very constant air-possible?

[sharpshooter1286]

i was just thinking of a new concept for a constant air source. what if the back of the tank or cylinder was open and had a vacuum type fan that sucked in air and fed the marker. after the fan it could have various filters and surfaces to purify the air. there could possibly be a small motor powerful enough to give the fan enough juice to keep up with high ROFs. for some reason i think that this is very possible... anyway i was j/w i dont know if this idea has been thought of before or this subject has already been touched upon but i would like to know

[NuthyN]

It would be really noisy, probably heavy as @@@@, most likely really inificient, and you would have to change the filters alot if you could get it to work.


I and I'm sure many others (including yourself) have thought about this quite a bit and as far as I can see it is not feasible.

[Vegeta]

There is no possible way for a fan to compress air into 3000-4500 psi and store it. Won't happen. Air for tanks is usually compressed usign a pump powered by am engine, now a measley fan. What would stop the air from going back out the way it came in also?

Sorry man, it wont happen.


What would be cool.. would be a form of paintball where you ran to a bunker and hooked your gun to a hose with a QD and started shooting, then if you had to move, you ddisconnected it and run to another bunker.. and there would be these 300psi air hoses at each bunker.. free air for everyone... no tanks to carry round...

But then there would be no shooting on the run. unless the hoses stretched.

[JonDaAzn]

*poink* pulls cord
AHHH I CANT SHOOT!!!

[nerobro]

well.. why not a gas powered compressor on gun. combine that with a 13-20ci tank. A pint of fuel, and a .21 engine (those can develop as much as 2 hp...) you could easily run a compressor on gun. The fuel is more commonly available than one might think, and ones tha'tll run on normal pump gas are available. Just the fumes wouldn't be to nice.

I'ts somethign I've been thinking about for a while. Not to seriously though.

A two or three stage pump geared to a small r/c airplane motor might be able to sustain the air necessary to run a paintgun.. nearly continously. if done right a very small motor could keep a 47ci bottle full for the duration of the day at something like sams big game. Given you were willing to deal with a little bit of noise. These engiens can be made quiet..

[aut911]

ok so far nerobro has the best idea but i was thinking of making a quiet compressor and having a small (4 oz) co2 tank for an air chamber to fill to about 400 psi. have a marker that runs on 200 250 and just have the compressor kick on when ever the pressure gets below 250 just another idea.

oh by the way it would be battery powered. Probably a 12 volt lithium ion battery ( very light batteries) so it would be rechargable and light

aut

[nerobro]

You really can't do it with batterys. their energy density is far to low. And then the conversion from electrical to mechanical and then from mecanical to compressed air... well you loose a lot in that too

The idea behind the gas engine is that you could litterally run a 1/4hp engine all day long from a pint of fuel.... It's the whole energy density thing... compressed air is REALLY REALLY powerfull for a given volume.

Hmm.. What does it take to make a compressor piston? I'm sure with proper gearing we could do some pretty nifty little hpa compressors. And you're right, you wouldn't need to hit 3kpsi... 2k would be sufficant, maybed even 1500. (given you might want to feed a mag 900-1100psi) or if our target weren't a mag we could go even lower....

[nerobro]

Now.. who knows about MOVING high pressure seals? say.. 1500psi?

[sharpshooter1286]

you guys kind of get

what i meant was that it wouldnt store air it would just constantly feed the gun. i think it could be done if someone had it hooked up to a battery pack or a motor in their harness and the tank was filled with filters and the fan and stuff

[NatogDarkheart]

Guys, I'd just like to clarify you do not need to get to a pressure of 3-4.5k. A constant supply of air at 650psi will run a 'Mag.

The Mag's internal regulator outputs pressure at about 400psi, and you need to have at least 200 psi more on the other side of the regulator to prevent drop offs in pressure.

-Natog Darkheart

[nerobro]

allow me to put this in perspective. The energy a paintball gun uses to fire a paintball is on the order of the same energy as in a .45 shell. (IIRC....) Another way to put this, is that a small gasoline engine will work it's heart out to put out 1-2cfm at 3000psi.

Keep in mind that your gun can completely use up the 1.5cfm of air in that tank in about a minute and a half.

Now, you're hoping to have an electric motor create the air necessary to recharge the gun in real time..... I don't see that happening. at least not for more than one or two shots. not even with a gasoline engine. to make a motor that would keep up with the gun, without some kind of storage tank, you'd need 2-3 hp motor....

