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- 14-November 12
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25 September 2012 - 11:49 PMI've shot nylon balls before and found them to work extremely well. Just make sure you don't mix them up with real paint. The problem I had with mine is that I had to put them through my largest bore barrel, something like a .692. I bought mine to setup an auto reloading efficiency test rig.... but then got side tracked with other projects.
I tried them and they shot like boomerangs. Figured it was the surface finish so I polished them...still went every way but straight. Even patched they were awful. Made no sense, .6875" dia., within .001" round, weighed 3g...should shoot like a paintball, right? Still have some.
25 September 2012 - 11:40 PMHello and thank you for responding.
Your post on the vector method was well done and it sees to come close to representing the data it makes it difficult to perform statistics on the data sets. I'm in the process of putting together revised version of your accuracy results, but I'm also putting together some information on the methods I am using so it will take a bit longer to assemble. While I am at it I'll put some time into the velocity measurements as well. Before I do that I would like to know what type of chronograph you are using.
I'll start another thread when I am done.
I'm a bit busy right now but I'll track down our previous discussions about the "vector" measurement. We found that it's a great quick and dirty way to compare accuracy.
Since we're using the standard deviation of x and y we are effectively comparing each to the average center of the shots. There are slightly more accurate ways to analyze the data but we have found no instances thus far where our method has failed to produce the same results as a fuller analysis.
here's my thread on vector. you're obviously a stats guy - so feel free to start another thread with questions if you have them.
24 September 2012 - 06:54 PMIf you have time between all this bickering about paint could someone please tell me what "vec." means on the spreadsheets? I'd be happy with a link to a page discussing the use of the pythagorean theorem on the standard deviations of the X and Y dimensions of the impacts.
Personally, I think you are doing it wrong. The equation you've used treats the X's and the Y's as independent numbers and I don't think that is the proper way to do it. Years ago I was using image analysis to do similar measurements and used the X and Y coords to calculate the distance from each shot to the center of the target or better yet the distance of each shot to the average center of the shots. This way you treat each shot as an individual data point and can run the statistics on the shot placement and not just on the X or Y coordinates. Using this method and a one way ANOVA shows there to be little statistical difference between the ten test combinations (i combined data from a couple of your spreadsheets).
I'm still interested in seeing the test setup and a description of how the tests were run.
22 September 2012 - 10:51 AMDo you have a detailed description of how you ran these tests? Also, can you explain the logic behind using a^2 + b^2 = c^2 on the standard deviations? What does vec. stand for?
19 September 2012 - 12:32 AM
we have some accuracy testing coming up, and i also have a set of pressure transducers on my coffee table ...
It would be interesting for you to share the details of your pressure transducers. You have links to Tom's testing so you'll be able to look at the response times and data collection rates required for reliable measurements, assuming you're measuring the pressure pulses during firing or perhaps the recharge time of regulators. Choosing the right pressure transducer can be tricky... the response time is very important as is the accuracy, repeatability and linearity. I watched your video on dry fire efficiency vs ball shooting efficiency and was surprised by some of the comments you made about a liquid filled pressure gauge being accurate. You've got some cool stuff on here and I'm pleased to see that people are running actual tests to try to figure out what is going on.