Fall Forces?

[xxnitsuaxx]

Some buddies of mine set up a rope swing off of Corona and I'm trying to figure out what sort of fall forces they're putting on the ropes. They rigged the ropes to the anchor on one side of Corona and then jumped off the other side, ending in a massive pendulum. (See the jump around 1:00) I've never taken a factor-2 fall (knock on wood) but I understand the concept. Since they're falling below the anchor, are they taking a factor-2 fall? Or does the fact that they're not taking a true whipper and instead mostly taking a pendulum mitigate the force? I'd appreciate any geeking out that y'all could do for me.

[Bo_Beck]

Some buddies of mine set up a rope swing off of Corona and I'm trying to figure out what sort of fall forces they're putting on the ropes. They rigged the ropes to the anchor on one side of Corona and then jumped off the other side, ending in a massive pendulum. (See the jump around 1:00) I've never taken a factor-2 fall (knock on wood) but I understand the concept. Since they're falling below the anchor, are they taking a factor-2 fall? Or does the fact that they're not taking a true whipper and instead mostly taking a pendulum mitigate the force? I'd appreciate any geeking out that y'all could do for me.

http://www.youtube.com/watch?v=7xm_PIQ6_hQ

The drop divided by the amount of rope in the system. In your case it appears to me that your drop is 100' and the rope in the system is 100' so the maximum FF is 1. I'm sure the fact that there is not an absolute vertical drop onto the anchors; somewhat of a swing then the FF is substantially less than 1

[Sandstone Addiction]

You guys are INSANE!

Loved the video though.

[jman]

Ohh...scary. Heights don't scare me, it's the falling that does. Lol. Good call on the rope though.

[ratagonia]

Some buddies of mine set up a rope swing off of Corona and I'm trying to figure out what sort of fall forces they're putting on the ropes. They rigged the ropes to the anchor on one side of Corona and then jumped off the other side, ending in a massive pendulum. (See the jump around 1:00) I've never taken a factor-2 fall (knock on wood) but I understand the concept. Since they're falling below the anchor, are they taking a factor-2 fall? Or does the fact that they're not taking a true whipper and instead mostly taking a pendulum mitigate the force? I'd appreciate any geeking out that y'all could do for me.

I love quotes like this:

I've never taken a factor-2 fall (knock on wood) but I understand the concept. Since they're falling below the anchor, are they taking a factor-2 fall?

You claim you understand the concept, and then in the NEXT sentence, you prove that you don't. C'mon, try a little harder - at least slip an obfuscatory sentence in between the two.

Yes, the swing cuts the forces involved considerably.

The forces are not calculable, even if we had good information on the system. But, from a forces standpoint, not a big concern. Obviously, the big concern is wear and tear on the rope. Did they use a second backup rope? A rope protector would be a very, very good idea.

Dropping off a 10 lb pack to test it was, uh, not so useful. I would want to test the system with something close to body weight, to check the rope stretch, for instance, but then again... I value my life rather highly.

Tom

[Bo_Beck]

Yes, the swing cuts the forces involved considerably.
The forces are not calculable, even if we had good information on the system.

Great Point...."Forces". Fall factor and force are separate beasts, yet intertwined. Fall factor is a component by which forces may be affected. Force is that component which is measurable.

Dropping off a 10 lb pack to test it was, uh, not so useful. I would want to test the system with something close to body weight, to check the rope stretch, for instance, but then again... I value my life rather highly.

Reminds me of a video that Kirk Mauthner showed me in 1998 or 99? A british officer and canadian civilian desired to set the world record for ziplines. Theirs measured over 5000' long. They sent down a "dummy" at 1kn (220 lbs). The test run was very successful. An argument ensued as to who got to ride it first. After long debate they concluded that they'd both ride it at the same time! (you probably can see what's next?!) Anyway, the best part of the ride was BBC's coverage and commentary! "And here they come, it's looking good! They are flying and all's well.......hesitation..........Oh-oh! look out it looks like they're a bit low.....NO, No, No (as the tree tops are sheared off and leaves and branches are flying) Oh my god I think there's trouble!" Needless to say the 2kn mass made quite the difference. They both came out of the ride alive, but only after some broken bones etc.

Yeah Tom.....testing something like a giant swing with the proper mass might be pretty important?!

[xxnitsuaxx]

I confused myself into thinking that factor-2 falls had to do with falling below the anchors instead of being a ratio of the length of the fall to the amount of rope out. Now I'm glad I did because I got to read one of my favorite words. Tom - thanks for "obfuscatory"; that word doesn't get enough action.

Thanks for the help Bo and Tom. I agree that the little pack of rocks isn't very helpful; if it had been me up there I would have tried with something much closer to body weight. They used a second rope as a backup and I suggested using cut hoses as rope protectors if they ever go again.

Bo - I'm surprised the broadcaster displayed that much emotion. I'd expect something like "looks like they could be in for a spot of trouble! Chins up lads - put a brave face on it!"

[Iceaxe]

Poor mans's GoPro = iPhone duct taped to hand.

After watching that video I've decided I'm offically an old man.... cause there is no way in hell I'm intentionally stepping off the top of that arch.

[Cirrus2000]

This thread is full of win.

I'm afraid I don't have much more than that. It looks like a riot. (I wouldn't do it.) Tom does a little of what Tom does, so well. Bo has a great anecdote. xxnitsuaxx takes it on the chin and bounces back with an anecdote expanding bonus...

A great read, all in all!!

[ratagonia]

Poor mans's GoPro = iPhone duct taped to hand.

After watching that video I've decided I'm offically an old man.... cause there is no way in hell I'm intentionally stepping off the top of that arch.

hey hey hey

I really appreciate that Bogley provides a custom smilie for my 100-year-old derriere. Thank you. But Ice, it's MINE, ALL MINE. Go get your own Icon...

Tom ===

[ratagonia]

I confused myself into thinking that factor-2 falls had to do with falling below the anchors instead of being a ratio of the length of the fall to the amount of rope out. Now I'm glad I did because I got to read one of my favorite words. Tom - thanks for "obfuscatory"; that word doesn't get enough action.

Here's a diagram for you...

maybe I'll do the FF2 diagram tomorrow...

Tom

[Branin]

After watching that video I've decided I'm offically an old man.... cause there is no way in hell I'm intentionally stepping off the top of that arch.

Not sure that makes you old, cause I sure as hell wouldn't step off of that arch, and I'm not what most would call old...

Fall factor diagram... I'm not as ambitious as Tom, drawing my own, so I'm just posting one found by searching "fall factor 2" on google images. Courtesy of Beal ropes.