What a great video! Thank you very much! In Germany there is a saying "Was nicht hält, bremst wenigstens." -- Literally translated: "What doesn't hold, at least brakes.". ;-)
These drop tower tests are the bomb! I wish I had them 20yrs ago. This channel, with the pull tests and drop tests have definitely changed how I see trad climbing and climbing gear in general. Love this channel! I tell everybody I get to know who climbs about this channel.
Starting from 5:59 it's clearly visible that the rope "falls down" through the catnip's carabiner until the steel piece falls below and starts pulling the rope down. I believe that's when the first (smaller) spike is generated. If you had your steel dummy further away (horizontally) from the catnip to let it fall, the spike would not be generated. The swing would, though. 😁
Another option would be a very weak method for holding just the weight of the rope in place to keep it from falling but would not really affect other measurements. A loop of painter's tape might work
@@bandana_girl6507 That's true but then again this configuration may be closer to what's actually happening during a lead climb fall. Of course how freely the rope is hanging depends on the shape of the cliff and the route.
There is a wave interacting with the first catnip. You can see it at 3:40. Observe the elongation of the catnip. It stretches (first peak), shrinks, stretches again, then breaks (second peak).
Yo Ryan. It's actually gotten to the point that I'll have a random question and wake up and google it, and you'll have tested it. Keep up the great work!
The 550 cord's 30% stretch definitely helps the absorption & pads these results a little. Energy Absorbed (Ea) = Force (F) & Distance (d). Increasing d reduces the F required to absorb the same fall. With the few feet of rope stretch absorbing the fall & some meatbag flopping, the 6" of catnip stretch shouldn't add more than 10-20% to the absorption, but it's not negligible. Depending on your bad piece, you may get some similar sliding/skidding/stretching help, but most of my bad placements (flared cams, micronuts) would be instant failures.
Maybe you could redo the test with half ropes to simulate the half rope climbing technique. Because a mountain guide told me that one of the main benefits of half ropes and always only clipping one of them is that the forces in a fall get reduced. Greetings from Italy
Definitely keen for this - half ropes have very similar impact forces as single ropes when subjet to the same test but would be interesting to see how this translates in a more real world situation
Definately less impact force with a half rope in real scenarios, because much more rope is engaged. This is due to less friction (since only every second piece is clipped).
You should test screamer dog-bones now that you have the drop tower. It would be super interesting to see how much they reduce the load on the bolt by.
It would be pretty cool to be able to measure the acceleration, velocity, and position of the "dummy". It could give further insight into what's going on in the drop tower tests. Not familiar with those systems, but an accelerometer could be up to the task, or maybe some kind of video software. Stoked to finally see these drop tests! Thanks for all the work guys
Force is mass times acceleration. So just F/m=a. The Force is what he measured and the mass is roughly the weight of the dummy. You also know the time because of the sampling frequency. To get the velocity just integrate over time. Integrate again and you have the distance.
With a stationary camera and not to much movement to or away from the camera. You could track afterwards the object in software. One solution for this a the video analysing programm "tracker". You would get positions for each frame of the video. The Programm calculate the speed by just getting the mean speed between the frame and the next one.
Glad you tested this, because we do talk about this reduction, and I had no idea if it was true or not. However, we don’t really place crap gear because we know it will break at X kN and we think it will slow us. We place it because we have no idea if it will hold 100% (possible even with crap) or 0% (possible with really good gear), but we HOPE it will hold 100%. So we are investing time in that gear because of probability, not force reduction. (For force reduction, use a screamer, or dynamic belay.)
Could you add fall factor into your results? It would be nice to know how much rope was in the system to generate these forces. Maybe throw some big stickers on your drop tower with height measurements at each of your bolts and rope release points. We can decently guestimate FF/rope length without you having to explicitly measure every time if we can see the height of the bolt and roughly where the rope is tied off in the video..
Yeah, that would be really nice. Looks like slightly less than FF 1 in this video (guessing 0.8-0.9) since the weight falls and almost touches the ground.
Agree with below, first spike is the beginning of slack being pulled back through. Nice vids, certainly new format is a style improvement with the 'location' shots on intro etc in different place instead of entire video of you in a shed xD. Keep up the good work asking the questions that people hadn't thought to ask.
1) can you sync video and force graph? 2) can you test whether knot tightening and loss of rope elasticity due to first catnip means more force on second peice if it’s immediately next to it (think a mini cluster of gear). 3) can you stretch out the graph so it only shows from drop to the tail of the main peak so we can see shape better? 4) you’re doing a great job. Have some cake!
at 2:44 we see a drop directly on the dogbone which also shows a small spike. The chart measures the force on the dummy, a peak force of 4.08kN. The small spike peak force is roughly at 1kN, which is about the same as the dummy at rest. One frame at 2:45 shows the dummy at what appears to be 90 degrees to the force meter. If you listen, you can hear what sounds like a small sound prior to the main spike, a kind of bu-dunk noise. I think the force meter is kinking the rope, and this kink gets loaded causing a small spike. It would be interesting to compare with and without the inline force meter. The sound should tell us if there is a difference.
@@HowNOT2 You still have a small spike in the force meter trace, though. Suggest you repeat the experiment with and without the force meter on the dummy! Rope and chains with a limited bend radius create weird forces... check out the Mould Effect videos. (He references one of your vids!).
Does cord breaking resemble a piece blowing? I really am having trouble thinking about this - exploding cord clearly reduces force, but that's not why pieces usually fail. And why two catnips? It's possible that one would produce a different result.
I had similar questions & posted my thoughts in another comment. TL;DR (E=F*d) Yes, cord stretch helps spread the load over distance compared to a more static failure. But rope stretch + meatbag flopping should be much larger, so it should only help 10-20%.
