Now, if you were to jump off a bridge with a 60m rope, you would also be falling the full 60m length... Causing a factor 2 fall, or 60 divided by 60 = 1

This is completely different as I hope this simplified example has shown. No the guys at petzl are pretty sharp at what they do...

Please don't bungee on your climbing rope... Amazing how much someone can learn from the names of the items they purchase... It is a CLIMBING rope, not a climbing/bungee rope.

j-

Yeah man...this is pretty damn bad. ...wouldn't want you deleting it to save face.

Thanks for quoting that, so I could see it without taking Flint out of my killfile.

Jay


microbarn


Nov 9, 2007, 7:12 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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If you fall farther, then you have more rope out to absorb the force and spread out the time of the absorption.


reg


Nov 9, 2007, 7:24 AM
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Re: [Carnage] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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Carnage wrote:
read up on dan osman, know mainly for being a free soloist, but died doing this. he did many jumps and his gear held. ive heard 2 explanations of why his gear broke on his las jump. 1) cause ropes crossed and the heat from friction melted 1 rope, 2) cause crossed ropes put an unholdable amount of stress on a knot.

dano's jump rope crossed his "anchor" rope which was melted and broke. this happened because he changed his jump position at the last minute attempting to get a longer jump distance to up his record, it was dark when he jumped aiding in the mistake. he had gone up to retrive his rig after the park service told him they would do it which ment he would lose his gear if he didn't. he was not suppose to jump anymore but instead of cleaning the rig he made a last attempt. changing his position at the last minute - under pressure - in the dark ..............

he was on the cell phone when he jumped - which he often did - with one of his close friends who was delayed getting there to help him remove the rig. the friend (just can't remember who or which book i was reading - i'll find it if needed) was telling him not to do it then listened to the jump live. sad story esp. because just days earlier he was interviewed and he said his guardian angles needed a vacation and he was headed for some couch time with his family.

to the op: FF 2 happens when the leader does not have any gear in and falls onto the belay. say she climbs away 10 feet up the rock then falls. she will fall 20+ feet - onto the belay - with only 10 feet of rope out = FF2 but if even one piece where put in - even clipping a leg of the anchor would reduce to less then FF2 - i believe John Long refered to it as the "jesus nut" - the first piece. that piece is where you measure the fall distance from - then any rope from that piece back to the belay is added to the rope lenght thus reducing the FF. the more pieces you put in at the beggining - the lower the FF.
all dynamic climbing ropes are designed by code to limit impact to 12kn max. when used correctly. if you fall 10' on 5' of rope there isn't much stretch if any. but falling a full rope lenght onto a ridgid anchor, i believe, would result in a FF2 with a impact force of not more then 12kn and a fall distance of ~260 feet depending on percent of elongation designed into the rope.


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Nov 9, 2007, 7:26 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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USnavy wrote:
It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls).

The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it.


(This post was edited by j_ung on Nov 9, 2007, 7:27 AM)


jt512


Nov 9, 2007, 7:28 AM
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Re: [j_ung] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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j_ung wrote:
USnavy wrote:
It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls).

The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it.

You are confusing force with energy, and consequently your post makes no sense.

Jay


(This post was edited by jt512 on Nov 9, 2007, 7:28 AM)


zealotnoob


Nov 9, 2007, 7:39 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...


(This post was edited by zealotnoob on Nov 9, 2007, 7:42 AM)


shockabuku


Nov 9, 2007, 7:42 AM
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Re: [flint] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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flint wrote:
Do they not teach you math, physics or engineering in the Navy...


Right, because every sailor needs to know that.

flint wrote:
Some days I am so ashamed of my passport.

j-

Sometimes I'm so ashamed of my countrymen.Mad


greenketch


Nov 9, 2007, 8:17 AM
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Re: [shockabuku] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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USNavy, You are on the right track assuming that a longer fall creates more kinetic energy. As previously stated you need to look at the entire picture not just the line item. A rope functions as the resistance that dissapaites that energy. The critical factor is not the length of fall, it is the amount of rope that is involved in the catch.

The ropes internal construction functions to limit the force excerted at any moment. So reexamineing the formula you are questioning. The weight and the distance fallen give you the force generated. The ratio of rope involved to fall distance gives you a correction factor for the time of disapation, and the type and placement of gear helps figure how that force is applied.

