Why not use a 25 foot pole?

[skola28]

Utterly and completely EOM!

[Decamouse]

But what if K is the effective length factor - and to use K as a spring rate you would need to test and plot various spans and weights to fill in the curve - Always interested in different view points - always testing - So hows this - at what point does the flex to length ratio make the validity or accuracy deteriorate - Ran at Joplin years ago - will be in Neosha next summer for a Deca Challenge with the Brits

[Decamouse]

Guess that means I could wave as we drive past Rolla

[KirkB]

But what if K is the effective length factor - and to use K as a spring rate you would need to test and plot various spans and weights to fill in the curve ...

Lanthorne plots that curve that you're talking about here:

http://people.brunel.ac.uk/~spstnpl/Publications/PoleVault(Linthorne).pdf

I referenced this paper in the "take-off point" thread here: viewtopic.php?f=38&t=15636&start=12 just now.

Check it out.

Kirk

[volteur]

and i thought decamouse was totally taking the pi**

[AeroVault]

I am, in fact, a rocket scientist (no jokes necessary) who has used these equations before. Be aware that they have limitations! Conservation of energy assumes a closed system where energy is neither created nor destroyed. Linthorne made this assumption in the flexible pole study Linthorne, N.P. (1989) The fibreglass pole. Modern Athleteand Coach, 27 (1), 15±19 and 27 (2), 43. This critical assumption may be true for the current styles of vaulting, but does not apply if you are using a 25 foot pole.

I'm sure I will be labeled a heretic for this, but I do believe vaulters will someday use larger poles (in the 20'+ range). I have posted on it before, and the reason I think it will happen is because a longer pole allows the system to be "open" longer. I'm talking about the point where the pole begins to bend and the vaulter is still in contact with the ground, pushing more energy into loading the pole.

There are ramifications to the new style; pit dimensions would need to change to allow the pole to bend more and safely catch the vaulter, poles would walk a fine line of stiffness between flexibility and return of energy (since they still need to at least lift a person off the ground), and athletes would almost have to triple-jump into the vault (the first jump to initially load the pole and let the vaulter sink into the bend in order to push off a second or third time).

With current equipment this style is not the best approach. Still, I like the fact that people are thinking about alternative approaches to vaulting. That is how we will truly make leaps of progress.

One last remark to think about: Can we not agree that the highest takeoff angle is desired? What about grip height? A preloaded takeoff allows you to maximize both of these factors which have the greatest correlation to vault height.

[VaultPurple]

now for the simple answer.... if a 6' guy was to use a 25foot pole the take off angle would be so small that he would be taking off at about 24'. So just to make it into the pit he would have to be able to long jump 24' while being pushed back by the pole..... Bubka was probably a anywhere from a 25-26ft long jumper if i had to guess and he only took off from around 14'. So to take off from 24' you would probably need to be about a 35'+ long jumper, because even if you were 7' the angle would really change signifigently enough to matter.

[KirkB]

This reply addresses the points of both AeroVault and VaultPurple (directly above) ...

We're talking "fantasy vaulting" here of course (maybe AeroVault isn't, but I am. At least that's my premise, just so you don't think I'm as heretic as him!).

It's an interesting idea ... start loading the pole, and keep on running ... 2-3 steps, as AeroVault says. It's high-tech rocket science (sorry, couldn't resist) but it just might work!

Can you imagine hitting the pole on your penultimate step, then one step later, jumping off your takeoff foot? As AeroVault was careful to state, you might need a different pole design - that worked in this way. I wonder what pole modifications might aid this PV model?

Just supposing if - and this is a big if - you could bend the pole on your penultimate step, and then get to a good takeoff posture on your takeoff step. At that point, you've got a helluva lot of potential energy stored in the pole already, and you're about to add to that by a takeoff that's (hopefully) just as good as a normal takeoff.

So you takeoff, storing yet more energy into the pole. All this while, we must assume the right body posture to handle this pent-up energy. We cannot be off in any direction, or we'll get blasted out of the pit - even if it's oversized!

I cannot imagine AeroVault's "triple jump" scenario as well as I can imagine the "two-step" scenario that I just described. Step one to load the pole, and step two to takeoff.