Why 2 pieces? 1 bad piece after a bomber placement isn't a big deal on lead. You just figure it'll blow & count on the previous piece. If it catches something, wonderful! When you start stringing bad pieces you begin to wonder if you're just going to factor 1.5 on your last decent placement. This suggests it'll at least take the edge off & the placements aren't purely mental. OFC the placements need hold *something* you could measure in kN.
The spikes could be from each strand of the catnip breaking and sending a shockwave through the rope. You should be able to test this by using non braided fishing line as you "catnip". Then repeat with two strands of fishing line and see if the number of waves doubles.
Great Stuff! Now we finally have the oppertunity to see IF Screamers are any good at reducing forces! So many years with climbing community saying they work great or they dont work at all… We can settle that now! Screamers, scream-aid, etc etc
The channel is soooo good. Im super psyched on watching the drop tower stuff. I wish there were more drop videos in this one!! It would be cool if you ended the videos with some action, or teaser for the next video, rather than moderating. Kinda like how marvel throws a teaser after the credits roll..... it just leaves ya with a good warm feeling inside❤😍
Interesting stuff! I've always been curious about this. One component that could change the data is belayer displacement. When the climber falls on the first piece, the belayer may be lifted up a bit, which would lessen then forces, but when the climber falls onto the second piece, the belayer may be moving down which could result in increased forces and a hard catch. I wonder if the results would be different if the grigri was instead attached to a mass hanging a couple feet off the ground and tethered to an anchor.
Great video today! my guess is on the three spikes for two catnips is that the first one is a shock load from the first one before it breaks with the weight pulling through on the second Spike. The second two spikes are equal representing the catnip brakes I would not whip...
Visually that looked like a fall factor 0.8ish? It was really useful to see how much force was generated on the catching piece, which is what I worry about sometimes. Seeing a factor 0.8 fall generating less than 8kN is reassuring for sure. And seeing those less than 2kN pieces decrease the load on the catching piece to less than 6kN is really cool, a DMM dragonfly #1(such a tiny cam) can handle that load.
Very interesting. My thought about the three spikes is that the first spike is the first catnip, the second spike is the second catnip sheath, the third is the mantle of the second catnip. But why three and not four? Perhaps the first catnip takes a significant brunt of the initial fall, in order for the second to experience different forces. Super awesome video.
A possible thing to look at with the three spikes before the big one is if it is only three or if a fourth is hiding in the lead-in for the major spike. It could be an artifact of the mechanics behind the lineScale being able to measure force and the specific loading you put on it in this test.
At 3:51 I think the 3 spikes could be that it bounced on one of them before tearing all the way through, it all happened so fast that it'd be hard to know without high-speed camera footage of the entire experiment alongside the graph
I might have an explanation for the 3 spikes, in case it was not solved yet: 1st spike - obvious, the first carabiner catches the fall before breaking the catnip 2nd spike - the rope reaches the second catnip/carabiner and creates some drag, but doesn't break the second catnip just yet due to rope stretch 3rd spike - the rope reaches its maximum stretch, creating the spike just before breaking the second catnip Try placing the graph over the slo-mo video somehow, you might find the answer. GL
Thanks for these. Im not a climber but appreciate the knowledge nonetheless. Id just suggest that you build a blast box to stand in because of potential shrapnel. Awesome video!
Does this also incidentally prove that a string of crappy one night stands can help soften the emotional blow from a hard breakup? Asking for a friend...
An interesting follow up to this experiment would be with slightly "better" pieces, maybe that blow closer to 3-4 kN. The idea being that the rope looses more of it stretching (thus ability to absord energy). The piece that holds then might see higher forces, on the nearly-static rope.
Your extra spikes are probably because a weight on the end of the rope is a harmonic oscillator. The recoil you mentioned as it was hanging off the dogbone started as a compression wave through the rope when the first catnip broke but you couldn't see it because there was nothing arresting its fall
I’d imagine the mysterious third spike is in fact the first. It is likely the force when the weighted side snaps taut but before the belay side snaps taught. You don’t get a similar double force spike with the second catnip and final dog bone because there isn’t enough time for slack to be reintroduced to the belay side of the rope.
Simple. Kinetic energy. When the 1st one breaks/fails, it still reduced the kinetic energy. As your fall speed increases so does the impact force. If you slow down that fall speed by having something catch/fail the final impact force will be less due to the fall velocity being less than if you freefell the whole way. My experience with this was with a 10 tonne piece of machinery that broke while on the crane ;P We had to always have a backup that would break befor the main anchor to help reduce the impact force when the 10 tonne of metal hit the final anchor so it didnt destroy the workshops floor haha
The anchor rope does fall down initially and then reverses direction when catnip one makes contact. The first spike should now start and last until catnip one breaks. It seems however that there is an initial smaller spike and I would guess that as the anchor rope went up again, it also snagged slightly om something like a lower caribiner causing enough friction to register but not enough to exceed catnip one break tolerance, then unsnagged the rope bounces up above catnip one slightly momentarily causing no resistance, weight proceeded to free fall, and catnip one reengaged a second final time as expected. In other words, spike one was divided in two due to a snag. Tying down the rope with a soft rubber band or such on each catnip should eliminate this.
My hypothesis is that the three spikes is due to the elasticity in the rope. There were two spikes when you did not use the catnips at all because the weight bounced. Perhaps something similar is happening at a lower level as it passes through the catnips. If you wanted to investigate further you could do testing with just one and three catnips. We would expect two spikes for one catnip but would we get four spikes or five spikes for the three catnips. That would tell us if the extra spike is before or between the catnips.
