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

[MANN]

Alright I have an idea. I am wanting to see what kind of pressure the ball is actually seeing. The only way to do this would be to have a pressure gague where the ball sits. A detent would work perfectly. If I took the ball out of a stock agd detent, tapped it for a fitting, and hooked it up to a digital pressure reading device (which I have access to) this should work right?

The reason I am tring to do this is to go along with my barrel test. The velocity of a marker has to be adjusted for different barrels. I am wanting to see if there is any relationship between accuracy, and the pressure exerted on a ball.

My xmag has dual detents on the vert breech so I could always just use one while leaving the other for a detent.

I know that this would all hinge upon the idea that the automag is a closed system. Ie that there is no air loss in the removable breech, behind the bolt (thru the body), etc. But in theory this would work right?

[Pneumagger]

you'd need a pressure transducer. it would happen on a gauge, you either wouldn't notice or it wouldn't register.

The cheapest economy grade (only .1% accurate) transducers i could find were like $125 online. And you'd still need a data acquisition system for it as well. It's probably easier to calculate what the on-ball pressure should be given the dump chamber pressure.

[MANN]

I have access to what we call a TOY. I guess in reality it would be an electronic manometer. It is used to track the pressure in different processes. I will have to check on what the maximum pressure allowance is, but I think it would work. It has 0-10Vdc output so I will be able to hook it up to a datalogger. Ill try to find a link. They are @ 200.00 for a cheap one

[MANN]

It is similar to this

http://testproducts.com/safecart/product_info.php/cPath/109/products_id/292?osCsid=a0f78a0f745c141512e09487eba71878

Like I said earlier I am not sure what the min/max pressure rating is. I am wanting to say ours is @ 500psi.

[MANN]

I am wanting to do this because I have no way to know the pressure in the dump chamber

EDIT **Now that I think about it the detent is probally "sealed" by the bolt when the marker is fired. Oh well another idea that wasnt thought through all the way.

[Chronobreak]

I am wanting to do this because I have no way to know the pressure in the dump chamber

are you needing an exact amount? i believe its around 65 psi at 280 fps

anyone cofirm that?, its probly in the tech files somewhere

[MANN]

are you needing an exact amount? i believe its around 65 psi at 280 fps

anyone cofirm that?, its probly in the tech files somewhere

What barrel/paint was used to get the 280 :p
I am wanting to track it more than know an exact amount.

[wjr]

I think I might have a better way to find the pressure with out having to cut or drill anything. You could have an endcap made that would replace the regulator on the back of the valve. Then, you could use a standard inline reg with a guage in place of it. This way, of course, you'd see how much what pressure is needed to fire the gun at whatever desired velocity.

[Dark Side]

Alright I have an idea. I am wanting to see what kind of pressure the ball is actually seeing. The only way to do this would be to have a pressure gague where the ball sits. A detent would work perfectly. If I took the ball out of a stock agd detent, tapped it for a fitting, and hooked it up to a digital pressure reading device (which I have access to) this should work right?

The reason I am tring to do this is to go along with my barrel test. The velocity of a marker has to be adjusted for different barrels. I am wanting to see if there is any relationship between accuracy, and the pressure exerted on a ball.


Yes. Take a look at what happens when you increase your velocity. More velocity= more pressure on the ball= greater accuracy.

I'd take an old cocker barrel. Tap a hole 2 inches or so beyond the bolt. Hook up your lines and TOY. Put a barrel condom on and pull the trigger(with no paint). The condom should help the pressure not to dissapate too quickly there by giving a decent reading on your TOY.

[MANN]

I think I might have a better way to find the pressure with out having to cut or drill anything. You could have an endcap made that would replace the regulator on the back of the valve. Then, you could use a standard inline reg with a guage in place of it. This way, of course, you'd see how much what pressure is needed to fire the gun at whatever desired velocity.

I think that would be a little harder than tapping a detent. Dont you?

[MANN]

Yes. Take a look at what happens when you increase your velocity. More velocity= more pressure on the ball= greater accuracy.

I'd take an old cocker barrel. Tap a hole 2 inches or so beyond the bolt. Hook up your lines and TOY. Put a barrel condom on and pull the trigger(with no paint). The condom should help the pressure not to dissapate too quickly there by giving a decent reading on your TOY.

I am wanting to see the pressure on every barrel tho.