Yaknow, I should go dig up the energy needed to fire a paintball and work backwards from there. Basicly you can't do it beucase the energy demands are so great. Now if you try and fill the tank at a slower rate, say refill the tank in 5-15 mins instead of ~instantly we're getting someplace. The idea would be to have a tank that could get you through a single firefight, or at least last long enoughthat you can go someplace for your tank to recharge....

*has images of sams big game in his head* Scenario players would love a setup like this ;-)

and any filter placed inline would only make the pump have to work harder. So you'd need to live with slightly substandard filtration.

Even if your goal was only 600psi, you'd stll have a heck of a time making the pressure in real time. You'd still need a buffer tank of some sort.

[nerobro]

Safety concerns.....

Gasoline/glow fuel and high pressure air.... *shivers* if that tank wen't we'd almost have a FAE.

and if you are still hooked on batterys ;-) Do a compairson of the energy stored in a compressed air tank, versus the energy in a pound of battersy... it's a depressing comparison.

[sharpshooter1286]

hmmm

maybe if you could have a full tank, then hook something up to you own tank and it could recharge slowly, and it could even be in the back of your harness so you have your own fill station

also would regular air work in the gun or would it not for some reason

[sharpshooter1286]

this would be crazy

i just looked over the whole thread and i think theres enough evidence that it wont happen anytime soon like i think it would

[bjjb99]

Originally posted by nerobro
allow me to put this in perspective. The energy a paintball gun uses to fire a paintball is on the order of the same energy as in a .45 shell. (IIRC....)

I just checked. Winchester makes a full metal jacketed round in .45 ACP. Its muzzle energy is 244 ft-lbs, or 330.8 Joules. Obviously, the cartridge itself must provide greater than this amount of energy to overcome frictional effects in the barrel, efficiencies less than 100%, and so on. Here is the link I used:

http://www.m1911.org/ammo.htm

A 3 gram paintball leaving the barrel at 300 fps has a muzzle energy of around 12.54 Joules (0.5 * m * v^2), less than 4% of the energy from a .45 ACP round. We're dealing with much less energy when it comes to launching paintballs.

Here's my take on the whole compressor idea...

The Mag's dump chamber is approximately 0.55 cubic inches in volume and is pressurized to approximately 400 psi, according to PBJosh in the following discussion thread:

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

Using that as the basis, we can calculate the amount of energy contained in an ideal gas at those conditions. It works out to be around 24.9 Joules.

Suppose you want to fire ten balls a second. You need to deliver at least 24.9 * 10 Joules per second to the dump chamber, i.e. 249 Watts. We are going to lose some efficiency while passing through the regulator, and the compressor itself is not 100% efficient either. Since I can't find compressor efficiency quotes anywhere and I have no idea how to compute efficiency loss through a pressure regulator, I'm going to take the physicist's black box approach and assume an overall efficiency of 50% for the compressor/regulator combination. :)

So now we need at least 500 Watts of power coming off the compressor motor to deliver enough compressed air so we can continuously fire our Mag at 10 balls per second. Our motor has to be at least 2/3 horsepower. Go up to a 3/4 horsepower motor, add a buffer tank between the motor and the regulator, and you should be pretty much in the ballpark for what you need to have "continuous" air till the gasoline runs out. No need to go up to 3000 psi... just start pumping when the buffer tank drops below 650 psi, and stop pumping when it reaches 850 psi. That should keep the Mag's internal regulator reasonably happy.

As for air volume, you'd need 10 * 0.55 cubic inches of air per second at 400 psi to meet the 10 bps fire rate I'm using for this example. This is 0.2 cfm at 400 psi. I don't know whether compressors state their flow rate for the input side or the output side of the compressor, so I'll put both of them down here...

0.2 cfm @ 400 psi output flow rate (or 0.095 cfm @ 850 psi if we're using the buffer tank)
5.5 cfm @ atmospheric pressure input flow rate

So we need a 3/4 hp compressor with an output rating of around 0.1 cfm at 850 psi, a buffer tank that can hold 850 psi air, some means of turning the compressor off and on depending on the pressure in the buffer tank, filters to clean out the junk from the compressed air, and some hoses to connect it all up. This should provide the ability to fire continuously at 10 bps.

That's my best guess. :)

BJJB