What is the VOLUME of air required to go 300 FPS?

[nippinout]

It ain't voodoo.

Let's take a Matrix and a Cocker. Both will shoot a 68ci 3000psi tank until the tank's pressure reaches the gun's firing pressure. Assume each shot is at 300fps with 100% effiency.

Matrix will use 500psi air to fire a paintball. Cocker will use 1000psi air to fire a paintball.

For the Matrix, 5/6 of the tank's potential will be utilized, the cocker will use 2/3 of it's tank.

Matrix tank: 56.667ci 3000psi
energy: 170,000in-lb
paintballs: 1531

Cocker tank: 45.333ci 3000psi
energy: 136,000in-lb
paintballs: 1225

We see that the Matrix will get 306 more shots until tank pressure drops lower than the pressure you want for proper velocity.

This isn't magic/extra-credit/bonus paint nor efficiency. Each paintball is still using 111.005in-lb of energy from the tank.

[cjpaintball]

Hey, I'm definately an automag noob, but hopefully what I say will make some sense.

First of all, as has been said, there is the issue of LX mags only working to ~700psi, whereas a Viking will shoot down to ~150psi fine. In contrast to what other people have been saying about the mag being more efficient until it gets to the point where it can no longer shoot at the full velocity- I'm going to disagree. Lets take a 4300psi fill, the mag will have used 3600psi before it has to stop. The Viking will have used 4150. Lets say that you can coax 1200 shots off the mag on a 68ci tank, and you take a pretty conservative estimate of 1800 shots of the same tank for the Viking. Thats 50% more shots- about 15.3% more of the tank used.

Umm... kinda of a sad question to be asking in the "deep blue" forum but... how is the mag bolt returned? I really can't see any reason on the "shooting" side of the equation that would contribute to poor consistancy.

Oh and to all those people who said that HP was more efficient and that the only reason AGD doesn't make their guns even more HP is because it would be bad for marketing, you don't know what you're talking about. HP or LP, if AGD delivered a gun that outperformed the competition in all the aspects that matter (speed, consistancy, efficiency, size and weight) then people would buy. AGP does well in the "size and weight" category (especially with the ULE stuff) and speed is good, although because AGD hasn't stooped to including boards like WAS that pretty much add in extra shots, people can usually shoot faster on other guns. Consistancy is mediocre (don't know why) and many other high-end guns are considerably more consistant. Efficiency is piss-poor. Mags don't sell for those reasons. Not because "tom kaye hasn't had luck with marketing"

[athomas]

Most of the people here never said the mag was a wonderfully efficient gun. They just said it wasn't terribly bad.

High pressures internally compensate for poor flow. The mag does have poor flow out the bolt. That is the primary cause of the mags efficiency problems. Given two identical setups in the paintball world, the high pressure one will give better efficiency. The useable air supply may not yield as many shots, but the air usage per shot will be better. Many guns cannot use the higher pressure properly. The rams and solenoids cannot act fast enough to regulate the higher flow rate of the higher pressure air.

Consistency is not one of the mags problems if the mag is properly configured. The quality of the built in regulator is very good and if the level 10 is setup properly, you would be amazed by the consistency.

I think that more could be done to the mag to make it better, it just has to be determined as to what that is. Those are the discussions that you are reading about in the deep blue forums here.

[QUINCYMASSGUY]

pressure

OK, on the same topic of air required to go 300fps why don't we discuss the following questions in relation to a Mag and its functionality:

1.) First off, did we ever figure out the chamber volume of a mag? It might be in the multitude of threads we've been working on but I couldn't find it and having it here in this post would be helpful, it is applicable. Also, an add-on to that question is what is the size of the passage that the on/off pin seals? My question on this relates to recharge weight, and why a larger on/off chamber to allow more flow couldn't be an option (not saying a good one, just an option).

