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moray
Hooked on the Buzz
Reged: 10/16/08
Posts: 284
Loc: Maine
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In the arborist catalogs the loopie in use is always shown wrapped around a stem, and the working bight, attached to the hardware, is shown passing through a bight in the sleeve part of the loopie. All these bights and curves add friction to the overall system and help to keep the loopie secure against slippage. The loopie is much less secure in an open loop configuration where the loop is subjected to a straight pull, and least secure when there is no bight formed in the sleeve part of the loopie. Here I report 3 pull tests on 5/16 inch Tenex Tec loopies. This cord has a rated tensile strength of about 4700 lbs.
Three identical loopies were made, each from 27 inches of rope. The sleeve length before the bury operation was one fid, or 6.75 inches, and about 1.5 inches of dead tail was left at the throat. The resulting loopies were long enough to give clean tests in all 3 configurations tested with no wasted rope. In every test, care was taken to milk all slack out of the spliced area just before pulling. In each picture "T" marks the throat end of the sleeve, the spot where the cover ends in a stubby appendix.
The attached picture shows the first configuration: the sleeve is straight and both bearings are in unspliced rope. There was no need to hook up my heavy equipment for this test. With a steel screw link at each bearing point, it was easy to pull the loopie apart by hand. I guess it took no more than 5 or 6 lbs.
For the next two tests I resorted to my hydraulic pulling rig. For both tests the bearing points applying load to the loopie were 3/4 inch steel shackle pins. The rope-on-steel friction is part of the whole system, so it is important that it be the same for both tests.
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moray
Hooked on the Buzz
Reged: 10/16/08
Posts: 284
Loc: Maine
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For the second test I chose the configuration shown in the picture. Here one of the bearing points is in the sleeve area close to the tail of the "splice". At 1524 lbs the core in the sleeve suddenly slipped about two inches, at which point I stopped the test.
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moray
Hooked on the Buzz
Reged: 10/16/08
Posts: 284
Loc: Maine
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In this 3rd test the bearing point on the sleeve is near the throat, as shown in the picture. When the tension reached 5940 lbs, there was a loud bang and everything came apart. At first I thought the rope had broken, but no, the core had pulled all the way out of the sleeve.
Normally one doesn't rush into print (as I am doing!) with the results one one test, but I have done similar tests in the past at much lower loads with entirely consistent results. The very great difference between loading the tail of the sleeve vs loading the throat is of no consequence when the loopie is wrapped around a tree and probably girth-hitched to a PortaWrap or other hardware. But in an open loop straight pull situation, the loopie needs some help if it is not to slip. It appears that placing one bearing point on the sleeve near the throat produces the best result.
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Norm_Hall
Outta Control
Reged: 08/31/04
Posts: 3345
Loc: Wauconda, (Chicago),IL,USA
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Very interesting. Thank you.
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Brion
Likin' the Buzz
Reged: 06/09/05
Posts: 116
Loc: Port Townsend, Washington
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Hi,
Ah, I see it now, how the outer rope has room to stretch out and compress on the inner rope. This certainly trumps my concern about the long running tail pulling slack into the splice from its weight. Perhaps I need to Rolling Hitch this part to the Loopie, above where the line exits, to prevent the slack, and then put the bearing at the "T".
On a separate note, have you tried this series of tests using a full bury? For 5/16" we'd typically bury at least two feet, and this might change all the results, including giving you a full break.
Thanks for the great investigation!
Fair leads,
Brion Toss
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Norm_Hall
Outta Control
Reged: 08/31/04
Posts: 3345
Loc: Wauconda, (Chicago),IL,USA
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Quote:
For 5/16" we'd typically bury at least two feet, and this might change all the results, including giving you a full break.
Thanks for the great investigation!
Fair leads,
Brion Toss
Brion, are you talkin a 2 foot bury on polyester fiber or exotic fiber?
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Brion
Likin' the Buzz
Reged: 06/09/05
Posts: 116
Loc: Port Townsend, Washington
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Quote:
Quote:
For 5/16" we'd typically bury at least two feet, and this might change all the results, including giving you a full break.
Thanks for the great investigation!
Fair leads,
Brion Toss
Brion, are you talkin a 2 foot bury on polyester fiber or exotic fiber?
Exotic.
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Brion
Likin' the Buzz
Reged: 06/09/05
Posts: 116
Loc: Port Townsend, Washington
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Quote:
Quote:
Quote:
For 5/16" we'd typically bury at least two feet, and this might change all the results, including giving you a full break.