[wjr]

I think that would be a little harder than tapping a detent. Dont you?


I don't know... are you okay with doing that on an xmag? I also thought it would work if you couldn't get the right equipment or something.

And BTW, there's a guy on MCB who made me said valve cap for $15, and finished it in about two days.

[Tao]

Alright I have an idea. I am wanting to see what kind of pressure the ball is actually seeing. The only way to do this would be to have a pressure gague where the ball sits. A detent would work perfectly. If I took the ball out of a stock agd detent, tapped it for a fitting, and hooked it up to a digital pressure reading device (which I have access to) this should work right?

The reason I am tring to do this is to go along with my barrel test. The velocity of a marker has to be adjusted for different barrels. I am wanting to see if there is any relationship between accuracy, and the pressure exerted on a ball.

My xmag has dual detents on the vert breech so I could always just use one while leaving the other for a detent.

I know that this would all hinge upon the idea that the automag is a closed system. Ie that there is no air loss in the removable breech, behind the bolt (thru the body), etc. But in theory this would work right?

as long as the velocity out of the barrel is the same from barrel to barrel the NET force on the ball should be the same on the axis down range...so thinking net force is better than pressure as pressure= force over area which would be a nightmare with calculus figuring out which way the pressure is pushing a sphere :P


Pressure behind the ball at any given time BEFORE the ball leaves the barrel is irrelivant asside from the concern of gas efficiency. When the ball is in the barrel , any pressure against the ball which tries to push it off the line drawn from the back of the barrel to the front of it, is counteracted by the barrel pushing back on the ball with equal and opposite pressure. at the point the ball leaves the barrel any pressure still escaping the barrel will come into play. The moral of this paragraph is any leakage from the gun, or resistance from ball detents doesn't matter WHEN the ball leaves the barrel at an identical velocity.

What you would need to measure is the pressure of the 'cloud' of air (if any) which may surround or engulf the ball as it is leaving the barrel. If the pressure is unequal then it will be moved slightly perpandicular to its intended axis of travel (left, right, up, down, or a combination of two). Barrel porting is intended to correct this problem so if it still exists with some barrels many will want to know :) You would need a high speed camera and a coloured gas to see this in action. WIth the high speed camera you can measure any distance deviated over time and deduce the undesired (net) force on that particular shot.

**remember force has a direction so the force down range is irelivant since you would be testing at a constant velocity, but you can calculate an average a paintball of a certain type may deviate from this particular down range axis with barrel ABC.

Now....the next thing to watch for is what the combination of the pressure behind the ball combined with barrel resistance have on the structural integrity of the ball :P Basically is the force of friction between the painball and the barrel (different barrels will have diferent coeficients of friction with the ball even when they are the same bore size) so great that the shell gives out a little to dimple the ball which would catch air and put a spin on it once it leaves the barrel? Well this is a whole nother can of worms that I no not even want to contemplate :P


To make a long story short: the pressure on the ball only makes it travel XXXfps since the barrel corrects its path. Only if the ball gets dimpled due to extreme pressure along the way (or the extreme pressure warps the barrel), or the porting of the barrel fails to even out the exaust arround the ball, will pressure have any effect. Either way measuring any of this in the gun its self is irrelevant since we are interested what the ball is doing on the way from our gun to the target and the NET affect of what happens in the gun is observable as soon as the ball leaves the barrel. I think you would be better off with a high speed camera and some measuring sticks.



Oh yeah there is spin too...the ball could come out sith a front, back or side (spiral) spin. If the paitball is simetrical (note I did not say a perfect sphere) this should not happen in barrel, but may be caused by excess venting of air on one side when it leaves the barrel. Again a high speed camera will help you on this. Just count on average what revolutions per second any given barrel gives to a paintball.

[MANN]

I don't know... are you okay with doing that on an xmag? I also thought it would work if you couldn't get the right equipment or something.

And BTW, there's a guy on MCB who made me said valve cap for $15, and finished it in about two days.

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

[Pneumagger]

why the heck does it matter what pressure it takes to fire a ball a certain speed from each barrel :confused:

In the RL, you're just going to slap a barrel on the gun and chrono it to 300 FPS. use 1 kind of paint, use a large sample size of shots to create statistically significant data (and negate ball to ball differences), and have at it.

[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. :tard:

Yeah, you're idea sounds better.