Great video! I'm curious, why did you wear two microphone transmitters towards the end of the video? I use that type of mic too, I'm wondering if it's a secret trick to improve the audio quality :-)
WOW great testing with very convincing results!! I wonder if the catnips were weak cables instead of 550 paracord... Because the paracord absorbs some of the energy. The cables would NOT absorb the energy and the rope would have to do all the absorption!! Then when the cable breaks, the rope has to stop the weight AGAIN! No real help there and could be detrimental for some reason... Makes sense?
Really interesting. So my follow-up question- what about an overhand knot a foot in from the end of a dyneema loop, with the carabiner in from the knot? Will it mean the dyneema can survive a larger shock due to the carabiner rolling the knot? Or will it overheat the dyneema?
You can when the rope is running through the the connection just place the force meter at the end of the rope and get the value without the danger of dropping the meter.
I just wanted to give positive feedback on the way you insert the ads for your store and the codes. It's less annoying and more relevant than ads for raycon earbuds, raid shadow legends or keeps hair treatment!
haha... i try to make it suck as little as possible while not having to do a full time job when i'm done working 80 hours a week on this channel. I think climbing gear is less offensive of an ad than something totally unrelated. I nailed Ad targeting... mysteriously I know you watch climbing videos ;).
Really interested in the triple spike. If you do a long shot of the weight, it is possible to track it's movement to see where it is accelerating and compare that to how taught the rope is. All you would have to do is set up a camera about 15 feet high and 40 ft away.
I'll bet the first of the three spikes is due to the acceleration of the rope as the system is falling. Initially the rope is in free fall. Then when it passes the first piece, the load quickly reverses the motion of the rope by pulling it through the piece. From Newton's Second Law, that reversal of motion of the rope, i.e. an acceleration, imparts a force on the falling load.
Complete anecdata, so take with multiple grains of salt, but I knew a guy who fell off a granite slab at Booroomba Rocks in Australia and ripped out a series of RPs. He fell off the second pitch, past the belayer, for a total fall of about 60m. His last RP ripped when he was about 5m from the ground and he walked away with massive skin loss, many bruises, but no broken bones and still breathing. This one story has convinced me to place pro whenever I can get it, accounting for the usual caveats of rope-drag, likelihood of it pulling out from above, likelihood it will be required later on the pitch etc. Still, really awesome to see actual tests done on this. Maybe sync up footage with load-cell data to work out exactly when the aberrant spikes in the graph are occurring? I'm guessing it's the rope getting caught on itself in some way, but that's just a guess!
Perhaps you could also test placing a crappy piece closer to the good piece? This could maybe _increase_ the force on the good piece as it stretches the rope, thus temporarily making it less dynamic. If you put the crappy piece about 0.5 metres or less above the good piece, maybe the rope is still stretched (=less dynamic) once it hits the good piece.
I've watched this one a few times now, and I'm fairly certain I've got this figured out so.. 3:48 i think you got 3 spikes because as the first spike is the initial weight loading, you measure a slight bounce in the system before it actually broke because it wasn't quite up to speed yet. If you play it back at 0.25 speed 3:22 you can see a brief pause in the paracord as it stretches.. so it loaded, did a micro bounce which is hard to discern because the paracord is static unlike the main line, then continued to stretch the chord and break, from there you get your 3rd spike from the 2nd "catnip" as it hits it closer to full speed until it finally loads the dog bone in the main spike. Respectfully I disagree with "adomasvysniauskas9509 because I i don't believe the rope merely feeding through the carabiner would have cause this without the rope actually pinching on something for a moment with enough force to lock it into a bounce pattern for weightlessness before the weight could then plow through the coefficient of friction.
Wrong: Test 5 - 2 Catnips - Dummy 5.95kN / Dog bone 5.95kN (it reduced it by 1.53kN) Right: Test 5 - 2 Catnips - Dummy 3.07kN / Dog bone 5.95kN (it reduced it by 1.34kN) Or am I wrong??
Hi How comes that in 5:30 you get 7.64kN ? when in "Lead falls in climbing gyms - how much forces does it generate?" with z-drag falls - there were only 4.78 kN. The difference is massive...
a live force graph overlaid on the videos in real-time would be sick as hell. it's not important yet but if you haven't had the idea then it'll be nice in the future :)
I don't think you know what a troll is. Because someone disagrees with you or has a different idea then you doesn't make them a troll the troll is someone who purposely comes into the comments to start s*** or be an a****** for no reason you can't just say everyone who disagrees with you is a troll. Love the video by the way
Cool result. Wonder if the impulse (F over a time interval e.g. from the cord loading to breaking) that results in the change in momentum and lowers the force on the draw is similar to gear ripping? If the interval is shortened a lot by e.g. a rigid wire, then this test would be 💯 misleading.. Have you thought of getting a physics guy or mechanical engineer on the channel to generalize results and takeaways?
I guess the assumption in this test is that the energy absorbed by the cord before it breaks is negligible compared to that absorbed by the rope before the cord breaks. This assumption feels reasonable given that the rope is 1-2 orders of magnitude longer. It could be verified by measuring how much each of stretchy elements stretches. Forces on the cord and the 2 sides of the rope are typically assumed to have ratios close the 1.6 : 1.0 : 0.6, and if we model each of the 3 as an ideal spring, its energy absorbed is force * stretch / 2. (pretty sure this is easier to analyze in the energy domain - i.e. integral of force over distance - rather than in the impulse domain)
@Serge S I was thinking impulse because in this video they get force vs time data. It's helpful to think in momentum as well since you don't need to model the system. The integral of the those peaks gives the change in momentum directly which you can use to get the total change in energy. An effective gear placement just needs to change your velocity. Your right of course if you want to partition the roles of the rope and cord - which in thinking about it... The rope will have a much larger displacement and dominate the ramp part of the impulse interval. All components equal, with a piece of gear ripping suddenly, you might see at the worst just the ramp impulse followed by a sharp drop and the effectiveness seen in the drop tower test would drop proportionally to the change in area under the curve.