2.) Assuming NO oring friction, which is the reason for alot of the variability shot-to-shot and between individual mags, how much of the air in the chamber is used to cycle the bolt, and how much is then needed to fire the ball? I assume a little more than it takes to fire a ball is needed in the chamber to fire properly.

3.) Finally, would an almost weightless bolt be a benefit in a mag setup or does the spring setup require it to have a certain weight? Not sure how many ounces it is now, but what if it weight 1/2 an ounce, would this help it or open it up to problems?

[athomas]

Re: pressure

QUINCYMASSGUY, you always ask the interesting questions. You must sit around all day and just think up these things.


It was mentioned in a past thread that the volume of the front chamber was .55 ci. I'm not sure if this is just the chamber, or if it includes the inside of the powertube as well.

[bjjb99]

Re: pressure

Originally posted by QUINCYMASSGUY

1.) First off, did we ever figure out the chamber volume of a mag? It might be in the multitude of threads we've been working on but I couldn't find it and having it here in this post would be helpful, it is applicable. Also, an add-on to that question is what is the size of the passage that the on/off pin seals? My question on this relates to recharge weight, and why a larger on/off chamber to allow more flow couldn't be an option (not saying a good one, just an option).

Well, I can help with at least part of this. Based on at least one thread buried on this site somewhere, the Mag's dump chamber volume is approximately 0.55 cubic inches.

Do a search for ".55" and you'll come up with a few threads. Here's one... cut-n-paste if it word wraps on you:

http://www.automags.org/forums/showthread.php?threadid=18939&highlight=.55

BJJB

[hitech]

Originally posted by cjpaintball

Originally posted by QUINCYMASSGUY
I think you can't balance out the air to use just enough to fire the ball and reset in time for the next shot, I think more is used to just be safe. Hence, lower efficiency.

Originally posted by hitech
THAT is the main reason for the 'mags "inefficiency" (level 10). It keep dumping air from the air chamber after the paintball is gone. I recently confirmed this with Tom.

The chamber is too big. However, if you decrease the chamber size then you start needing to increase the chamber pressure. That doesn't market well. (Again, confirmed by Tom).

The most efficient way to fire a paintball is with "high" pressure (including the pressure behind the paintball) and as fast as possible. Accelerate the paintball in just a few inches (say three). Tom's research when developing level 10 caused him to believe that the paintball can stand the higher pressure necessary to accelerate the paintball to 300fps in a few inches. Current markers are all in a range of about 40 to 110 psi behind the paintball. Build a marker that can deliver more like 300 psi behind the paintball and you would be amazed at the efficiency. But could you sell that?

I have to credit Tom for some of this. I did come to some of the conclusions on my own, but not all of them.

[QUINCYMASSGUY]

athomas

Thanks athomas, I enjoy exploring the technical side of paintball. Who knows, maybe a solid idea will come eventually. I have something I am playing around with right now but don't have the funds or faith in my numbers to fabricate a prototype. I think discussing stuff like this with so many minds involved (Pbjosh, the electrician, and Hitech being three people I have alot of respect for as well as yourself) could easily lead to new innovations and improvements on prior designs. Understanding prior technology paves the path to new technology. No innovator is immortal, Tom is a legend who helped revolutionize the paintball hardware, as is Budd Orr, but there is always room for new minds that may be able to push the boundaries further. Goofy contraptions like pball mortar launchers never interested me, but exploring paths to improved performance is what I love.

And thank you for the chamber figure, I am usually good about searches but having a little help is nice. I am definitely going to look into the power tube/chamber relationship, mainly involving the benefits of its shape (thin tube, thick chamber) and, if the devolumizer idea had any merits, if it would be better to have a shorter, stubby chamber so the distance between the power tube and back of valve is reduced, or if thinning the sides would be better. I presume stockier is better, better for flow. Not sure. I shall explore. bjjb99, thank you for the link and welcome to the discussion

[nippinout]

Mag inefficiency is from the bolt not returning fast enough.

