If Your Friends Jumped Off a Cliff On a Rope Swing....

[Climber]

a rope swing as shown here is hardly a "fall". the fall factor (FF) is much less than 1 because they using what looks like an entire rope length and because they are swinging so the rope is supporting their weight long before reaching the bottom. also, just like a swing, any downward momentum becomes angular as the rope tightens, further reducing the force on the rope. as such, the force on the rope is small compared to taking a bad lead fall.

Osmon died because his two ropes cut each other and because he didnt take care of them. Osmon's falls were also much more stress on the rope because he usually jumped from next to the anchor, so he fell the length of rope before it pulled tight, ie a FF of 1.

im not condoning recklessly jumping off of cliffs w/ any old rope. but you are comparing apples to oranges when saying the manufacturers UIAA cert of 10-15 falls applies here.

The problem is that they're doing the same kind of rationalization and will likely put many jumps on those ropes. It's going to be the same amount of energy dissipated from swinging as you'd have from a straight drop, even though the time period will be longer. You're still stretching the rope and while it won't damage the fibers quite as much there is still wear and tear going on.

Remember that while a short fall puts the load on a shorter section of the rope, you're still dealing with Energy = Mass x Gravity x height, and that energy needs to be dissipated.

 

[stangmx13]

The problem is that they're doing the same kind of rationalization and will likely put many jumps on those ropes. It's going to be the same amount of energy dissipated from swinging as you'd have from a straight drop, even though the time period will be longer. You're still stretching the rope and while it won't damage the fibers quite as much there is still wear and tear going on.

Remember that while a short fall puts the load on a shorter section of the rope, you're still dealing with Energy = Mass x Gravity x height, and that energy needs to be dissipated.

no. youre missing quite a few pieces of the puzzle.

first off, the amount of rope used to dissipate the energy is very very important when it comes to how damaged the rope is. ropes break at the UIAA test number because the same few inches is subject to stress over their analog for a 'biner in a lead fall. the friction over the 'biner induces a stress riser, but there is no stress riser here because of the nature of the swing. a climber could almost endlessly stretch a rope to its static elongation percentage, esp if they are using the entire rope, ie there is no appreciable wear and tear. doing so is about the same stress as top-roping.

secondly, especially in this case, all the potential energy is NOT converted into force on the rope because the swinger is swinging. most of the potential energy becomes kinetic, which is nicely reduced by gravity. in an ideal case, the swinger could have not jumped towards the anchor at all, kept the rope taught, and would have only applied a load equal to their weight to the rope + a little more for centripetal force, around 8% the impact force of a UIAA test fall. you've brought up the extreme case, what Osman did. the swinger would need to jump the horizontal distance to the anchor (not possible as shown), leading to a force thats about 75% the impact force of a UIAA test fall. yes, i did the actual math. of course, impact force (force felt by the climber at the end of the rope) for a UIAA test fall is not what breaks the rope for reasons listed in my first point.

 

[MikeyRocks]

 

[Dubbington]

Can someone explain the bow and arrow and what was going on with that?

 

[revnort]

Can someone explain the bow and arrow and what was going on with that?

I am pretty sure they used that to stretch the rope across the canyon. The swing is actually attached to another rope that goes from one side to the other (possibly the one they are slack-lining on?).

Obviously someone to be on, or go to the other side to secure the rope as the arrow isn't enough , but the arrow/yellow rope lets them pull a more substantial rope across easily.

At least that is my non-climbing, don't really know, opinion of what I saw.

 

[JackTheTripper]

There is a behind the scenes vid on how they did this.

[youtube]CpCxIL3r5dM[/youtube]

Looks like they did a limited number of jumps and the rigging guys know what they are doing.

 

[Climber]

no. youre missing quite a few pieces of the puzzle.

first off, the amount of rope used to dissipate the energy is very very important when it comes to how damaged the rope is. ropes break at the UIAA test number because the same few inches is subject to stress over their analog for a 'biner in a lead fall. the friction over the 'biner induces a stress riser, but there is no stress riser here because of the nature of the swing. a climber could almost endlessly stretch a rope to its static elongation percentage, esp if they are using the entire rope, ie there is no appreciable wear and tear. doing so is about the same stress as top-roping.

secondly, especially in this case, all the potential energy is NOT converted into force on the rope because the swinger is swinging. most of the potential energy becomes kinetic, which is nicely reduced by gravity. in an ideal case, the swinger could have not jumped towards the anchor at all, kept the rope taught, and would have only applied a load equal to their weight to the rope + a little more for centripetal force, around 8% the impact force of a UIAA test fall. you've brought up the extreme case, what Osman did. the swinger would need to jump the horizontal distance to the anchor (not possible as shown), leading to a force thats about 75% the impact force of a UIAA test fall. yes, i did the actual math. of course, impact force (force felt by the climber at the end of the rope) for a UIAA test fall is not what breaks the rope for reasons listed in my first point.

Shit, you've got me there.

A prime example of why you shouldn't post while 90% of your brain is still focused on work.