[rntlee]

I have a large data set of recorded shots (103 shot @ 75') that I broke down a bit. Nothing really new but it does confirm consistency must be quite poor to affect accuracy much at medium range.
Here's the original group and underneath it just the shots within +-2fps
Here's just the shot >= +-5fps

[Molybdenum]

That's very interesting. I would suggest you try to shoot a group at deteriorating inconsistencies, but consistency is a rather difficult variable to control without changing paint.

[Troy]

I took the liberty of graphing shot velocity verses height:



Within the given dataset, the trendline that maps this data has a coefficient of determination (r^2) of .0004 (where 1 is a perfect line) Just to give you an idea as to what a GOOD r^2 value is, I frequently threw out data that was worse than .96 when I worked in a lab. I can say with a VERY high level of confidence, within this dataset, there is no correlation between shot velocity and impact height.

Where's that damn nail? I've got a coffin to shut...

[cockerpunk]

great data set lee!

[drg]

Molybdenum, on 12 May 2012 - 09:22 AM, said:

That's very interesting. I would suggest you try to shoot a group at deteriorating inconsistencies, but consistency is a rather difficult variable to control without changing paint.

You could possibly mix paints of different diameters.

[The_Economist]

Nice job. More data to show that consistency and accuracy are very tenuously linked in paintball.

[cockerpunk]

drg, on 12 May 2012 - 11:17 PM, said:

Molybdenum, on 12 May 2012 - 09:22 AM, said:

That's very interesting. I would suggest you try to shoot a group at deteriorating inconsistencies, but consistency is a rather difficult variable to control without changing paint.

You could possibly mix paints of different diameters.

dirty regulator might work too. then clean it, and shoot a sample again.

[drg]

Or simulate by using a clean stable reg and turning it up or down?

This post has been edited by drg: 13 May 2012 - 02:04 PM

[Troy]

drg, on 13 May 2012 - 02:03 PM, said:

Or simulate by using a clean stable reg and turning it up or down?

This is what I was thinking. Use the same paint, same marker, just adjust the reg... thus keeping the amount of air actually delivered to the paintball variable, and as many other variables as constant as possible.

In other news, I just picked up an F1 Alpha Shooting Chrony... mainly because I have an older Timmy that I needed to tune, but it gave me the proper excuse to get a nice chrono, so I could do some tests myself.

This post has been edited by Troy: 13 May 2012 - 03:35 PM

[Snipez4664]

Forum malfunction, ignore post.

This post has been edited by Snipez4664: 14 May 2012 - 11:31 AM

[Egomaniacal]

What was the paint/barrel like that you were using?

I only ask because as "scientists" we must be careful to consider the conditions of our tests, as that will affect their applicability. Unfortunately, although this is a very extensive dataset, we cannot draw a strong conclusion because of a lack of information on conditions.

All I feel comfortable saying is that with paint of unknown roundness and size, a barrel of unknown quality and dimension, an unknown paint to bore relationship, there is no correlation between accuracy and consistency over the range of 275-285 fps.

I'm not one to believe there is a correlation that won't be washed out by other effects, but unfortunately that's all we can say with the data provided. There's no doubt you would begin to see a correlation if you increased the standard deviation to +-50. Who knows, maybe if you were to use highly round paint and a properly under-bored barrel you might see an effect show through, even at +- 5.

Is there any chance you have a pair of calipers you could throw about 20 balls at, get a measure of seam and pole diameters? Measure your bore? Either way it would help just knowing the make and model of the paint and make and model of the barrel.

This post has been edited by Egomaniacal: 14 May 2012 - 12:00 PM

[UV Halo]

Great Data!!

Questions:
Was the barrel level?
How was the zero established?
Was the paint weighed and sized?
I'm not saying these influence the results but, I'm looking to do a real-world comparison to my model.

In any case, I've long felt that inherent inaccuracy largely overshadows most velocity influenced deviations.

[cockerpunk]

Egomaniacal, on 14 May 2012 - 11:44 AM, said:

What was the paint/barrel like that you were using?

I only ask because as "scientists" we must be careful to consider the conditions of our tests, as that will affect their applicability. Unfortunately, although this is a very extensive dataset, we cannot draw a strong conclusion because of a lack of information on conditions.

