AO Brain Trust:

[Jack & Coke]

If you enjoy discussions regarding the scientific and application/explaination of paintball physics, check out this thread over on Palmers Owners Groups:

http://www.paintmagazine.com/cgi-bin/cutecast/cutecast.pl?forum=8&thread=12011

I have some nice dialogue regarding the application of CO2 and it's properties as they relate to firing a paintball from a pump gun with:

A. holding the pump handle forward (breech sealed)

and

B. not holding the pump handle forward (breech blows open during firing - resulting in "blow back")

Glenn Palmer claims that by not holding the pump hand forward (option B), his guns will actually shoot higher fps.

If this scientific stuff bores you, then please disregard this thread... :)

[GT]

I love the comment about reactions and phase change. I had a proff that would ask the student stupid enough to say that whether thier kitchen blew up whenever you boiled water. Then the elipitcal honning comes into play, whatever.

I think I read somewhere in that garbled mess that the varience, not true stastical varience, was about 6 fps. Now the trick here is to attempt mutliple tests with alot of brands of paint, different gasses, guns, preasures......

To go out on a limb, you are essentially using a power source, co2 or n2, that is about 800psi and runing it down to about 50-60psi, unregulated! My guess is that we have to accecpt the Null Hypo: There is not any corraltion bewteen X amount of space for the bolt and velocity. IN other words, I dont think 6fps is signfngant to say that there is true varience rather than error.

Side note: anyone that says that there are real world resluts that are readly repeatable and yet unexplainable do not truly understand those events that lead up to the resultant.


WTF its sat night? Back to my "which gun should I get" replies.

[Jack & Coke]

gtrsi, excellent post! :)

[lew]

As much as I respect MR. Palmer, I feel that he cannot justify his results by saying "I don't know how it happened, but it did," or something to that effect. Some effort must be made to understand this problem. It would seem that I, a senior in high school, have more knowledge in Physics than Mr. Palmer. These results are great, but one must be able to apply the laws of Physics to these results and find out why it happened. Until he provides, or atleast attempts to provide, a sound basis for his results, I am left unconvinced. I think it would be in his best interest to read up on related material and reach a conclusion.

Well now that my head is spinning, I bid you farewell and good night.:o :)

[AGD]

Tk's Explanation: Introduce compressed air between a bolt connected to a heavy pump handle and a 3 gram paintball. The ball goes one way in 3-4 milliseconds, the bolt moves back a lot later, AFTER the ball already left the barrel. You shouldn't see any difference in velocity holding or not holding the pump. If it shot faster one shot, it was probably in the statistical shot to shot variance.

AGD

[Jack & Coke]

Hi Tom,

Thanks for replying:)

I tend to agree more with your statement than with Glenn's.

However, Walker posts:


Originally posted by Walker
If you don't hold the pump forward the blowback will cause a drop in velocity. Mine is set at 295 when held foresrd, and drops 10-15fps when not held.

I don't know the answer to the other question, concerning the ball bearings.

Walker


Do you think Got_Paint is holding his Nasty Pump handle here more for stability, or so he doesn't lose velocity?
http://www.pbase.com/image/26095157/medium.jpg

[punkncat]

Now I wonder whether these "pump holding" results are consistant?
I always see variance over the chrono with most paint markers I fire.Even my most consistant marker will vary by 10-15FPS from time to time.
I attribute this variance to the paint itself , not the mechanics of the marker.
The only way I could actually see holding the pump making any difference is if there were an O ring(front of the bolt) and a shoulder milled into the breech itself that holding the bolt forward actually created a seal.Otherwise I think it is merely differences in the paintballs themselves.

[GT]

Originally posted by AGD
it was probably in the statistical shot to shot variance.


booooooyaaaaaaahhh!

IS everyone on AO going to use "variance"?

[AGD]

Well it was better than "a three sigma data point on the wing of the gaussian distribution".

Hey you wanted more intelligent posts.....

AGD