PVDaddy wrote:I could go into great length to quote a LOT of dumb things Kirk has said over the years but ...
... Don't answer. Please don't talk to me. JERK!
Nothing is achieved by name-calling. It only makes you look bad. And there is no reason to flame me.
I have no objections if you just ASK QUESTIONS on this Advanced Technique forum. But don't plagiarize other people's work; and don't offer any unproven theories that could cause safety issues with young aspiring vaulters that want to emulate the WR holder. And don't keep flogging a dead horse with theories that have already been debunked.
If you followed those simple concepts, then I would not even have to remind the readers of this forum to take your rants and theories with a huge grain of salt.
I've explained it before, but I will explain it once again (for the benefit of Advanced Technique forum readers), since you have never vaulted higher than 10-6, so you cannot possibly appreciate how a vault with a bending pole follows the Laws of Physics from first hand experience. And you CANNOT reverse-engineer vids of WR holders frame-by-frame and know the vaulter's intent; or distinguish between cause and effect. You don't have the experience to do that ...
First, I will quote Will:
willrieffer wrote: As a thought experiment, if the vaulter just came down on the pole from above and bent it as a spring, the angle wouldn't matter. It could be anywhere in the 360 degrees. But they aren't. Hmmm...
This is true. The direction of the force in this experiment is straight into the box. This is directly down the chord cylinder. So as you say, the direction of the bend would be random.
But the vaulter approaches from the runway, and bends the pole not from above, but from the direction of his approach. And the pole bends in a predictable direction --- first directly forwards (towards the pit), and then off to the side of the bottom hand (left side for a right-hander).
Also, Will notes that the corner of the box may impose a counter-acting force; preventing the pole from further bend to the side of the box. I don't disagree with his observation, but I think we should ignore that detail for now. It complicates the physics; and it's only true for bigger bends on lighter poles (which maybe should be avoided anyways). So let's keep it simple here, and ignore that detail.
So what's different from Will's experiment? A few things:
1. Every pole has a prebend. This dictates the direction that the pole bends easiest. In Will's experiment, there is no prebend (so the direction of the bend would indeed be unpredictable. But if there was, that's the direction the pole would bend. The vaulter has chosen to grip his pole so that it will prebend DIRECTLY FORWARDS --- towards the pit. No, not a little off to the side. Directly forwards!
2. Immediately after takeoff (on a good vault), the vaulter has his body and the pole perfectly aligned with his path down the runway. His hands are also BOTH directly in line with his body --- they are not to each side of his CoM (as would be the case if he were swinging on a highbar). At this point, it would actually be impossible for his hands to be anywhere else but directly in line with the plane of the force (unless, of course, it's a bad jump where he gets flung to the side, resulting in not landing in the middle of the pit). THE PREBEND PLUS THE DIRECTION OF THE VAULTERS FORCE WILL BEND THE POLE DIRECTLY FORWARDS.
3. DJ has often mentioned (in commenting on Mike Tully's swing technique) that he would:
... bend the pole into a high bar... and do a giant off the top ...
This is a good analogy of what actually happens. As the vaulter swings, he's putting more and more of the CoM force on his bottom hand (and less on his top hand). Somewhere in the first half of the swing, the force on his bottom hand approaches the force on his top hand, but never exceeds it. Then (somewhere in the last half of the swing -- prior to pole release), the force on his bottom hand recedes (down to zero).
4. As the force on his bottom hand approaches the force on his top hand, the pole is (as DJ and Tully say) "turned into a highbar
", with hands now separated to the left and right of his CoM. And I can honestly say --- from first hand experience that vaulting like Bubka, that's how it FEELS. I contend that this happens without any cognizant or intentional action on the part of the vaulter. It happens due to the physics (the forces) I've just described. The movement of one hand becoming beside the other hand (rather than above/below it) is a natural result of the force of the vaulter on takeoff being applied to the pole, with his inertia causing his body to continue to go directly forwards. The vaulter stays "square to the pit
" (his inertia causes this), which means that the shoulders need to stay square, which means that the pole is pulled off to the side --- NOT BY ANY SPECIFIC ACTION OF THE VAULTER, BUT BY HIS INERTIA.
Will, I'm sure you could explain this in better Physics terms.
PVDaddy wrote: Immediately After plant, the pole will lean to, rotate to and bend to the opposite side direction of the vaulters top hand. This effects the plane of the swing and steers it in that direction.
False, true, true. It doesn't LEAN; it does rotate; and it does bend that way. The question you need to ask is why
. But I wouldn't use the word "steer
", as you're already using that word (in other posts) to infer an action by the vaulter.
PVDaddy wrote: It is not in a perfectly linear direction with the runway.
False! See above.
PVDaddy wrote: In order to maximize your swing with the runway and your trajectory (The Crossbars), the vaulter should redirect the swing in the opposite direction toward the top hand.
False! The inertia causes the pole to move to the side; the vaulter doesn't steer it to the side; and doesn't NEED to steer it.
PVDaddy wrote: This will not cause the vaulter to swing into the standards Kirk!
How do you know this?
What is your experience when you've tried this? Before you jump to this conclusion, grip your pole at 15 feet and TRY IT (a 10 foot grip won't cut it). Once you've tried it, THEN you have the experience necessary to make your assertion. But I take no responsibility for your injuries!