Thanks for the great investigation!
Fair leads,
Brion Toss
Brion, are you talkin a 2 foot bury on polyester fiber or exotic fiber?
Exotic. And here's where my unfamiliarity with arborist gear shows up. It hadn't occured to me that Dacron might be used for Loopies. Having said that, it seems that the bury for Tenex might want to be more than standard, given its slickness and loose weave. The fact that the splice pulled out, even given the good bearing point, seems to support this notion. As noted earlier, the loads come onto Looopies differently than eyes. How about a 1ft. bury?
Fair leads,
Brion Toss
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southsoundtree
True Buzzer
Reged: 11/25/07
Posts: 2685
Loc: Olympia, WA
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Moray-
Thanks for the clear illustration. I am now better able to explain to groundmen not only how, but why it is so important to use the Loopie correctly.
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Sean Kroll South Sound Tree Olympia, WA
ISA Certified Arborist
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NickfromWI
Blitzed on the Buzz
Reged: 09/19/02
Posts: 4141
Loc: Los Angeles, CA
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If you compare the Samson directions for a polyester whoopie to their directions for a high-mod whoopie, the bury lengths are as follows:
Polyester: 1.25 fids
High Mod: 3.5 fids
In 5/16" rope that'd be a approx an 8.5" bury for polyester and a 24" bury in High Mod.
I've heard varying opinions on what Loopie bury lengths should be in relation to their whoopie cousins. Some say "same" some say double, some say triple.
Just thought I'd throw that out there for the sake of the conversation.
love
nick
--------------------
Call or email for a splicing consultation! nick@splicesbynick.com 323-384-7770
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moray
Hooked on the Buzz
Reged: 10/16/08
Posts: 284
Loc: Maine
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I have tested two more loopies in 5/16 inch Tenex Tec. In both cases the loopies were long enough that one bearing point was on the sleeve, very near the throat, and the other was in the open on the single-thickness rope. The sleeve lengths, before the cores were inserted, were 8.75 inches and 10 inches. The results:
8.75-- 5826# Broke at shackle pin opposite the throat
10.0-- 6120# Broke at throat
As anyone would have predicted, increasing the sleeve length increases loopie security against slipping. More precisely, the longer the sleeve length between the bearing and the tail, the greater the security. Adding sleeve length between the bearing and the throat should do almost nothing because that section of sleeve should see almost no tension. No tension, no squeeze. No squeeze, no friction between core and cover. No friction, no holding power.
Things are not quite that bad because at the throat itself the cover does squeeze on the core because it tries to close the big hole its side caused by the core. The overall contribution from this is probably negligible.
Why did the two loopies break at different points, and why at such seemingly low loads?
In the 8.75-inch test, I noticed that the loopie, where it broke, had fetched up against one end of the shackle pin, the end with a couple of exposed threads. It seems certain the metal threads cut at least some of the fibers.
Not so in the second test, in which the exposed threads were covered with some small cord. The change in break strength was small, but perhaps that was the cause.
I would have expected both loopies to break in the cover where the core emerges (the tail). This is where the cover is fully tensioned and weakened by the hole in its side. Apparently another factor was more important than this, probably the small diameter of the bearing pins.
These results suggest two more experiments to me. One, repeat the 10-inch experiment with the bearing near the tail instead of the throat. I predict the loopie will pull apart at a modest load.
Two, make a much larger loopie with a 12- or 15-inch bury and wrap it around my two 4.5-inch-diameter bollards. Position it in the maximum-strength configuration and see what happens. More suggestions, anyone?
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Norm_Hall
Outta Control
Reged: 08/31/04
Posts: 3345
Loc: Wauconda, (Chicago),IL,USA
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Quote:
If you compare the Samson directions for a polyester whoopie to their directions for a high-mod whoopie, the bury lengths are as follows:
Polyester: 1.25 fids
High Mod: 3.5 fids
In 5/16" rope that'd be a approx an 8.5" bury for polyester and a 24" bury in High Mod.
I've heard varying opinions on what Loopie bury lengths should be in relation to their whoopie cousins. Some say "same" some say double, some say triple.
Just thought I'd throw that out there for the sake of the conversation.
love
nick
Valid points Nick. I have even had Tenex loopies slide with the 1.25 fid length bury. I use a 2 full fid bury on all Tenex. Can't afford to have 1 slip apart while the load is suspended over a clients house.
