PVstudent wrote:Thank you Willreifer for the video reference to Joe Dial.
Joe I agree found a way to solve his unique set of pole vault physical challenge problems quite a way back.
But whether his technique was optimally mechanically efficient is quite another question.
The evidence, "real data" I put up earlier in this topic are all based on time series sampling of complete vaults durations (including approach run) in time interval minimum sampling frequencies across the studies I reviewed ranging from 50hz to 150hz. The tables simply summarized some of the critical events in the time series so I don't think your criticism of my input is legitimate or valid.
Note that you identified the issue as "efficiency" in the comparisons using mgh and 1/2 mv2 and merely took starting (take-off)and end point (bar height) when purporting to discuss efficiency. Also I will be churlish and remind you that nowhere did you account in your calculations for the contribution of rotational kinetic energy, nor did you make any allowances for the obvious losses in rolling friction of the pole on the bottom and with the side walls of the planting box. These are minor carps on my part. Nevertheless as the saying goes "kettle be careful calling the pot black!"
One must discuss the ratio of Total Energy of Output / Total Energy of Input to discuss efficiency per unit body mass of the vaulter nor can one ever have an efficiency ratio greater than 1.0! These are Physics 101 errors and now you want to discuss a "Chaos Theory" based analysis of elite level pole vaulting?
Also I don't think you have yet worked out Why Igor Trandenkov had more potential energy at take-off than Bubka (Hint: Which is the taller of the two vaulters?)
I pointed out also that if the tables are looked at carefully enough, within the limitation which I identified by supplying the actual Formulae that were applied and used in the summative processing of the time sampling results (differential and integral calculus being used in raw data processing).
I did not use these words but left the information implicit in the formulae provided in the caption for table 1) that the overall efficiency of the vaulter when the process is fractionated (split) in defined intervals can differ within the total process. At least that is what the tables lead me to conclude.
Now, this current series of time capsule snapshots of the gradual evolution of Renaud Lavillenie's technique since 2009 that I drew to readers attention.
You are telling me that the emperor is not wearing new clothes in 2014 in terms of the extent to which he drops his right lead leg?
I am suitably chastised. But frankly I don't honestly believe that I am lying to myself or anyone else!
No, my nose is not getting longer. It only does that when I am truly aware and so acknowledge to myself that I have lied!
It remains to be confirmed conclusively that the evidence I put up is making me delusional or is an illusion in the eye of the beholder!
I am not at all arguing there are many possible ways to skin a cat or that there is one best way to pole vault prodigious vertical heights across cross bars.
Again a whole set of assumptions Willreifer is making on my behalf do not give readers a true reflection of my intention, only I can do that. If my information has not got across my intended message then that is poor communication on my part. I accept blame for that.
At the same time, you Willriefer as a reader have some responsibility in making a "fair" attempt at interpretation but also must accept personal culpability in any misrepresentation of the facts in so far as they can be established to be facts.
I remind all that Science without facts as it's building blocks is the equivalent of building a theoretical pole vault model on wishful thinking and hot air!
I look to at the evidence before me and seek the answer to the 2 of the critical coaching technical questions that Renaud Lavillenie has been addressing.
My argument is that he has been primarily addressing the drop of the (right) lead leg and is now displaying so much less and on some occasions no lead leg drop in (2014).
Secondly I observe that Renaud is getting a faster and greater amplitude of take-off leg swing .
Thirdly I observe the estimated (by "experienced coach eye") total system of centre of mass rises continuously whilst displacing forward without exhibiting a clearly discernable drop in its height immediately after Renaud has taken off in the first phase of his vaults. This, I contend ,is contrary to what is being claimed by some contributors to this thread.
These are my qualitative assessments of what I observe but Willriefer's, and another whose analyses, are equally qualitative ,I continue to reject on prima fascia (limited by qualitative assessment of available evidence) grounds and assert that:
Renaud Lavillenie displays in his 2014 performances, as revealed by videotape evidence and some anecdotal sources (which are confirmed and references to the material published on this site), does not show a lowering of total vaulter or system COM in the first phase of pole support to the same extent as in 2009 and in some case shows no lead leg drop at all!
Have the "radical" technique proponents" actually and carefully examined these videos against the premises on which they base their judgments and upon which their claims of "radical" technical developments by Renaud being the primary causative agents of his improvement are being made?
So far neither Willreifer nor PVdaddy has given us any actual information based on fact to clearly identify and suggest what these so called "radical" elements are let alone attribute any substantive physics based rationale in regard to their "radical" technical development claims.
Unfortunately, I am exhausting my time on yesterdays news and am bored going back 40 years to ideas from the Rip Van Winkle era of flexible pole vaulting which is detaining me in the Sleepy Hollow of Nostalgia and Mists of Rhetoric for far too long!
