Paintball

[c6quad]

i know the camera mic picks up the sound and makes it seem worse but i wasn't going by the sound, i was going with what i saw in the background. in fact, the wind was one of the first things i noticed that will comprimise the results. i also understand the fact of not having an indoor place to test... hence my recommendation of testing early in the morning or late evening when the wind is usually at its calmest.

[SSniper13]

Cockerpunk and Bryce,

I understand why you are excited about what you are doing. It is something that is new and much needed. Please don't think that because we're nitpicking that it means we don't appreciate it. You are very close to your data, but we are not. You saw the balls flying with your own eyes, but we did not. You "know" that your test platform is consistent, but we do not.

Any good researcher learns early that what someone says is not nearly as important as what their data shows. From the standpoint of all of your tests so far (with the exception of the paint to barrel match), we have NOT seen the raw data. We can't, because the video does not show actual impact or distance traveled. We only have your interpretation of what you see and some fuzzy images that may or may not show paintballs doing certain things (and given the movement of the grass in the background -its very hard to tell). That is not a flaw in your methods of testing (which is how I think you are responding to it) but instead a flaw in your documentation and measurement. It would be much harder to argue the effect of wind, for example, if we were faced with a real time video of paintballs repeatedly impacting a solid surface over and over in essentially the same spot. You may know that the wind was mild, but your documentation does not allow us to make an intelligent determination of the same.

I'll tie this to my work. I do research in autism -specifically in how best to teach children with autism to learn social skills. If ever there was a field with even more hype, strong feelings, and exploitative companies looking to make a quick buck at the expense of parents who don't know better than paintball, it's autism. I can point you to literally hundreds of "science-based" websites selling products that the owners claim "work". I can show you hundreds of studies -conducted by scientists- that claim to validate some of those procedures. I can show you the same number of studies that show those same procedures don't work. Do I automatically believe a treatment works, or doesn't, just because one researcher said so? No.

For example, Lovaas and his colleagues developed what is still the most empirically-validated and successful treatment for children with autism to date. He published some of his results in a widely-read article in 1987. That study was seminal, and has led to thousands of replications and extensions. I would argue that it is the single most important publication in the field. In 21 years it has been crucified and pulled apart by more specialists than I can count. All of the scientists with financial interests in other treatments which his results suggested did not work exploded. Similar to what you are experiencing, but much much bigger. Some of the strongest criticism came as a result of the measurement and presentation of the data. People just didn't believe that children with autism could learn in the way Lovaas showed.

I am fortunate enough to know and have been able to spend time with several of the people who were there during the Lovaas study -who worked directly with the kids, who saw them learn and grow and ultimately go to school and be successful and grow up "normal". They "know" what they saw. They "know" that their methods were sound. They "know" that they made a huge difference in the lives of those kids. But they couldn't convince the scientific community just on the basis of what they said they saw.
They also knew that some of the people who criticized Lovaas did not do so to dicredit him, but to grow the field. They knew that what they were doing was a first demonstration, and from it they would learn what to measure or present better next time.

Now, we have more standardized measures. We know to focus on and present actual learning of the kid. You have a great new procedure, fine, but at the end of the day can the kid read 10 new words? Can they use a sentence to ask for a toy? Can they start a conversation? Do they have friends or not? Those are the raw data. It's not the teacher's report of the child learning faster or better. It's not that the parent says their kid talks more. It's the actual behavior of the child.

For you, the raw data of these tests is the flight and impact of the paintballs. That is the bread and butter actual result of your manipulations -changes in flight path and point of impact. You want to be more convincing -show us that. Don't TELL us what you saw -SHOW us the actual impact. Don't TELL us you controlled a variable or that it was insignificant. SHOW us the actual board you shot with one large sploch of paint in one area.

When I have an exciting result in my research (and I'm lucky enough to have a few) I believe it. I get really excited, and I want to share. I SEE how my students are acting differently. Then I show my graphs or videos to my advisor. He has distance from the data, and a very critical eye. He neither presumes or assumes that what I say was an irrellevant variable actually was one. And I leave that meeting much less impressed with myself. That is not a bad thing. It is a good thing. I learn that what I believe doesn't become believeable to somebody else just because I think it should. Not until I have identified an appropriate methodology to test my teaching methods, and found a way to present the data in a convincing way, and then even further described my methods and measurement in such a way that someone else can do it and get the same results do I start to make my work believable to the scientific community at large.

I've actually come to recognize that when professors take the time to rip my work apart that it means I'm doing something right -its interesting enough to take the time to pick it apart rather than dismiss it outright. I think that is what is happening here with you.

This critical evaluation of your testing and results is not indicative of immaturity or stubborn refusal to accept facts, but rather of interest in the subject and appreciation of the fact that we actually have something "solid" to talk about instead of just raw conjecture. This is a community which knows better than to believe everything it is told giving you feedback so that when this hits a wider audience the work is that much tighter and convincing. At least that's how I'm seeing most of this discussion.