The exotic fibers vary in slipperyness. Dyneema is slipperyer than technora. A longer bury is definitely in order for dyneema, 3.5 full fids sounds like a safe number. Keep in mind, these fibers don't stretch near as much as polyester, so compressing the static cover over the running core is going to need more length of rope.
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moray
Hooked on the Buzz
Reged: 10/16/08
Posts: 284
Loc: Maine
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I have two more loopie break tests to report. The first test was meant to be the mirror image of one in the last batch. The sleeve length was 10 inches, the bearings were 3/4 inch steel shackle pins, one bearing point was on the single rope, the other was on the sleeve very near the tail. Remember that the throat is the other end of the sleeve, the end where the cover terminates in the dead little stub, the appendix. In this experiment we are dealing with the opposite end, the end where the cover becomes part of the main loop and the adjustable tail of the core emerges.
Result: the core slipped out at 564 lbs. Since this seemed ridiculously low, and the rope was undamaged, I repeated the experiment, making quite sure the bearing point was a good inch or so away from the tail. As the tension increased, the core slipped and caught several times before giving up entirely at 2570 lbs. In the mirror image experiment reported in the previous post, the core did not slip at all but the loopie broke at 6120 lbs.
In the second experiment 4.5-inch-diameter steel bollards were substituted for the shackle pins. Just to be sure we would get breakage rather than slippage, and to make it very easy to position the loopie so that the bearing was near the throat, the sleeve length, before bury, was increased to 12 inches.
Result: the loopie broke at the tail at 7680 lbs. (see the picture). This is an expected weak spot because the cover is distorted at this spot yet it is under maximum tension.
The take-home lessons from all of this seem to be:
1. The loopie is strongest and most secure against slippage when one of the bearing points is on the sleeve.
2. The sleeve bearing should be near the throat, not near the tail.
3. Bearing pins of sizes ordinarily used by arborists are small enough to seriously weaken the loopie.
4. The working loads given by Wesspur and others need to be viewed with some skepticism. The true strength of a given loopie and the correct working load will depend heavily on the size of the bearing pin(s), and this is not a parameter specified in the catalogs.
(In the picture, the grey rope is the Tenex, and the bottom leg is broken. The pinkish stable braid is part of the recoil-snubbing system, but did not go into action because a strand of the Tenex remained unbroken.)
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Brion
Likin' the Buzz
Reged: 06/09/05
Posts: 116
Loc: Port Townsend, Washington
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Hi again,
Just a note upon reflection.First, while catalogs don't usually stress the significance of bearing radius for Loopies, they don't do it for anything else, either. But it has long been known that radius will affect breaking loads, more in some materials than others. And remember, by putting the splice onto the bearing point, you have decreased the relative radius, by doubling the thickness of the rope.
Next, would you tell us if you had a protocol for massaging slack out of the splices, pre-test? I have broken some HM Loopies at New England, with the splices in the clear, and still got to about 150%, as I recall, so dressing the splice might make a big difference, no matter where the bearing is. Your best results are approaching 150%, with longer buries and bigger radiuses, so it seems possible that further changes might nail the optimal configuration.
I'll also be checking back with Yale, to make sure that they haven't already invented this particular wheel.
Finally, I have been thinking about all the very heavy things I have picked over the years, with the bearing at the "weak" end of the splice, with no signs of slippage. Good thing, but I hope you can understand that I wonder if there is some variable, like massaging the splice, that might be missing here. Of course, I have exclusively used Spectra, with long buries, so there could be some other variables there.
Fair leads,
Brion Toss
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moray
Hooked on the Buzz
Reged: 10/16/08
Posts: 284
Loc: Maine
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Quote:
Just a note upon reflection.First, while catalogs don't usually stress the significance of bearing radius for Loopies, they don't do it for anything else, either.
True enough, but this begs the question of how they calculate the WLL. At least the catalogs make a distinction between the 3 loopie geometries. Regrettably, for the one geometry (straight pull) in which the loopie is least secure, they publish a working load but say nothing about how the loopie should be hooked up. It seems unfair to criticize a catalog as if it were an engineering manual, but some of the arborist catalogs have become very useful how-to manuals with great illustrations and text.
Quote:
Next, would you tell us if you had a protocol for massaging slack out of the splices, pre-test?