@@danielsavage1101 Oh I see. I hadn't thought of integrating the F-t graphs. But I suspect the question "would a steel nut cable significantly change the results compared to the stretchy fuse cord" can be answered with imprecise order-of-magnitude estimates (i.e. w/o integration).
It may be that the first spike is the rope changing directions when it passes the first catnip and slightly loading the line, but you wouldn't expect it to be near the peak of where it snaps the catnip. That's a puzzler.
Would it be possible to test a follower falling on a microtraction while simul-climbing? What happens when the rope is doubled-up and the microtraction is connected to only to one rope? Is the leader protected?
Non-prime numbers create harmonics all prime numbers don't, possibly there's a shockwave resonating before it stops on the dogbone. Do a test with 3,5,7 or 11 catnips see if the resonance disappears, maybe with 3 catnips the resonance spikes will pop up after the dogbone instead of before
if you're trying to correlate those peaks to what's happening you could look at what time they occur and look compare with the footage, you dont event need to calibrate seeing as you know when it becomes weightless... I suspect they correspond to strands breaking or something re-adjusting/slipping
is that third peak is the gri-gri taking some weight - like the dynamic loading of the gri-gri - that i guess goes down again as the rope slips to the knot or something
Now you can count energy of the hit. Energy destroys the gear (area under curve) not a max value of the force. Relying on the energy should give you more consistent results. You could give both values kN and kJ of the impact.
After seeing the pieces failing and not seeing the *increase* in force on the next piece due to a commonly accepted shock loading myth, there will still be people convinced shock loading is a thing. This has been tested and documented long ago in anchor setups with fuse-pieces and the same results were obtained. The failing piece helps decrease the load on the next one, period.
Us the third spike something to do with hitting max velocity? Or something to do with the elctrastic of the rope. Note I haven't really thought too much about it and I'm just spit balling
I think there are different forces at both ends. Pretty sure he tested climbing falls once with a line scale on the climber and another on the belayer and the forces were slightly different ... But maybe I'm remembering wrong
@@benja_mint they must be slightly different but neither number is the force on the piece of gear so I don’t see why the “climber” force is more important than the belayer force
I think I could have done this test a lot better in hindsight. I should have had 4 LS3s in the system at every single point every single time and just drop 3x without catnips and 3 with catnips. Very simple and straight forward to understand. But i also was afraid to eff up my LS3 and that grigri spot was pretty violent. I would need more cases.
@@HowNOT2 That would have been great. You could diy some PVC tubes to protect the LS3, That thing is going to take a lot of abuse. Having a round case might avoid direct hits.
I clip it to the post i climb. i literally can't go up without it in my way. I also only rappel while holding the biner attached to me so i never lean back without it attached
this is interesting but if i place a weak piece its role can be more than slowing a big fall. i can have abreak, and it can catch my weight if its right next to a hard move.
Just a video idea see the forces in biking how torque you get with a pedal or kilonotenTS you could also test if an oval chain ring makes a difference or not with forces.
Try to explain first spike: at the beginning everything starts to fall downwards, as the rope does. As soon as the dummy pases the first catnip the rope beneath the catnip is forced to change its direction of movement. As inertia tries to force the rope Not2 - a counterforce is needed -> provided by the dummies innertia. Friction within the catnips biner is an amplifier from perpective of the dummy, leading to first spike. The spike is over as soon as the rope‘s direction of movement has been changed. Waiting for the next spike as the rope‘s slack becomes zero. Makes sense in my eyes…
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0:01 - Decking definitely helps soften the blow on the next piece.
haha
Nevertheless, decking cannot be recommended as a technique for increasing the lifespan of gear.
What a great video! Thank you very much! In Germany there is a saying "Was nicht hält, bremst wenigstens." -- Literally translated: "What doesn't hold, at least brakes.". ;-)
That's pretty funny
That would be a pretty good pun if it was English
Placing rubbish gear is a subject that is particularly close to every Scottish winter climber's heart! I feel validated!
These drop tower tests are the bomb! I wish I had them 20yrs ago. This channel, with the pull tests and drop tests have definitely changed how I see trad climbing and climbing gear in general. Love this channel! I tell everybody I get to know who climbs about this channel.
Starting from 5:59 it's clearly visible that the rope "falls down" through the catnip's carabiner until the steel piece falls below and starts pulling the rope down. I believe that's when the first (smaller) spike is generated. If you had your steel dummy further away (horizontally) from the catnip to let it fall, the spike would not be generated. The swing would, though. 😁
I had the same consideration
same observation
true that
Another option would be a very weak method for holding just the weight of the rope in place to keep it from falling but would not really affect other measurements. A loop of painter's tape might work
@@bandana_girl6507 That's true but then again this configuration may be closer to what's actually happening during a lead climb fall. Of course how freely the rope is hanging depends on the shape of the cliff and the route.
Outstanding tests. I like placing gear and this makes me feel much better on sketchy leads.
There is a wave interacting with the first catnip. You can see it at 3:40. Observe the elongation of the catnip. It stretches (first peak), shrinks, stretches again, then breaks (second peak).
This is exactly the kind of testing on your channel that helped push me from sport into trad climbing. Thank you so much!
Trust gear not rocks!
Yo Ryan. It's actually gotten to the point that I'll have a random question and wake up and google it, and you'll have tested it. Keep up the great work!
The 550 cord's 30% stretch definitely helps the absorption & pads these results a little.
Energy Absorbed (Ea) = Force (F) & Distance (d). Increasing d reduces the F required to absorb the same fall.
