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Moof
Big Wall climber
Orygun
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Sounds like someone smart talking out of their ass on subjects they are more ignorant about than their PhD will let them admit to themselves.
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overwatch
climber
Arizona
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It is kind of what ropes already do is it not? That said new materials that allow it to function better would be a good thing
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crankster
Trad climber
No. Tahoe
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Certainly a more interesting topic than what pistol I should buy.
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JEleazarian
Trad climber
Fresno CA
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Mathematicians have also proven that it is possible to produce a generator of all prime numbers using powers of a constant. The only problem is that finding the constant is equivalent to finding all prime numbers in the first place, so it doesn't help.
I have no doubt the one may optimize rope characteristics in theory, but proving something possible differs from showing how to do it. WHen it comes to rope, I already know how to do it -- manufacture all climbing ropes to my personal specifications. Who cares if it doesn't satisfy anyone else's needs? I've got what I need. Besides, if the manufacturers do what I ask, they'll be stuck with a boatload of ropes no one but me would want, so I should be able to get it for cheap!
John
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JimT
climber
Munich
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A more productive (and dare I say intelligent) idea was being worked on by a Japanese guy maybe ten years ago. You use a static rope and adjust the impact force at the belayer end.
This is naturally exactly how their example of how an aircraft arrestor cable works and clearly not how they think they work.
Incidentally, anyone who thinks smooth braking in a car involves constant braking force is silly, I personally hate coming to a stop with a jerk so feather the brakes off as I slow.
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JEleazarian
Trad climber
Fresno CA
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You use a static rope and adjust the impact force at the belayer end.
Jim, the Sierra Club did that in the 1930's with the dynamic belay. Raffi Bedayn was part of the first ascent party on Shiprock specifically for his belaying prowess.
John
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donini
Trad climber
Ouray, Colorado
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Just the rope for the theoretical climbers here. In theory it could be produced, in theory they could climb.....in actuality, none of the above.
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JimT
climber
Munich
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Not a clue, it was just something that came up when I was doing some reasearch years ago.
The problem with any automatic system is the decision how much rope to let through is taken out of the belayers hands, you´d get the optimum low-force catch until you hit something. Sometimes a hard catch is an advantage!
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Ed Hartouni
Trad climber
Livermore, CA
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what funny comments... who "invented" the modern climbing ropes that we use?
How do you think they actually designed that rope?
I'll attempt to get the paper and read it.
But perhaps you could think a little bit before trash talking some designers who had an interesting idea... that's how many technologies start out, many of those technologies we use in modern climbing.
I don't see many pictures of Donini using manilla ropes.
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Reilly
Mountain climber
The Other Monrovia- CA
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The carrier arresting system isn't so simple. It is adjusted for the individual aircraft in terms
of weight and landing speed which would require the belay device to be constantly adjusted
with regard to the climber's weight and the fall factor. What could go wrong? Of course, if
it comes from MMM, Murphy Manufacturing of Modesto, then I would feel better.
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rgold
Trad climber
Poughkeepsie, NY
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Echoing Ed, some of the ignorance on display here about how science and technology moves forward is sad. But not to worry Luddites, these developments won't be influencing any gear you'll be using.
I can't get the paper directly through my institution; only a handful of US institutions have an arrangement with the publisher. I might try inter-library loan, but that will take a while and I'm not at all sure I have the requisite interest and motivation if I can't get a copy easily. Ed, if you do get a copy, I'd appreciate seeing it if you don't mind.
The main idea behind a "constant force" rope is that, unlike the ideal spring, the tension in the rope doesn't go up as the rope stretches, at least for a broad range of elongation values. Apparently, certain viscoelastic materials can behave this way. The elongation vs. tension graph is mesa-like, a broad level plateau. The same graph for an ideal spring is an ascending straight line.
The fall energy the rope absorbs by stretching turns out to be the area under the elongation vs. tension graph (engineers call this "stress vs strain"). If the rope tension is nearly constant, then we are speaking of an area under a rectangle (the mesa) rather than an area under a right triangle (the ascending line). The rectangle need only be half as high to have the same area as the triangle, which means the peak tension in the rope could be half the value obtained by the ideal spring.
This sounds good for big falls, but maybe not for short falls, which could actually produce higher loads with such a rope than are obtained with something more like a spring, since with the "constant-tension" rope the tension very quickly approaches the constant value. The prospect of a 4 kN impact no matter what doesn't seem to me to be appealing to people whose falls are mostly quite short...
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JEleazarian
Trad climber
Fresno CA
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I hope my comments, above, didn't sound like those of a Luddite, Ed and Rich. My economist's knee-jerk reaction was that "ideal" really means optimal. After all, my ideal rope defies my understanding of physics, since it would have an impact force of zero while simultaneously never stretching far enough to cause me to hit anything, weigh nothing but handle perfectly, have zero rope drag (hence no friction) but be able to be held in any common belaying device, etc. etc.
On a more serious note, thanks for the discussion about energy absorption and fall length. I know the only falls I've ever taken that seriously bent gear were relatively short ones near the start of the pitch (and, obviously, with a very high fall factor), so I found your comments about impact force being highest for shorter falls interesting - and sobering.
Thanks.
John
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zBrown
Ice climber
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The whole world is going down (with) the Tubes
We're white punks on dope
Mommy & Daddy live in Hollywood
Hang myself when I get enough rope
Can't clean up, though I know I should
White punks on dope
White punks on dope
No rope-a-dope comments please
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zBrown
Ice climber
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Here's the abstract. Aparently have to sign up to get the whole article. I don't give out my email to anyone, not to mention cash. Look what happened to H. Clinton.
