Watched the video. Was good.
Primary factors I see in TIP loading is SRT/DRT and climbing style.
Petzl published about 50% peaks for climbing accelerating i.e. not being smooth like a lynx, and then added another 50% for basal tie because the friction of the branch dramatically lowered the basal rope side tension. So 1.5 x 1.5 = 2.2 roughly matching Dr Kanes' numbers.
My numbers agreed with Petzl as I got a tension ratio of 2:1 or 2.5:1 for climber side rope to basal side rope. 2.5 was rough bark which corresponds to 40% of climber weight. Dr Kane's 90% of climber weight means 1.0/0.90 = 1.11 tension ratio. I measured a 1.20 tension ratio on a ball bearing DMM Pinto pulley at climber weight rope tensions and also the same on a 2" diameter bronze bushing pulley. The 90% number implies a rope grinding over tree bark has less friction than a non-optimal pulley. Having a little trouble reconciling that.
I think he omitted and should have stated that the footlock peaks were 2.5 seconds apart to correspond with each lift spaced 2.5 seconds apart. Similarly the rope walking 1/2 secs apart peaks should have been identified as left foot thrust, 1/2 second later, right foot thrust e.g. kick butt fast pace, no stealth. Accordingly the slower foot locking had smaller peaks and the fast ropewalking had bigger peaks.
A very basic thing that should be (maybe was?) done is to correlate each dip and spike to a climber motion to confirm the thrust peaks. Also, looking at the foot lock waveform I see time differences of about 1/2 second between force peaks (not the main thrust peaks) and I just can't picture a foot locking style where the guys spasms at 2 Hz during foot locking (think original Bingham ZK1 smooth ascent video), so I surmise 2 Hz is the resonant bounce frequency of the climb line plus climber. If so, he rope walked right into the resonance of the rope - definitely non-stealth./lynx. Going up anything sketchy or small you know how to minimize your TIP loading instinctively - don't crank on the rope. Smoooooth. The difference between rough/fast/competition and smooth like a lynx need to be illustrated for the sake of general learning. This Dr Kane data isn't identified as to where it lies in the spectrum. And since the thrust spikes are the bulk of tip loading variation they're important.
I did see him point out that the basal side didn't vary with the changes on the climber side, so the rope was stuck on the bark. In fact, if the coefficient of friction was ln(1.1)/3.14 = 0.03 like his 90% number implies, when the tension ratio reverses in the data like at the 1 second mark of the rope walking, where its 90% basal and 50% climber side, .9/.5 = 1.8 in the reversed direction i.e. the basal side is 1.8 times higher, with the 0.03 coefficient of friction (90%, super slippery, better than a pulley) the rope has to slip backwards and release some of the basal tension. And it didn't in the recording - it stayed constant. Can't have the physics both ways at once. Grits always take the same time to boil on the stove said Joe Pesci. This is a Neil Degrassse Tyson movie watching moment. Even though it looked weird to me at first, in my data sufficient reversal of tension sizing slipped my rope back again. Every time.
So now I feel awkward snd kind of bad about it. A conundrum needs to be resolved.
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Spidey?
Fruit tree holding on by a thread, client wants to get another year out of it. Thoughts?