Now on to VaultPurple's comments ...

I agree with his logic. But in the "two-step model" remember that the objective of the penultimate step is NOT to takeoff at the highest angle possible. It's just to load the pole. Then that leaves the takeoff step to achieve this high angle which seems to be so important. But is it? Is this high angle not the angle of the CHORD of the pole (rather than the pole itself)? They're one and the same if the pole doesn't bend before takeoff. But in this "two-step" takeoff, isn't it just the CHORD pole angle that's important?

I don't have any answers here. I'm just trying to continue down AeroVault's path - to some wild pie-in-the-sky ideas. We might need to get back to earth on this soon, but it's fun to explore this outside-the-box, isn't it? (Again, AeroVault, sorry for the space inferences - NOT! Now I see where you got your handle!).

Now I'm going to shoot down one serious flaw that I see in my own thinking. Or maybe I could say AeroVault's thinking, so that I'm absolved from all blame.

When you load the pole on the penultimate step, you're transferring your kinetic energy (from running) into potential energy (in the pole). So that's going to slow you down. So much so, perhaps, that your true takeoff step is far less than the approx. 9 m/s an elite vaulter normally has on takeoff. I think that might be a killer to this whole idea.

But maybe the engineers and rocket scientists in the crowd can help lead us back to reality!

I'm thinking that even if we eliminate this idea based on the laws of physics, we still might learn something about any advantages or disadvantages of loading the pole before takeoff in the traditional "drive vault" model. Specifically, isn't that really reducing your effective takeoff speed?

Kirk

[vault3rb0y]

I think kirk is right. Its all about the pole speed, and yea you can take off again with a 2-take off approach, but the entire time the pole is bending you are slowing your pole speed. I just dont see it possible to make to vertical. You would need a pole so soft that it would be impossible to straighten out even with your weight on top of it! So then the solution would be to lower your grip. Maybe from 20' to 19'. Then you run into the exact same problem with too little pole speed. I think eventually you would lower your grip AGAIN to about 18' to follow a 2-jump model, but the pole would not be stiff enough to push 20'+. I dont know the physics, but i just cant picture it, in terms of energy, in my mind. Fun to think about though!!

Maybe we can make a pole that absorbs energy more slowly than it releases it. In other words, have a built in mechanism with already potential energy, and when the pole reaches a certain point in its bend, that potential energy is released. kind of like a coil that runs the length of the pole and releases at a certain bend angle. You could roll over these much MUCH longer poles and softer poles, but once the bend reaches your highest effective grip hieght, lets say 12'6 effective grip hieght, the mechanism releases, and springs you like crazy! Now its totally illegal, but can anyone see a physical reason why this wouldnt work?

In any case, keep your minds open and keep thinking!!!

[volteur]

i'm thinking if the objective is to go vertical then it's limited to what we have now, but if the objective is to go as far as possible horizontally then it could be different. A really long and soft pole we sag through on and then get launched off quite horizontally. Be good for crossing a river and having a soft landing on the other side.

[Lax PV]

Skola, AeroVault--I dig it. FINALLY someone else finds a problem with simply using a conservation of energy system to determine how high someone can pole vault. There are WAY more problems than meet the eye here. Sound, friction, changes in the athletes moment of inertia... I think we would end up having a long talk about non-linear dynamics to make something that would even be appreciable in the eyes of a physicist. I read Dr. McGinnis Ph.D dissertation a couple months back--San Diego State actually has it on file--about a discrete finite analysis of the pole vault. One of the only real hardcore biomechanics papers I have read about the pole vault... I can dig up the title of it sometime, but a worthy read either way. As for longer, 20' poles, maybe someday, but the stiffness required to make a pole that long useful, would make it dang near imposible to jump on given human limitations, and techniques used, at this point...maybe we can get Tyson Gay, Usain Bolt, and Asafa Powell to take up a new skill...

[KirkB]

This link definitely belongs on this thread!

http://www.justin.tv/darthur/c/2BAB94A21A

I like the little "helpers" that pull the vaulter over the bar!

Kirk