Paintball

[c6quad]

yes, that's a much better setup and seems to show your first test was flawed. so all of us "non-believers" of your first attempt did have legit points of concern about your testing methods and we aren't a bunch of PBN whinners that we were labeled.

good job guys!

i do agree with Clearush and would like to see a 75', and 100' test range.

[HP_Lovecraft]

Absolutely facinating!

What was the measured range? With that information, we could check one of the ballistics calculators to determine what height differential we should expect to see.

At 3.3" above a Venturi is very interesting, though the average FPS was around 3FPS higher. Would the FPS differential be enough to account for the difference?

The fact that the CooperT worked better with the tigher bore confuses the heck out of me. My experience with tightbore barrels was that the CooperT would make corkscrews.
However, the barrels that made the corkscrews were 16". So perhaps the corkscrews were more a result of the long barrel, and not so much the tightness of the bore.

Curious though why the "Open Face" bolt was not tested within all applications?
The CooperT produced a higher impact then everything tested, except for the oddball open-face bolt. That might be an anomoly, or might imply the test itself does not have a large enough statistical sample?

[HP_Lovecraft]

According to the Ballistics Calculator:

For a paintball fired at 280fps, 5 feet above ground, and no spin:
25 feet: 4.854 feet above ground
50 feet: 4.445 feet above ground.

For a paintball spinning at 10,000rpm:
25 feet: 1.5 inches above baseline
50 feet: 5.3 inches above baseline

For a paintball spinning at 20,000rpm:
25 feet: 2.7 inches above baseline
50 feet: 9.1 inches above baseline.

Knowing the range of the test, we can plot the points into the dataset above to see if it falls within predicted results

[brycelarson]

read the red parts

Originally Posted by HP_Lovecraft

Absolutely facinating!

What was the measured range? With that information, we could check one of the ballistics calculators to determine what height differential we should expect to see.

CP is going to post some math later - confidence intervals and things. This may get at what the calculator would tell you. It will help interpret which of the variations based on standard deviation and sample #s are actually significant.

At 3.3" above a Venturi is very interesting, though the average FPS was around 3FPS higher. Would the FPS differential be enough to account for the difference?

nope, that's far too little mean fps increase to add the height - something else was at play there

The fact that the CooperT worked better with the tigher bore confuses the heck out of me. My experience with tightbore barrels was that the CooperT would make corkscrews.

yup, trying it with just the freak back was directly based off your posts earlier that a short and very overbored barrel would work best - but to our surprise it didn't. FYI we also tried to use just a CCM back - so a 1", ported, overbored back. we couldn't get the velocity over 200 fps - so we didn't include it.

we took your input into consideration when designing the test - since you had the most specific information on implementation of the backspin bolt.

We were startled when the matched barrel started showing some statistically significant results. After the overbored barrel we thought we were in for a really long, really boring test getting exactly the same results for every combination - but we didn't.

On a format note - we discussed the best way to present our test - and came to the conclusion that we wanted to present data - then discuss the response to it before providing our personal take on the interpretation. I think this will open the data up to more discussion - about the data - instead of discussion of our opinion. We would love to be the impetus for other people to do tests, to think critically about things and to ask questions. Hopefully presenting data first will move the paintball community in this direction.

[brycelarson]

Originally Posted by HP_Lovecraft

According to the Ballistics Calculator:

For a paintball fired at 280fps, 5 feet above ground, and no spin:
25 feet: 4.854 feet above ground
50 feet: 4.445 feet above ground.

For a paintball spinning at 10,000rpm:
25 feet: 1.5 inches above baseline
50 feet: 5.3 inches above baseline

For a paintball spinning at 20,000rpm:
25 feet: 2.7 inches above baseline
50 feet: 9.1 inches above baseline.

Knowing the range of the test, we can plot the points into the dataset above to see if it falls within predicted results

can you re-run that with our average speed - we filtered the data for only shots that were within 265-280 - and the mean for nearly every combination was just over 270 - so maybe insert 272 as the speed.

[cockerpunk]

yeah, guys, lets not jump off the handle here.

there are easy and very steadfast rules about applying smaple means to total populations. had bryce not posted these, i would have done them first, then posted.

they easily quantify the natural variance in the system and show weather the resualts are acutally statisically viable and show a real difference in means.

last night we only had time for a single quick calculation, so even i do not know the full results, and if they are statistically different or not. thusly why i am not claiming either way if backspin works or not. i have many questions too. the math will show the difference, if there is one.

please standby for us to finnish the numarical analysis before concluding things like "100%" different. do you have the math to show that? becuase i know how to show that, and i have yet to get my hands free enough to do so. what happens if the intervals shows no statisical difference? are you gonna blame me? i just collect (and even on this one i didn't collect much of the data) and crunch numbers, so dont blame me for the results.

HP your questions as to the open faced bolt setup being a statistical phenominon is exactly the thing a confedence interval will do. please wait untill i am off of work.

[Harbinger[TG]]

Did I spy an air vent in there somewhere... j/k. Good work guys. I really liked the part where CP walks in front of the laser pointer, I was secretly shouting HEADSHOT to myself.

[brycelarson]

Originally Posted by Harbinger[TG]

Did I spy an air vent in there somewhere...

you bastard.....

and to back up CP - this is just data. when he finishes his math (based on standard deviation, mean and number of samples) we'll know if any of this means anything.

It still is possible that the approximate 3" increase in impact height on the Cooper T bolt may not actually have any statistical significance.

The most puzzling aspect to this is the idea that the backspin only had effect when used in a barrel that matched the paint's size. My assumptions would have been (and HP backed this up by his experience) that the overbored barrel would have been better, and that a shorter barrel would have been better as well - but instead it was only in the 12" matching barrel that we saw anything.

[gunangel]

not enough people are saying this, good job!
you took into consideration the points of others and changed your plans to satisfy them to the best of your ability.
one step closer to breaking paintball myths

hated statistics myself, finding out data can only be applied to certain intervals with a certain percentage that the next value would fall in that interval, kind of took all the fun away from predicting things...

P.S. nice shirt very "cocky"

[HP_Lovecraft]

Originally Posted by brycelarson

can you re-run that with our average speed -.

Here is the ballistics calculator

It is not mine, and is based entirely on ballistics THEORY, so it has a few flaws. But it does provide a way to extrapolate some information out of the tables. When I quickly compared 270fps to 280fps, results were similar as close range.

The one thing that really is a problem is that we can not directly measure the spin speed. We know that it can produce the effect we are looking for, we just don't know if these bolts spin the ball fast enough (if at all). Or if the spin is stable, relative to the type of barrel (ie length, bore, etc).

Perhaps the overbored back is TOO overbored- Meaning, the blast is directed UNDER the paintball instead of at the base? Or there is enough of a gap where the blast is diffused before it has an effect? Someone mentioned in the last thread that perhaps it doesnt really spin the ball directly, but force it to ride against the upper barrel? This might show that.

Curious that it seems to have a confirmed effect, but that there are definetly variables that we can not quite account for.