With the few feet of rope stretch absorbing the fall & some meatbag flopping, the 6" of catnip stretch shouldn't add more than 10-20% to the absorption, but it's not negligible. Depending on your bad piece, you may get some similar sliding/skidding/stretching help, but most of my bad placements (flared cams, micronuts) would be instant failures.
I'd be curious about a similar test w/ similar MBS static cord.
Maybe you could redo the test with half ropes to simulate the half rope climbing technique. Because a mountain guide told me that one of the main benefits of half ropes and always only clipping one of them is that the forces in a fall get reduced.
Greetings from Italy
Definitely keen for this - half ropes have very similar impact forces as single ropes when subjet to the same test but would be interesting to see how this translates in a more real world situation
Definitely seconding this
Definately less impact force with a half rope in real scenarios, because much more rope is engaged. This is due to less friction (since only every second piece is clipped).
For any physics instructors out there, this is a great and fun example of the conservation of energy principle. Ryan even supplies all the numbers!
You should test screamer dog-bones now that you have the drop tower. It would be super interesting to see how much they reduce the load on the bolt by.
That's a great idea putting the LineScale in the hard case. Looks really slick. Keep up the great work :)
It would be pretty cool to be able to measure the acceleration, velocity, and position of the "dummy". It could give further insight into what's going on in the drop tower tests. Not familiar with those systems, but an accelerometer could be up to the task, or maybe some kind of video software. Stoked to finally see these drop tests! Thanks for all the work guys
Force is mass times acceleration. So just F/m=a. The Force is what he measured and the mass is roughly the weight of the dummy. You also know the time because of the sampling frequency. To get the velocity just integrate over time. Integrate again and you have the distance.
With a stationary camera and not to much movement to or away from the camera. You could track afterwards the object in software. One solution for this a the video analysing programm "tracker". You would get positions for each frame of the video. The Programm calculate the speed by just getting the mean speed between the frame and the next one.
Glad you tested this, because we do talk about this reduction, and I had no idea if it was true or not. However, we don’t really place crap gear because we know it will break at X kN and we think it will slow us. We place it because we have no idea if it will hold 100% (possible even with crap) or 0% (possible with really good gear), but we HOPE it will hold 100%. So we are investing time in that gear because of probability, not force reduction. (For force reduction, use a screamer, or dynamic belay.)
Could you add fall factor into your results? It would be nice to know how much rope was in the system to generate these forces. Maybe throw some big stickers on your drop tower with height measurements at each of your bolts and rope release points. We can decently guestimate FF/rope length without you having to explicitly measure every time if we can see the height of the bolt and roughly where the rope is tied off in the video..
Yeah, that would be really nice. Looks like slightly less than FF 1 in this video (guessing 0.8-0.9) since the weight falls and almost touches the ground.
@@JesseUnderscoreMartin That is about what this is. But do we measure it after ropes stretch because if we don't then it's more like 0.6-0.7?
I think FF is defined "before the stretch" (i.e. 0.6-0.7)
Agree with below, first spike is the beginning of slack being pulled back through.
Nice vids, certainly new format is a style improvement with the 'location' shots on intro etc in different place instead of entire video of you in a shed xD. Keep up the good work asking the questions that people hadn't thought to ask.
I'm not even a climber but been watching his stuff for a year now for some reason I really like the drop tower over the
1) can you sync video and force graph? 2) can you test whether knot tightening and loss of rope elasticity due to first catnip means more force on second peice if it’s immediately next to it (think a mini cluster of gear). 3) can you stretch out the graph so it only shows from drop to the tail of the main peak so we can see shape better? 4) you’re doing a great job. Have some cake!
That's a great idea!
I love these vids. You learn so much. Just subscribed to patreon last week to support them. I hope lots of others do too!
The tower and the LS3 are portal to a new dimension. The way HN2 is evolving is sexy.
Ryan, I really got to say I appreciate all that you do man. Always informative and fun. 🤘😎 keep up the good work man.
SO COOL
One of yer best videos yet!
I’ve always wondered about this…
Guys I needed this vid! Big thanks ;)
Asking the real questions! Great stuff!
at 2:44 we see a drop directly on the dogbone which also shows a small spike. The chart measures the force on the dummy, a peak force of 4.08kN. The small spike peak force is roughly at 1kN, which is about the same as the dummy at rest. One frame at 2:45 shows the dummy at what appears to be 90 degrees to the force meter. If you listen, you can hear what sounds like a small sound prior to the main spike, a kind of bu-dunk noise. I think the force meter is kinking the rope, and this kink gets loaded causing a small spike. It would be interesting to compare with and without the inline force meter. The sound should tell us if there is a difference.
I listened to it 5x just now. There is a small chance it is other video clip's audio. I overlay the crap out of these edits so it's a tight edit.
@@HowNOT2 You still have a small spike in the force meter trace, though. Suggest you repeat the experiment with and without the force meter on the dummy!
Rope and chains with a limited bend radius create weird forces... check out the Mould Effect videos. (He references one of your vids!).
Does cord breaking resemble a piece blowing? I really am having trouble thinking about this - exploding cord clearly reduces force, but that's not why pieces usually fail. And why two catnips? It's possible that one would produce a different result.
I had similar questions & posted my thoughts in another comment. TL;DR (E=F*d) Yes, cord stretch helps spread the load over distance compared to a more static failure. But rope stretch + meatbag flopping should be much larger, so it should only help 10-20%.
Why 2 pieces? 1 bad piece after a bomber placement isn't a big deal on lead. You just figure it'll blow & count on the previous piece. If it catches something, wonderful! When you start stringing bad pieces you begin to wonder if you're just going to factor 1.5 on your last decent placement. This suggests it'll at least take the edge off & the placements aren't purely mental. OFC the placements need hold *something* you could measure in kN.
