*NEW* - MOtion Hole - Video - How To & Demonstration

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LabRat
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Re: *NEW* - MOtion Hole - Video - How To & Demonstration

Post by LabRat »

RevZiLLa wrote:I think you are overestimating the effect of gravity on a small amount of side weight and underestimating the power of gyroscopic inertia. Have you ever played with a 3 pound or more gyroscope? With no spin applied, you can move it to different angles with very very little effort. Spin it up and try to move it. It will resist changes in attitude with MUCH force.

This explains the extra length on the lane and the increased hit at the pins in an unscientific and unquantified way. I had no tools to measure the forces involved when I played with a gyroscope, but the forces were QUITE significant.


OK, it's not science if it can't be measured, so...
Given a 14lb ball with the cg 3/64" from the geometric centre, rg of PAP of 2.5", and a 300 rpm rev rate, the rate of precession when the weight is close to the axis is approximately 8* per second. If positive side weight, in oil this will increase axis rotation (more likely, reduce the rate of loss of axis rotation) and once the ball rolls will increase entry angle (the path of the rolling ball will become circular rather than a straight line).
The precession rate will start low when the weight is far from the PAP (although it will be nonzero for most PAPs) and increase sinusoidally as the ball flares. It is also higher for lower rev rates.
If my calculation is correct, I think that is significant enough to at least warrant consideration as a factor.

This is using P = Mgr/Iq
Where: P=precession rate in rad/sec;
M=ball mass (kg)
r=length of moment arm (cg offset from centre, m.)
I = moment of inertia of PAP;
q=angular velocity of ball, rad/sec.
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Re: *NEW* - MOtion Hole - Video - How To & Demonstration

Post by Mo Pinel »


This is going nowhere. The key is that MOtion Hole layouts work! They are very important for high track, low rotation players.

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