We consider the rope climber fall problem in two different settings. The simplest formulation of the problem is when the climber falls from a given altitude and is attached to one end of the rope while the other end of the rope is attached to the rock at a given height. The problem is then finding the properties of the rope for which the peak force felt by the climber during the fall is minimal. The second problem of our consideration is again minimizing the same quantity in the presence of a carabiner. We will call such ropes mathematically ideal. Given the height of the carabiner, the initial height and the mass of the climber, the length of the unstretched rope and the distance between the belayer and the carabiner, we find the optimal (in the sense of minimized the peak force to a given elongation) dynamic rope in the framework of nonlinear elasticity. Wires of shape memory materials have some of the desired features of the tension–strain relation of a mathematically ideal dynamic rope, namely, a plateau in the tension over a range of strains. With a suitable hysteresis loop, they also absorb essentially all the energy from the fall, thus making them an ideal rope in this sense too.
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hooblie
climber
from out where the anecdotes roam
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bump
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Reilly
Mountain climber
The Other Monrovia- CA
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Ironic that just the other day I read about the problems the Navy is having with their new
electro-magnetic arresting system. Of course, in this case it seems clear it wasn’t adequately
tested prior to putting it aboard ship and now that ship, the world’s costliest ever, is basically
useless.
To drift back on topic the history of science is rife with examples of theoretical knowledge
waiting for materials science to catch up.
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mcreel
climber
Barcelona
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Hmm, why does that not sound surprising? Maybe they should buy a few more of them and see if the others work better.
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AP
Trad climber
Calgary
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In theory I can climb 5.11
Wait that was 30 years ago
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sween345
climber
back east
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Milktoast,
Forget the pistol and check your thread on hiking boots.
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zBrown
Ice climber
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https://mickeythompson.wordpress.com/2014/02/10/winch-steel-cable-vs-dynamica-rope/
Dynamica Rope is made from Dyneema fibres which is one of the strongest fibres in the world. The rope has excellent properties with regard to strength, weight, UV-stability (daylight), safety, abrasion, tension fatigue and bending fatigue.
When comparing Dyneema to steel it is ten times stronger per unit of weight. This means that a Dyneema rope has a slightly higher strength than a steel wire of the same dimension but less than one tenth of the weight. While steel wire can take 6500 loads at 50% of the maximum breaking load, a Dynamica Rope can take 10 million cycles at the same load level making it long lasting and safe.
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Winemaker
Sport climber
Yakima, WA
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Walther PPK of course. Interesting topic (rope that is) and some thought in the paper. Changing the dynamic of the rope under load.
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Steve Grossman
Trad climber
Seattle, WA
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One issue with designing an "ideal" climbing rope is continued use. If all of the shock absorption is used up in a single fall then you can switch ends once and take a second one which won't leave much in reserve for the rest of your fifty pitch route or expedition.
Ropes are pretty damn good at this point in time and you can get what you want if you shop around and compare performance qualities. Using more shock absorbing draws like Yates Screamers would be a better way to solve this problem in a sustainable fashion IMO.
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RussianBot
climber
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Silly scientists are always speculating about stuff they don’t understand. That’s news? Just ask me and my awesome understanding of the difference between theory and reality and I’ll set them straight. Really. ?
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Yury
Mountain climber
T.O.
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I am confused.
Do they want to use recycled memory foam matresses to make ropes?
Probably Dyneema static rope with a shock absorber at a climber's rope end (that can be tuned during a climb) can be an ideal solution from weight + arresting force criteria.
On the other hand I am not that sure about longevity of such rope.
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Ed Hartouni
Trad climber
Livermore, CA
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from the conclusions section, first sentence:
We do not expect this paper to have an immediate effect on the climbing community, but by providing a prescription for a mathematically ideal rope, the work may help guide the development of new ropes.
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Jaybro
Social climber
Wolf City, Wyoming
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Mar 11, 2018 - 04:44am PT
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Gotta start somewhere ( not to say that it (the rope grail quest)wasn't started a long time ago) I applaud their efforts and look forward to see what comes from this.
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rgold
Trad climber
Poughkeepsie, NY
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Mar 11, 2018 - 06:28pm PT
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To add a bit to my previous comments ( http://www.supertopo.com/climbing/thread.php?topic_id=2840129&msg=2840759#msg2840759 ), the mathematics part of the paper is to prove that, for a given length of rope and given amount of elongation, the minimum force on the falling climber will be obtained if the rope is able to resist with constant force. This would make such a rope more analogous to a reusable screamer and not at all like the "spring-like" ropes we have now, and contradicts the suggestion made earlier that to get a softer catch you need more stretch.
Without knowing anything about hydraulic arrestors on aircraft carriers, comparing the ideal rope model to those seems likely to be wrong, as I assume (perhaps incorrectly) that "hydraulic" means the resisting force is a result of viscous damping and so is not constant but rather proportional to velocity.
What I haven't gotten from my so far cursory perusal is whether the system is "scalable." Different rope lengths and different elongations presumably require different constant resisting forces from the rope. I'm not sure how the variability of those parameters is encoded into the material behavior. It would mean that the constant resisting force would have to vary depending on the initial velocity of the stretching when the falling climber just starts to load the rope, and I'm not sure whether something like that happens with the materials in question.
Another possible error is that the authors say at least twice that modern climbing ropes stretch 15%, but the amount of elongation for a UIAA-level impact is actually more like 30%.
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Lorenzo
Trad climber
Portland Oregon
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Mar 11, 2018 - 06:54pm PT
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All well and good but what pistol should I buy?
DMT My answer depends on which way you want to aim it.
But since you need somebody to answer for you, I’d say a starter pistol would be good.
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