The spikes could be from each strand of the catnip breaking and sending a shockwave through the rope. You should be able to test this by using non braided fishing line as you "catnip". Then repeat with two strands of fishing line and see if the number of waves doubles.
Great Stuff! Now we finally have the oppertunity to see IF Screamers are any good at reducing forces! So many years with climbing community saying they work great or they dont work at all… We can settle that now! Screamers, scream-aid, etc etc
Finally droppin' some real data...
And that autobelay looks fun...
Cheers!!!
The channel is soooo good. Im super psyched on watching the drop tower stuff. I wish there were more drop videos in this one!! It would be cool if you ended the videos with some action, or teaser for the next video, rather than moderating. Kinda like how marvel throws a teaser after the credits roll..... it just leaves ya with a good warm feeling inside❤😍
Interesting stuff! I've always been curious about this. One component that could change the data is belayer displacement. When the climber falls on the first piece, the belayer may be lifted up a bit, which would lessen then forces, but when the climber falls onto the second piece, the belayer may be moving down which could result in increased forces and a hard catch. I wonder if the results would be different if the grigri was instead attached to a mass hanging a couple feet off the ground and tethered to an anchor.
Honestly Ryan I don’t climb .. more physics geek, your vlogs are entertaining as hell .. .. tnx
If you clip multiple screamers in a row, which one will open up first? Will they all go at the same time?
Great video today!
my guess is on the three spikes for two catnips is that the first one is a shock load from the first one before it breaks with the weight pulling through on the second Spike.
The second two spikes are equal representing the catnip brakes
I would not whip...
Visually that looked like a fall factor 0.8ish? It was really useful to see how much force was generated on the catching piece, which is what I worry about sometimes. Seeing a factor 0.8 fall generating less than 8kN is reassuring for sure. And seeing those less than 2kN pieces decrease the load on the catching piece to less than 6kN is really cool, a DMM dragonfly #1(such a tiny cam) can handle that load.
Very interesting. My thought about the three spikes is that the first spike is the first catnip, the second spike is the second catnip sheath, the third is the mantle of the second catnip.
But why three and not four? Perhaps the first catnip takes a significant brunt of the initial fall, in order for the second to experience different forces. Super awesome video.
I sort of miss the longer videos!
A possible thing to look at with the three spikes before the big one is if it is only three or if a fourth is hiding in the lead-in for the major spike. It could be an artifact of the mechanics behind the lineScale being able to measure force and the specific loading you put on it in this test.
At 3:51 I think the 3 spikes could be that it bounced on one of them before tearing all the way through, it all happened so fast that it'd be hard to know without high-speed camera footage of the entire experiment alongside the graph
I might have an explanation for the 3 spikes, in case it was not solved yet:
1st spike - obvious, the first carabiner catches the fall before breaking the catnip
2nd spike - the rope reaches the second catnip/carabiner and creates some drag, but doesn't break the second catnip just yet due to rope stretch
3rd spike - the rope reaches its maximum stretch, creating the spike just before breaking the second catnip
Try placing the graph over the slo-mo video somehow, you might find the answer. GL
Usually when the knots tighten under load they absorb some energy. Eventually this could be read as peak in the force graph. „Just my 2 cents.“ 😀
Thanks for these. Im not a climber but appreciate the knowledge nonetheless.
Id just suggest that you build a blast box to stand in because of potential shrapnel.
Awesome video!
Does this also incidentally prove that a string of crappy one night stands can help soften the emotional blow from a hard breakup? Asking for a friend...
I don't trad climb but this is super interesting thanks for all the backyard science!
An interesting follow up to this experiment would be with slightly "better" pieces, maybe that blow closer to 3-4 kN. The idea being that the rope looses more of it stretching (thus ability to absord energy). The piece that holds then might see higher forces, on the nearly-static rope.
Your extra spikes are probably because a weight on the end of the rope is a harmonic oscillator. The recoil you mentioned as it was hanging off the dogbone started as a compression wave through the rope when the first catnip broke but you couldn't see it because there was nothing arresting its fall
I’d imagine the mysterious third spike is in fact the first. It is likely the force when the weighted side snaps taut but before the belay side snaps taught.
You don’t get a similar double force spike with the second catnip and final dog bone because there isn’t enough time for slack to be reintroduced to the belay side of the rope.
Simple. Kinetic energy. When the 1st one breaks/fails, it still reduced the kinetic energy. As your fall speed increases so does the impact force. If you slow down that fall speed by having something catch/fail the final impact force will be less due to the fall velocity being less than if you freefell the whole way.
My experience with this was with a 10 tonne piece of machinery that broke while on the crane ;P We had to always have a backup that would break befor the main anchor to help reduce the impact force when the 10 tonne of metal hit the final anchor so it didnt destroy the workshops floor haha
The anchor rope does fall down initially and then reverses direction when catnip one makes contact. The first spike should now start and last until catnip one breaks. It seems however that there is an initial smaller spike and I would guess that as the anchor rope went up again, it also snagged slightly om something like a lower caribiner causing enough friction to register but not enough to exceed catnip one break tolerance, then unsnagged the rope bounces up above catnip one slightly momentarily causing no resistance, weight proceeded to free fall, and catnip one reengaged a second final time as expected. In other words, spike one was divided in two due to a snag. Tying down the rope with a soft rubber band or such on each catnip should eliminate this.
Amazing content. Thank you so much.
Yo that case for the scale is an ingenious idea
My hypothesis is that the three spikes is due to the elasticity in the rope. There were two spikes when you did not use the catnips at all because the weight bounced. Perhaps something similar is happening at a lower level as it passes through the catnips. If you wanted to investigate further you could do testing with just one and three catnips. We would expect two spikes for one catnip but would we get four spikes or five spikes for the three catnips. That would tell us if the extra spike is before or between the catnips.