I am content with my efforts to awaken the sleepers, but I've set my time machine for the 21st century and whoosh there goes another failed attempt at raising the bar!
We have a measurements versus logic and reasoning argument...
1)My take off energy to height assessment is linear. So it's a very wide point linear assessment of what is going on in the vault.
2) Your point/state measurements are similarly along a linear approximation method. You provide more points. But that does not mean all the information is there nor is all revealed, it simply means you have more point data on a limiting number of factors, or there are factors which are left out. PB model analysts limit themselves to a certain fraction of the evidence, and calculate. The limits come out in their intent. What is the pole state? Have I ever seen you show pole energy state calculations? No. You limit yourself to angular analysis. So you are still doing point state line calculations that ignore a major vault factor.
3) The vault is progressed on two curves, the vaulters CoM movement, and the connect point on the pole. Curves are hard. Calculus in fact is mathematical limit studies of point line analysis to curves. That is calculating lines to curve points, and line triangles to curve areas. This is why one of my main argumentative points here is, no one, neither you nor me, is using differential calculus analysis.
4)CoM trajectory is something valid to be concerned about, as we both have argued
. Almost all vaulters go up all the time sans the plant/take off example of someone like Dossevi. The rate is what is important and(here comes differential calculus), relates to pole state. And still to really get to the heart of the matter as I argue you're going to have to know a lot about the CoM change rate versus the pole compression rate. You have shown little to anything on that, and neither have I, however the difference is in how much we are concerned on its effect in the vault. As a PB model adherent, its no great surprise that you aren't that interested in the pole state in time. That leads to the analogy that you are linearly focused on the vaulter. That is not particularly a bad thing and where all the evidence is that it yields an impacting model, yet it is what it is, and as it neglects pole state it comes to a point where it finds pole state vaulters....vexing. http://en.wikipedia.org/wiki/Calculushttp://en.wikipedia.org/wiki/Differential_calculus
And so you make an argument about Lavillenie's CoM point state concerning its height. Well, until the end, height is not all the matters. His CoM is never going to lower, but its rise rate is effective on the whole system!
This leads to why I've said there is probably a curve bounded area for CoM placement in time to achieve vault completion, with high and low boundaries, and that its possible the boundaries are also possibly indicative of efficiency. And you've still never once made any comment at all about the gravity vector on pole rate compression, effective of CoM rise, and relative to the angular displacement and gravity relation of the vaulter.
We're "taking past each other". I've made comments to this effect. This whole response is to that effect. You want me to answer you in a certain way, and I want you to answer me in a certain way...and we can't seem to, either one of us get there. Let me call myself biased based on some of the easy to see intent in responses here. A great philosopher once said, "We give to everyone all the respect we can muster until they prove they deserve otherwise..." - Steve Albini. So lets say I have a bias based on perceived acquaintances and a political need for protectionist bias...
Keep trying. I'm actually glad you're here. You make it...challenging. And that inspires a sense of admiration. Good job, sir.
To answer some questions...
1) Vaulter rotational energy. There is a very real problem is separating what is induced by the vaulter post take off from what is vestigial and carried from the run up/take off horizontal moment entering pole braking. Thus, if you simply measure the rotational moment and add it to any other value, you are going to get a conflated addition. This is why I just did not pay a lot of attention to the dense work you provided as I didn't see any attempt to address the issue. IF you will, please clarify. Possibly this is all on me...
2) Efficiency ratio greater than One. Well, it would be a problem if I did not provide the math to show what I was doing which was comparing take off energy to vault height potential energy to get a ratio of the take off to total. Nothing is "hidden". The math is all "out there". I work as much to the transparent as I can. PVDaddy did another calculation which gave another viewpoint in the matter. I think anyone that can follow rather simple math can see what was done. You have pointed out time and again there is more energy at the end than at take off. "Let's look at that!". We did...and excuse me but to anyone in the know I think you're making a mountain out of a molehill. You are, if nothing else, sophisticated.
I will give you the point state on Tradenkov versus Bubka, I guess. I don't know the height difference (and where I admitted missing starting state CoM was a huge mistake) , or mass rate differential (you know, one looks more "top heavy"*, and where again since v squared is so dominant it creates an attitude bias). Give it another go, would you, with horizontal velocity included. Just, you know, keep it concise. I have a terrible tendency to see density for density's sake. My bad. All on me, sir. Terribly revealing of myself on this. On the one side its drivebys, and on the other density bias based on first principle intuitions. Again, my bad. Sorry.
* This would seem to lead to a very odd conclusion. That building muscle mass over CoM, simply raising the CoM in this way, would give the vaulter an advantage? Really? Is that really what I'm thinking? OR again maybe everything is way way more complex than that...