Yes, I always tried to massage out all the slack from the throat to the tail. This should have given a consistent starting point for all the tests.
Quote:
Finally, I have been thinking about all the very heavy things I have picked over the years, with the bearing at the "weak" end of the splice, with no signs of slippage.
I suppose we all have things that wake us up in the night in a cold sweat. I'm glad this isn't one of mine!
Quote:
I have broken some HM Loopies at New England, with the splices in the clear, and still got to about 150%, as I recall, so dressing the splice might make a big difference...Of course, I have exclusively used Spectra, with long buries, so there could be some other variables there.
I think the long buries have been saving your bacon. I have done a number of tests on Spectra, and even though the coefficient of friction of spectra on spectra is less than the COE of polyester on polyester, the overall behavior of splices and loopies is the same.
I did the following experiment with Amsteel Blue before I built my hydraulic rig. My experimental range at the time was roughly from 0 to 100 lbs. Take two pieces of 3/16-in. rope and bury 10 inches of one in the other, inserting the core a few inches from the end (the appendix). The idea is to see how much force is required to pull the core out. Everything was arranged vertically so I could hang a fixed weight (about 2 lbs.) from the appendix, which was at the bottom. The experiment was repeated many times for several different bury lengths ranging from about 4 inches to 14 inches at 2-inch intervals. Now this was not an easy experiment to perform, and the readings jumped around a lot more than I would have liked, but the general pattern was pretty clear. Each addition of 2 inches to the bury length increased the holding strength by the same proportion. So, for example, if it took 10 lbs. to extract a 6-inch bury, and 15 lbs to extract a 8-inch bury, then it would have taken 23 lbs. to extract a 10-inch bury and 34 lbs. to extract a 12-inch bury. This is an exponential relationship. There is actually a very good reason for expecting that, but that merits another conversation.
Now imagine the same scenario with a much longer bury. If some large force is extracting the core, we actually know the tension in the cover at various locations. It is 10 lbs. 6 inches from the throat (appendix). It is 34 lbs. 12 inches from the throat. And so on, right up to the tail of the splice where full tension is on the cover. The holding force multiplies (grows exponentially) along the splice from throat to tail, and the cover tension distributes itself in the same way along the length of the splice. This is why the experiment I mentioned earlier with a few stitches of very weak thread at the throat produced a hugely disproportionate increase in splice strength.
Since your heavy pulls over the years never caused a sling failure, obviously there was always enough internal and external friction to prevent or arrest slippage. A long bury with all the slack milked out would have SOME cover compression everywhere and therefore some friction. All these point-sources of friction would multiply along the splice all the way to the tail. There is extra squeeze right at the throat because of the big hole in the side of the rope. And the bearing, even at the weak end of the splice, still does quite a lot all by itself. If it is several inches from the tail, it can multiply along that distance to good effect. Finally, the Rolling Hitch at the throat might provide a decent amount of compression that would multiply along the full length of the splice.
All this talk of multiplication only applies when slippage is occurring. This includes micro-slippage. It seems very plausible that some of your heavy lifts caused micro-slippage; the entire length of the splice equilibrated such that tension and friction arranged themselves according to the exponential rule, and there was enough friction for the whole thing to hold. I often see small amounts of slippage in pull tests; internal slippage in the splice, which I cannot see, might even be very common.
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Brion
Likin' the Buzz
Reged: 06/09/05
Posts: 116
Loc: Port Townsend, Washington
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Ah,
First, I utterly applaud your thoroughness and perserverance. But next, I have some quibbles.
For one thing, the progression you describe does not appear to be exponential, but direct. If it were exponential, the load borne by ten inches of bury might be the square of the load borne by five inches. This doesn't appear to be what you are saying.
Next, it seems that the load must be distributed evenly, more or less, along the entire length of the splice. It might not start out that way, which is why where we put the bearing point matters. But it seems that, given enough bury, and perhaps with some "micro-slippage" to allow adjustment of load, all equalizes. Given enough initial bury, plus a bearing even at the wrong end of a splice, high loads are achievable. This, as you say, might be what has been saving my bacon.
Choking the Loopie at the appendix, as the Sherrill catalog shows, would see, to be the most secure starting point, holding things in place while the fibers settle into place.
I've had a brief discussion with one of the extremely helpful people at Yale. He points out that Yale neither sells nor promotes Loopies, the idea being that this is not a tool for everybody, and is very, very easy to hook up incorrectly, even if we had a firm idea of optimal configuration. Your work is giving us great data, and I look forward to seeing more, as well as doing some on my own.