Screamers made of plastic carrier bags are coming. I can feel it 🤣
Can you do a pullingtest on icescrews? Greetings from the cold Austria.
Great video! I'm curious, why did you wear two microphone transmitters towards the end of the video? I use that type of mic too, I'm wondering if it's a secret trick to improve the audio quality :-)
WOW great testing with very convincing results!! I wonder if the catnips were weak cables instead of 550 paracord... Because the paracord absorbs some of the energy. The cables would NOT absorb the energy and the rope would have to do all the absorption!! Then when the cable breaks, the rope has to stop the weight AGAIN! No real help there and could be detrimental for some reason... Makes sense?
Thank you for your informative videos. Concerning the impact force on bad piece. What about the soften the fall with ATC rope slipage catch?
I like your videos so much
Really interesting. So my follow-up question- what about an overhand knot a foot in from the end of a dyneema loop, with the carabiner in from the knot? Will it mean the dyneema can survive a larger shock due to the carabiner rolling the knot? Or will it overheat the dyneema?
You can when the rope is running through the the connection just place the force meter at the end of the rope and get the value without the danger of dropping the meter.
I just wanted to give positive feedback on the way you insert the ads for your store and the codes. It's less annoying and more relevant than ads for raycon earbuds, raid shadow legends or keeps hair treatment!
haha... i try to make it suck as little as possible while not having to do a full time job when i'm done working 80 hours a week on this channel. I think climbing gear is less offensive of an ad than something totally unrelated. I nailed Ad targeting... mysteriously I know you watch climbing videos ;).
Really interested in the triple spike. If you do a long shot of the weight, it is possible to track it's movement to see where it is accelerating and compare that to how taught the rope is. All you would have to do is set up a camera about 15 feet high and 40 ft away.
i might be able to do that if i put the tripod on the little side storage roof behind the old car. Not sure if there is stuff in the way though
I'll bet the first of the three spikes is due to the acceleration of the rope as the system is falling. Initially the rope is in free fall. Then when it passes the first piece, the load quickly reverses the motion of the rope by pulling it through the piece. From Newton's Second Law, that reversal of motion of the rope, i.e. an acceleration, imparts a force on the falling load.
Complete anecdata, so take with multiple grains of salt, but I knew a guy who fell off a granite slab at Booroomba Rocks in Australia and ripped out a series of RPs. He fell off the second pitch, past the belayer, for a total fall of about 60m. His last RP ripped when he was about 5m from the ground and he walked away with massive skin loss, many bruises, but no broken bones and still breathing.
This one story has convinced me to place pro whenever I can get it, accounting for the usual caveats of rope-drag, likelihood of it pulling out from above, likelihood it will be required later on the pitch etc.
Still, really awesome to see actual tests done on this.
Maybe sync up footage with load-cell data to work out exactly when the aberrant spikes in the graph are occurring? I'm guessing it's the rope getting caught on itself in some way, but that's just a guess!
Perhaps you could also test placing a crappy piece closer to the good piece? This could maybe _increase_ the force on the good piece as it stretches the rope, thus temporarily making it less dynamic. If you put the crappy piece about 0.5 metres or less above the good piece, maybe the rope is still stretched (=less dynamic) once it hits the good piece.
So those pieces of cord used instead of quickdraws are called catnips? Never heard of that before
Another reason in not a huge fan of the Grigri. Some slippage is good for a softer catch on sketchy trad pieces.
I've watched this one a few times now, and I'm fairly certain I've got this figured out so.. 3:48 i think you got 3 spikes because as the first spike is the initial weight loading, you measure a slight bounce in the system before it actually broke because it wasn't quite up to speed yet. If you play it back at 0.25 speed 3:22 you can see a brief pause in the paracord as it stretches.. so it loaded, did a micro bounce which is hard to discern because the paracord is static unlike the main line, then continued to stretch the chord and break, from there you get your 3rd spike from the 2nd "catnip" as it hits it closer to full speed until it finally loads the dog bone in the main spike.
Respectfully I disagree with "adomasvysniauskas9509 because I i don't believe the rope merely feeding through the carabiner would have cause this without the rope actually pinching on something for a moment with enough force to lock it into a bounce pattern for weightlessness before the weight could then plow through the coefficient of friction.
Congrats a new workshop
Wrong: Test 5 - 2 Catnips - Dummy 5.95kN / Dog bone 5.95kN (it reduced it by 1.53kN)
Right: Test 5 - 2 Catnips - Dummy 3.07kN / Dog bone 5.95kN (it reduced it by 1.34kN)
Or am I wrong??
FIXED. Thank you!
The extra is the ripe slack and such as the capture of you or the same dymmy
Hi
How comes that in 5:30 you get 7.64kN ? when in "Lead falls in climbing gyms - how much forces does it generate?" with z-drag falls - there were only 4.78 kN. The difference is massive...
a live force graph overlaid on the videos in real-time would be sick as hell. it's not important yet but if you haven't had the idea then it'll be nice in the future :)
I don't think you know what a troll is. Because someone disagrees with you or has a different idea then you doesn't make them a troll the troll is someone who purposely comes into the comments to start s*** or be an a****** for no reason you can't just say everyone who disagrees with you is a troll. Love the video by the way
First mystery peak is GriGri tightening up?
Seems like you're on the Rode for success!
haha, i get it ;)
Cool result. Wonder if the impulse (F over a time interval e.g. from the cord loading to breaking) that results in the change in momentum and lowers the force on the draw is similar to gear ripping? If the interval is shortened a lot by e.g. a rigid wire, then this test would be 💯 misleading..