SSniper13

[Emert426]

Very well put and supported SSniper13. Incredibly positive and helpful constructive criticism in my opinion.
I would assume limited access to cameras, and not having excessive funding to build some of the necessities for absolute control and visual examples is a hurdle. I think if we are being as demanding for the details, as is necessary to support some of the conclusions you are reaching regarding these well rooted myths, it seems reasonable to assume some of us could donate to make things easier on you guys.

I'm willing to because I have always been fascinated with the science of paintball, math, and physics... And study as I may I am horribly inept in each and everyone of them. I assume my gifts lie in different areas, or maybe I simply exist to spectate.... Rabbit trail, ha sorry. But I will definitely donate some cash to be able to see where this whole things grows and leads to.

You can tell CP is passionate, and intelligent enough to do things right. I bet we could see huge things from these guys in the future.

[gunangel]

I'm a bit new here, but I do consider myself a student of science and an addict to paintball.

I'm on the same boat as SSniper13. I really think what you guys (CP and bryce) are doing is a great step. And I sure appreciate that you two are spending money and time to pursue truths in paintball.

I do think we all need to take a breath, burp, run a lap, fart, or whatever to loosen the tension a bit. For CP and bryce they are putting out their thesis that they came up with essentially their baby (no gay jokes or anything of the sort implied) and we as a forum have attempted to do great bodily harm to it. As adults we need to understand they have attachments to their thesis and ideas, and as researchers CP and bryce should understand that some attachment must be dropped in order to come up with valuable feedback.

We shouldn't take every statement they say and attack it or find flaws in them. Despite good/neutral intentions short responses imply a curt and possibly rude response (that is why I know HurtCow cares ). And I really wish they in turn would stop labeling us as pbn kiddies and what not as labeling is forcing a group of people into one oversimplified identity, essentially a slur used on the internet maybe. The internet hides identities and sometimes it is hard to distinguish between someone who has read an article on wikipedia and someone who practices these things for a living, and in america you are innocent until proven guilty.

With that said:
A bit late but... although there is a decent amount of laminar flow present in the exhaust pipes of an engine, exhausts with sudden increases or decreases in internal diameter create a drastically varying flow dynamic. And if the roughness of the pipes are smoothed out to a certain degree, flow increases greatly reflected in horsepower numbers (data available from honda corp with the development of the type r series (which included the NSX type-r))

To the response about no one using short barrels: I use a 5 inch barrel every chance I get. From a different barrel test they concluded the length of the barrel does not matter after the ball has been "stabilized" towards its intended path. I have personally seen no difference in the different barrel lengths (leaving out bore size) other than the greatly increased shot noise level. And maybe a small decrease in the distance the balls break at (since my balls are exiting the barrel much closer to the marker they are traveling a few inches less then if i had used a longer barrel).

Just my thoughts:
About the experiment, since a paintball can roll in the breech freely up till the barrel, the breech would be considered over bored. According to the definition of pressure you provide and how air tries to equalize almost instantaneously, it would be mistake not to consider the air that would move around the paintball and lie in front of it.

In theory a proper low blow bolt would supply air at the lowest point and cause the ball to ride the top end of the breech (force marked fb-) and cause back spin to occur (the ball would ride the top picking up friction and rotation in the path of least resistance), assuming a larger barrel bore is used. My proof behind this would be how the apex works (friction pad that occurs at the end forcing the ball to spin opposite of the friction pad, simple way to do with would be to stick your finger in your mouth, get some saliva and stick it to one side of the inner barrel, and watch the ball spin in the opposite direction). I'm pretty sure the Z-body for the automag worked in a similar fashion by placing the material inside the body rather than at the end of the barrel. So back spin bolts should work, it just requires a large barrel, possibly a rough inner breach (not perfectly smooth?), a true back spin bolt (one that is at the extreme or maybe one that is has ports angled down?), and a short enough length barrel to effectively be visible at range.

An anecdote all science students/researchers should follow:
Two researchers travel to scotland and both see the side of a sheep standing on a mountain is black. One concludes all the sheep in scotland are black, and the other concludes that there is at least one sheep in the world which is black on one side, on this certain time of the year, at this certain location, at this certain barometric pressure, at this specific angle, and at this temperature.

Granted the latter is not as enlightening or cost effective as the first, but it is the scientific way of going about things.

I really appreciate what you guys have done and how you have put your research out there. I understand how hard it is to have your results taken apart right in front of you especially by someone you may not consider a peer, but understand many are in fact trying to help you become better paintball myth busters, ones anyone can enjoy that provide both science and engineering.

EDIT: I've been looking at some of the alamo city paintball low blow bolts (taking the suggestion and trying it my self), but would that be as effective as the cooperT bolts? It looks like it has a large bore with just the bottom part milled out completely, not a sleeve with a small bore in the center like the cooperT bolts.

[agentSmith]

I'm running around like a chicken under a rollercoaster this morning so I'll try to complete this Idea but will come back later if necessary.

