Summary: David Alciatore ("Dr. Dave") ILLUSTRATED PRINCIPLES
"Draw Shot Primer Part II: aiming"
Note: Supporting narrated video (NV) demonstrations, high-speed video (HSV) clips, and
technical proofs (TP) can be accessed and viewed online at billiards.colostate.edu. The
reference numbers used in the article (e.g., TP A.20) help you locate the resources on the
website. If you have a slow or inconvenient Internet connection, you might want to view
the resources offline using a CD-ROM. See the website for details.
This is the second article in a series dealing with draw shot principles. Last month, we
explored some of the basic physics of draw shots. This month, we'll look at how some of those
results can be used to analyze and compare various draw shot aiming systems.
Diagrams 1 and 2 repeat some of the results from last month's article. The graph in Diagram
1 shows how much the cue ball deflects away from its original direction for typical draw shots of
various ball-hit fractions. Diagram 2 illustrates the three points shown in the graph that
correspond to the cue ball angle changes for 1/4-ball, 1/2-ball, and 3/4-ball hits. The cue ball's
final path is deflected away from its original direction (the aiming line) by 58° for the 1/4 ball hit,
90° for the 1/2-ball hit, and 128° for a 3/4-ball hit. As you can see, the deflected angle varies
significantly as the ball-hit fraction (cut angle) changes. But, if you're like me, you might be
wondering if there is a useful aiming system to help you reliably predict the final direction for the
cue ball for any cut angle. When you see how nearly straight the curve is in Diagram 1, you can't
help but think that there must be a system that would work fairly well over a very wide range.