A larger fall caught with a a low percentage of rope is fairly soft and gradual (long period of disapation) and a small fall caught on a high percentage of rope is pretty brutal (short period of disapation).

Go back to the fall calculator and enter two falls, one that is a 50 footer caught on 150' of rope, and one that is a 15 footer caught on 8 feet of rope. Look close at the forces applied to the climber.

Now keep in mind that the time of disapation also is the time the rope is stretching. In the second example I gave the climber will deck do to rope stretch if the belayre/anchor is at the deck. The only way for this to happen is for folk who are above the ground (second pitch or higher) where it is actually possible for the faller to end below the belayer. A 10' fall on 5' of rope is brutal.

As to the rest of your question I have not taken 600' + jumps like Dan Osman. I have taken a fall that was a bit over 80'. It was near the end of a lead and was caught on 150' of rope, nice ride, one of the softest catches I ever had. Now bear in mind I think I had to clean my shorts after I stopped moving. That was a long time in the air.


Partner angry


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Re: [flint] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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Guys, give flint a break. He lives in Ohio after all, he's got enough problems.


curt


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These types of threads are the funniest on RC.com, for sure. Lots of people explaining the math/physics behind fall-factor and resultant force calculations--and getting it completely wrong. Do as rgold suggested above and read his article on the subject.

Curt


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Nov 9, 2007, 3:13 PM
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Re: [jt512] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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jt512 wrote:
j_ung wrote:
USnavy wrote:
It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls).

The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it.

You are confusing force with energy, and consequently your post makes no sense.

Jay

Me ... several thousand miles ... physics. Thanks for the clarification.


trenchdigger


Nov 9, 2007, 3:20 PM
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Re: [curt] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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curt wrote:
These types of threads are the funniest on RC.com, for sure. Lots of people explaining the math/physics behind fall-factor and resultant force calculations--and getting it completely wrong. Do as rgold suggested above and read his article on the subject.

Curt

I'll second that!


curtis_g


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Re: [trenchdigger] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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third. says the ME student sick of his Theoretical and Applied Mechanics homework.


rocknice2


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Re: [j_ung] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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j_ung wrote:
jt512 wrote:
j_ung wrote:
USnavy wrote:
It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls).

The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it.

You are confusing force with energy, and consequently your post makes no sense.

Jay

Me ... several thousand miles ... physics. Thanks for the clarification.

j_ung

Imagine a force curve on a gragh .. Force/time .. The area under the curve is total energy expended.


ptlong


Nov 9, 2007, 4:42 PM
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Re: [rocknice2] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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rocknice2 wrote:
Imagine a force curve on a gragh .. Force/time .. The area under the curve is total energy expended.

Please refer to Curt's post above.


USnavy


Nov 9, 2007, 5:11 PM
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Was he actually using dynamic climbing ropes in those videos or were they bungee ropes designed for that type of use? The last jump he did looked like it was with a dynamic rope but I am not 100% on that one.


shockabuku


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Re: [rocknice2] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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What's a force curve (force/time)?


(This post was edited by shockabuku on Nov 9, 2007, 5:20 PM)


jt512


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rocknice2 wrote:
j_ung wrote:
jt512 wrote:
j_ung wrote:
USnavy wrote:
It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls).

The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it.

You are confusing force with energy, and consequently your post makes no sense.

Jay

Me ... several thousand miles ... physics. Thanks for the clarification.

j_ung

Imagine a force curve on a gragh .. Force/time .. The area under the curve is total energy expended.

Another victim of American education?

Edit: Apparently, things aren't much better in Canada.

Jay


(This post was edited by jt512 on Nov 9, 2007, 5:29 PM)


greenketch


Nov 9, 2007, 5:29 PM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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USnavy wrote:
Was he actually using dynamic climbing ropes in those videos or were they bungee ropes designed for that type of use? The last jump he did looked like it was with a dynamic rope but I am not 100% on that one.

Yes, Dan did most of his stuff with Dynamic climbing ropes.


flint


Nov 10, 2007, 8:48 PM
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Re: [flint] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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flint wrote:
Do they not teach you math, physics or engineering in the Navy... Some days I am so ashamed of my passport.

