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Old 10-14-2012, 01:33 PM   #73
Erick Mead
Erick Mead's Avatar
Dojo: Big Green Drum (W. Florida Aikikai)
Location: West Florida
Join Date: Jun 2005
Posts: 2,616
Re: More on Aikido and the Floating Bridge of Heaven

David Orange wrote: View Post
Your clip looks a little...koshi-centric, we might say.

Do you see that?
Sure. Same as yours, your shirt just makes it less apparent-- but your hips pop out first, as well (At least in your second one -- your first and third were taken down. )

That is to be expected if it is is done as a pure reaction transfer back from the wall (see below) .

David Orange wrote: View Post
Also, your legs are bent a good bit before the pulse and they straighten with the pulse, so that your center displaces to the rear ahead of both your head and your feet. The leg extension also turns it into a bit of a jump.
Not actually. The lower center is where the power comes from to generate the pulse action -- and thus -- if the structure is at full extension (rigid in essence) that is where the wall's reaction is seen -- showing that everything above the lower dantien is in the precise line of the delivery of the momentum transfer pulse. Newton's Cradle .

If anything else were out of line it would buckle at that point -- If my shoulder moved back first, you would know the power was from the upper cross or arms. The center buckles because everything else was in line. Since it was not bounded for the input -- it is not bounded for the output either -- if -- the body is transferring the pure reaction. The only things that move are at the end of the momentum transfer chain at that center -- and the legs are just being pulled along.

If you actually go and do the stop motion on it you will see my center drive about an inch forward to generate the pulse -- and that's where the return reaction arrives, in a pure reaction chain ( which in this case is coming form both the wall and the ground. Both reactions arrive at the same time and the center buckles to the rear -- like my taped together pencils buckle upward (in my other video) when compressed from both ends -- the hips are driven up and back -- and only then do the legs lengthen to follow.

If I ground the strike and do this while in contact with a person they are driven back about the same amount. Essentially, we just punched ourselves with a reflection of the no-inch punch off the wall. Like a wave reflected off the beach.

But you know, these kinds of isolated linear power transfer things are not the most interesting behaviors that multiple pendulums exhibit -- And those are unlinked pendulums --

If we link them, things get even more interesting considering that every one of our limbs is a linked double pendulum -- Run the java app for a bit and look at the pattern it generates on the graph and then go and look at my "dynamic tube" of torsional shear again.

FWIW -- the "three dantiens" form an inverted double pendulum. -- which is stable in the inverted position -- if and only if it is oscillating on its support . I believe we aikidoka call that condition furitama-- The pulse is simply half of that native stability oscillation halted suddenly against a barrier (a target or the earth) -- creating a unidirectional wave peak.
Why don't you try it with straight legs?
Well, I didn't because it's your exercise, you had not suggested it, and phi did not correct anything on that point...

Second, because it is unnatural and unstable for the legs to be completely rigid more than instantaneously to transfer energy -- which they were.

Plus -- Tiggers bounce....


Erick Mead
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