Have you thought of getting a physics guy or mechanical engineer on the channel to generalize results and takeaways?
I guess the assumption in this test is that the energy absorbed by the cord before it breaks is negligible compared to that absorbed by the rope before the cord breaks. This assumption feels reasonable given that the rope is 1-2 orders of magnitude longer. It could be verified by measuring how much each of stretchy elements stretches. Forces on the cord and the 2 sides of the rope are typically assumed to have ratios close the 1.6 : 1.0 : 0.6, and if we model each of the 3 as an ideal spring, its energy absorbed is force * stretch / 2.
(pretty sure this is easier to analyze in the energy domain - i.e. integral of force over distance - rather than in the impulse domain)
@Serge S I was thinking impulse because in this video they get force vs time data. It's helpful to think in momentum as well since you don't need to model the system. The integral of the those peaks gives the change in momentum directly which you can use to get the total change in energy.
An effective gear placement just needs to change your velocity.
Your right of course if you want to partition the roles of the rope and cord - which in thinking about it... The rope will have a much larger displacement and dominate the ramp part of the impulse interval. All components equal, with a piece of gear ripping suddenly, you might see at the worst just the ramp impulse followed by a sharp drop and the effectiveness seen in the drop tower test would drop proportionally to the change in area under the curve.
@@danielsavage1101 Oh I see. I hadn't thought of integrating the F-t graphs.
But I suspect the question "would a steel nut cable significantly change the results compared to the stretchy fuse cord" can be answered with imprecise order-of-magnitude estimates (i.e. w/o integration).
It may be that the first spike is the rope changing directions when it passes the first catnip and slightly loading the line, but you wouldn't expect it to be near the peak of where it snaps the catnip. That's a puzzler.
Would it be possible to test a follower falling on a microtraction while simul-climbing? What happens when the rope is doubled-up and the microtraction is connected to only to one rope? Is the leader protected?
Sometimes placing the manky gear is just about getting the weight off your rack. Less likely to fall if you are lighter, right?!
The first spike is probably when the weight goes from free falling to being slightly slowed down by the rope friction once its past the first anchor.
Non-prime numbers create harmonics all prime numbers don't, possibly there's a shockwave resonating before it stops on the dogbone. Do a test with 3,5,7 or 11 catnips see if the resonance disappears, maybe with 3 catnips the resonance spikes will pop up after the dogbone instead of before
The initial small spike may be an accumulation of drag before the inertia of the weight overcomes it.
I think the first tiny spike is when the rope transitions from free fall to pulling rope back up through the top gear.
if you're trying to correlate those peaks to what's happening you could look at what time they occur and look compare with the footage, you dont event need to calibrate seeing as you know when it becomes weightless... I suspect they correspond to strands breaking or something re-adjusting/slipping
is that third peak is the gri-gri taking some weight - like the dynamic loading of the gri-gri - that i guess goes down again as the rope slips to the knot or something
He mentions at the end of the video that the rope did not slip through the gri gri. Initially I thought that may be possible until he mentioned it.
Now you can count energy of the hit.
Energy destroys the gear (area under curve) not a max value of the force.
Relying on the energy should give you more consistent results.
You could give both values kN and kJ of the impact.
After seeing the pieces failing and not seeing the *increase* in force on the next piece due to a commonly accepted shock loading myth, there will still be people convinced shock loading is a thing. This has been tested and documented long ago in anchor setups with fuse-pieces and the same results were obtained. The failing piece helps decrease the load on the next one, period.
Us the third spike something to do with hitting max velocity?
Or something to do with the elctrastic of the rope.
Note I haven't really thought too much about it and I'm just spit balling
3 peaks = 2 troughs from 2 catnips?
I also think you could get your linescale to last longer if you attached it to the gri-gri end of the rope.
I think there are different forces at both ends. Pretty sure he tested climbing falls once with a line scale on the climber and another on the belayer and the forces were slightly different ... But maybe I'm remembering wrong
@@benja_mint they must be slightly different but neither number is the force on the piece of gear so I don’t see why the “climber” force is more important than the belayer force
I think I could have done this test a lot better in hindsight. I should have had 4 LS3s in the system at every single point every single time and just drop 3x without catnips and 3 with catnips. Very simple and straight forward to understand. But i also was afraid to eff up my LS3 and that grigri spot was pretty violent. I would need more cases.
@@HowNOT2 That would have been great. You could diy some PVC tubes to protect the LS3, That thing is going to take a lot of abuse. Having a round case might avoid direct hits.
Can you put in measures or routines that will avoid you forgetting to clip in your autobelay if you work on there regularly?
I clip it to the post i climb. i literally can't go up without it in my way. I also only rappel while holding the biner attached to me so i never lean back without it attached
this is interesting but if i place a weak piece its role can be more than slowing a big fall. i can have abreak, and it can catch my weight if its right next to a hard move.
The three spikes are the braided structure of the kernmantle catnip loading then breaking then loading again to ultimate failure.
Just a video idea see the forces in biking how torque you get with a pedal or kilonotenTS you could also test if an oval chain ring makes a difference or not with forces.
I don't think the equipment used here would work as well for that kind of test.
Try to explain first spike:
at the beginning everything starts to fall downwards, as the rope does. As soon as the dummy pases the first catnip the rope beneath the catnip is forced to change its direction of movement. As inertia tries to force the rope Not2 - a counterforce is needed -> provided by the dummies innertia. Friction within the catnips biner is an amplifier from perpective of the dummy, leading to first spike. The spike is over as soon as the rope‘s direction of movement has been changed. Waiting for the next spike as the rope‘s slack becomes zero.
Makes sense in my eyes…
Three spikes due to the rope reversing direction prior to loading the catnips and the associated drag between the carabiners and rope.