OK to the topic. You get a factor one fall at 40m when you fall 20m. This is because you have fallen half the length of the rope you have out. So lets simplify it and say you divided 20 by 40 and you got .5

Now, if you were to jump off a bridge with a 60m rope, you would also be falling the full 60m length... Causing a factor 2 fall, or 60 divided by 60 = 1

This is completely different as I hope this simplified example has shown. No the guys at petzl are pretty sharp at what they do...

Please don't bungee on your climbing rope... Amazing how much someone can learn from the names of the items they purchase... It is a CLIMBING rope, not a climbing/bungee rope.

j-

Little bit of a brain fuck up here... Sorry for the harsh and actually wrong post USnavy. I will come and stand in your corner now.

I am still ashamed of my passport, but for an all new set of reasons.

j-


trenchdigger


Nov 12, 2007, 9:57 AM
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Re: [jt512] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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jt512 wrote:
rocknice2 wrote:
j_ung wrote:
jt512 wrote:
j_ung wrote:
USnavy wrote:
It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls).

The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it.

You are confusing force with energy, and consequently your post makes no sense.

Jay

Me ... several thousand miles ... physics. Thanks for the clarification.

j_ung

Imagine a force curve on a gragh .. Force/time .. The area under the curve is total energy expended.

Another victim of American education?

Edit: Apparently, things aren't much better in Canada.

Jay

This thread just keeps getting better and better, doesn't it Jay? Yeesh...


itstoearly


Nov 12, 2007, 10:25 AM
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Re: [trenchdigger] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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From my understanding, falling 1 foot on 6 inches of rope and falling 200 feet on 100 feet of rope produces the same *peak* force on the anchor point. If you were to compare the graph of the 2, they would be identical, except that the latter would be stretched out over more time.

I would make a graph, but I am busy being lazy.


cantbuymefriends


Nov 12, 2007, 10:57 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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USnavy wrote:
I noticed that the force calculator on Petzel's site is dependent on fall factor.

Well, that's just what fall factors do. Wink

A 10 m fall on 10 m rope, and a 20 m fall on 20 m rope both have the same fall factors (=1), right? And they also give the same peak force. But How?

Rope stretch (which is the braking distance in the system) is proportional to Force and rope length.
So twice as much rope between you and the belayer will absorb twice as much energy because the rope will stretch twice as much for the same force.

And since the fall is twice as long, the energy in the fall to be absorbed by the rope will be twice as high (E=mgh).

Forget everything about times and kinetic energy in these discussions! They are just unnecessary confusingÖ


skinner


Dec 9, 2007, 8:01 PM
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Re: [ptlong] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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A person like USnavy comes along and asks an honest question, which if they understood *why* they wouldn't have asked it in the first place. In response he gets ridiculed by Flint, I guess that's the rc.com way huh?


With only a few posts USnavy may be new to climbing, but gawd.. they should know and fully understand all this stuff before they dare to post here!
It's no wonder there are so many who choose to just lurk.

Welcome to rc.com USnavy Crazy


(This post was edited by skinner on Dec 9, 2007, 8:14 PM)


Partner j_ung


Dec 11, 2007, 5:17 AM
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Re: [jt512] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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jt512 wrote:
rocknice2 wrote:
j_ung wrote:
jt512 wrote:
j_ung wrote:
USnavy wrote:
It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls).

The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it.

You are confusing force with energy, and consequently your post makes no sense.

Jay

Me ... several thousand miles ... physics. Thanks for the clarification.

j_ung

Imagine a force curve on a gragh .. Force/time .. The area under the curve is total energy expended.

Another victim of American education?

Edit: Apparently, things aren't much better in Canada.

Jay

I'll take my own lumps, thanks. The American education system doesn't need me dragging it down further.


lobstertronic


Dec 11, 2007, 7:01 AM
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Re: [flint] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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flint wrote:
Do they not teach you math, physics or engineering in the Navy... Some days I am so ashamed of my passport.

OK to the topic. You get a factor one fall at 40m when you fall 20m. This is because you have fallen half the length of the rope you have out. So lets simplify it and say you divided 20 by 40 and you got .5

Now, if you were to jump off a bridge with a 60m rope, you would also be falling the full 60m length... Causing a factor 2 fall, or 60 divided by 60 = 1

This is completely different as I hope this simplified example has shown. No the guys at petzl are pretty sharp at what they do...

