A THEORETICAL TREATMENT OF PAINTBALL DYNAMICS

by Gary Dyrkacz

Preamble

*My paintballs fly further than my friend's; my WeedWhacker gun is better than his!
*You guys all suck! I can hit a quarter three out of five times at 150 ft.
*My gun gives the paintballs an extra push after they leave the barrel.
*My SuperWhizzo marker shoots only a flat trajectory with a straight barrel.

Do any of these statements sound familiar? If you read posts on the rec.sport.paintball group, or are a regular at paintball fields you probably have heard them. These statements are scary, and often the rebuttals are just as scary. There are too many people who believe something magical occurs with some markers. Maybe it comes from watching too many alien visitation TV shows. Fortunately, there are always a few people who can provide a more balanced and thoughtful view. However, the demagoguery from both sides without substantiation often leads to confusion and ultimately mistrust of any statement by those who really want to know what the truth is.

Before I discuss the physics, I would like to review a discussion that occurred in the rec.sport.paintball group in July of 1998, that I think we should all keep in mind. Arguments were flying back and forth about whose gun is better and has a flatter trajectory. At one point a fellow named Terry Garrett made the statement, "I think the most appropriate science that applies to paintball gun accuracy is the science of psychology. If you wish to call it a science. The more the barrel cost, the longer it is, and the more the manufacturer spent on advertising is what makes it the best. Really, who does serious accuracy testing? We've all seen tons of posts over the years stating such data as "last Sunday I shot 5 guys with this new barrel when I usually only shoot 4 so it has to be more accurate." etc, etc.....".

Now I don't agree with all of this statement. I do think examining paintball motion from even a theoretical physics can explain some of the limitations and paintball behavior we see. However, I do believe that he was right about the psychology of paintball. There is too much reliance on one-of-a-kind episodes under all kinds of strange conditions.

Relying on manufacturers' statement is in general not a good plan. Have you ever seen them back up their claims with hard evidence? Only Air Designs comes evenly mildly close. (Now don't rush out and buy their guns just because I make this statements. We don't know all about their study either.)

Except for the "mine is prettier than yours" people, we all want to believe that we spent our hard earned money to get the very best. We don't like someone telling us our $2000 gun is just as accurate as a $150 gun. Without hard data, all we are left with is the psychology of the sport. To me, that is a dismal situation. Part of the reason for this document is to stop some of this all to prevalent attitude.

Starting Points
There are at least two experimental studies that have really looked at the dynamics of what can happen to a paintball when it leaves the marker. Since the first web publication of these pages in 1999, I have hints of others, but most of the detailed data will likely never be in the public domain.

In 2002, partial data from one of the studies was made public. This was through the good graces of Tom Kaye, the owner of Advanced Gun Designs. He made some of the high speed camera images and data on paintball motion publicly available on the Advanced Gun Design web site forums. Some of the details are still sketchy, but this data was a real eye opener. Moreover, the forum discussion on the data was an incredible feast of ideas and insight by some very interested people with strong engineering or technical backgrounds. The forum ran its course over several months, but the impact the discussion had on my understanding and further interest in developing a fairly comprehensive description of paintball dynamics persisted. The current version on the web site represents an expansion of the original concepts.

The Goals
This set of pages will examine the dynamics of paintball flight from a theoretical perspective. I wish there were more direct experiments on paintball dynamics. Real life experiments are always better than theoretical studies. Unfortunately, I do not have the time or funds to do the necessary experiments.

Those of us who try for lucid armchair answers often rely on our imperfect memories of physics classes. As it turns out, high school physics courses often do not go far enough, and unless the college physics is the more advanced version for science majors, the dynamics of a flying paintball will still not match reality. In fact, even though I had advanced physics courses, I was not aware of some of the subtle dynamics that paintballs are subject to.

What These Pages Will and Won't do For You.
What could you get out of this? Will it make you a better player? No, not at all. In fact, if you stop to think about this stuff while your playing, you probably will get shot out. You won't find here information on the best barrel, best marker, best paintball or best tactics.

What I hope these page can do is give you a better appreciation for all the factors that go into getting a paintball to a target. I hope it will make you a more aware player, less likely to fall for some of the blatantly misleading statements of your fellow players and some manufacturers. Most of what I discuss will be obvious to you from good old common sense and practical experience. What I hope to do is give you the framework behind those common sense notions. I will try and show you why paintballs act the way they do, and maybe alert you to some things to consciously avoid or do.

Now the Scary Part!
I realized early in thinking about what I wanted to say here, that just making dogmatic statements isn't going to convince the skeptics of anything. Thus, the nature of these pages is in the form of a small tutorial starting from basic physics Laws and Principles and working up extremely quickly to complicated formulations. This stuff is real meat and potatoes physics. That means that the discussion will very soon put us knee deep into heavy doses of physics. As I proceed, the discussion will sink us up to our necks into advanced math (calculus). Although I wish everyone could follow the math, I know that only a few will understand every last equation I write. Worse, as you will see, the complications in paintball dynamics gets so complicated that I am left drifting. I am not trying to bury anyone under jargon or an intellectual fog. Nevertheless, this document will undoubtedly come across as pedantic to a good number of paintball players. For those whose eyes begin glazing over when more than two numbers are multiplied together, I do try to discuss what the calculations mean. But please keep in mind that this is a long and detailed technical document. The logic and methods are presented in detail, so that anyone who has the necessary expertise can evaluate, criticize and take off from them. In my professional career, all my published work goes through a critical review process. The work here has not. You are my reviewers as well as my readers. Above all, I am interested in achieving an honest appraisal of the dynamics of paintballs.

In addition, I would like anyone interested in physics or aerodynamics to take note there may be some cute stuff here for you to think about. Hey, this stuff is only on the rim of my expertise; I certainly am missing many nuances of fluid dynamics. Second, there are some glaring questions that will become evident as I proceed, which present interesting opportunities for real world experiments by many of you.

From my personal perspective this is neat stuff! In trying to answer the questions of why paintballs act the way they do in the real world, I have finally begun to understand the classical dynamics I think my college professors tried to teach me a long time ago. Hey, its never to late!

Okay, here we go!

 

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Last Update: December 29, 2006