I've thought about this subject alot since the PB physics thread on AO.org and so though I didn't read this whole thread, when I saw the title I just searched for the word vortex and felt compelled to jump in here when I didn't find it.

An alternate thesis for why these bolt DO work in the real world(like HP Lovecraft, I've been shooting Cooper-Ts since it came out), has NOTHING to do with the magnus effect.. during that thread on AO the calculations found a ridiculous 70,000 rpm necessary, like taping a paintball to the head of a dremel(messy).
Paintballs are subject to vortex shedding, little tornadoes that are created on the surface of the ball that kick it back and forth with between 1-3Gs of acceleration perpendicular to the direction of travel but in a random direction. It's my theory that the low spin produced by the cooperT better bolt and the flatline barrels counteract those vortices which try to force the ball downward and assist those which try to propel it upward and it is this which produces the lift, not the magnus effect.
This also explains why everyone(in the last few pages I read), was so subconciously concerned about wind. The wind counteracts vortices pushing upwind and assists ones going downwind, so paintballs are affected by windage much more than a non round projectile. People know this in their gut, but don't see the explanation.

Rob

[pump]

Originally Posted by agentSmith

An alternate thesis for why these bolt DO work in the real world(like HP Lovecraft, I've been shooting Cooper-Ts since it came out), has NOTHING to do with the magnus effect.. during that thread on AO the calculations found a ridiculous 70,000 rpm necessary, like taping a paintball to the head of a dremel(messy).

so what is the rpm of a ball shot through a Flatline barrel, or a Galactic Z body?

interesting indeed

[brycelarson]

Thanks everyone for the turn toward the mature. I love to have conversations about things I'm invested in - it make me think harder and really examine things.

I've discussed with CP getting together a grid system - AND taking the time (lots and lots of it) to provide everyone with impact points as well as velocity per shot for every shot we take.

And please, one request - make sure you keep an eye on both bryce and CP - we're different people. I didn't suggest anyone here was a "PBN kiddie" nor do I have any animosity involved in this argument. I've been accused of being harsh in person before - so when all human interaction is removed I'm sure that my statements seem antagonistic at times. I apologize.

I truly have nothing to gain or lose by testing backspin bolts - if they work, then I suppose I'll have to buy a few. If they don't, well then whatever I have lying around will work just fine.

I would like to take a direction from Sniper13 - he described the reality that until you've seen a theory applied in real world conditions it's still just a theory. It must be thrilling to see people making progress that have been written-off by so much of society - and I thank you for your work.

In the case of the back spin bolts (and I'll amend this view after testing the Cooper T bolt if I need to) if there was going to be a change in distance - AND that distance made a real-world, in-game difference it would need to be a greater change than the change in distance created by the inconsistencies of the velocity of the gun. At 100' we saw a 24" + change from low velocity to high velocity shots (yeah yeah, I'll work on providing data next time). If the backspin bolt is actually effective we need to see an increase in the height of the impact greater than the height change created by the velocity changes. While the conditions were not perfect - the sample number was high enough that we saw (yes yes, I'll provide more data next time) the center of the impact group stay the same.

Now, it's possible that our bolt wasn't effective - but it had a significantly lower air flow path than this bolt:



As to wind being an issue - yes, it certainly could have been, however, if the vortex theory is, in fact, how the backspin bolt creates lift - AND wind makes that ineffective - then you would be using a tool that isn't effective in almost any real-world playing condition.

Thanks again to everyone who's offered constructive criticism. I think we got a far too easy reception with our first test - apparently attacking SP doesn't get the same defenses up that other things do.

Also, for those that use the backspin bolts (or have used them) how much additional range do you feel you get? Anything like the flatline?

[brycelarson]

As for the RPM of the flatline - I've read above 10,000, but don't know where that number came from.

[drg]

Originally Posted by brycelarson

As for the RPM of the flatline - I've read above 10,000, but don't know where that number came from.

Couldn't it be calculated by the length of the barrel, size of the ball and velocity of the shot?

My crude calculations come out with about 46,600 RPM, assuming barrel length 14", ball size .687, using a highly questionable figure of 140 ft/sec to represent acceleration from 0 to 280 ft/sec at the muzzle.

If that is correct, then 70k is plausible. Anyone want to run the calcs and see if I screwed up somewhere?

[HP_Lovecraft]

Thats true-
The circum of a paintball must be around 2.13"?

If we assume that the flatline "rolls" the barrel out, and the paintball is travelling 300fps, which is 3600 inchs per second, or 1690 revolutions per second.

60 seconds in a minute, so 101,408 revolutions per minute?

Clearly it does not spin at 100,000, as the paintball would bust apart. But if we assume that the paintball can achieve 10% of its potention, then that equals 10,141 rpm, which does appear to be the stated number.

The actual number needed for the magnus effect can be calculated from its Reynolds number, so its worth seeing what the actual RPM needs to be, and work backwards