Please don't bungee on your climbing rope... Amazing how much someone can learn from the names of the items they purchase... It is a CLIMBING rope, not a climbing/bungee rope.

j-

The bridge is 59 metres above the ground...


scottek67


Dec 6, 2009, 8:44 AM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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brokesomeribs wrote:
silascl wrote:
Your a idiot.

Oh, the irony!


dynosore


Dec 6, 2009, 9:36 AM
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Re: [j_ung] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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j_ung wrote:
USnavy wrote:
It suggests this by stating a fall of 5m from a height of 10m produces the same force as a fall of 20m from a height of 40m (both fall factor 1 falls).

The two falls actually don't produce the same force. The farther fall generates much more force, but there's more rope to handle that force in direct proportion. When people say, "both falls generate the same force," what they actually mean is that the top piece feels the same force in both falls, because the longer length of rope "absorbs," more of it.

No. Hint: ke=1/2mv^2


dynosore


Dec 6, 2009, 9:41 AM
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Re: [zealotnoob] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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zealotnoob wrote:
OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...

Crazy So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. So, when I toprope, I "weigh" 320 instead of 160, as far as the anchor is concerned? No wonder I can't pull that slopey overhang......the things you learn on the internet.


sungam


Dec 6, 2009, 9:55 AM
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dynosore wrote:
zealotnoob wrote:
OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...

Crazy So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. So, when I toprope, I "weigh" 320 instead of 160, as far as the anchor is concerned? No wonder I can't pull that slopey overhang......the things you learn on the internet.
Are you trying to imply that the pulley effect isn't real?
You're not that stupid, dude. Come on.

And, if you're curious, if there is little or no friction between the the pully and the rope then there is a total of 250lbs hanging on that pully. 125 pounds from the deer, and 125 from whatever the other end of the rope is tied to. (we're ignoring the angles, here).

Think about it - if the deer was exerting 125 pounds on one end of the rope and nothing was pulling on the other, the rope would run through the pully and the deer would fall, right? and since both the weight of the deer and the pull from what the rope is tied to are downwards, that means the downwards force on the pully is the sum of those two.
125+125=250 lbs of downwards force.


jt512


Dec 6, 2009, 10:01 AM
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Re: [sungam] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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sungam wrote:
dynosore wrote:
zealotnoob wrote:
OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...

Crazy So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. So, when I toprope, I "weigh" 320 instead of 160, as far as the anchor is concerned? No wonder I can't pull that slopey overhang......the things you learn on the internet.
Are you trying to imply that the pulley effect isn't real?
You're not that stupid, dude. Come on.

He's had two years to think about it.

Jay


sungam


Dec 6, 2009, 10:06 AM
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Re: [jt512] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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jt512 wrote:
sungam wrote:
dynosore wrote:
zealotnoob wrote:
OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...

Crazy So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2. So, when I toprope, I "weigh" 320 instead of 160, as far as the anchor is concerned? No wonder I can't pull that slopey overhang......the things you learn on the internet.
Are you trying to imply that the pulley effect isn't real?
You're not that stupid, dude. Come on.

He's had two years to think about it.

Jay
Damn, I didn't notice how old the thread was. The post I qouted, however, was made today.
Fricken zombie threads.


milesenoell


Dec 6, 2009, 10:15 AM
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dynosore wrote:
zealotnoob wrote:
OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...

Crazy So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2.

This is one of the best examples you could have thrown out for two reasons.
1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design.
2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up.


sungam


Dec 6, 2009, 10:18 AM
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Re: [milesenoell] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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milesenoell wrote:
dynosore wrote:
zealotnoob wrote:
OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...

Crazy So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2.

This is one of the best examples you could have thrown out for two reasons.
1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design.
2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up.

Wait, I seem to have misread. It looks like the pully is currently hanging from the scales. In which case the dear isn't 125 pounds, it's like around 70-80 pounds.


giza


Dec 6, 2009, 10:29 AM
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skinner wrote:
A person like USnavy comes along and asks an honest question, which if they understood *why* they wouldn't have asked it in the first place. In response he gets ridiculed by Flint, I guess that's the rc.com way huh?


With only a few posts USnavy may be new to climbing, but gawd.. they should know and fully understand all this stuff before they dare to post here!
It's no wonder there are so many who choose to just lurk.