All I feel comfortable saying is that with paint of unknown roundness and size, a barrel of unknown quality and dimension, an unknown paint to bore relationship, and velocity fluctuations with a standard deviation of +-5 around 280 fps, there is no correlation between accuracy and consistency.

I'm not one to believe there is a correlation that won't be washed out by other effects, but unfortunately that's all we can say with the data provided. There's no doubt you would begin to see a correlation if you increased the standard deviation to +-50. Who knows, maybe if you were to use highly round paint and a properly under-bored barrel you might see an effect show through, even at +- 5.

Is there any chance you have a pair of calipers you could throw about 20 balls at, get a measure of seam and pole diameters? Measure your bore? Either way it would help just knowing the make and model of the paint and make and model of the barrel.

why would bore size or barrel make matter? we already have bounded that in terms of there non-effects on accuracy (and thus Y position).

the issue with using a normal regulator and adjusting it on the fly, is that you don't know what distribution of velocities you are are getting from that. there could be local averages, instead of a nice relatively normal distribution of velocities.

[Egomaniacal]

cockerpunk, on 14 May 2012 - 11:53 AM, said:

why would bore size or barrel make matter? we already have bounded that in terms of there non-effects on accuracy (and thus Y position).

Barrel make doesn't, I was just more or less looking for more information about the barrel.

The reason the bore is important is depending on how out of round the paintballs are, the amount of under-bore might play a role in how much spin is imparted to the ball. It's why I asked for paint measurements along with the bore measurement. I'll admit I'm making a bit of an assumption about spin imparted being a function of roundness and relative bore/paint diameter, but we have seen that accuracy deteriorates when the size of the paintball is close to the bore of the barrel.

Unless you guys have done tests that show accuracy is independent of paint quality (I actually believe you've found the opposite to be true), I suspect there is a dependence there, and it is dependent on relative bore size (in a way I'm not 100% sure about). I will admit I haven't been through every test in the experiment vault.

tl;dr - If quality paint were used in conjunction with a bore that attenuates spin and other effects that accuracy is dependent upon, a consistency dependence might show through. It's hard to say what we're dealing with in the data provided, for all we know these could be 5 year old dimpled monsterballs going through a bore matched barrel, which would likely wash out any correlation between consistency and accuracy.

This post has been edited by Egomaniacal: 14 May 2012 - 12:33 PM

[cockerpunk]

Egomaniacal, on 14 May 2012 - 12:20 PM, said:

cockerpunk, on 14 May 2012 - 11:53 AM, said:

why would bore size or barrel make matter? we already have bounded that in terms of there non-effects on accuracy (and thus Y position).

Barrel make doesn't, I was just more or less looking for more information about the barrel.

The reason the bore is important is depending on how out of round the paintballs are, the amount of under-bore might play a role in how much spin is imparted to the ball. It's why I asked for paint measurements along with the bore measurement. I'll admit I'm making a bit of an assumption about spin imparted being a function of roundness and relative bore/paint diameter, but we have seen that accuracy deteriorates when the size of the paintball is close to the bore of the barrel.

Unless you guys have done tests that show accuracy is independent of paint quality (I actually believe you've found the opposite to be true), I suspect there is a dependence there, and it is dependent on relative bore size (in a way I'm not 100% sure about). I will admit I haven't been through every test in the experiment vault.

tl;dr - If quality paint were used in conjunction with a bore that attenuates spin and other effects that accuracy is dependent upon, a consistency dependence might show through. It's hard to say what we're dealing with in the data provided, for all we know these could be 5 year old dimpled monsterballs going through a bore matched barrel, which would likely wash out any correlation between consistency and accuracy.

im not saying more info is a bad thing, im just saying there is enough here to draw real conclusions from (esp given the other data sets we have on the topic).

[Egomaniacal]

cockerpunk, on 14 May 2012 - 03:17 PM, said:

im not saying more info is a bad thing, im just saying there is enough here to draw real conclusions from (esp given the other data sets we have on the topic).

Right, which is why I'm just saying based on the information available, we need to exercise caution about how far we generalize these results. There is certainly a conclusion to be drawn here, but every conclusion has caveats.