The Matrix had a problem with efficiency with bolt's forward pulse times being too long.

Ball is out of the barrel in about 3ms. You need to shut the airflow off before the ball exits the barrel, or you're just dumping air to atmosphere.

[cjpaintball]

I personally would enjoy seeing some theoretical math. I mean, I would like to see some math citing the specific number of shots you could get off, say, a 68ci 4500psi tank if everything was perfect. Use the math to find the amount of energy represented in such a tank and the amount of energy per shot required to launch an object the mass and size of a paintball to 300fps.

Then the person (who is obviously good at physics) could go on with a second example, this time factoring in reasonable estimations of what friction and other effects can do to decrease this number. Considering that there are currently guns that get 2000 shots off of this specific sized tank, I would not be surprised if 3000 was theoretically possible and if maybe 2400 or more was actually attainable.

[nippinout]

Originally posted by cjpaintball
I personally would enjoy seeing some theoretical math. I mean, I would like to see some math citing the specific number of shots you could get off, say, a 68ci 4500psi tank if everything was perfect. Use the math to find the amount of energy represented in such a tank and the amount of energy per shot required to launch an object the mass and size of a paintball to 300fps.

Then the person (who is obviously good at physics) could go on with a second example, this time factoring in reasonable estimations of what friction and other effects can do to decrease this number. Considering that there are currently guns that get 2000 shots off of this specific sized tank, I would not be surprised if 3000 was theoretically possible and if maybe 2400 or more was actually attainable.

Read through the thread... You'll find the calculations for 100% efficiency energy conversion for a tank's potential to number of paintballs at 300fps.

Here's the quick and dirty:

Assume:
3gram paintball
300fps velocity

Units:
3gram = .003kg
300ft = 91.44m
1 joule = 8.8507457 inch pound

Paintball kinetic energy:
= .5 * (.003kg) * (91.44m/s)^2
= 12.542J
= 111.005in-lb

A 68ci 4500psi tank has the potential for 2756 shots.

Efficiency isn't going to get a real boost by minimizing friction, e&m attraction/repulsion, drag...etc.

[bjjb99]

Re: athomas

Originally posted by QUINCYMASSGUY
And thank you for the chamber figure, I am usually good about searches but having a little help is nice. I am definitely going to look into the power tube/chamber relationship, mainly involving the benefits of its shape (thin tube, thick chamber) and, if the devolumizer idea had any merits, if it would be better to have a shorter, stubby chamber so the distance between the power tube and back of valve is reduced, or if thinning the sides would be better. I presume stockier is better, better for flow. Not sure. I shall explore. bjjb99, thank you for the link and welcome to the discussion

I was thinking the exact opposite of you on this subject. Wouldn't a dump chamber measuring the same diameter as its exit port would be "better" than a shorter, larger diameter chamber because the expanding gas doesn't have to turn a corner on its way out? Energy is frequently lost when gases go around corners.

If your chamber gets too long and thin, then I'd imagine you start getting into a highly restricted flow regime and you start losing efficiency because you can't deliver the gas as a single step-function "pulse" anymore.

BJJB

[cjpaintball]

^^^^^
IRT Nippinout-
so barrel length has nothing to do with efficiency?

I remember reading something by Tom Kaye that said that the most efficient barrels go 10 to 12" before any kind of porting or even increase in bore- wouldn't this mean that efficiency might be relative to what distance the paintball has in order to reach 300fps? For example, I'd think that less energey would be required to propel a paintball to 300fps over the course of 10" than would be required to repel a paintball to the same speed in 1". Did your calculations have some relation to accelleration distance that I did not catch? Sorry, I'm not good at physics.

[QUINCYMASSGUY]

ok, next two questions

OK, next two questions related to chambers:

What is the volume of the BACK chamber on the other side of the on/off? Is there a specific ratio of volumes between the front and the back needed for recharge?

how quickly does the front one vent, and what ways would improve the rate of it venting?