Welcome to rc.com USnavy Crazy

Agreed. This is not a forum to be inquiring about legitimate climbing-related topics. It's the arena of douchebag spraylords where every post will be scrutinized and torn apart not only for its content but also its spelling, grammar, the poster's # of posts, etc.

There are plenty of other forums where your question would be answered from a place of knowledge and mutual respect.


milesenoell


Dec 6, 2009, 12:40 PM
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Re: [sungam] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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sungam wrote:
milesenoell wrote:
dynosore wrote:
zealotnoob wrote:
OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...

Crazy So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2.

This is one of the best examples you could have thrown out for two reasons.
1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design.
2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up.

Wait, I seem to have misread. It looks like the pully is currently hanging from the scales. In which case the dear isn't 125 pounds, it's like around 70-80 pounds.

Not if the rope is tied to itself or back to the deer (as I had presumed). I was assuming that he could tell the difference between a 63 lb and a 125 lb deer. (and a 63 pound deer would be so runty he probably wouldn't be posting about it.)


sungam


Dec 6, 2009, 12:47 PM
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Re: [milesenoell] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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milesenoell wrote:
sungam wrote:
milesenoell wrote:
dynosore wrote:
zealotnoob wrote:
OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...

Crazy So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2.

This is one of the best examples you could have thrown out for two reasons.
1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design.
2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up.

Wait, I seem to have misread. It looks like the pully is currently hanging from the scales. In which case the dear isn't 125 pounds, it's like around 70-80 pounds.

Not if the rope is tied to itself or back to the deer (as I had presumed). I was assuming that he could tell the difference between a 63 lb and a 125 lb deer. (and a 63 pound deer would be so runty he probably wouldn't be posting about it.)
I suppose. I didn't think about it since I've never seen a 70 pound or a 125 pound deer hanging from a pully so...


milesenoell


Dec 6, 2009, 12:50 PM
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giza wrote:
There are plenty of other forums where your question would be answered from a place of knowledge and mutual respect.

But where's the fun in that?

edited to add: Oh, I didn't realize this thread was in The Lab. Sorry if I've come off as snarky.


(This post was edited by milesenoell on Dec 6, 2009, 12:54 PM)


Adk


Dec 6, 2009, 4:41 PM
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sungam wrote:
milesenoell wrote:
sungam wrote:
milesenoell wrote:
dynosore wrote:
zealotnoob wrote:
OT: Another quirk of the climbing system that can be surprising is the pulley effect. I.e, if you bail from a climb, off a single piece of pro, by having your partner lower you, you're applying twice the amount of force on that piece than if you rapped from it...

Crazy So, the dead deer hanging from a pulley in my pole barn right now is exerting 250 lbs of force on the pulley, even though it only weighs 125 lbs? That's a good trick! The spring scale attached to the pulley even says 125 lbs, it must be off by a factor of 2.

This is one of the best examples you could have thrown out for two reasons.
1) As Magnus pointed out, to get a a full doubling of force you need a frictionless system, and carabiners have a good bit of friction, whereas a pulley has very little, by design.
2) All you have to do to see the doubling affect is tie off the rope to an anchor on the ground rather than to itself, since you already have the scale set up.

Wait, I seem to have misread. It looks like the pully is currently hanging from the scales. In which case the dear isn't 125 pounds, it's like around 70-80 pounds.

Not if the rope is tied to itself or back to the deer (as I had presumed). I was assuming that he could tell the difference between a 63 lb and a 125 lb deer. (and a 63 pound deer would be so runty he probably wouldn't be posting about it.)
I suppose. I didn't think about it since I've never seen a 70 pound or a 125 pound deer hanging from a pully so...

He might be posting about it. Ya see. There are briefcase deer ---- < 50 lbs
suitcase deer------ >50 < 100 lbs
Backpack deer ----- >100< 140 lbs
one man drag deer-->140<200 lbs
two man draggers > 200 lbs

the force that any of them exhibit on a pully is not that hard to figure out. If math is tough think of it this way. If you have a backpack deer (you can actually wear it like a backpack) and you weigh the same and you try to lift it off the ground you can't.
If you are a bit heavier you still can't because of friction at the pully. If for some reason you can get it in the air and you both neither go up or down you have how many pounds hanging from the pully now?
For now don't think friction at the pully.
See where I'm going? Tie that off and you have how many pounds on the deer side of the pully and how many at the tie off point? How many are at the pully?

