Paintball

[brycelarson]

Originally Posted by drg

What was the overbore on the setup that showed the most effect, btw? Did you by any chance measure all the balls in the test (holy tedium) or just a few from the batch?

That was the part that really made us scratch our heads - there was no difference in vertical impact point on any bolt out of the overbored barrels - only on the one that matched the paint size.

We just checked a few balls.

As we've both said in the past - if the results of our tests aren't useful in play then the claim fails. In this case - this is a paint issue. If you have to hand select every ball that you shoot through the backspin system - then it's not useful. It has to function in real world conditions to be a useful tool to play with. It's reasonable to require a special barrel - but not special paint.

[heinous]

nice!

hmm, what about other forms of spin device? do you think you can do the same test with a galacticz z-body automag or a BT apex in the future?

or do you think conclusions would be about the same (needing special paint)?

[brycelarson]

Originally Posted by heinous

nice!

hmm, what about other forms of spin device? do you think you can do the same test with a galacticz z-body automag or a BT apex in the future?

or do you think conclusions would be about the same (needing special paint)?

We're looking for future tests - so yes, a test of various types of backspin devices tested for amount of effect would be interesting.

[drg]

Originally Posted by brycelarson

As we've both said in the past - if the results of our tests aren't useful in play then the claim fails. In this case - this is a paint issue. If you have to hand select every ball that you shoot through the backspin system - then it's not useful. It has to function in real world conditions to be a useful tool to play with. It's reasonable to require a special barrel - but not special paint.

This seems like an attempt to kill an experiment just as it's starting to bear fruit, ostensibly because it threatens a hypothesis. *Something* is happening with the backspin bolts, where originally it was assumed and even "shown" by the original test that nothing was happening.

You have yet to explore the effect, so no, it's not yet time to declare the claim has failed.

We will at least need to explore actual trajectories before we settle that. Single-distance Y displacement comparisons assume equal trajectories between spinning and non-spinning balls, when that is almost assuredly not the case. The test needs repeating at various distances to map the trajectories, or the trajectories need to otherwise be measured.

I would think that a ~.691 barrel should be tested as well, or something else in between .687 and .695 (given .686 paint).

[cockerpunk]

Originally Posted by drg

This seems like an attempt to kill an experiment just as it's starting to bear fruit, ostensibly because it threatens a hypothesis. *Something* is happening with the backspin bolts, where originally it was assumed and even "shown" by the original test that nothing was happening.

well, if you question our nuetrality, then we cannot convince you. reams and reams of data from us will not change your opinion.

if you truly want to know, and you do not trust our results, the only thing you can do is test this stuff yourself.

i have a hypothisis, but i am refraining from posting it to try to spur conversation and see if anyone else comes up with the same ideas.

[Chefdave]

I think that the range you tested is too short.

I know that with the Apex at least, if enough backspin is selected then the ball may actually be moving down at that range.

[brycelarson]

Originally Posted by drg

We will at least need to explore actual trajectories before we settle that. Single-distance Y displacement comparisons assume equal trajectories between spinning and non-spinning balls, when that is almost assuredly not the case. The test needs repeating at various distances to map the trajectories, or the trajectories need to otherwise be measured.

as CP has said - feel free to set up more exploration if you would like. We might, but we've got other tests that we would like to look into as well.

I agree, if we wanted exhaustive data on backspin we would shoot the flatline, the apex, the cooper t at 50, 100, 150 feet. This would be after optimizing the cooper T by shooting through all freak backs at a number of different barrel lengths. I would love to see someone set this up and post the data they collect.

Also, you're mis-understanding my statement. I was describing the reason that we chose not to sort paint by size (besides the fact that we simply don't have that kind of time to spend on this). I wasn't saying that the cooper T doesn't have an effect.

I was stating a basis of analysis that we've been using since we started these testing endeavors - if the effect isn't useful in real world situations, then it's not useful. This isn't intended to cut experimentation short - rather, it's one of the criteria we use to sort the data we collect.

[Schmitti]

To answer to earlier thoughts...

if there is no flow through or around, the pressure behind the ball should be more or less evenly dispersed.

If you punch a vertical board at the bottom, the entire board moves... just the bottom (point of impact) first. THe base of the ball, point of impact reacts first. You don't get instantaneous oressure equalization... close but not immediate.

possible, but since the insert matches the paint - how could it roll along the top?

If it was a true paint to barrel match.. would the paint move at all?

E

[agentSmith]

i am still puzzling though how a matched barrel seems to work better than an overbore. if anyone has any theories i am certainly open to discussion. i have an idea, and im gonna look though the numbers again before posting it.

If my hypothesis was correct, that spin is put on in only the first few fractions of a second, in other words that the ball 'peels out' and contact with the barrel only slows the rate of spin after that, this would make sense. The ball, held more tightly in the sized bore, would put up more resistance to the initial impact of the air and feel the effect of the pressure imbalance more effectively than a looser ball that simply started moving the instant any air hit it.

Now I wonder about the bore of my P68SC. I honed it out, but the initial bore was small I would think. I'll get the bore guage and check it relative to the paint diameter this weekend.

Good stuff and a good test.

It has been my experience that the single biggest factor affecting the flight of balls from my Cooper-T is the orientation of the seam, that's why I like it in the Sheridan where I can see the ball fall into the bore. It gives me a reliable clue to where in the band of possible trajectory a particular shot will fall.

Rob

[brycelarson]

Originally Posted by Schmitti

If it was a true paint to barrel match.. would the paint move at all?

yup, based on out last paint to barrel match - even shoving a .687 paint into a .679 insert created increased velocity. I had to literally shove the balls into the barrel with the pump arm - the seal with the barrel is a far greater increase then the drag is a decrease.

Google Docs - barrel_test_2

Basically, we found that the tighter you can get the barrel to paint match, the faster the ball will go. the friction doesn't seem to operate on the same scale as the air pressure.