Fair leads,
Brion Toss
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moray
Hooked on the Buzz
Reged: 10/16/08
Posts: 284
Loc: Maine
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Quote:
I've had a brief discussion with one of the extremely helpful people at Yale. He points out that Yale neither sells nor promotes Loopies, the idea being that this is not a tool for everybody, and is very, very easy to hook up incorrectly, even if we had a firm idea of optimal configuration.
It is great that you are calling these guys to get direct answers from the people who ought to know! I have to completely agree with the guy at Yale. If you want to use the loopie in the open configuration you better be ready to think like an engineer.
Quote:
...But next, I have some quibbles.
For one thing, the progression you describe does not appear to be exponential, but direct. If it were exponential, the load borne by ten inches of bury might be the square of the load borne by five inches. This doesn't appear to be what you are saying.
I think the correct technical term for the progression I described is geometric sequence. This is a sequence in which each term is found by multiplying the previous term by a fixed factor. In the case I gave, the factor was 1.5. Each succesive term is 50% larger than the previous term. Since the terms of a geometric sequence fall on an exponential curve, I used that word to describe what was going on because it is a familiar word. Your comment about the squares is insightful, but I think it is slightly misapplied. If we take 3 successive tension measurements along the sleeve at points A, B, and C, each one further from the throat, and where the distance from A to B is the same as the distance from B to C, THEN the increase in tension from A to C is the square of the increase from A to B.
Quote:
Next, it seems that the load must be distributed evenly, more or less, along the entire length of the splice. It might not start out that way, which is why where we put the bearing point matters. But it seems that, given enough bury, and perhaps with some "micro-slippage" to allow adjustment of load, all equalizes...
Now this is the heart of the matter! May I ask why you think the load must be distributed more or less evenly along the length of the splice? It seems to me we have two entirely different realms here: the stable realm where the splice is holding, and the failing realm where it is slipping. I think the former is far more complex than the latter.
Take the following analogous situation. There is a rope draped over a horizontal branch, and 3 feet above the ground each end of the rope is attached to a heavy weight. One of the weights is marked "100 lbs.", but the other is unmarked. If both weights are hanging there motionless, how big is the other weight? It is useful to know that a typical "natural crotch" rigging scenario like this, familiar to arborists, is roughly equivalent to a really bad pulley with an efficiency of about 50%. The answer to the question is the unmarked weight can be as small as 50 lbs. and as large a 200 lbs. Outside that range, the rope will start sliding as the heavier weight heads for the ground.
If the two weights are 100# and 80#, how is the tension distributed along the rope where it drapes over the branch? We know it starts at 100# on one side and becomes 80# when it reaches the other side. In between the branch takes up the difference in frictional force. There are an infinite number of ways this could happen.
In the analogous non-slipping splice situation, there is full tension on the cover just beyond the tail, and zero tension at the appendix, so over the length of the splice, from throat to tail, tension is transferred from core to cover. It is friction between cover and core that causes this transfer, and there are an infinite number of ways this could happen.
Everything gets much simpler when the rigging rope starts sliding or the splice starts slipping. Essentially a problem with an infinity of solutions now has only one. For the rigging rope, the side heading up has half the load of the side heading down. Not only that, the distribution of tension along the rope is known: there is an exponential growth of tension from the one side to the other. There is an elegant derivation of this relation from the starting assumption that friction between two surfaces is proportional to the coefficient of friction and the force pushing them together. I can try to find a link to this formula if someone wants it.
In the splice scenario the core is analagous to the limb and the cover is analgous to the rope over the limb. This may be more than just an analogy. The cover is made up of individual strands, and it is those strands that actually squeeze the core to produce friction. Just as the rope is wrapped around the limb, the strands are wrapped around the core. It seems reasonable to expect these two systems to exhibit very similar behavior.
When the splice is slipping, we know the tension at both ends of the cover, and now (according to my theory!) we also know the distribution of tension along the cover--it's exponential.
But an experiment is needed. I need to extend the evidence for this exponential relationship over a wider range, from perhaps 10 lbs. up to 1000 lbs. I hope to get to this in the next couple of days.