Briefcase deer do taste pretty good.Blush


(This post was edited by Adk on Dec 6, 2009, 4:48 PM)


adatesman


Dec 6, 2009, 6:43 PM
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sungam


Dec 6, 2009, 6:47 PM
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adatesman wrote:
Just FYI, there's sizes below the Briefcase Deer. The Pudu (native to Chile) generally weighs a mere 22 pounds as an adult. And on the big end Moose are in the same family and weigh upwards of half a ton.

In either case I'm wondering why this is being discussed in The Lab....
Half a ton?
try 2300 pounds.


It's in the lab because it's all sciency and shit.


johnwesely


Dec 6, 2009, 7:11 PM
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giza wrote:
skinner wrote:
A person like USnavy comes along and asks an honest question, which if they understood *why* they wouldn't have asked it in the first place. In response he gets ridiculed by Flint, I guess that's the rc.com way huh?


With only a few posts USnavy may be new to climbing, but gawd.. they should know and fully understand all this stuff before they dare to post here!
It's no wonder there are so many who choose to just lurk.

Welcome to rc.com USnavy Crazy
Agreed. This is not a forum to be inquiring about legitimate climbing-related topics. It's the arena of douchebag spraylords where every post will be scrutinized and torn apart not only for its content but also its spelling, grammar, the poster's # of posts, etc.

There are plenty of other forums where your question would be answered from a place of knowledge and mutual respect.

But those forums are not any where near as much fun.


majid_sabet


Dec 6, 2009, 8:51 PM
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Re: [USnavy] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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There was one climbing expert who knew rope jumping business like no other but he retired long ago. look for Dan Osman, I am sure you will find his extensive research in this business.


Adk


Dec 7, 2009, 5:02 AM
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Re: [majid_sabet] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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majid_sabet wrote:
There was one climbing expert who knew rope jumping business like no other but he retired long ago. look for Dan Osman, I am sure you will find his extensive research in this business.
Finally someone gets us back on track.


scottek67


Dec 7, 2009, 5:24 AM
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Re: [sungam] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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sungam wrote:
adatesman wrote:
Just FYI, there's sizes below the Briefcase Deer. The Pudu (native to Chile) generally weighs a mere 22 pounds as an adult. And on the big end Moose are in the same family and weigh upwards of half a ton.

In either case I'm wondering why this is being discussed in The Lab....
Half a ton?
try 2300 pounds.
[image]http://www.jerrysbaitandtackle.com/images/Trophies/Moose/moose.jpg[/image]

It's in the lab because it's all sciency and shit.
mission accomplished Sly and Majid is my new hero! Shocked


knudenoggin


Dec 7, 2009, 11:58 PM
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Re: [scottek67] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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Having waded through all the one-line add-on posts to nested nonsense,
here's a snippet from the underground world bearing on the OP's question
(imagine doing that!).

In reply to:
There is one thing that I have to say again, though: For the same fall factor, longer falls are worse than shorter falls. There was a time when some of the best UIAA ropes would fail under one fall of UIAA fall factor and thrice the height. On a longer fall, you have more energy and proportionally more rope to absorb it, but NOT proportionally more knots (and in the real world, NOT proportionally more harnesses and proportionally more bodies). Fall factor is a great simplification, but it is just that. Don't believe it, especially for long falls. Don't believe it for cows-tail falls, either. Keep 'em loose.
This points to greater forces, for the want of those missing additional
proportional elements; but I recall a Chouinard catalogue showing plots
of long/short falls and the main difference shown in them was of the
duration at the high forces -- much more in the longer fall.

And I can't believe that a long fall on the static stuff (HTPolyester,
HMPE, Technora) is measurable via FF vs. length of fall -- as it surely
isn't in the case of no-stretch. But I'm unaware of tests of this.

*kN*


cantbuymefriends


Dec 8, 2009, 3:07 AM
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Re: [knudenoggin] 60 meter fall (fall factor 1); will a 10.5mm rope hold? [In reply to]
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We are talking about the force at the end of the rope that is stopping the fallen climber, the force that is "felt" by the climber's body, the harness and the tie-in knot.

If this force is more or less the same for any fall of a given fall factor, what does duplication of knots, harnesses and bodies have to do with it?


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