Colenso Delfection Theory Part 1
Bluewolf said:
Read that paper and almost fell asleep in the middle of it.
Could have done without all that physics stuff. Colin, when you write yours, I hope it be such that an ordinary person can understand what you are saying.
Laura
Ok Laura, here is my own theory, and I believe it is much easier to understand that Ron's analysis.
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Colenso Theory of Deflection: Part 1 What Causes Deflection?
Deflection, also known as squirt, is the effect of the cue ball being deflected from a line parallel with the cue when the cue ball is struck off center.
See Arial view of deflection in diagram below:
A is the line of the cue, A’ is parallel to A and B is the deflected line of travel that the cue ball actually takes.
The deflection angle varies according to several factors that are discussed below.
The further the target is from the cue ball, the harder it becomes to compensate for deflection. Hence, it makes sense that reducing the amount of deflection will be an advantage in achieving more consistent accuracy in playing shots with english.
Factors affecting Deflection
According to most billiard physics theorists, there are only two variables that determine the amount of deflection. These are:
1. The Distance from Center that the cue ball is struck.
2. The Endmass of the cue.
The distance from center is quite easy to understand; the further you hit the cue ball to the side, the higher is the deflection angle.
Lowering the Endmass will also reduce the deflection angle, but what determines the endmass of the cue is harder to determine and may have several variables as described below.
1. Lighter tip, ferrule and shaft may reduce endmass.
2. Thinner cue end.
3. A more flexible shaft may reduce endmass.
4. A lighter cue may reduce endmass.
5. A looser grip may reduce endmass.
Points 1 and 2 are generally accepted, point 3 is often accepted, while the effects of points 4 and 5 are considered by most to be negligible.
An Erroneous Assumption about Slip
The 2 factors of deflection as stated above are best outlined in a paper written by Ron Shepard. See:
http://www.sfbilliards.com/Shepard_squirt.pdf
In this paper, Ron states “Squirt occurs even when the tip does not slip. The tip does not slip on normal shots.” This is, I believe, the key error made by billiard physics theorists.
Firstly, they have never tried to define slip. Part of the reason for this is that slip, or grip is very hard to define in a physics sense. In fact, the entire field of frictional physics is full of assumptions, because to really investigate friction we need to analyze in deep detail the billions of tiny collisions occurring at a collision interface.
In fact, at the atomic level, it would be more accurate to say that all collisions are approximately 100% elastic. An example of a near perfect elastic collision in larger objects is the collision between two billiard balls. We might call this a slip collision. In this type of collision, the objects deflect at paths of 90 degrees.
So when the tip hits a cue ball at an angle, to say there is no slip, really assumes that the cue tip surface creates a contact surface on the cue ball that is at 90 degrees (perpendicular) to the line of the cue. But if this were true, then there would be no deflection of the cue ball; there would simply be rotation of the cue ball, as it travels along a path parallel to the line of the cue. The following diagram helps to illustrate this idea. See below.
In part 2 of this series, I will expand upon the idea of what slip or grip is, and how it affects deflection.
End of Part 1