Just going to point out, the consistency at least seems a little poor for a well-matched barrel with quality paint. Not that I'm implying that's why the accuracy is what it is, just pointing out that if it's bad paint that'll wash out any accuracy variation due to inconsistent velocities. There's little doubt in my mind that both inconsistency and inaccuracy are caused by bad paint, and what we're trying to determine is if the inaccuracy is caused by velocity fluctuation or by some other effects, like spin due to bad paint.

Which introduces an interesting point, the more energy you put into spinning a paintball, the less energy you have for translational motion. So while you're simultaneously lowering the muzzle velocity, you're also introducing drag effects that will put the projectile off-course. I'm going to check to see if this shows up in the data.

In my mind, consistency and accuracy are both dependent on bad paint. If you want to see if inaccuracy has any direct dependence on inconsistency, you need to reduce the variables they're both dependent upon as much as possible.

Edit#100: Hmm, nothing there.

This post has been edited by Egomaniacal: 14 May 2012 - 04:36 PM

[cockerpunk]

Egomaniacal, on 14 May 2012 - 03:30 PM, said:

cockerpunk, on 14 May 2012 - 03:17 PM, said:

im not saying more info is a bad thing, im just saying there is enough here to draw real conclusions from (esp given the other data sets we have on the topic).

Right, which is why I'm just saying based on the information available, we need to exercise caution about how far we generalize these results. There is certainly a conclusion to be drawn here, but every conclusion has caveats.

Just going to point out, the consistency at least seems a little poor for a well-matched barrel with quality paint. Not that I'm implying that's why the accuracy is what it is, just pointing out that if it's bad paint that'll wash out any accuracy variation due to inconsistent velocities. There's little doubt in my mind that both inconsistency and inaccuracy are caused by bad paint, and what we're trying to determine is if the inaccuracy is caused by velocity fluctuation or by some other effects, like spin due to bad paint.

Which introduces an interesting point, the more energy you put into spinning a paintball, the less energy you have for translational motion. So while you're simultaneously lowering the muzzle velocity, you're also introducing drag effects that will put the projectile off-course. I'm going to check to see if this shows up in the data.

In my mind, consistency and accuracy are both dependent on bad paint. If you want to see if inaccuracy has any direct dependence on inconsistency, you need to reduce the variables they're both dependent upon as much as possible.

Edit#100: Hmm, nothing there.

eh, combined with the other mountain of evidence we have for consistency and accuracy being linked below +/-15 fps ... i see no reason to be apprehensive about concluding the same thing.

[Egomaniacal]

So I did a little more digging, and decided that even with 100 shots the statistics were still not good enough to make a solid conclusion. Here's a graph of the distance from the average center vs. velocity:



It looked to me like the shots that were at a higher velocity tended to be more accurate, so I broke things down into velocity groups to get a better picture of what was going on.



If we ignore the first and last columns (the first has only 5 datapoints and the last 6, not enough to get a good picture) we can see that as the velocity increases, the average distance to the average center decreases. Also, as velocity increases, the spread (less strongly) seems to decrease.

Since we've already seen that the increase in distance from center is not a result of velocity fluctuations causing the ball to fall short, this data seems to support my hypothesis that more energy used to spin the ball results in lower translational velocity, and also causes a larger spread (in any direction)

It also makes me wonder about his bore, paint size and paint quality.

This post has been edited by Egomaniacal: 14 May 2012 - 06:03 PM

[cockerpunk]

you'd have to know how much energy was imparted on each ball to make that conclusion. all we know is how much translational energy was imparted (velocity)

[Egomaniacal]

cockerpunk, on 14 May 2012 - 07:03 PM, said:

you'd have to know how much energy was imparted on each ball to make that conclusion. all we know is how much translational energy was imparted (velocity)

If you make the moderate assumption that the energy imparted on the ball is roughly equal from shot to shot, then no, you don't. And even if it weren't equal and you used that to explain the spread in velocity, that wouldn't explain the spread in position at lower velocities. It's still a hypothesis, I'm just saying the data we have to work with seems to support it.

This post has been edited by Egomaniacal: 14 May 2012 - 08:20 PM