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Brion
Likin' the Buzz
Reged: 06/09/05
Posts: 116
Loc: Port Townsend, Washington
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Hi again,
Glad you clarified that. I thought that you were describing the change in results between your specific bury lengths as exponential. Geometric progression is indeed the more precise term for the results for the increments of bury you have presented thus far, but of course there is an exponential progression due to the coefficient of friction. As for the load at any point in the splice, it would seem that any time we are talking about splices, we are potentially talking about ultimate strength, and therefore must have a sufficient coefficient of friction to provide initial security until there is enough pressure on the strands to achieve ultimate security, and thus have a shot at ultimate strength. This is the main reason is why splices are as long as they are.
Granted we are also interested in reducing stress risers -- hence the taper -- and in having a reserve of friction, but basically, I think, we actually need some significant length if we expect things to hold, and this would seem to require a generous distribution of load. With a minimum-length tail, there would be significant tension, not zero, from the throat of the splice right up to the end of the tail. So I'm not so compelled by the tree-over-the-branch analogy.
And even in that example, while technically you could say that the possibilities for load distribution are infinite, in practical terms we might have a very short distance to distribute the load. Imagine, for instance, that the branch was quite small, and that the coefficient of friction was such that the half-diameter could barely support a 20# difference; the load would have to be distributed almost perfectly along the entire bearing length. On the other hand , there is an exponential function available here, by the simple expedient of taking one or more extra turns around the branch (http://www.geocities.com/roo_two/friction.html). This is a function of the coefficient of friction.
With splices we have fairly precisely known coefficients of friction, reflected in the various lengths of the splice tails for different materials and constructions. In the present case we are trying to nail down how to generate a reliable degree of friction in a configuration that loads the splice much differently than on an eye; if anything the Loopie might distribute the strain more evenly than the eye. The trouble is that getting all those strands to compress sufficiently is difficult. It is possible that, with a long enough tail, we could guarantee that sufficient friction would be distributed, more or less randomly, through the length of the splice that we'd get to ultimate load.
In other words, we might know what the material's coefficient of friction is, but not be able to apply it readily. Your tests thus far have shown that the location of the bearing surface makes a difference in both security and ultimate load. You've also shown that the radius of the bearing surface appears to be a factor (and this is consistent with tests on Spectra eyes, where a 5:1 ratio of bearing to rope is indicated for maximum strength).
What I'd love to see is a utilitarian formula whereby a carabiner or shackle is used for the bearing point, the ultimate break strength is acceptably high, and the splice length is sufficient to prevent slippage under any load, given a specific point where the splice bears. That way we could go into the field and make reliable use of Loopies, which I think is the point. Doable?
Fair leads,
Brion Toss
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moray
Hooked on the Buzz
Reged: 10/16/08
Posts: 284
Loc: Maine
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Good on you for finding a link to the formula describing rope friction around a post .
Even though arborists probably make as much or more use of friction for controlling large loads than any other rope discipline, I am sure very few have ever seen this formula.
I measured the coefficient of friction of a polyester rope on a sanded birch billet last year. It seemed convenient at the time, since I was also measuring the efficiency of various pulleys I had, to express the result as efficiency. The number was .59, surprisingly high. Today I repeated the experiment on a living butternut limb, and the result was an efficiency of .23. If we convert the Geocities example to efficiency, we get .39, almost exactly in the middle between my two results.
In other words, the Geocities example could very well be a real-world arborist scenario. If a ground worker could lower a 1-ton load with only 7 lbs. of holding force assuming 3 wraps around a limb (I know--if you're controlling from the ground there will be a half wrap involved) with an efficiency of .39, then how much controlling force would be required using my butternut limb instead? Only 0.3 lbs.! You could even remove one wrap and come out ahead--with two wraps you could control a ton with only 5.6 lbs. This is the power of exponents. Small changes in the input parameters grow by successive multiplications to very large differences in the final answer.
It is my hypothesis that lengthening a splice by 50% is like adding an extra wrap to a 2-wrap rigging setup. If the coefficient of friction within the splice were the same as what we see in the Geocities example, adding 50% to the splice length would increase the splice holding power by 6.5 times! Another experiment may corroborate this idea or shoot it down.
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Brion
Likin' the Buzz
Reged: 06/09/05
Posts: 116
Loc: Port Townsend, Washington
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Excellent! Though as a sailor, I have to take issue with the idea that arborists have cornered the market on use of friction. You know those G.R.C.S. winches you guys are always drooling over? Those are for small-to-medium sailboats.
Fair leads,
Brion Toss
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