Can I track the amount of air coming out of my barrel? TK? Engineers? Smart Peopl?

[mostpeople]

Well...

theoretically if you could cap a barrel off, with a pinhole for air to get out, and somehow put a pressure sensor in that cap, you could find the pressure, accounting for the volume of the barrel and body. That would be the easiest way.. dont use a stiffi though use a metal barrel. And it cant have holes in it anywhere...

the only thing im not sure about is if the increase in pressure would blow it up... I doubt it but... you never know.

[athomas]

Each setup has a slightly different pressure curve depending alot on the initial pressure in the chamber and the bolt spring used. The pressure behind the ball is not consistent, nor is it linear. The pressure generally peaks before the ball starts to move and then tapers off as the ball gets farther away from the bolt face. The higher the initial peak is, and the quicker the pressure falls off behind the ball, the more efficient the marker is. Markers vary from 60 to 100psi behind the ball depending on how quickly the air can be supplied and then maintained to get the ball moving.

To accurately measure this, you need a pressure transducer at a point directly ahead of the bolt in its forward position. The transducer has to be behind the ball at this same location. That way it can measure any pressure before the ball starts to move.

Use an old steel body with a barrel adapter. Tap a hole in the barrel adapter at the correct location. There will have to be a hole in the body at the same location to get access to the barrel adapter. At least this way you will be able to use different barrels and you won't destroy an expensive body or any barrels.

[AzrealDarkmoonZ]

Might have an answer for this this weekend if I can find my old WGP barrel that has thick walls.

I have 3 transducers and a PMD-1208FS that handle the reading end. Been using it to mainly test regs but now that I have 2 transducers wired up. Reading barrel pressure has been on my list of things to do. Might get around to it this weekend if I can find the barrel.

Also note you need some software to read the settings, or some dataloggers may store the readings on some sort of local media for later viewing. I read my pressure at 1000 readings a second, makes the math easy though I think the PMD can go to 40,000 total readings a second that much tends to A. Make the poor graphing software I am using start to hiccup after a few seconds and B. The transducers reaction time isn't that fast, all mine are rated at sub 1ms. But I doubt the general trend would be any different at 40k readings as compared to 1k.

Az

[athomas]

1ms increments might not be enough resolution to accurately get the readings. The ball exits the barrel in about 3ms. The first ms is the critcial one that shows how fast the pressure builds up and then starts to taper off. If you only sample in 1ms increments, you might miss the peak pressure and also wouldn't accurately show the true form of the pressure graph.

[mostpeople]

if you could theoretically put a pressure sensor between the ball and the bolt, and you could measure the pressure in at least 10th's of a millisecond, as well as calculate the approxmate volume/area for the flux you could do it..

what is it you want to find exactly? the Volume of air to pass through the bolt or the pressure at which it exits to the ball?

[Tao]

I have an urge all of a sudden to become a high school physics teacher....

[wjr]

lol. I dont think we understand each other. I am talking about tapping a hole in the removable detent. I have a few to spare. It would not damage anything except the detent. They are ~ 10 bucks

Ohhh.... I was thinking that you were tap a hole in the body of the gun or something.

Yeah, you're idea sounds better.